PhD Opportunities

PhD Opportunities

Possible research topics to be undertaken in the Aerospace Sciences Division are given below. If you are interested in any of these projects, you should email the prospective academic.

Alternatively, you are welcome to identify a different project topic within any relevant research area by emailing your project proposal to the Head of Division, Prof. Konstantinos Kontis, who will direct you towards a prospective supervisor with expertise in that area.

Effects on roughness shape and distribution on performance of aero- and hydrofoils

Dr Angela Busse and Dr Marco Vezza

Description


Due to their exposure to harsh environments, wind and marine turbines suffer from pitting and fouling during their service resulting in the formation roughness on the turbine blades. Once the surface roughness exceeds the hydraulically smooth limit, it will affect the boundary layer over the surface and result in altered performance of the aero- or hydrofoil, e.g. a reduced lift and an increased drag coefficient. 

However, roughness comes in many different forms, e.g. surface fouling will result in a different topography compared to surface pitting or gouging. In addition, the roughness topography of the turbine blade will evolve as the processes causing the formation of roughness progress in time. Finally, the change in the performance will strongly depend on what part of the blade is most strongly affected by roughness built-up, i.e. the spatial distribution of the roughness.

The aim of this project is to systematically investigate the effect of roughness topography and distribution on the performance of aero- or hydrofoils using RANS and large-eddy simulations. In the first part of the project, the numerical approach will be validated against existing experimental data. In the next stage of the project, numerical simulations will be performed for a wide range of realistic roughness types and for representative aero- and hydrofoil shapes. In the final part of the project, the influence of roughness shape and distribution on the flow over moving aerofoils, e.g. undergoing a pitching motion, will be investigated. The aim is to develop a comprehensive classification of roughness effects on aerofoils, which will help in developing cost-effective maintenance strategies for off-shore wind turbines.


Aerodynamics of road vehicles: flow control and platooning

Dr Angela Busse and Prof Kostas Kontis

Description

Forecasts predict that the individual transport landscape will fundamentally change in the next decades. Conventional, human-driven vehicles with diesel or petrol engines will be replaced by autonomous electric vehicles. For electric cars, optimal aerodynamic efficiency is of high importance to increase range between recharges. Self-driving, autonomous cars will open up new opportunities for cooperation between road vehicles which can also be exploited to improve aerodynamics further, e.g. by forming platoons or road trains.

This project will investigate, both experimentally and numerically, the aerodynamics of road vehicles. The application of passive and active flow control techniques for the optimisation of vehicle aerodynamics will be studied. In addition, the aerodynamics of platoons will be explored.

In this project, both wind-tunnel experiments and numerical simulations will be used to obtain detailed information about the instantaneous flow field around the chassis and in the vehicle wake. State-of-the-art experimental techniques such as high-speed stereo Particle-Image Velocimetry, Laser-Doppler-Anemometry, and Pressure Sensitive Paint will be employed to get detailed, time-resolved information on the flow field. Computational Fluid Dynamics (CFD) simulations using eddy-resolving methods will be validated against experimental data, and then used for exploring the influence of further parameters, such as cross-winds, on both single- and multi-vehicle configurations.


Improvement of wheeled vehicle safety and performance using inverse simulation

Dr Douglas Thomson and Euan McGookin

Description

Wheeled vehicles are used for many different transportation applications e.g. road transportation, off-road travel, mobility.  Each scenario has its own requirements in terms of performance and the specification of the vehicle.  However, all have safety as a main concern and requirement for the operation of these types of vehicle.  In particular road safety has become a focus for government bodies and the automotive industry in an attempt to reduce fatalities. One way of improving safety is through in-vehicle assistance where the driver is provided with assistive cues that direct their driving in a safe manner.  In addition, the operation of the vehicle on rough terrain can be enhanced through assistive control systems that compensate for variations in the ground profile. To implement such assistive technologies there needs to be knowledge of how desired driving trajectories can manifest themselves as inputs to the vehicle.  A novel technique that can generate such a relationship from the dynamics of the vehicle is Inverse Simulation. 

Inverse Simulation is a method by which the control inputs necessary for a given system to respond in a defined manner can be calculated.  The most common area where this method is applied is in the aerospace field where the pilot control inputs necessary for an aircraft to fly a specific manoeuvre can be calculated based on an inverse structuring of an appropriate mathematical model.  Recent work at the University of Glasgow has demonstrated that the mathematical model can be treated as a module of the Inverse Simulation algorithm allowing its use for various dynamic systems.  Inverse Simulation works by taking such a standard mathematical model and solving it in a conventional form over a discrete time step.  It is an iterative process where step changes in the various controls are applied until the predicted response matches the predefined response.   Its value can be as a predictive tool for design or optimisation, or it can be inherent in the basic control system design. 

For wheeled vehicle safety, Inverse Simulation could be used to define an optimum driving corridor that would provide safe and/or efficient utilisation of the vehicle.  This corridor would be a spatial/temporal path for the driver to follow.  The underlying Inverse Simulation would be based on a mathematical model of the vehicle and suspension system dynamics for an estimate of the current driving conditions ahead.  The driver would be instructed on the best way to improve their own driving skills and maximise the performance of the vehicle. 

The aim of this project will be to develop an appropriate mathematical model of wheeled vehicles for different applications (e.g. road driving, off-road and mobility) and apply the techniques of Inverse Simulation to them. The Inverse Simulation will then be used in a number of case studies to demonstrate the capabilities of this method in the design and analysis of systems for wheeled vehicles.  These applications will include driver assistance and automatic control of the vehicles being considered.


Aerodynamics and aeroelasticity of a very flexible kite wing

Prof George Barakos and Dr Rene Steijl

Description

Very flexible wings are currently used for recreational flight (paragliding, parachuting etc.) but have large potential to be used as wind energy harvesters. Tethered flexible wings flying in a loop can deliver enough mechanical power on the ground to drive electric generators.

Within aerodynamics and aeroelasticity, there is very little knowledge on the behaviour of very flexible wings and this knowledge gap is to be addressed with the proposed project via state-of-the-art simulation. The HMB set of tools of Glasgow University is to be used for this purpose and the research will focus on the distribution of the aerodynamic loads on the wing during a wind gust or a rapid manoeuvre where the wing shape changes quickly and the kite efficiency is reduced.

The project requires coupled aerodynamic and structural dynamic calculations and falls within the area of low-speed aeroelasticity. In addition to the simulation data, existing experimental data for a rigid wing at low speed conditions will be used for comparisons.

The project objectives are:

  1. Demonstration of the HMB tool for aeroelastic computations for a very flexible kite
  2. Investigation of the flow field around the kite wing and study of the unsteady aerodynamics of a manoeuvring lifting body
  3. Study of the wing loads during rapid changes of the inflow angle combined with a simple model of the kit flight dynamics
  4. Aeroelastic investigation of the collapse and recovery of the wing shape during rapid inflow changes
  5. Extraction of guidelines for the design of flexible manoeuvring wings

The computations will be performed using local and remote high performance computing clusters and there is close collaboration with an innovative company specialising in the design of wind energy harvesters using flexible wings.

An ideal candidate for this project should have a first degree in Aerospace, Mechanical or Applied Mathematics degree. Knowledge of CFD, Aeroelasticity, computer programming and high performance computing are additional advantages. 


High-fidelity simulations of unsteady flow over rough hydrofoils at low reynolds numbers

Dr Kiran Ramesh and Dr Angela Busse

Description

Unsteady fluid dynamics is ubiquitous in modern aerospace research problems such as aerodynamic optimisation of wind-energy harvesting devices, design of flapping wing fliers, use of flapping foils for bio-inspired propulsion/high-lift, and design of aircraft with flexible wings (such as HALE - High-Altitude Long Endurance, or futuristic aircraft with large aspect ratios). The flow physics in these problems exhibits significant nonlinearities arising from added mass effects, flow separation and vortex shedding. Owing to the already large parameter space in these problems, studies have typically been restricted to conventionally smooth geometries. The effects of surface roughness, which may play a crucial (beneficial/detrimental) role in these applications haven’t received much attention. Some results on unsteady flows past rough surfaces are well known from biological studies. Sharks for example, utilise rough skin to obtain a significant improvement in swimming performance and efficiency. Small longitudinal ridges on rows of scales on fish can reduce shear stress in the boundary by a maximum of 10% compared with the shear stress of a smooth surface. The surface structure of the sword of a swordfish is both rough and porous, and the height of the roughness elements on the tip of the sword is close to the critical value for the induction of a laminar-to-turbulent flow transition at moderate cruising speeds. In this project, we investigate this topic from a fluid dynamics perspective. The effects of various kinds of surface roughness on the unsteady flow behaviour (specifically related to transition, flow separation and vortex shedding) will be systematically investigated. 

 

The activities in this project will comprise the development of a new computational method based on a hybrid Eulerian-Lagrangian method. The unsteady flow will be represented by discrete vortex blobs that satisfy the incompressible Navier-Stokes equations. A grid-based immersed-boundary method will be used to resolve the near-wall flow and to model the effects of porosity/roughness through a penalisation method that acts as a source term for vorticity in the momentum equation. An efficient implementation will be achieved using parallelisation and GPU computations. Owing to the high-fidelity of the method to be developed, simulations will be restricted to low Reynolds number regimes in this project, which encompass many of the biological flows and aerospace applications outlined above.  

 

After development and suitable validation of the computational method, a systematic study will be undertaken to describe the effect of surface roughness and complexity on unsteady flow phenomena in various reduced frequency regimes for the first time. 


Investigation of novel hybrid wind turbine configurations

Dr Kiran Ramesh and Prof George Barakos

Description

Horizontal-axis wind turbine configurations, despite having higher efficiencies than their vertical-axis counterparts, are limited by the aerodynamic torque that they can withstand at high speeds. A novel strategy to improve on their performance would be to couple them with a vertical-axis turbine such that their drivetrains are integrated. Excess torque from the HAWT would then be transferred to the VAWT rotor, thus increasing the rated wind speed for power generation of the whole system. This concept also alleviates the self-starting problem typically encountered by VAWTs.  

In order to systematically investigate the benefits of this proposed hybrid system, a large parametric study encompassing the various HAWT and VAWT design variables will be performed in this project. The interactions between wakes generated by the two rotors are also of academic interest, and will be explored in detail.  

Preliminary studies and the initial sweep of the parameter space will be performed using the in-house low-order UNSflow solver which uses the vortex-blob method to represent the free wake and shed vorticity, and the viscous-inviscid interaction approach to resolve the aerodynamics boundary layers.

High-fidelity studies and state-of-the-art simulations will be performed using the in-house HMB solver on local and remote high performance computing clusters. 


Development of theoretical and low-order numerical methods for unsteady aerodynamic flows

Dr Kiran Ramesh

Description


Unsteady fluid dynamics is ubiquitous in modern aerospace research problems such as aerodynamic optimisation of wind-energy harvesting devices, design of flapping wing fliers, use of flapping foils for propulsion/high-lift, and design of aircraft with flexible wings (such as HALE - High-Altitude Long Endurance, or futuristic aircraft with large aspect ratios). The flow physics in these problems exhibits significant nonlinearities arising from flow separation and vortex shedding which cannot be adequately represented by closed-form theoretical formulations. Though computational fluid dynamics (CFD) and experimental methods have contributed much to the understanding of unsteady flow features, they are unsuitable for use in preliminary design and optimisation because of time and cost considerations. This project aims to develop low-cost, physics-based models for unsteady aerodynamics based on the discrete-vortex method, which will enable fast simulations of medium-fidelity, and provide a simple framework for parametric studies, design optimisation, real-time simulation and interdisciplinary studies (by coupling with other solvers).

The aim of this project is to develop a new class of low-cost solvers (under the UNSflow project on GitHub) that sacrifice an acceptable level of accuracy in fluid simulations for a tremendous speedup in simulation time, while being fully physics-based and retaining the fundamental flow quantities. The guiding philosophy in development of the solver is to retain only the physics which are significant in the flow regimes of specific applications. They are hence not an alternative to high-fidelity CFD and experiments, which will still be needed in the final phases of industrial production, but for fewer ideas/concepts. In effect, this will lead to reduced time and cost in the design cycle, and perhaps even a better solution in the long run, because more exploration of the design space will be possible. The research to be carried out in this project is fundamental in nature and underpins several applied problems. It is intended to derive new theoretical and numerical tools to study general unsteady flows with intermittent flow separation and reattachment.

The modelling methodology in this proposal is unique in that it phenomenologically augments theory with numerical computations to account for departures from the assumptions made in theory. It is hence valid even in complex flow regimes, provides insight into the underlying flow physics, is of low cost and suitable for applied studies. The UNSflow code and flow solvers proposed are inspired by XFOIL, which has performed similar functions for steady aerodynamic flows. 


Optimising active flow control on swept wings using sweeping jet actuators

Dr Rene Steijl and Prof George Barakos

Description

In the area of active flow control for aircraft applications, significant progress has been made in controlling the flow at low to moderate angles of attack at which large-scale flow separation does not occur. Key challenges remain at higher angles of attack, in particular when amount of airflow through the devices needs to be limited for practical reasons. A further complicating factor is that for practical applications such as unmanned aircraft and tail planes of commercial airliners, a large sweep angle is typically used, creating cross-flow instabilities in the boundary layers as well as more complex flow separation patterns as compared to a wing with small sweep angle. 

In this project, the emphasis is on a new type of active-flow control approach using 'sweeping jets'. These are actuators with a relatively small mass flow rate, designed to have a time-periodic angle of the jet emanating from the device. This 'sweeping' motion of the jet transfers momentum to the boundary layer and in a number of experiments this approach has proved effective in delaying stall. At present, the flow physics in the 'sweeping jet' devices is not yet fully understood. 

The proposed project aims to provide a systematic, detailed analysis of the flow field within the actuators, as well as the interaction with the main flow. Of particular interest is a reduction in the required mass flow rate, to be achieved by increasing the jet velocity to high transonic or even supersonic conditions.

Based on the increased understanding of these flows from the detailed analysis, a second step would then be an optimization process using advanced CFD techniques including an adjoint method to create optimized designs for these actuators.

One target applications of this work would be tail planes of airliners, where the flow separation delay to higher angles of attack would enable the use of smaller tail planes with a reduction in aerodynamic drag in cruise flight. A second application would be the stall delay of the highly swept wing of unmanned combat aircraft.

In summary the objectives of the proposed project are to:

1. Identify and understand the main physical processes and parameters in the design of ‘sweeping jet' actuators with supersonic outflow.


Effects on roughness shape and distribution on performance of aerofoils

Dr. Angela Busse and Dr. Marco Vezza

Description

Due to their exposure to harsh environments, wind and marine turbines suffer from pitting and fouling during their service resulting in the formation roughness on the turbine blades. Once the surface roughness exceeds the hydraulically smooth limit, it will affect the boundary layer over the surface and result in altered performance of the aero- or hydrofoil, e.g. a reduced lift and an increased drag coefficient.

However, roughness comes in many different forms, e.g. surface fouling will result in a different topography compared to surface pitting or gouging. In addition, the roughness topography of the turbine blade will evolve as the process causing the formation of roughness progresses in time. Finally, the change in the performance will strongly depend on which part of the blade is most strongly affected by roughness built-up, i.e. the distribution of the roughness.

The aim of this project is to systematically investigate the effect of roughness topography and distribution on the performance of an aero- or hydrofoil using a RANS and large-eddy simulations. In the first part of the project, the numerical approach will be validated against existing experimental data. In the next stage of the project, numerical simulations will be performed for a wide range of realistic roughness types and for representative aero- and hydrofoil shapes. In the final part of the project, the influence of roughness shape and distribution on to flow over moving aerofoils, e.g. undergoing a pitching motion, will be investigated. The aim is to develop a comprehensive classification of roughness effects on aerofoils, which will help in developing cost-effective maintenance strategies for off-shore wind turbines.

 


Effect of turbulent flow structures and river-bed roughness on sediment transport

Dr. Angela Busse and Dr. Manousos Valyrakis

Description

Over 5 million people in the United Kingdom live in regions of elevated risk from extreme hydrologic events such as flooding and storm surges. The December 2015 flooding in North-West England has demonstrated once again the big impact these events have on society. The number of extreme hydrologic events is expected to further increase due to the combined effects of climate change and urbanisation. As weather phenomena intensify, so do the geomorphic processes that are primarily responsible for shaping the Earth’s surface. Such effects can be alleviated by improving the management of rivers and estuaries considering linkages between form and function of the water surface bodies. This however requires a better understanding of the mechanics of sediment transport, so that better numerical tools can be developed to predict these phenomena.
Recent developments have highlighted the role of highly fluctuating turbulent forces on the transport of sediment grains laying on the river bed surface. However, in many established models only a time-averaged representation of the turbulent flow field is considered, failing to take into account the highly intermittent small-scale fluctuations. In addition, the structure of the turbulent flow and the topography of the river bed have a strong influence on sediment transport.

In this project direct numerical simulations will be used to investigate the properties of the instantaneous near-wall turbulent fluctuations in riverbeds and their influence on sediment transport. The numerical results will be compared to experimental measurements and will improve our understanding: a) of flow over different types of bed roughness and b) of flows past flow obstructions of varying structural complexity (e.g. from solid cylinders to flexible-porous vegetation elements).


Development of novel chemical reaction models for hypersonic flows

Dr. Craig White and Dr. Rene Steijl

Description

Vibrational energy, electronic energy, and chemical reactions are an important physical feature of hypersonic flows. The extremely high temperatures found behind shock waves can provide enough energy to activate the vibrational and electronic modes, and allows endothermic reactions, such as dissociation of nitrogen and oxygen, to take place. The level of uncertainty in reaction rates at high temperatures is high because no reliable experimental data is available, but using accepted rates for the occurrence of these reactions is important from an engineering perspective, in order to predict the flow temperature and heat flux to the hypersonic body.

This entirely numerical project will make use of two in-house numerical codes, for both continuum and rarefied gas regimes. A parrticle method will be used for the rarefied conditions at higher altitudes and to inform new models to be implemented in the continuum solver. The continuum solver uses gas-kinetic schemes and is applicable to low levels of rarefaction. Coupling these solvers would be a novel research direction, but some work is first required to bring their physical models into closer alignment.

An anharmonic oscillator model for the vibrational energy states will be implemented in the particle solver for rarefied flows. Such an approach for the vibrational modes will have an influence on the implemented chemical reaction rates. This influence has not previously been documented and will need to be carefully examined. In the foreseen main part of the project, data from the rarefied code’s chemical reactions will be collated and used to propose and implement novel engineering level chemical reaction formulations in the continuum solver that will return results in agreement with the rarefied solver, allowing coupling of the two solvers through a flux and state based scheme.


Aero-elastic tailoring of laminated composite wing-box structures

Dr. Christopher York and Dr. Marco Vezza

Description

This research project will investigate new composite laminate tailoring strategies for improved aero-elastic compliant fixed wing designs. The interaction between the aerodynamic loading and structural response will be investigated using fluid and structural analysis software, for validation against experimental studies; supported by industrial collaborators and recent investments in the wind tunnel facilities at GU.  Laminated composite wing skins possessing mechanical Extension-Shearing coupling properties are known to induce Bending-Twisting coupling at the wing box level as a result of normal aerodynamic forces.  However, the use of thin-ply material technology, required for specimen manufacture at this scale, adds additional design restrictions, particularly in the context of tapering skin thickness, where the desired mechanical properties must be preserved and thermal distortions eliminated.


Design, Simulation & Control of Unconventional UAVs for Novel Commercial Applications

Dr. David Anderson and Dr. Douglas Thomson

Description

Unmanned Aerial Systems (UAS) represent one of the largest growth areas in the aerospace industry worldwide. Current annual budgets for UAS systems exceed $10B per annum and that figure will dramatically increase when civilian airspace is cleared for commercial UAS operation, expected early 2015 in both US and Europe. Therefore significant engineering research effort is being directed at addressing some of the current limitations of UAS systems (as judged from commercial vs. military viewpoints) and exploring new civilian markets that could benefit from UAS technology.

One of the civilian applications of UAS technology already identified is that of remote inspection. In this application, the multirotor is used to position an inspection sensor (usually a small camera mounted on a stabilised platform) to detect any structural fatigue, wear and tear etc. Conventional multirotor configurations are design to fly with only small attitude angles i.e. close to the hover condition. This limits the usefulness of the vehicle for close inspection purposes as many of the surfaces to be inspected may be ‘above’ the rotors, and therefore outside of the field-of-regard of the camera platform.

In this project, a new, agile multirotor configuration using tilting rotor mechanisms will be designed and suitable control strategies researched. Use will be made of two simulation techniques and toolsets developed within the University of Glasgow, a new simulation engine and integrated development environment specifically tailored to conduct research in autonomous systems called MAVERIC (Modelling of Autonomous Vehicle Environments using Robust, Intelligent Computing) and an inverse simulation API implementing techniques such as GENISA (Generic Inverse Simulation Algorithm). Inverse simulation enables an early-stage investigation of operational control strategies for complex nonlinear systems performing tightly-constrained tasks, helicopter nap-of-the-earth flight is a good example. By integrating inverse simulation within MAVERIC, operational vignettes of typical inspection tasks will be simulated (aircraft inspection, power line inspection, wind turbine inspection etc.) and nonlinear controllers then designed to implement these strategies.

 


An Experimental Investigation of Predictive Control Methods in Limiting Atmospheric Turbulence Response in Small and Micro UAVs

Dr. David Anderson and Dr. Richard Green

Description

All flight controllers must be designed to stabilise the aircraft against atmospheric turbulence. Effective controller design becomes more difficult for platforms whose aerodynamic surfaces are lightly loaded – a common situation for small Unmanned Aerial Systems (UAS) – and/or platforms with movable lifting surfaces such as the quadrotor, coaxial helicopter, ornithopter (flapping wing) etc. As the principal operational function of most UAS is airborne surveillance, accurate platform stabilisation is imperative for such systems. Therefore it is essential that accurate, validated models of the effects of atmospheric turbulence on the UAS be available to the flight control systems engineer during the design.

This research project is a continuation of a current investigation into the use of CFD-based simulation methods for predicting the response of small UAVs (quadrotors in this case) to atmospheric gusts typical of those found in an urban environment. Recent outputs from this research have shown that fusing the spatio-temporal turbulence field generated by the CFD models within the MAVERIC simulation environment generates qualitatively correct responses. However, conventional simulation methods alone cannot yield truly accurate models of the combined, interactional aerodynamic effects, for this we need to conduct wind tunnel experiments. Recently, the main wind tunnels in GU have undergone considerable modernisation which now allows experimental investigation of this type to be performed. However, to accurately quantify the response characteristics of small UAVs operating within low Reynolds number environments, an appropriate method for accurately generating statistically relevant turbulence within the wind tunnel will have to be determined and constructed. The turbulence field will be measured and tracked using PIV equipment and the UAV response measured using the balance. Assuming a safe operation mode can be determined, free-flight of the UAV will also be conducted inside the tunnel using motion capture cameras from the MAST lab.

The second phase of research will be to use the experimental data to populate models to assist in the design and analysis of nonlinear predictive controllers for optimal alleviation of atmospheric turbulence. The turbulence models will provide usable feedforward information to improve the efficacy of the predictive flight controllers. It is also hoped that the experiments will provide a database of sufficient scope to be able to ascertain if Kolmolgorov’s turbulence model of atmospheric turbulence is valid for small/micro UAV systems and if not, to propose a new turbulence model for these platforms.


An inverse simulation study of tilt-rotors for handling qualities assessment (Funded)

Dr. Douglas Thomson

Description

To improve mission effectiveness for future rotorcraft, higher cruise speeds will be required however the ability to take-off vertically and to hover are still essential.  The next generation of rotorcraft are likely to be of a more advanced configuration than the current fleet and may include compound configurations and tilt rotor aircraft. 

The aim of this research will be to use conventional and inverse simulation techniques to investigate the performance, stability and handling qualities characteristics of the tilt-rotor configuration.  An inverse simulation approach will be used as this allows the vehicle’s states and controls to be calculated using a mathematical model of a manoeuvre as the input.  This information can be used to assess just how viable a particular manoeuvre is for the simulated vehicle to fly (within se performance parameters).  This gives the basis of a method of designing appropriate MTEs for testing titl-rotors.  The objectives which will have to be met in order to achieve this aim include the modification of an existing simulation to represent a tilt rotor, an assessment of tilt rotor dynamic stability, development of appropriate MTE models, calculation of predicted HQ Ratings.

DSTL have an interest in this type of vehicle as it is possible that the future replacement of the current U.K. fleet of military helicopters may be (at least in part) include tilt rotor aircraft.  Further, Agusta-Westland (AW), the Anglo-Italian helicopter manufacturer is involved in the development of a civil tilt-rotor aircraft at its U.K. facility in Yeovil.  This PhD project will help to expand and develop the portfolio of projects being undertaken by the Aerospace Science Division’s Defence Modelling & Simulation Group.  The work of this group is under consideration as a possible future Impact Case Study.


An Assessment of Airborne Wind Energy Concepts

Dr. Douglas Thomson and Dr. David Anderson

Description

Airborne Wind Energy (AWE) is the concept of harnessing the energy in the winds external to the earth's boundary layer (~1km), potentially even those at jetstream altitudes (8-12km). These winds are faster, cleaner and typically much more consistent than winds currently driving conventional wind turbines.  As the relationship between wind speed and power generated follows a cubic law, harnessing the higher speed and more consistent winds at altitude offers much better energy recovery than ground (or offshore) based turbines.  Of course the infrastructure required to harvest this energy is not simple, and a number of concepts have been proposed including tethered kites, generators kept aloft using either autorotating rotors or lighter than air vehicles (airships).  These concepts are very much in their infancy with several small scale, proof of concept systems already in operation, and providing very promising results.  Before developers can move on to systems which are of a scale large enough to be of practical use, it is essential that mathematical models be developed of these systems capable of making reliable assessments of the practicality of the proposed systems.

The aim of this research will be to assess the various proposed concepts both in terms of their technical viability, and their potential deployment in Scotland.  This will require the development a range of mathematical models of the most likely systems.  Both complex and conceptual models will be required – the conceptual models can be used in understanding the basic capability of the system, and estimating its potential energy output, whilst the complex models will be used to look the likely technical difficulties such as flight control of these vehicles.


Design Optimisation for Future Rotorcraft Configurations

Dr. Douglas Thomson and Dr. David Anderson

Description

The designers of the next generation of rotorcraft will have three critical factors to take into account.  Firstly environmental impact – this includes the need to develop rotorcraft which are more energy efficient and quieter.  Also, improved performance will be required – higher top speed, better manoeuvrability and improved mission effectiveness.  Finally, future rotorcraft will increasingly have multi-role capability – it is likely that operators (military and civilian) will require future aircraft to satisfy a number of roles or missions.  To meet these requirements a range of potential configuration options are available to the designer – compound helicopters, tiltrotor, autogyro, and hybrids.  Each vehicle type has it’s own benefits and characteristics as well as technical challenges.  Further, even once the configuration is selected, and design completed, there is the issue of the influence of the control system design on the handling qualities and therefore mission effectiveness of the vehicle. 

This project will involve creating a series of mathematical models of potential future rotorcraft configurations, then developing a set of test missions to assess them using inverse simulation.  This is a technique whereby the input to the mathematical model is the required response (the manoeuvre) and the output is the vehicle response and control displacements.  This offers the opportunity to compare and assess different configurations flying the same test missions.  Metrics will be developed based on the output from the inverse simulation (for example attitude excursions or control activity required to complete the mission).  The mathematical models will be generic in structure allowing design optimisations to take place once the appropriate metrics (cost functions) have been devised.  The aim of the research will be to identify which configurations give the best overall performance in specific mission profiles.


Comparison of Biologically Inspired Propulsion and Navigation Systems for AUVs based on Fish and Aquatic Mammals

Dr. Euan McGookin

Description

The utilisation of Autonomous Underwater Vehicles (AUVs) has increased dramatically over the last decade and given rise to an associated multi-million pound industry. Initially this was due to the increase in oil exploration and extraction, which have come with the need to dive deeper in the world’s oceans in order to exploit reserves.  As a consequence AUVs have been deployed in deep water areas that are potentially hazardous to human divers. Their crucial functions within the underwater arena have made them invaluable for all underwater applications e.g. subsea survey, pipeline monitoring, pollution detection.

The operation of these vehicles has one main limiting factor: the lifespan of the on board power supply. With conventional AUV designs, propulsion is provided through the propeller based systems. This type of system draws large amounts of power from the battery during operation and the power drain is more severe during low speed manoeuvres where the motor is over used to maintain incremental motions. Consequently the power supply becomes depleted very quickly and the operational capability of the vehicle is greatly impaired. 

One approach to improve the propulsion efficiency of AUVs is to mimic the biological propulsion techniques exhibited by aquatic creatures i.e. tail based swimming. Instead of propeller systems, the AUV would have a biologically inspired or biomimetic propulsion system similar to a fish or aquatic mammal. Such a system would provide the required undulation to generate the unsteady vortex flow field along the body of the vehicle, which in turn produces the propulsive force for manoeuvring the vehicle. This approach has potential benefits over conventional methods including greater propulsive efficiency and increased manoeuvrability thus allowing increased mission duration and operational longevity. Also a biomimetic propulsion system would allow the AUV to operate within areas containing dense marine flora without becoming entangled. Further, the undulation of the tail will not disturb the water and river/sea bed as violently as a rotating propeller. This enables Biomimetic AUVs to operate without disturbing their swimming environment unnecessarily.

Obviously the physical characteristics of the AUV determine its functional capability and the environment it can operate within.  In this project the design of the biomimetic systems shall be based on horizontal fish tail undulation and vertical mammalian propulsion.  The design of both these types of system shall be the focus of this study, where the system will be developed and performance analysed through simulation.


Development of a Biomimetic Planetary Rover

Dr. Euan McGookin and Dr. Matteo Ceriotti

Description

Rovers have been used extensively for the exploration of planets, moons and other celestial bodies. Furthermore, recent scientific discoveries have sparked interest in exploring other planets’ moons such as Saturn’s Titan and Jupiter’s Europa. Naturally the diverse range of environmental conditions that could be encountered during exploration may not be suitable for existing rover systems.

Conventional rover designs have been wheel based for operations on firm ground surfaces and have proved successful in the exploration in this type of environment e.g. Mars. However, these types of rovers are not suitable for more fluidic environments where operation would be within dense gaseous or liquid atmospheres. In such scenarios the rover should have the capability to manoeuvre effectively within such atmospheric media and its design must reflect these operational requirements.

One suitable approach is to base the design of the rover on biological entities that live in similar environments on Earth e.g. fish and aquatic mammals. This would involve the development of a robotic system that was able to replicate the swimming gate of the particular biological species under consideration. In addition, an American university has recently proven that shape-morphing vehicles can be used as means to move both in the air and in the water, adapting to two fluids of very different density.  This approach could be used to morph the rover so that its swimming characteristics adapt to the operational environment.  

This proposed research project will involve the design and analysis of a biologically inspired or biomimetic rover concept, for example based on fish swimming, particularly anguilliform (eels) and sub-carangiform (salmonid). Such robotic systems should be highly robust and capable of adapting to a range of environmental conditions and properties, such as fluid composition, density, and temperature, as these not accurately known beforehand. This is typical of an unknown environment such as an unexplored area of a planet or moon.

Design considerations will include types of environments, materials, propulsion mechanisms, efficiencies and power requirements. These will be evaluated through simulations in MATLAB that have been validated against previous studies involving biomimetic autonomous underwater vehicles. Additional research will optimise the caudal motion to maximise its efficiency and minimise the reactions on the body. Proposed case-studies will involve the exploration of the atmosphere of Europa and Titan.


Fault Tolerant Guidance of Planetary Rovers Using Inverse Simulation

Dr. Euan McGookin and Dr. Douglas Thomson

Description

Rover systems have been increasingly used for planetary exploration over the last decade with particular success in the missions to Mars. Conventional operation of such planetary rovers has been based on remote guidance. However, future rovers are likely to have more autonomous functionality to improve mission effectiveness and minimise operational reliance on commands from Earth.

Although increasing the autonomy of the planetary rovers would improve operational capability, it does raise concerns about reliability. Therefore, the rover systems have to be designed to be fault free throughout their entire lifespan, which is impossible to achieve.  Alternatively they could be designed to be fault tolerant through health monitoring and appropriate fault recovery strategies. 

The fundamental process of health monitoring involves the detection and isolation of faults. For the autonomous operation of rovers the most important systems are the sensors and the actuators. If any of these crucial systems develop faults the rover would no longer operate correctly. To detect these faults the actual state of the rover is compared with an estimate provided by a suitable mathematical model. If the resulting residual exceeds specified thresholds then a fault is detected. Although this mechanism detects faults, it is difficult to ascertain which particular system is faulty due to the coupled dynamics of the rover. 

The process of automating the recovery of acceptable operation is susceptible to similar ambiguity. If the source of a fault cannot be isolated then it is difficult to determine an appropriate course of action that will compensate for the fault and ensure continued operation of the rover.

Existing methods used to overcome these hurdles require considerable amounts of historical data in order to generate relationships between observed symptoms and associated faults. Unfortunately in the case of planetary rovers the availability of such data is limited. Therefore, these classification methods for symptom/fault mapping would not be effective.

This project proposes that a novel alternative is to use Inverse Simulation to make autonomous rovers fault tolerant. Inverse Simulation uses mathematical models to determine the required inputs to generate predetermined output trajectories. In the context of fault tolerance, Inverse Simulation can be used to detect and isolate faults in sensors and actuators. Also, Inverse Simulation can be used in the recovery process once a fault has been detected. The utilisation of Inverse Simulation in both ways would allow the rover to continue to operate and thus complete its mission.


Improvement of Automotive Safety and Performance Using Inverse Simulation

Dr. Euan McGookin and Dr. Douglas Thomson

Description

Road safety has become a focus for government bodies and the automotive industry in an attempt to reduce fatalities. One way of improving road safety is through in-vehicle training or assistance where the driver is provided with assistive cues that direct their driving in a safe manner.  To implement such assistive technologies there needs to be knowledge of how desired driving trajectories can manifest themselves as inputs to the car.  A novel technique that can generate such a relationship from the dynamics of the vehicle is Inverse Simulation

Inverse Simulation is a method by which the control inputs necessary for a given system to respond in a defined manner can be calculated.  The most common area where this method is applied is in the aerospace field where the pilot control inputs necessary for an aircraft to fly a specific manoeuvre can be calculated based on an inverse structuring of an appropriate mathematical model.  Recent work at the University of Glasgow has demonstrated that the mathematical model can be treated as a module of the Inverse Simulation algorithm allowing its use for various dynamic systems.  Inverse Simulation works by taking such a standard mathematical model and solving it in a conventional form over a discrete time step.  It is an iterative process where step changes in the various controls are applied until the predicted response matches the predefined response.   Its value can be as a predictive tool for design or optimisation, or it can be inherent in the basic control system design. 

For road safety, Inverse Simulation could be used to define an optimum driving corridor that would provide safe and/or efficient utilisation of the vehicle.  This corridor would be a spatial/temporal path for the driver to follow.  The underlying Inverse Simulation would be based on a mathematical model of the vehicle and suspension system dynamics for an estimate of the current road conditions ahead.  The driver would be instructed on the best way to improve their own driving skills and maximise the performance of the car.

The aim of this project will be to develop an appropriate mathematical model of a road vehicle and apply the techniques of Inverse Simulation to it.  The Inverse Simulation will then be used in a number of case studies to demonstrate the capabilities of this method in the design and analysis of systems for road vehicles.  These will include driver assistance systems.


Ice-prediction simulation method for rotary wings

Prof. George N. Barakos and Dr. Rene Steijl

Description

The formation of ice on rotary wings (helicopter, wind turbine, propeller blades) is a complex problem that has so far been addressed by a very small number of researchers. Taking helicopters as an example, all-weather operation is necessary and icing on the blades can reduce their usefulness for performing vital operations of search and rescue. Much the same way, the installation of wind turbines off-shore, on floating platforms leads to the need for ice protection.  Ice protection is a much wider topic that anti-icing with the later including only the use of systems designed to remove ice once formed via electric hearing or via pneumatic boots near the leading edge of the wings.

The project takes a different approach to this problem and aims to develop design features on the blades that can reduce the formation of ice using passive designs that limit the amount of water in the proximity of the blade surface.

The first step (i) of the project is the development of an icing method capable to resolve complex icing cases within the Helicopter Multi-Block 3 solver of Glasgow. The method development in itself has 3 steps. The first step (i.1) is the addition of water vapour model that is based on transport equations. The second step (i.2) is a thermodynamic model of water condensation. This is combined with a water impact model that will deliver the exact amount droplets impacting a blade at every instance in time during flight. The last step (i.3) is a mesh deformation method that allows complex shapes to be accounted for. This last method is built on adaptive, immersed boundary algorithms that already exist in the flow solver but are only used for improving the prediction of flows. Making the ice prediction method available will provide a tool to engineers that can be used at design stage alongside the blade shape optimisation method. The second step (ii) is the exploitation of the method for computations at icing conditions using an advanced blade planform as the starting point. The ultimate goal is to improve the icing characteristics of the blade without severe penalties in the blade performance. The exercise will be repeated for a wind turbine blade of a large (10MW) machine.


Dynamics of Solar Power Satellites

Dr. Gianmarco Radice

Description

This project will develop and in-depth analysis and modelling of the long term attitude, rotational and orbital dynamics of large space structures, specifically solar power satellites, located in planet-synchronous orbits. In particular the focus will be on structures located in the Laplace Plane orbits.  A gravity gradient stabilised orbit approach will be used initially as this allows extremely large  structures to be built at synchronous altitude with basically no orbit-attitude control required. The system will be modelled as a non-point mass-spring-damper subject to perturbation forces and torques from gravity due to a central attracting body and other disturbance torques such as those originating from the offset between the centre-of-pressure of incoming sunlight and the centre-of-mass of the solar power satellite. The transmission of the microwave beam to the Earth's surface may also induce a torque depending on the geometry of the SPS.

Following on from this, we will develop optimal control laws for different SPS designs. For which comprehensive attitude stability analysis will be carried out for selected designs. The equations of motion of the spring-damper model will be linearised so that stability conditions can be derived.

For a more complete understanding of the dynamics of SPS systems, and for detailed stability analysis ithe orbit perturbation equations have be incorporated into an energy-dissipation model to assess the full dynamics of SPS systems. The full orbit-attitude dynamics model will allow for the most appropriate orbit and attitude cofigurations to be identified for candidate SPS designs. The solar radiation pressure gradient torque, caused when the SPS passes into penumbra/umbra and there is uneven distribution of solar, should be investigated for modern SPS designs.

Along with more detailed analysis of the GGSO attitude mode, other possible attitude modes for SPS will be investigated research. The quasi-inertial pointing mode of Elrod and the quasi-sun pointing mode of Sincarsin will be re-examined, with the application to modern SPS designs investigated.


Combined Experimental and Numerical Approach into the Fluid-Structure Interaction of Nature’s Silent Flyer: The Owl

Dr. Hossein Zare-Behtash and Dr. Kiran Ramesh

Description

Owing to their optimised noise suppression mechanism, owls have evolved to become effective night hunters. To understand and hence, apply the science behind this trait, a specialist experimental test rig (from my successful Royal Society proposal) is proposed to replicate and understand the flow physics associated with the motion of their wings. The proposal will explore the combined pitch, plunge, and surge degrees of freedom motion and how the nano-structures on their feathers contributes to their silent flight through passive or active flow control.

The project is comprised of a strong experimental component (supervised by Dr Zare-Behtash) complemented by a reduced order modelling approach (supervised by Dr K Ramesh).


Numerical analysis of advanced hybrid propulsion systems for hypersonic flight

Dr. Ian Taylor

Description

The retirement of the Space Shuttle, now over 5 years ago, has focussed attention on the technological hurdles that must be overcome to sustain future access to space. Major economies must be achieved, and the key is the ability to achieve single-stage to orbit (SSTO) with a re-usable launch vehicle. The realisation of SSTO relies heavily on the development of appropriate advanced propulsion systems. Indeed, the Shuttle failed to live up to economic expectations largely because of the incompatibility of its propulsion system with its intended mode of operation. The outstanding technological problems are huge: SSTO engines need to operate efficiently over the whole flight envelope, from take-off to hypersonic speeds, from continuum-gas conditions near the surface to the rarefied gas conditions at the edge of space.

Recent research activity by Dr Ian Taylor on propulsion systems has been focussed on scramjet engines, firstly using high resolution CFD to model the detailed shock structures at inlet and how they influence combustion, and secondly developing low fidelity, modular engine models to optimise engine performance and configuration. This proposal aims to build on this research by investigating hybrid engines that incorporate various engine architectures each optimised for different aspects of the flight envelope.

Hybrid engines are considered to be the most efficient approach for SSTO propulsion systems, with “conventional” gas turbines used for the low-speed and altitude flight, ramjet/scramjets at high speeds and altitudes, and rockets to extend the flight beyond the atmosphere. The research proposed will undertake a detailed numerical (CFD) investigation of the intake and engine-airframe configuration, assessing the effect on combustion at high speeds and on achieving stable engine operation. There will be a particular emphasis on understanding the transitions between the various engine operation modes, as any associated unsteady effects could strongly affect efficient engine operation. Also, the low fidelity model will be enhanced, with new models of the hybrid engine architecture and extended trajectory analysis to allow optimisation the flight envelope, thus identifying the ideal transition point between engine configurations. In both cases, open-source software, already available to Dr Taylor, will be used to undertake the numerical investigations. The deliverables of the research will be enhanced, state-of-the-art suite of numerical models for advance propulsion systems. Additionally, it will deliver a greater understanding of the physical phenomena associated with these systems to enable future solutions to be developed that bring SSTO closer to reality.

 


Aerodynamics of transport vehicles

Prof. Konstantinos Kontis and Dr. Angela Busse

Description

This project will investigate, both experimentally and numerically, the aerodynamics of road vehicles and rails. Particular focus will be on resolving instantaneous flow field around the chassis and the under-floor flow. This is a challenging project as state-of-the-art modern experimental techniques like high-speed stereo PIV, volumetric PIV, high-speed Background Oriented Schlieren (BOS), Pressure Sensitive Paint (PSP) measurements will be employed so that three-dimensional information of the flow could be obtained. Computational Fluid Dynamics (CFD) will also be used to predict the under-floor flow field as well as for validating the experimental data.

The importance of this project is that currently our understanding on vehicles and train aerodynamics is still remained at the level of time-averaged flow field. Only limited studies have been conducted to resolve the instantaneous flow field around vehicles and rails. The information obtained from the instantaneous flow field is particular important for understanding the flow physics of under-floor flow of road vehicles. It is generally believed that the interactions between the rolling wheels and the chassis create significant amount of noise and drag. The interactions also affect the handling quality of a vehicle.

In addition, the unsteady flow generated by the rolling wheels of a vehicle also affects the stability of vehicles which are riding near a heavy vehicle. Understanding the under-floor flow of a vehicle or a train could improve the vehicle design in order to reduce drag (i.e. reduce fuel consumption) and also could improve the handling quality. This in turn will improve road safety which is beneficial to the public.


High-Speed Aerospace Vehicles

Prof. Konstantinos Kontis

Description

The design and development of high speed transports include a number of challenging phenomena and interactions: transition, SBLI, plumes, high speed intakes and sonic boom. The proposed research will address a combination of these phenomena using a range of wind tunnel facilities, advanced flow diagnostics and modelling/simulation tools. The effects of turbulence, instabilities and contamination will be assessed. Active and passive flow and flight concepts will be tested. The research feeds directly to the development of future aerospace vehicles and transport concepts.


Low-Speed High-Lift Lamda Wings and their Control

Prof. Konstantinos Kontis

Description

The project will involve research to study the fundamental flow physics and aerodynamic effectiveness of novel configurations and platforms using low-speed wind tunnels, and advanced flow diagnostics and instrumentation. The investigation will be supported by numerical simulations and theoretical analysis including multi-disciplinary design optimisation and uncertainty quantification techniques. Advanced flow control devices will be employed. The impact of the research will be on the development novel UAVs, HALE, MALE platforms, and will contribute to the design of the next generation of aircrafts.


Single Stage to Orbit (SSTO) Payload Launcher

Prof. Konstantinos Kontis and Prof. Colin McInnes

Description

Mission and trajectory studies will be performed on a variety of SSTO concepts assessing different launching strategies and engine types. Full modelling and simulation of the launcher will be performed assessing its flying quality characteristics over the entire flight domain. Altitude, Mach number, and angle of attach profiles will be investigated. Advanced optimisation techniques will be utilised, and refinement of available aero-database will be conducted.


Interaction of Engine Exhaust Flows with Surfaces for VSTOL and Space Applications

Prof. Konstantinos Kontis and Dr. Craig White

Description

The global objective of this activity is to investigate engine exhaust flows with surfaces at a fundamental level using computational tools and experimentation. An assessment of the scaling phenomena, ambient, vacuum effects and pulsing of flows will performed on a variety of surfaces. The impact of the research programme will be on the development of VSTOL aircrafts, ascending/descending vehicles etc.


Powered Plasma Manifolds for Intakes, Ducts, Exhausts and External Flows

Prof. Konstantinos Kontis and Dr. Craig White

Description

Advanced DBD (Dielectric Barrier Discharge) and Nanopulse plasma actuators will be developed to provide better control authority for intakes, ducts, mixers, exhausts and external flows for both low and/or high speed applications. This is a joined experimental and computational campaign that will improve the plasma flow coupling performance. It is part of an on-going international collaboration. The expected impact of the proposal is in the following three areas: 

a. Aerodynamic design and performance assessment of vehicles; 

b. Manipulation of noise characteristics and signature;

c. Combustion.


Study of vortex structures in 3D unsteady aerodynamics using experiment and simulation

Dr. Kiran Ramesh and Prof. Konstantinos Kontis

Description

Vortical structures are amongst the most fascinating aspects of unsteady aerodynamics. Leading-edge vortices in dynamic stall (seen on helicopters and wind turbines), result in violent vibrations and mechanical failure. On the other hand, leading-edge vortices (LEVs) have been credited for being solely responsible for high-lift flight in insects and for providing high lift on aircraft employing delta wings.

In both insect flight and on delta wings, a stationary leading-edge vortex on the airfoil is seen. This is very interesting, as in 2D aerodynamics, it can be mathematically shown that a stable LEV cannot exist and that it would tend to convect over the chord. In 3D however, such stationary LEVs are seen, and the conditions under which they exist are not clear. Experiments and CFD methods have shed some light on vortical structures in 3D, but because of time and expense considerations, these methods cannot be used to study the parameter space and identify conditions where such favourable LEVs exist.

Dr. Kiran Ramesh has developed a reduced-order discrete vortex method which models leading-edge vortices, but at the same time is computationally inexpensive. In this project, it is proposed to combine this methodology with a vortex-lattice formulation, so as to extend it to 3D. With the method thus developed, a range of wing kinematics and planform shapes will be studied to analyse unsteady vortical behaviour, and identify conditions where stationary LEVs may exist.

Experimental work will be conducted to support the development of the reduced-order method and for validation, using the University of Glasgow’s subsonic wind tunnel facilities. A range of generic model configurations will be tested using advanced flow diagnostics (Particle Image Velocimetry, Pressure Sensitive Paints, 3D LDA etc) and a 6 component sting balance.


Real-Time Flow Simulation using Hybrid Vortex Methods

Dr. Kiran Ramesh and Prof. George N. Barakos

Description

The advent of fast computers and the need for more realistic flight simulations put new demands on computational aerodynamics for methods that have a good level of fidelity and can run efficiently for large-scale problems. Application examples in include simulations of helicopters landing on ships or aircraft flying in close formation or in the wake of wind turbines. These are large-scale problems where coupling between the wakes generated by rotor or wind turbine blades have to affect and be affected by the flow generated by a building structure or an aeroplane.

In this project, a 3D discrete-vortex model will be developed for full-wake simulations behind arbitrarily shaped bodies. The model will be parallelized to speed up the vortex interactions (N-body problem), and further optimized so as to make it real-time. The solution near the body will be based on the full Navier-Stokes equations to resolve flow separation accurately.  The proposed features of this methodology make it attractive for rotorcraft and wind-turbine applications. The real-time capability will also allow integration with flight simulator and/or control systems. Key steps of the project include:

  • The project will begin by extending to 3D a method that has already been developed by the PI of this project. This is a complex task that will require the involvement of the investigators at least at the early stages of the CFD study.
  • Once this is achieved, parallelization will b.e attempted using techniques similar to what is used in the HMB3 CFD solver of the CI. In is expected that applications for CPU time will be sent to EPSRC and schemes related to software development will be explored to add further support to the project.
  • A separate phase will look at stalled flows and how the method predicts the onset of stall on lifting surfaces as well as massively stalled flows past bluff bodies.
  • The project will proceed with simulations in real-time for flows that are wake-dominated with large areas of flow separation. The flow past a cylinder or a cube will be used for this effect. With confidence on the method established the technique will be used for more realistic problems including the wakes of wind turbines. The results will be compared with benchmark solutions obtained with the HMB3 solver using the ARCHER super-computer as part of a current project of the CI.

Flapping Wings for Underwater Propulsion and Power Generation

Dr. Kiran Ramesh

Description

Fish, cetaceans, birds, and insects are, by engineering standards, astoundingly adept flyers and swimmers. The basic source of locomotion and manoeuvring forces is the oscillating/flapping foil, which can generally undergo simultaneous translation and rotation in two or more degrees of freedom. Under proper conditions, a propulsive oscillating foil reverses the rotational direction in the wake structure so that the vortices induce a velocity in the same direction as the mean flow, creating a jet. In addition to efficient generation of propulsive force, unsteady vortex control creates very high lift coefficients for manoeuvring. For example, tuna, dolphin and shark exhibit excellent hydrodynamic performance with high cruising speed, high efficiency and low noise through the flapping motion of their caudal fins. Moreover, through these oscillatory motions it is possible to extract energy from the incoming vortices or unsteady flows. This has inspired energy-harvesting devices where the oscillating wing extracts energy from the flow field through the principle of hydrodynamic flutter. Water (in the form of tides, oceanic currents and rivers) has the potential to provide up to three terawatts of power globally, with greater reliability in comparison with wind, and with less negative effects on humans and animals.

The efficiencies for both propulsion and power generation using flapping foils are related to the vortical structures formed during the foil oscillation. A deeper understanding of the flow physics including the effects of vortex and wake structures is required to commercially exploit this technology. The aeroelastic effects resulting from interactions between the nonlinear aerodynamics and structural dynamics is also poorly understood.  In this project, the propulsive and power-extraction efficiencies of oscillating foils will be studies using analytical and computational methods. Parameters that affect the flow physics such as wing geometry, wing flexibility, and structural stiffness will be investigated in detail.

Depending on the applicant’s interest and motivation, experiments on the topic can be performed at the Water Engineering Lab in the division of Infrastructure and Environment.


Fast Simulation of Highly Flexible Flight Dynamics

Dr. Kiran Ramesh

Description

The aerospace industry worldwide is seeking to develop “green aircraft” which are cleaner, quieter and more efficient, based on demands for the reduction of fuel burn, emission of pollutants and costs of operation. This has motivated studies into new aircraft designs and configurations by leading aircraft manufacturers such as Airbus, Boeing and Embraer. Most of these futuristic designs involve a higher level of structural flexibility than in conventional aircraft. Even currently, the trends in the aviation industry are to increase wing length (to reduce induced drag) and maximise use of composites, which lead to increased structural flexibility. Flexible aircraft structures result in the aeroelastic behaviour becoming closer in frequency to that of the flight dynamics. Current procedures for flight control laws which are based on decoupling between flight dynamics (rigid-body) and aeroelastic dynamics, are thus not valid for flexible aircraft. A combined formulation of aeroelasticity and flight dynamics, using Computational Fluid Dynamics (CFD) for aerodynamics and Finite Element Method (FEM) for structural dynamics is an expensive problem, requiring several hours of computational time even with High Performance Computing (HPC) resources. This project proposes to develop a low-order model for the combined flight dynamics and aeroelastic simulation of flexible aircraft.

In this project, analytical and numerical methods will be used to develop a fast computation tool for nonlinear wing aeroelasticity. This tool will be capable of modelling any instances of flow separation and vortex shedding on the wing, as well as the structural deformations resulting from the aerodynamics loads, thereby striking a balance between cost and fidelity. After suitable validation against experiments, this model will be used to study specific problems in control and design, such as simulation of the flight vehicle dynamics to design a stability augmentation system, and study of coupled response between large elastic wing deformations and the aircraft body.


Rotor wake in the vicinity of an obstacle

Dr. Richard Green and Dr. Douglas Thomson

Description

Helicopters are versatile aircraft that often operate in challenging environments. Of particular concern is flight near the ground or obstacles, where the rotor aerodynamics can become far more complex than in free air and the pilot workload is higher. There is a clear lack of information available about these types of flows, and unexpected phenomena may occur during practical helicopter operations, which have accounted for the loss of many lives and airframes. Improved designs and operating procedures can only be the result of more information, and the purpose of the project is to investigate the rotor wake aerodynamics when the rotor is close to an obstacle. This shares many of the characteristics of the flow in free air and the flow close to the ground, and the emphasis of the project is to investigate what happens as the rotor clearance from the obstacle changes. One of the uniquely challenging aspects of rotor aerodynamics is that the flight mechanics and aerodynamics are intimately linked, and this is rotor aeromechanics. Thus it is not enough to investigate the flow alone, but to gather data pertaining to the rotor state that can in turn be used for flight simulation and handling qualities assessments. This requires the use of specialist rigs and measurement techniques that can provide a complete picture of the control state of the rotor and the flow field.

The objectives of the project are, through the use of appropriately instrumented rigs and measurement techniques, to perform an investigation of the flow field of the rotor in a variety of rotor/ obstacle configurations, to assess the trim state of the rotor and the control inputs required to achieve trim under these conditions, assess loads exerted on the obstacle by the rotor wake, and relate observations of the flow to the changes of rotor trim state, to anticipate vehicle behaviour in these circumstances. Major achievements will be an improved understanding of the rotor wake in a particularly challenging scenario, information for the rotorcraft operating and simulation community about the controls required, and the generation of a database of flow field measurements to inform the wider rotorcraft community worldwide. This will be a unique experiment of interest to a candidate who wishes to become an expert in the particularly challenging area of rotor aeromechanics, and has a primary interest in experimental techniques.

The successful researcher will publish articles in journals such as Experiments in Fluids, Journal of the American Helicopter Society, AIAA Journal, and is expected to present work at major international conferences in the EU and USA.


Tail rotor blockage effects

Dr. Richard Green and Dr. Douglas Thomson

Description

The performance of a tail rotor of a helicopter is critical to the operation of the flight vehicle. A tail rotor is often mounted in the vicinity of a tail empennage consisting of a fin and horizontal elevator. Rotor performance is well know to be affected by the presence of a surface nearby, and practically all research effort in this respect has been concerned with ground effect, where the helicopter is flying close to the ground. The presence of a tail fin close to a rotor would constitute a partial ground effect, but there are many variables to consider. What is surprising is that there is very little in the literature about the effect of tail rotor blockage on a tail rotor performance, and this research project aims to address this.

Experimental work will be conducted in the deHavilland wind tunnel using rotor systems available. Small fin models will be constructed and instrumented with surface pressure tappings, and rotor system pressures, loads and flow field data will be measured using the instrumentation available with the wind tunnel.   One of the objectives of the project will be to use the data obtained from the wind tunnel tests to improve the tail rotor load predictions used in rotorcraft simulation models.  In many simulations simple correction factors are used to modify the predicted tail rotor loads to account for the proximity of the fin.  To date there has been insufficient experimental data available to refine this approach to take into account different tail rotor positions, fin shapes or separation distances, all of which can affect tailrotor blockage.  One of the anticipated outcomes of this research will be the development of guidelines for more accurate empirical modelling of tailrotor loads.

The successful researcher will publish articles in journals such as Experiments in Fluids, Journal of the American Helicopter Society, AIAA Journal, and is expected to present work at major international conferences in the EU and USA.


Experimental and numerical investigation of waverider vehicles with realistic leading-edge and aerodynamic control surface designs

Dr. Rene Steijl and Prof. Kostas Kontis

Description

The design and development of aircraft capable of flying at hypersonic speeds involves many challenges, including complex aerodynamic phenomena, creating an effective propulsion system as well as managing the thermal environment created at high speeds and the associated challenges to the thermal protection system, structure and materials.

The proposed research considers designs of the wave-rider type, with a shape optimized for efficient cruise flight. The relatively high aerodynamic efficiency of such configurations, however, is achieved using a sharp wing leading edge, which in high-speed flight creates unacceptable heat transfer rates. Also, the ideal wave-rider shape has no provision for engine installation and aerodynamic control surfaces and its aerodynamic stability is typically too marginal for practical use.

In the proposed research, the latest in-house developed Computational Fluid Dynamics methods will be used to create a realistic wave-rider design, with leading-edge bluntness and suitable tail/fin surfaces for enhanced stability at a range of speeds.

Then, the aerodynamics of the wave-rider vehicle at Mach 7 will be investigated in the high-speed wind tunnel at Glasgow University.  Advanced flow diagnostics will be used to analyse the flow in detail, while the loads on the vehicle will also be measured.

The main aims are to assess the aerodynamic performance and stability of the vehicle with the employed leading edge design and aerodynamic control surfaces. The combined experimental and numerical flow field data will provide detailed insight into the controls-surface effectiveness as well as the heat transfer into the vehicle surface. The results will be used to improve stability and control of improved designs. The project will make contributions to making wave-rider derived designs a more realistic prospect for future aircraft and space launch systems.

 


Aero-elastic tailoring of laminated composite blade structures

Dr. Marco Vezza and Dr. Christopher York

Description

This research project will investigate new composite laminate tailoring strategies for improved aero-elastic compliant wind turbine rotor blade design. The interaction between the aerodynamic loading and structural response will be investigated using available fluid and structural analysis software.  Additionally, experimental validation studies are also planned; supported by industrial collaborations and planned investments in the wind tunnel facilities at GU.  Tailored laminate designs possess exotic mechanical coupling properties such as a combination of Extension-Twisting, induced by centrifugal forces, and Extension-Shearing, induced by the normal aerodynamic forces.  Complex mechanical coupling of this form is associated with laminates that warp extensively on cooling, following a high temperature curing process, and therefore tailored solutions, which are immune to this warping behaviour, will be investigated.