Dr Kiran Ramesh
- Senior Lecturer (Aerospace Sciences)
I received my BTech in Instrumentation and Control Engineering from the National Institute of Technology (Trichy), India, and my MS and PhD degrees in Aerospace Engineering from North Carolina State University, USA. I worked a brief stint as a postdoctoral researcher at NCSU before joining Glasgow University as a Lecturer in Aerospace Engineering, in November 2014.
- Unsteady Aerodynamics
- Vortex particle methods
- Low/medium fidelity methods for engineering applications
- High fidelity methods to study turbulence and transition
- Flapping flight
- Bio-inspiration from insect-flight aerodynamics
- Dynamics, stability and control of flapping flyers
- Dynamic stall
- Performance enhancement of wind turbines and rotorcraft
- Fluid Structure interaction
- Small-scale power harvesting devices based on aeroelastic oscillations
- Aerodynamics of futuristic flexible aircraft and High-Altitute-Lon-Endurance (HALE) aircraft
Students interested in pursuing a PhD in the above or related areas, please contact me.
Development of a Fast Computational Tool for Highly Flexible Flight Dynamics
Funder : Newton Fund, under the Newton Research Collaboration Programme
Collaborators: Prof. Flávio Silvestre (Laboratory of New Concepts in Aeronautics (LNCA), Instituto Technológico de Aeronáutica (ITA), Brazil)
Investigation of Flapping Wings as a Means of Hydroelectric Power Generation
Funder : Carnegie Trust, under Carnegie Collaborative Research Grant
Collaborators: Dr. Ignazio Maria Viola, Fluid Dynamics Research Lab, Institute for Energy Systems, University of Edinburgh
Dr. Shaun Killen, Fish Lab, Institute of Biodiversity, Animal Health and Comparitive Medicine, University of Glasgow
People : Enhao Wang (research assistant)
Design Testing of the Hydrobox Energy Converter
Funder : Scottish Funding Council (SFC) and EPSRC-IAA
Collaborators: Scotstream Generation Ltd.
People : Wengiang Li (research associate)
Development of the InStream Rotor for Scotstream Ltd.
Funder : Scottish Enterprise (SE)
Collaborators: Scotstream Generation Ltd.
People : Lada Murdoch (research assistant)
UNSflow: A low-order, open-source solver for problems that involve unsteady and nonlinear fluid dynamics
Funder : EPSRC
People : Desanga Fernando (research associate)
Study of vortical structures in 3D unsteady aerodynamics using experiment and simulation
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.
In this project, a discrete-vortex methodology for 3D surfaces will be developed. 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
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 be 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
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.
The project ties in with a recent grant awarded to the PI by the Carnegie Trust, on investigating hydroelectric power generation with flapping wings. The collaborators on this grant who include academics from the Institute of Energy system (University of Edinburgh) and Fish Lab (University of Glasgow) will provide additional guidance to the PhD student. The student will be also have regular interactions with an postdoc working on this topic. It is expected that a collaboration with the Water Engineering Lab at the University of Glasgow for an experimental campaign will be developed during this project
Fast Simulation of Highly Flexible Flight Dynamics
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.
The project is on the same theme as a recent grant awarded to the PI by the Newton Fund, through which a collaboration with the Institute of Aeronautical Technology in Brazil has been established. The student will gain experience in working on a collaborative project, and will be involved in discussions with the team in Brazil. There will also be opportunities for research visits to Brazil, and for working with visiting academics/students.
ENG2084 : Dynamics 2
ENG4023 / ENG5046 : Aeroelasticity
ENG3022 : Dynamics and Control 3