Advanced Rotor Blade Design

Helicopters are complex, unique machines that serve many roles in the modern world and are present in the military, civilian, medicine and fire-fighting duties. Improvements in the aerodynamic design of the helicopter, main rotor blade in particular, can lead to reduced fuel burn and flight envelope expansion.  The variety of designs used in industry shows that the exact optimum rotor design is still unknown. The multi-disciplinarity of rotor blade design poses a significant challenge, as aspects such as aerodynamics, dynamics, vibration, acoustics, aeroelasticity and structural design must all be considered.

Method:

The Reynolds-Averaged-Navier-Stokes (RANS) approach is used to model the flow field around the rotor. Assumptions made by many comprehensive rotor codes based on blade element momentum theory and two-dimensional aerodynamics are not sufficient for advanced rotor blade design. These methods do not capture highly three-dimensional phenomena such as tip vortex formation and roll-up which can have a large impact on the rotor blade loading, and hence, performance. Due to fast turn-around times, low fidelity methods are still widely used in industry for rotor blade design.  The cost of time-accurate CFD simulations is very high, and hence other means of reducing computational costs will be utilised within this work such as the use of steady state hover formulation and frequency domain method. Aeroelastic effects will be captured by interfacing NASTRAN with the HMB3 CFD solver.

Results:

The first part of the work focused on assessing the CFD method for rotor blade performance predictions in hover and forward flight. Validation studies were performed for both advanced and more conventional rotor blade planforms. Most experimental studies, however, only report integrated loads, showing the requirement for a more comprehensive experimental data set for in-depth CFD validation.

Hover Performance predictions for the Langley BERP and Baseline rotor blades and comparison with experimental data.

Current Work:

Multi-Objective, multi-Point optimisation of a rotor blade with a arbitrary planform shape across the flight envelope will be perfomed using a coupled adjoint and harmonic balance method. This solution methodology leads to reduced computational costs, and an optimisation technique which can deal with a large number of design parameters. The final phase of the project will focus on appyling active twist and aeroelastic coupling to the optimised planform in search of even high performance benefits.

Contact:

Prof. George Barakos - George.Barakos@glasgow.ac.uk

Thomas Fitzgibbon (PhD student) - t.fitzgibbon.1@research.gla.ac.uk

Publications:

Fitzgibbon, T., Jimenez-Garcia, A., Woodgate, M. and Barakos G., " Numerical Simulation of Different Rotor Designs in Hover and Forward Flight," 44th European Rotorcraft Forum, Delft, 2018.

Fitzgibbon, T., Jimenez-Garcia, A., Woodgate, M. and Barakos G., " Numerical Simulation of Various Rotor Designs in Hover and Forward Flight,"  56th Aerospace Sciences Meeting, AIAA, SciTech, San Diego, 2019

References:

[1] Yeager Jr, W., Noonan, K., Singleton, J., Wilbur, M., and Mirick, P., "Performance and Vibratory Loads Data From a Wind-Tunnel Test of a Model Helicopter Main-Rotor Blade With a Paddle-Type Tip," Tech. rep., 1997, NASA-TM-4754.