The investigation of blade-vortex interaction noise using computational fluid dynamics

This thesis presents the development and validation of numerical methods for the study of Blade-Vortex Interaction. Aspects addressed in this work include the aerodynamics and aeroacoustics of the interaction between a vortex and an aerofoil. The phenomenon of Blade-Vortex Interaction (BVI) is central to the study of the aerodynamics of rotors as well as to the calculation of the acoustic field radiated by rotor craft. The simulation of BVI is challenging since the solution scheme tends to alter the characteristics of the vortex which must be preserved until the interaction. The basis of the present thesis has been the code developed at the University of Glasgow. Some numerical improvements have been carried out to allow the simulation of BVI. First, the numerical developments concerned the time discretisation with the comparison of two different implicit schemes for their robustness and reliability. The implementation of an implicit unfactored method allowed better results in terms of convergence. Secondly, the Compressible Vorticity Confinement Method (CVCM) has been implemented into the solver to allow the preservation of vortical flows. The CVCM has been tested and validated on a benchmark problem for the case of vortex convection. The use of the CVCM was found to be capable of preserving the vortex characteristics assuming the optimum confinement parameter was chosen for a given grid. Hence the use of the CVCM made the simulation of BVI possible. The capabilities of the CVCM were assessed with the simulation of head-on and miss-distance BVI cases. Results were compared against experimental surface pressure measurements and flow visualisation data. Good agreement was obtained. It appears that the CVCM is useful for preserving the characteristics of vortices on coarse grids. (Abstract shortened by ProQuest.)