A Gas-Kinetic Relaxation Scheme for Fan Broadband Noise Prediction

This SBIR project proposes to investigate the feasibility of using a gas-kinetic relaxation scheme for fan broadband noise prediction. Since fan broadband noises result from the interaction of turbulence with solid surfaces, it is important to resolve turbulent eddies up to a certain scale and further preserve those turbulent eddies shed from the rotor blades at least up to the downstream stator blades in order to achieve an accurate fan broadband noise prediction. Unfortunately, the so-called shock-capturing schemes are found too diffusive to resolve and preserve those turbulent eddies while they are able to handle the shocks better than the central schemes. To take advantage of both central and upwind approaches, this SBIR effort will pursue a gas-kinetic relaxation approach, in which the relaxation parameter is used to minimize the difference between the numerical dissipation inherent in the upwind approach and the subgrid-scale (SGS) model. As a feasibility study, the NASA 22-in fan noise source diagnostic test (SDT) case will be used in Phase I to demonstrate the capability of the proposed methodology for accurate prediction of fan broadband noise. Therefore, it is meaningful to further refine the methodology and develop a computational software tool for commercialization in Phase II.