01-壁面气动噪声的生成.pdf

TECHNICAL NOTES TN167 Aero-Noise Generation on Surface of Solid Bodies Yi Dai Fluent Inc. 10 Cavendish Court, Centerra Resource Park Lebanon, NH 03766-1442, U.S.A. Software: FLUENT October, 2001 1 Introduction Reduction of aero-noise becomes more important task in design of higher speed inter-city train in which aero sound may overwhelm mechenical sound, or in design of comfortbale vehicle with silent enviroment. To understand the level and spectrum of sound generation, and to identify where and what kind of sound is generated can be very helpful for a better design. Compared to acoustic measurement, numerical prediction can provide more detailed in- formation on aero acoustics with shorter time and lower cost. It may be straight forward to get data of sound level and sound spectrum in an acoustic measurement. But it may not be easy to identify the main contribution to the sound from certain location of ?ow ?eld via experiment. It would be more ef?cient to make guidance to a new designe to use numerical aero acoustic prediction approach combined with Computational Fluid Dynamic (CFD). Full numerical simulation of compressible turbulence ?uid dynamics which resolves all length scales and time scales in the ?uid ?ows will certainly provide all information required for acoustic analysis. The requirement for such full numerical simulation is that computation damain should be suf?ciently large to include several wave length of sound with its frequency to be resolved. The sound meassurement point should also be included in the computational domain. High frequency sound is usually generated from ?ne ?ow structure which needs very ?ne mesh to resolve. When ?ne mesh size is used, time step size enable to capture