Investigation of Flow Characteristics and Aerodynamic Noise for an Ahmed Body with Different Rear Slant Angles

Abstract:

The realizable k –ε method was used for steady simulation of external airflow of Ahmed model with different rear slant angles, and the large eddy simulation (LES) method was employed for transient simulation. Based on the pressure and velocity fluctuation distribution, Ahmed body surface pressure fluctuation level distribution and aerodynamic noise characteristics in the far field were studied. Furthermore, the relationship between wind noise radiated in the far field and aerodynamic drag was studied. The results show that there is a significant difference between model rear pressure and velocity fluctuation distribution of Ahmed model at different rear slant angles due to different flow separation pattern, which influences the noise power radiated to the far field and its distribution. Additionally, there exists a certain relationshape between noise power and aerodynamic drag. Therefore, optimizing rear slant angle is very important for rear wind noise control.

Key words:aerodynamic noise; Ahmed model; pressure fluctuation; large eddy simulation