Analysis of the Automobile’s External Aerodynamic Noise Field Characteristics Based on CAA

Abstract

This paper dwelled on the principle of Computational Aero-Acoustics (CAA), and utilized the Boundary Element Method (BEM) combined with the Computational Fluid Dynamics (CFD) based on Lighthill’s analogy to the automobile flow model, and converted the fluctuating flow pressure near the vehicle’s surface into the dipole source boundary condition in acoustics grid, and eventually succeeded in simulating the external aerodynamic noise field of automobile by introducing the dipole source boundary condition into the automobile’s BEM model. The distribution of vehicle’s external aero-acoustics field and the directivity of vehicle’s surface aerodynamic acoustic dipole source were also discussed carefully in this paper. The results show that: The head and tail of car are the main aerodynamic noise source radiation areas, and most of the dipole source’s SPL value is more than 70dB; the variation in car speed greatly impacts on the directivity of aerodynamic noise field near the car’s tail surface (θ=165°~195°).