关键词: 气动噪声, 标度律, 流体压力, 声学压力

Abstract: When vehicles are driving at high speed, aerodynamic noise is an important noise source affecting in-car comfort, while unsteady flow around vehicle body is an important factor, generating aerodynamic noise. On the one hand, hydrodynamic pressure generated by unsteady flow directly acts on the outer surfaces of vehicle body, which excites the vibrations of window glasses and radiates noise into the interior of vehicle. On the other hand, the unsteady flow itself generates aerodynamic noise, and acoustic pressure directly transmits noise into the interior of vehicle through window glasses and body panels. In this paper, a concept of scaling law is put forward to describe and distinguish the changing law of hydrodynamic pressure and acoustic pressure around vehicle body with vehicle speed and a scaling law analysis on wind tunnel test results is performed. The results show that under given conditions, aerodynamic noise is dominated by dipole source, the amplitude of acoustic pressure in the car and far field is proportional to the 3rd power of velocity, and frequency is independent of velocity; The magnitude of hydrodynamic pressure on front side window is proportional to the 1.5th power of velocity and frequency is proportional to velocity.

Key words: aerodynamic noise, scaling law, hydrodynamic pressure, acoustic pressure