Wind Noise Testing at Shanghai Automotive Wind Tunnel Center

Abstract

As wind speed goes up, aerodynamic noise makes more and more contribution to vehicle interior and exterior noise. So it is of great importance to investigate wind noise separately in an exclusive test platform called wind tunnel. But in conventional wind tunnels the isolated representation of aerodynamic noise of vehicles has proven to be difficult or impossible, particularly for aerodynamic exterior noise. Even measurements of aerodynamic interior noise can be severely influenced by the noise generated by the wind tunnel itself. So it is necessary to do the investigation in wind tunnels with low background noise. The full-scale aeroacoustic wind tunnel of Shanghai Automotive Wind Tunnel Center (SAWTC) is such a wind tunnel first of all in China and one of the quietest wind tunnels worldwide. There exist special difficulties for wind noise test when using conventional test techniques due to airflow around measuring object, for example pseudo noise, self-induced noise at the microphones themselves and their supports etc. So there is a need for alternative test techniques. In this chapter, after a brief introduction of aerodynamic noise generation mechanisms, the full-scale aeroacoustic wind tunnel of SAWTC is presented, especially the acoustic measures to achieve very low background noise. Furthermore, some special test techniques for vehicle interior, exterior noise and body surface pressure fluctuations are presented. Sound source localization techniques suited to the full-scale aeroacoustic wind tunnel of SAWTC are also listed both for vehicle interior and for exterior out-of-flow.