A computational fluid dynamics study of crosswind effects on vehicle A-pillar aero-acoustics

Abstract

The surface pressure fluctuations due to the flow separation in the A-pillar region on the front side windows of a passenger car is a dominant source of aerodynamic noise. Aerodynamically generated noise adversely affects vehicle occupant’s comfort and safety (due to fatigue caused by long time noise exposure). The size and magnitude of the A-pillar flow separation mainly depend on the local A-pillar and windshield geometry and yaw angles. The primary objective of this was to develop a computational fluid dynamic (CFD) and computational aero-acoustics (CAA) model to simulate aerodynamic flow and noise generation in the A-pillar region of a simplified 40% scale vehicle with elliptical windshield radius at ±15° yaw angles. Observations made from the CFD and CAA results showed trailing edge and boundary layer noise were generated, caused by turbulent airflow separation behind the A-pillar region. The trailing edge noise was dominant in the leeward region while boundary layer noise was seemed to dominate in the windward region. High sound pressure levels were observed on the vehicle body, close to the noise source, which gradually decreased as the aerodynamic noise propagated further from the vehicle body.