Keng D. Hseuh
Mike P. Haffey
Vehicle Wind Noise & Road NVH Dept., Core & Adv. Veh. System Eng., MD 45-Adv. Eng. Ctr., Ford Motor Co., 20000 Rotunda Dr., Dearborn, MI 48121-2053
Wind noise is becoming a critical comfort requirement to customers due to greatly reduced powertrain and road noise, particularly at high-speed driving conditions. The physical phenomenon generally can be categorized into: sources (A-pillar vortex and mirror wake) and path (door/window weatherstrip leakage). Two different vehicle greenhouse geometries that produce attached- and vortex-flow, respectively, were used in this A-pillar vortex minimization case study to correlate the CFD predicted A-pillar vortex size and sideglass pressure distribution (Cp) with measurements from wind tunnel testing. A-pillar vortex and pressure distribution have been shown to be key factors affecting wind noise excitation on sideglass and shape-induced aerodynamic suction force on door/window (which is required in designing door/weatherstrip to prevent aspiration leaks through weatherstrip under high-speed condition), respectively. Results demonstrate that the CFD can successfully predict the effects of geometry changes on A-pillar vortex size and Cp within >80% accuracy under various speeds/yaw angles. This study confirms that CFD can be applied with confidence as an upfront engineering tool to optimize vehicle greenhouse geometry for minimum wind noise excitation in a cost and time effective manner.