Abstract
The noise generated by the air-conditioning system of new energy sport utility vehicles (SUVs) is a primary sound source that impairs ride comfort. This study addresses the aerodynamic noise issue of the rear air-conditioning system in a new energy SUV under the floor mode. Optimization targets were established through combined experimental measurements and computational fluid dynamics simulations. The blower deflector was slotted on both sides. The air distribution plate was redesigned with an arc-shaped profile to reduce intake pulsation and balance outlet airflow. The floor duct geometry was optimized using a response surface methodology. Key parameters—including the duct inlet-turning radius, clearance groove width, and groove depth—were adjusted to enlarge the inlet cross-section, reduce flow resistance, and lower aerodynamic noise. The experimental results demonstrate that both the blower deflector modification and the duct geometry optimization effectively suppress the peak sound pressure and the low-frequency average sound pressure: the peak sound pressure was reduced by 16.22 dB (blower deflector) and 3.7 dB (duct), while the average sound pressure decreased by 1.8 dB and 3.34 dB, respectively. Finally, the combined optimization of the blower and the duct achieves a 5.79 dB reduction in the rear air-conditioning outlet noise at gear 8. The research provides theoretical and practical guidance for improving the NVH performance of rear air conditioning systems in new-energy SUVs.