Automotive HVAC Blower Blade Pass Noise Sensitivity - A Case Study

An automotive Heating Ventilation and Air Conditioning module’s function is to deliver air on demand to maintain passenger comfort inside the vehicle. While doing so, there are multiple active components; a blower to move air, and actuators to move door flaps that direct air to the different areas of the cabin. In common operating conditions, air rush sound is audible. However, there are other sounds whose presence can be perceived as objectionable.  During operating, the blower assembly generates sounds intrinsically linked to its design, e.g. wheel blade pass. Valeo has standards and design rules in place to minimize risk of blade pass occurrence, but depending on the application, there can be external integration factors that can increase the sound level.   This paper focuses on a case study to investigate if CFD can be utilized to optimize a design modification to mitigate blade-pass noise. An experimental study along with CFD simulation were performed to narrow down the placement of a partial wall commonly used to address blade pass noise sensitivity, and to provide useful information for future designs.