HVAC System Noise Prediction Through CFD Simulation 2019-26-0210
Vehicles with HVAC system have shown growing demand for in-cabin acoustic comfort in recent days. This is mainly due to advancement in new generation powertrains and improved cabin sealing which has made HVAC system noise more dominant inside the cabin. The HVAC system noise is predominantly flow induced. Further, considering future hybrid and Electric vehicles where engine powertrain noise will be insignificant, more attention will be required for HVAC system design. Contribution of noise in the cabin from HVAC system is in the frequency range 400Hz to 3000Hz. The noise produced by a HVAC system is mainly due to aeroacoustics mechanisms related to the flow fluctuations induced by the blower rotation and turbulence in HVAC flaps, duct and vents. This paper discusses simulation methodology developed to predict HVAC system level noise using CAA (computational aeroacoustics) approach. Detached eddy simulation with compressibility is used to predict sound generation and propagation at different receiver locations. Design feedback for HVAC, duct and vents are identified and countermeasures are suggested from this method, which resulted in noise reduction at system and thereby vehicle level. This method found useful for design ranking, design improvements during HVAC system’s design maturation stage in vehicle. This process is validated with test, and good correlation is observed with CFD prediction and test measurements.