HVAC Blower Aeroacoustic Predictions

In recent years, vehicle cabin quietness takes a growing importance particularly related to the emergence of hybrid and electric vehicles and “Idle Stop system” vehicles. Demand for quieter car air-conditioner systems is increasingly important also, especially the reduction of the flow-induced noise from the HVAC. In HVAC systems, the rotating blower is one of the main noise sources and the digital solution for predicting and analyzing the blower aeroacoustic noise in the early stage of design is needed for developing a quieter blower. The target of this study is to develop and to validate a flow-induced noise predictive tool for a HVAC blower and to analyze the noise source. In this paper, a low-dissipation, transient, compressible CFD/CAA approach based on the Lattice Boltzmann Method (LBM) is used to predict simultaneously the flow and aeroacoustic radiation of two production blowers. For validating the numerical method, aerodynamics and acoustics measurements are carried out following the ISO-5801 standard norm. Simulation results are compared to experiments and the absolute levels and the correct trend of the Sound Pressure Levels (SPL) for the two blowers are accurately predicted. Simulation results are analyzed in detail to identify the physical mechanisms likely responsible for the noise generation.