Experimental And Simulation Analysis Of Automotive HVAC Systems Aerodynamic Noise

As the noise level of other noise sources’ transmission into the car is effectively controlled,the aerodynamic noise of the automotive HVAC system has become the focus of attention.The aerodynamic noise generated by the HVAC system is directly transmitted into the vehicle through the air outlet,which seriously affects the ride comfort.Therefore,the flow field characteristics and sound field characteristics of a certain type of automotive HVAC system are analyzed in detail by the combination of experiments and simulations.Improvement and optimization schemes are proposed to improve the aerodynamic noise of HVAC systems.The main content of this paper is:The air volume experiment of the HVAC is carried out.The blower speed and the outflow air volume under different voltage conditions are obtained.Through the wind resistance experiment of the air filter,evaporator and heat exchanger components,the equivalent fitting parameters of the porous medium in the simulation of the three components are obtained.According to the fitting parameters and boundary conditions obtained by the experiment,the computational fluid dynamics model of the defrosting mode of HVAC system was established and the flow simulation was completed.The comparison with the experimental results verifies that the simulation has higher accuracy.The simulation results are analyzed to obtain the distribution of internal flow lines and physical quantities of HVAC systems.The relationship between internal flow and noise of HVAC systems is explored.The noise experiment is carried out on the HVAC system to obtain the noise information of the microphone position in the radiating sound field of the HVAC system under different working conditions.By analyzing the noise experiment results,the noise propagation characteristics of the radiated sound field of the HVAC system are discussed.Based on the broadband noise source model and the FW-H unsteady model,the steady sound field simulation and unsteady sound field simulation of the HVAC system are carried out.Comparing with the experiment results,it is verified that the calculation model has higher accuracy.According to the simulation results of sound field simulation,the sound source position and formation mechanism of the aerodynamic noise of HVAC system are analyzed.The high-speed rotating blades and volute tongues of the HVAC system are analyzed as the main noise source locations.Combined with the flow field and sound field simulation results of the HVAC system,the flow channel before the evaporator was improved,the uneven flow inside the evaporator of the original structural was improved,and the flow rate of the system is also improved.The influence of the structural parameters of the blower current collector on the acoustic response of the radiation sound field monitoring point is analyzed,and the optimization model is constructed by the experimental design.Through the modification of the structural parameters of the current collector,the flow inside the HVAC system is improved,and the noise response of the position of the radiation sound field monitoring point is greatly reduced.