Analysis and Control of Aerodynamic Noise of Automobile Air-Conditioning Ducts
Aiming at the aerodynamic noise in the car air-conditioning ducts,a periodic noise reduction struc-ture is designed.Transfer matrix method is used to establish the theoretical model for transfer loss of the noise reduction structure.The influence of parameters on the transmission loss of the noise reduction structure is ana-lyzed,and the correctness of the theoretical model is verified through experimental tests.By combining the fluid mechanics finite element method with the acoustic analogy method,the location of noise source in an air-conditioning duct of a commercial vehicle is predicted,and the main causes and characteristics of aerodynamic noise are analyzed to provide target frequency domain for the optimal design of the noise reduction structure.To maximize the silence frequency bandwidth,the aperture,expansion cavity length,expansion ratio,and interpo-lation length are used as design variables to optimize the noise reduction structure.Comparing the noise reduc-tion structure before and after optimization,it is found that the peak value of the transmission loss significantly increases,and the width of the silence frequency bandwidth broadens.Both the sound pressure level and the A-weighted sound pressure level at the outlet of the optimized air conditioning duct are reduced by about 7 dB.
automotive air-conditioning ductsaerodynamic noisenoise reduction structuretransmission loss
NETL
NSTL
万方数据
