Pneumatic Noise Analysis of Automobile Air Conditioning System in Vehicle Environment

With the improvement of material living standards, automotive air conditioners meet the need for refrigeration and heating, and pneumatic noise has gradually been concerned. Automotive air conditioning pneumatic noise is mainly derived from the fan and the air, including both discrete noise and broadband noise generated by the fan, and also includes noise generated by the interaction of the airflow and the air. Due to the complexity of flow field, the impact of the flow on the sound source has not yet been clear: the complex sound field has caused its noise transmission mechanism to be further studied. As the requirements for the compartment comfort are increasing, many automotive air conditioning systems have noise over-standard problems, so it is necessary to conduct in-depth research through testing and simulation means.

In recent years, some experiments and simulations have been carried out for rotary machinery in China. In terms of test, a. Broatch et al 1 measures aerodynamic noise in the centrifugal compressor using a single sensor method and a multi-sensor method. Liu Bo et al 2 using dynamic pressure sensors to measure the non-regular pressure pulsation of a single-stage axial compressor rotor leaf tip gap, the peak value of the main frequency increases with the increase of the speed, and as the exit back pressure increases reduce. The duty army et al 3 under different tip speed ratio conditions, using the sound array method to test the leaf tip area noise of the S-series airfoil, revealing the relationship between leaf vortex flow characteristics and aerodynamic noise characteristics. . In terms of simulation, Yang Zhendong et al 4 calculated aerodynamic noise of the car centrifugal fan using the Large EDDY Simulation, LES and FFOWCS Williamsha WKINGS Williamsha

WKings (FW-H) equation. Kangqiang et al. 5 calculates the non-normal flow of the interior of the heart blower by the separation vortex model (DES), and then the sound field distribution of the inner and outer space inside and outside the wind turbine is determined. M Kaltenbacher et al. 6 uses DES and LES to calculate the flow field of one-side channel fan, and then based on the finite element method, Perfect Match Layer technology predicts far field sound radiation. For air conditioning systems, especially air conditioning systems, aerodynamic noise in the vehicle environment, only find N. Hammad's literature 7, and the paper explores the impact of air conditioning on the noise in the vehicle by changing the fan speed, air conditioning switch state.

To this end, it is necessary to study the aerodynamic noise of the automobile air conditioning system in the vehicle environment. The automotive air conditioning system with a noise exceeds the standard is prototype, and it is measured to understand the sound pressure of each measuring point under different conditions, understand its noise distribution characteristics. On this basis, through a non-fixed flow simulation, the flow of the air conditioning system and the flow of the passenger is found, and the field pulse is found to provide the foundation for subsequent acoustic calculations and noise reduction research.

Simulation discovery, fan is the mainNoise sources, noise generated by the interaction between airflow and airwaves is a secondary noise source.The noise in the crest has a significant broadband noise characteristic, which is different from the discrete noise characteristics of the main source fan. It has an important impact on the production and communication of flow and noise.control.