Mechanism Analysis on the Flow Induced Low-Frequency Noise in NEV

A systematic analysis about the mechanism of flow induced low-frequency noise of new engine vehicle is presented. Firstly through the “opening-window” method in aero acoustic wind tunnel testing, the contribution and noise spectrum difference is analysed and compared about vehicle upper body and lower body. The test shows that low-frequency noise nearly totally generated by chassis parts because of the interaction between air flow and chassis, especially the tyre house contributes more. The SPL value of the chassis contribution is 9.8 dB(A) at driver seat and 13.8 dB(A) at rear seat and the main noise spectrum difference is below 500 Hz. Furthermore, deeply research about noise source in tyre house and the noise transfer path is performed. At last, an optimized method is carried out at the testing vehicle with enhancing sound absorption ability in tyre house and thickening the side glass. The maximum noise reduction achievement is 3.76 dB(A) at frequency domain.