Influence of Roof Sensor System on Aerodynamics and Aero-Noise of Intelligent Vehicle 2023-01-0841

The roof sensor system is an indispensable part of intelligent vehicles to observe the environment, however, it deteriorates the aerodynamic and noise performance of the vehicle. In this paper, large eddy simulation and the acoustic perturbation equation are combined to simulate the flow and sound fields of the intelligent vehicle. Firstly, test and simulation differences of aerodynamic drag and pressure coefficients on the roof and rear of the intelligent vehicle without roof sensor system are discussed. It is found that the difference in aerodynamic drag coefficient is 5.5%, and the pressure coefficients’ differences at 21 out of 24 measurement points are less than 0.05. On this basis, under the influence of the sensor system, the aerodynamic drag coefficient of the intelligent vehicle is increased by 23.4%. The incoming airflow hits the sensor system on the front, the flow separation occurs behind it and the streamlined car body is significantly disrupted, which are the main reasons of the extra pressure drag. The roof sensor system also greatly increases the local pressure fluctuation and near-field sound. When the whole vehicle is chosen as the noise source, compared with the original vehicle without the sensor system, the total pressure levels of the windshield and rear window are increased by 4.6dB and 10.0dB, and the total sound pressure levels are increased by 2.0dB and 1.8dB, respectively. The acoustic pressure levels on the windshield and rear window are increased in middle and high frequency bands. In addition, although the sensor system does not significantly increase the total static pressure levels of the side windows, it increases the total sound pressure levels of the front and rear side window, and the sound energy increases in low and middle frequency bands.