中文摘要：

针对交流发电机气动噪声声源组成的复杂性和不同旋转方向对交流发电机气动噪声影响问题,基于Lighthill声学理论,采用LES（Large Eddy Simulation,大涡模拟）和FW-H（Ffowcs Williams-Hawking方程）声学模型对交流发电机气动噪声进行数值模拟.研究结果表明：LES在交流发电机噪声数值预测方面其主要阶次及幅值与试验对比有很好的-致性;前后扇叶为该型交流发电机的主要气动噪声声源;第6、8、10、12 和18 等阶次为交流发电机气动噪声主要影响阶次,且主要能量集中在1 120 Hz～5 600 Hz频率范围内;反方向运行工况的交流发电机总声压级较正方向运行时大9.17 dB,质量流量较正方向运行的小62.87 g/s.研究成果可为车用交流发电机气动噪声性能的提高提供切实可行的参考.

英文摘要：

The influences of the complexity of sound sources and different rotation direction of a vehicle alternator on the aerodynamic noise were studied. Based on Lighthill acoustic analogue theory, broadband noise source model, large eddy simulation method and FW-H acoustic model, the aerodynamic noise for the vehicle alternator was simulated. The results show that the numerical predictions of the main alternator noise orders and their magnitudes obtained by LES are in good consistency with experimental results. The front and rear blades are the main aerodynamic noise sources for this type of alternator. The main components of the aerodynamic noise are the 6, 8, 10, 12 and 18th orders and the acoustic pressure level within 1/3 octave band frequency ranges from 1 120 Hz to 5 600 Hz. Overall sound pressure level (SPL) in the opposite rotation direction of the alternator is 9.17 dB higher than that in the positive rotation direction. The mass flow rate in the opposite direction of the alternator is 62.87 g/s lower than that in the positive rotation direction. This research can provide practical reference for the improvement of performance of aerodynamics noise for vehicle alternators.