近场项对车用交流发电机气动噪声影响分析

Effects of near field terms on aerodynamic noise of the vehicle alternator

为了探究近场项(反射面、端盖及定子)对车用交流发电机气动噪声的影响,基于Lighthill声比拟理论,大涡模拟(LES)方法及边界元法对交流发电机的气动噪声特性进行研究。结果表明:仿真得到的主要阶次及幅值与实验相比一致性较好,验证了仿真方法的正确性;第4、6、8、9、10及12阶次为该型交流发电机的主要阶次;反射面对各主要阶次皆有影响,端盖主要影响10阶次,定子主要影响6及9阶次;反射面对左、上测点声压级影响较大,端盖对左、右测点影响较大,定子对各测点几乎无影响;近场项对五点平均总声压级的影响大小依次为:反射面>端盖>定子。

In order to investigate the influence of the near-field term(reflector,end cover and stator)on the aerodynamic noise of the vehicle alternator,this paper studies the aerodynamic noise characteristics of the alternator based on the Lighthill acoustic analogy theory,large eddy simulation(LES)method and boundary element method.The results show that the main orders and amplitudes obtained by the simulation are in good agreement with the experiments,which verifies the correctness of the simulation method,and the order 4,6,8,9,10 and 12 are the main orders of this type of alternator.the reflection surface has influence on all the main orders,the end cover mainly affects the 10th order,and the stator mainly affects the 6th and 9th order.The reflection has a great influence on the sound pressure level of the left and upper measuring points,the end cover has a great influence on the left and right measuring points,and the stator has almost no influence on each measuring point.The influence of the near-field term on the five-point average total sound pressure level is in the following order:reflector>end cover>stator.