车用交流发电机气动噪声试验研究

针对某型汽车交流发电机在高速段（6 000 r/min以上）噪声源以及各主要阶次对总噪声的贡献量问题，对交流发电机进行噪声测试分析。通过阶次分析得出气动噪声的频率特性，采用交流发电机有无前、后扇叶分别单独运转等试验方法确定各阶次噪声的具体来源以及前后扇叶对主要单阶次贡献量的大小。得到前后扇叶为该型交流发电机的气动噪声声源，第6、8、10、12、18等阶次为该型交流发电机的主要气动噪声成分；前扇叶对12、18阶次噪声贡献明显比后扇叶大，后扇叶对6、8、10阶次噪声的贡献较前扇叶大。该方法对汽车交流发电机的气动性能和高转速下噪声的改进提供一种切实可行的依据。

Experiment Study on Aerodynamic Noise of an Automotive Alternator

To detect the noise sources and determine their orders which have major contribution to the total amount of the noise for a certain type automotive alternator at high speed （6000r/min or above）, the noise measurement tests are conducted for the alternator. Through the order analysis, the aerodynamic noise frequency characteristic of the alternator is derived. The alternator with the front or rear fan’s individual operating is tested respectively to detect the noise sources and determine their contribution to the global noise. It is found that the front and rear fan blades are the sources of the aerodynamic noise of the alternator, and the noises of orders 6, 8, 10, 12 and 18 are the main components of the aerodynamic noise. The front fan blades have larger noise contribution to the noise of orders 12 and 18 than the rear fan blades;and the rear fan blades have larger noise contribution to the noise of orders 6, 8 and 10 than the front fan blades. This method may provide a practical basis for testing and analysis of aerodynamic noise performance of automobile alternators at high speed and improvement of their structures.