车用交流发电机气动噪声优化

Optimization of aerodynamic noise for vehicle alternator

采用大涡模拟方法和FW-H声学模型对车用交流发电机气动噪声进行数值模拟,采用矢量合成方法优化交流发电机前扇叶分布角度,以低噪声、高流量与优化频谱结构降低单频旋转噪声为目标,分析了交流发电机气动噪声特性。分析结果表明：交流发电机噪声声压级、主要影响阶次与幅值的数值模拟与试验结果有很好的一致性;交流发电机气动噪声源为前后扇叶,总噪声的主要影响阶次为第6、8、10、12、18阶次,主要能量集中在1120-5 600Hz范围内;总噪声最大预测误差为6.97dB,第12、18阶次旋转噪声预测误差分别为2.30、3.30dB;前扇叶分布角度优化后总噪声最大降幅为3.10dB,平均降幅为2.58dB,第12、18阶次噪声平均降幅为5.80dB,降噪效果明显。

The large eddy simulation method and the FW-H acoustic model were adopted to simulate the aerodynamic noise of vehicle alternator.The vector composition method was used to optimize the front-blade distribution angle of alternator.Aiming at low noise,high flow and optimizing spectrum structure to reduce the single-frequency rotational noise,the aerodynamic noise properties of alternator were analyzed.Analysis result shows that the numerical simulation and test results have good consistencies on sound pressure level,main influencing orders and magnitudes of alternator noise.The aerodynamic noise sources of vehicle alternator are front and back blades.The main influencing orders of overall noise are orders 6,8,10,12 and 18,and the main energy centers on 1 120-5 600 Hz.The maximum prediction error of overall noise is 6.97 dB,and the prediction errors of rotational noise on orders 12 and 18 are 2.30 dB and 3.30 dB respectively.After optimizing the front-blade distribution angle of alternator,the maximum decreasing amount of overall noise is 3.10 dB,the average decreasing amount is 2.58 dB,the average decreasing amounts of noise on orders 12 and 18 are 5.80 dB,so the noise reduction effect is remarkable.