Numerical simulation and optimization of aerodynamic noise for claw pole alternator

Abstract

This study aims at minimizing the aerodynamic noise generated by claw pole alternator used in vehicles. In this paper, an effective and efficient hybrid test-analysis engineering approach has been proposed to predict and optimize acoustic performance of claw pole alternator. First, an experimental analysis was performed to predict the main components of the aerodynamic noise generated by the claw pole alternator. Then a hybrid approach was proposed to calculate the aerodynamic noise of the alternator. A computational fluid dynamics model of the claw pole alternator was developed for calculating the flow-field of the alternator. The pressure fluctuation in the flow field was analyzed to validate the computational fluid dynamics simulation. After the computational fluid dynamics simulation, the far-field aerodynamic noise generated by the flow field was calculated by adopting the acoustic finite element method. The accuracy and feasibility of the acoustic finite element model were validated with the experimental data. After the validation, the effects of the cooling fan parameters on the aerodynamic noise of the alternator were discussed and analyzed. According to the sound source information and the generation mechanism of the aerodynamic noise, the blade spacing angle of the cooling fan was optimized by establishing a theoretical model. The blade chord length of the cooling fan, the blade installation angle of the cooling fan and the tilt angle of the grille on end cap were optimized by structuring different surrogate models. After the optimizations, a significant reduction in the noise level of the claw pole alternator was found by the finite element method simulation. The overall sound power level has been decreased by about 6 dB (A).