Noise Reduction Design Method and Validation of Unequal-Pitch Blade Fan for Traction Motor

Abstract

The traction motor of trains is an essential component that generates the traction force, but it has a significant influence on the indoor and outdoor acoustic environment during the running condition. To enhance passenger comfort and bolster the environmental performance of trains, regulatory standards and specifications governing train noise have imposed elevated criteria on both tonal noise and the overall A-weighted sound pressure level emanating from traction motors. This paper proposes an aerodynamic noise optimization design method based on aerodynamic interference. The objective function of the optimization is defined as the blade-passing frequency (BPF) noise and the A-weighted overall sound pressure level of the traction motor fan. The simulated annealing algorithm is used to optimize the circumferential distribution of the blades. The optimized unevenly spaced blade configuration of the fan effectively reduces the BPF sound pressure level amplitude by 4.6 dBA and the overall A-weighted sound pressure level by 1.2 dBA. The calculation results agree well with the experimental results. The study reveals that unevenly spaced blades contribute to better noise reduction at lower rotational speeds. However, the effect diminishes at higher speeds. The relationship between noise reduction and blade count is nonlinear, suggesting an optimal count for specific speeds.