Multi-objective Optimization of the Bionic Blade in the Multi-blade Centrifugal Fan for Electric Vehicles Application Based on an Orthogonal Test

The multi-blade centrifugal fan, whose aeroacoustic properties significantly affect the noise, vibration and harshness performance of electric vehicles, is an important part of the automotive air conditioning system. A multi-blade centrifugal fan with a sawtooth trailing edge and a bionic blade is used. Multi-objective optimization of the bionic blade is investigated at the best efficiency point based on the orthogonal test to reduce sound pressure level (SPL) and ensure good aerodynamic performance. It is shown by the orthogonal test that the optimal combination of the three influencing factors is when the serration number, aspect ratio, and passivation ratio are 35, 1.5, and 0.2, respectively. The optimal model has 1.94% lower SPL than the original model, and the total pressure of both is basically unchanged. The presence of serration helps to mitigate vortex structures near the blade’s trailing edge. The dominant frequency is not influenced by the bionic blade and matches the frequency of blade passage. The maximum SPL is approximately 1,250 Hz for both models, with a maximum deviation of approximately 2.1 dB. The frequency bandwidth of the main noise source is between 1,250 and 1,600 Hz, showing a considerable difference between the two models.