Research On Noise Mechanism Of Vehicle Turbocharger

With the increasing requirement for the performance of modern turbo engineer, it isvery necessary to do researches on the turbocharger noise generating mechanism andcontrol methods. As an important part of turbocharger, to study the compressor noisegenerating mechanism is of great significance for the reduction of the overall aerodynamicnoise of the turbocharger.In this paper, the numerical simulation is employed to study the steady flow field ofthe compressor, which are used to compare the internal flow field characteristics underdifferent working conditions. Based on the results of the flow field calculation, near-fieldaerodynamic noise is obtained. Results show that the main noise source of the compressoris near impeller outlet, and the acoustic power level inside the volute is lower than thatinside the impeller.The simulation of unsteady flow field of the compressor is carried out based on thesteady calculation, and the compressor pressure fluctuation is exported. As a dipole source,the pressure fluctuation is imported to acoustics to calculate the far-field noise. The resultsshow that the noise is broadband and mainly distributed in the shaft frequencies and itsmultiples. Then the influence on pass-by noise is obtained through the simulation of thecompressor noise in7.5meters away. The acoustic simulation results were verified withexperiment.Finally, the system of turbocharger online testing is developed and the noise subjectiveevaluation is performed. The real-time detection and display of noise, speed, axialmovement and so on were realized. Through signal processing on time domain signal,frequency domain signal and subjective evaluation, the purpose of turbocharger statetesting and quality control has come true.