Research On Mechanism And Control Of The Noise Of Turbocharger Compressor

With the increasing demand for the performance of the turbocharged engine,the compressor with high speed running characteristics is widely used in the turbocharger to improve the overall efficiency of the turbocharger.However,with the increase of the speed of the compressor,the noise problem of the turbocharger is becoming more and more prominent.High noise has a great negative impact on the health of the driver,and it has become an important research topic to be solved urgently.Compressor is the core working part of compressing air,and aerodynamic noise is one of the main components of its noise.Therefore,it is very important to study the mechanism of compressor aerodynamic noise and optimize its structure from the poirnt of view of controlling noise.Combined with the existing experimental conditions and research hot spots,the internal flow characteristics of the turbocharger compressor are explored,the formation mechanism of the compressor near field noise and the frequency domain characteristics of the far field noise are studied.The structure optimization of the compressor impeller is carried out with the efficiency and noise as the optimization target,thus the aerodynamic noise of compressor can be controlled under the premise of same effi ciency.This topic provides a reference for the noise mechanism and control of turbocharger compressor.The main research work includes the following aspects.The unsteady flow field and near field noise of compressor are numerically calculated,and the formation mechanism of aerodynamic noise is explored.Through the numerical calculation of unsteady flow field of the compressor,the internal flow field characteristics of the compressor are analyzed,and it is found that there is a complex turbulence phenomenon at the outlet of the compressor impeller.The near-field noise of compressor is calculated by the broadband noise model.Comparing the distribution of near field noise and turbulence intensity,the formation mechanism of the compressor aerodynamic noise is analyzed.The analysis shows that the turbulence intensity is the key factor for the formation of aerodynamic noise,and the outlet area of the impeller is the core noise source of the compressor.Characteristic analysis of compressor far-field noise and experimental verification of simulation calculation model.The Adaptive Finite Element Method is used to analyze the far field noise of turbocharger,which effectively avoids the constraint of the acoustic calculation frequency to the grid size,thus reducing the calculation cost.The internal pressure pulsation obtained from the calculation of the compressor flow field is regarded as the boundary condition,and the far-field noise of the compressor is simulated.Through the analysis of the far field noise,the frequency domain characteristics of the far field noise of the compressor are explored.The noise is dominated by the broad-band noise and concentrates on the axial frequency and its multiples.The correctness of the simulation results is verified by the noise test experiment of the turbocharger compressor.A multi-objective genetic algorith:m is applied to optimize the structure of compressor impeller,so as to control its noise formation.The multi-objective genetic algorithm is used to optimize the structure of the impeller for the compressor efficiency and noise,and the three representative optimization schemes of high efficiency design,low sound pressure level design and comprehensive design are selected in the multiple optimization results.The optimization results show that the high efficiency design scheme is available on the premise of no loss of noise performance,and the efficiency of the compressor is improved effectively.And the low sound pressure level design scheme can ensure that the compressor noise can be effectively reduced under the condition that the efficiency is not reduced,and the comprehensive design scheme can obtain the balanced improvement of the performance of the compressor efficiency and noise.