Analysis Of Flow Field And Aerodynamic Noise Of Turbocharger Compressor

Turbocharging technology improves the intake capacity of the engine through the turbocharging device,so that more fresh air can be taken into the combustion chamber,then more fuel can be fully burned,and enhance the power,economy and emission performance of the internal combustion engine.In recent years,it has been widely promoted in the automotive field.In addition to mechanical noise and combustion noise,aerodynamic noise accounts for a considerable proportion.For turbocharged vehicles,a large part of aerodynamic noise comes from the compressor of turbocharger.Therefore,in order to reduce vehicle noise and improve passenger ride comfort,it is particularly important to study the mechanism of turbocharger compressor aerodynamic noise.The research object of this subject is the automotive turbocharger compressor,the relevant theoretical knowledge of the turbocharger compressor aerodynamic noise has carried on the simple introduction.On this basis,three-dimensional geometric model and finite element model of compressor are established,using Fluent software for turbocharger compressor calculation and analysis of internal flow field and aerodynamic noise.The flow field and noise changes at three rotating speeds were specifically studied,and the influence characteristics of different tip clearance on the compressor flow field,eddy current and rotary noise were analyzed by changing the tip clearance of the compressor.The main research contents and conclusions of this paper are as follows:(1)briefly introduce the research overview of engine supercharger technology,flow field and aerodynamic acoustic noise,and theoretical knowledge of compressor noise;The geometrical model and finite element model of the compressor are established to analyze and study the correlation characteristics of static pressure field,velocity,turbulent kinetic energy of impeller and static pressure distribution in the flow field.The negative pressure and flow rate of the compressor inlet to the impeller are increasing.After entering the non-blade diffuser,the velocity decreases along the radial direction and the gas pressure increases gradually.After the air flow enters the volute,the speed continues to decrease and the pressure continues to increase,and the pressure reaches its maximum at the outlet.(2)the eddy current noise source model is adopted to predict and calculate theeddy current noise of a compressor with tip clearance of 0.4mm at a speed of100000 rpm.RNG model and large eddy simulation model are used to predict and calculate the rotary noise,which is verified by experiments.The noise of the impeller is the main noise of the compressor.When the air flow enters the vortex shell,the velocity drop pressure increases and the sound power level becomes smaller and smaller.It can be seen from the large eddy simulation that with the increase of frequency,the sound pressure level becomes lower and lower,and the rotary noise of the compressor becomes less and less obvious.In addition,due to the influence of the shunt blade,even order noise is stronger than odd order noise.The experiment verifies that the noise error is less than 5%,which indicates that the method is feasible.(3)The effects of different rotational speeds on the flow field and aerodynamic noise of turbocharger compressor were analyzed.The effects of tip clearance on the flow field,eddy current and rotational noise were studied.With the increase of the rotational speed,the gas flow rate and noise of the compressor increase;the rotational speed has a great influence on the static pressure distribution of the suction surface;too large and too small tip clearance are not conducive to the operation of the compressor.When designing the compressor structure parameters,the appropriate tip clearance value should be selected.