The Aerodynamic Noise Analysis Of The Compressor Of Turbocharger

As a supercharging device,the turbocharger has been applied to marine diesel engine widely.In order to maximize improve the dynamic performance of diesel engine,the turbocharger gradually rounded into the direction of high pressure,high speed and high efficiency to fulfill the larger scale and higher speed of modern ship.On the contrary,the noise of turbocharger has become more and more serious.Compressor as the main part of the turbocharger,also one of the main noise source,so the study of compressor aerodynamic noise is very important to the reduction of turbocharging noise and the green manufacturing engineering of the marine diesel engine.First,the NUMECA software was selected to disperse the impeller and diffuser flow and the ICEM was selected to disperse the volute flow.Based on CFD approach,CFX software was used to calculate the compressor full-channel internal flow field and the numerical simulation turbulence model was standard k-?.The calculations of the compressor working characteristic curve of all conditions were compared to the test data,the results has confirmed the correctness of this simulation model.Then,three-dimensional flow of the compressor was analyzed.The pressure,speed and temperature distribution of each compressor flow were obtained by analyzing the compressor three-dimensional steady flow.Based on steady simulation results,the three-dimensional unsteady flow was calculated with the static pressure monitoring,the analysis results show that violent erratic flow happens at the leading edge of the blade and the stator-rotor interface,where the flow field parameters change dramatically,and it is the main reason for the compressor aerodynamic noise.The pressure pulsation was analyzed in the domain of time and frequency,and the results show that the discrete noise caused by the interference between rotor wake and stator is the main noise source.The results are consistent with the theoretical analysis.Third,the interior sound field and the radiated acoustic field of the compressor was calculated.By contrast,the dipole sources turned out to be the strongest in the compressor flow.The aerodynamic noise at the impeller inlet face was simplified as dipole source and the aerodynamic noise at the impeller was simplified as rotating dipole source when calculating radiated acoustic field.The sound pressure level contours of the field point at the at the impeller inlet face show that the noise caused by erratic flow at the blade leading edge often happened at low frequency.,the sound pressure contours of the field point at the impeller showed that sound pressure level at the blade passage frequency and its harmonic was larger,which further confirms the discrete noise caused by the interference between rotor wake and stator is the main noise source.Last,the influence of mass flow and rotating speed on sound filed performance was analyzed.It turned out that,with the decreasing of mass flow or increasing of the rotating speed,the discrete noise will increase,however the rotating speed has greater influence than the mass flow.