Study On The Aerodynamic Noise Of Diesel Engine Turbocharger

Turbocharger is an important part of the turbocharged diesel engine.Due to the increase of mass flow rate and pressure ratio of the turbocharger,aerodynamic noise of turbocharger has become more apparent.And the turbocharger noise becomes one of the major noise sources of the main engine system of the ship.Domestic and foreign scholars study the generation mechanism,the numerical analysis and the control methods for the turbocharger noise.So,it is significant to research the sources of aerodynamic noise and study the generation mechanism and the control method of the turbocharger noise.In the work,according to the design drawing of the compressor and turbo,three-dimensional models were established by the use of UG software.Based on the geometric model,the flow domains were meshed in the grid division software.On the basis of finite volume method,using the single stator and rotor blade passages,the flow field of the compressor and turbo were simulated.The compressor’s flow characteristic was predicted and agree well with the experimental value.The flow field characteristics and frequency spectrum of the fluctuating pressure in turbochager which agree well with the theoretical value were analysed.Based on Lighthill acoustic analogy theory and combining CFD and IBEM,The sound pressure level at the entrance of compressor and the exit of the turbo under working condition were calculated.The results show the spectrum of aerodynamic noise consists of discrete blade frequency noise angd its harmonics and broadband noise.The overall sound pressure level is determined by the discrete blade frequency noise.The maximum value is located at the blade passing frequency,and its harmonics noise reduces as its harmonics frequency increases.The results can provide a useful reference to low noise design and structure optimization of turbocharger.