Study On Noise Simulation And Low Noise Optimization Design Of Turbocharger Centrifugal Compressor

Since the turbocharging technology was put forward by Posey in 1907,Because turbocharged internal combustion engines have the absolute advantage of increasing power,reducing fuel consumption,and reducing emissions,most internal combustion engines today are turbocharged internal combustion engines.With the rapid development of turbocharging technology,the turbocharger speed and pressure ratio has been continuously increased,and the noise caused by the supercharger has become increasingly serious.As the main noise source of the turbocharger,the compressor mainly includes the aerodynamic noise generated by the internal gas flow and the radiation noise generated by the vibration of the volute.The study on compressor noise is of great significance to the optimization design of low noise compressor.The main contents of this article are as follows:(1)Fluent software was used to calculate the steady-state flow field of the compressor under five working conditions.The flow velocity and pressure distribution characteristics of the impeller,diffuser and volute were studied.The location and cause of the internal flow loss in the compressor were analyzed.It also provides data support for numerical calculation of compressor noise.(2)By broadband noise model and hybrid method based on morhing acoustic analogy,the noise source distribution characteristics and noise sound pressure level spectrum characteristics of the compressor are calculated and analyzed.The results show that the aerodynamic noise of the compressor is mainly caused by the highly complex gas turbulent flow inside the impeller and the diffuser.The high power level of the impeller blade noise is distributed in the leading edge of the blade,the tip clearance and the trailing edge of the blade,while the high noise power of the diffuser blade is distributed in the leading edge of the blade,and the noise power of the blade trailing edge is low.The internal aerodynamic noise has obvious discrete spectrum characteristics.At a speed of 30000r/min,the discrete noise frequency appears at the first-order shaft frequency,third-order shaft frequency,fifth-order shaft frequency and first-order blade pass frequency.The highest sound pressure level occurs at the first-order shaft frequency.(3)By hybrid method based on morhing acoustic analogy and experimental method,the radiated noise characteristics of the compressor at a rotational speed of 30000r/min was calculated and analyzed.The results show that the acoustic pressure fluctuation on the internal surface of the compressor volute is the main source of radiated noise,that is,the aerodynamic noise is the main source of the radiated noise of the volute,and it is also the focus of noise control.The discrete noise frequency of the radiated noise is consistent with the discrete noise frequency of the aerodynamic noise.The highest sound pressure level occurs at the first-order blade pass frequency,and the volute plays a good role in sound insulation.(4)Based on the broadband noise model,the influence of leading edge inlet angle parameters on isentropic efficiency and sound power level was studied.The results show that proper increase of leading edge inlet angle can improve the isentropic efficiency of the compressor while reducing the sound power level of the compressor noise.According to the results of the study,isentropic efficiency and sound power level were taken into consideration to optimize the parameters of leading edge inlet angle.In summary,this paper systematically studied the numerical calculation method of compressor aerodynamic noise and radiation noise,analyzed the distribution characteristics of sound fields and the relationship between aerodynamic noise and radiation noise.Taking the optimization of leading edge inlet angle of impeller main blade as an example,it provides a method support for the optimization design of low noise compressor structure.