Study On Flow Field And Sound Field Simulation And Aerodynamic Noise Control Technology Of High Pressure Ratio Centrifugal Compressor

Centrifugal compressor plays an important role in all sectors of the national economy,especially in the industrial sectors such as power industry, metallurgy, petrochemical and natural gas transportation. It is mainly used in exhaust gas turbocharger for internal combustion engines in marine power filed. With the improvement of argument that energy saving and emission reduction of internal combustion engine, internal combustion engine pressurization technology has been a great development, and high-pressure technology has become one of the core technology of advanced internal combustion engine. However, the high pressure ratio technology causes the flow of centrifugal compressor becomes more complicated, and the followed noise problem is paid more and more attention. Therefore,the study of flow field and sound field of high pressure ratio centrifugal compressor has important significance for compressor performance improvement and noise control.In this paper, the BladeModeler software platform is used to perform the geometric preprocessing of the impeller model, and the parameters of the model are extracted by BladeGen. Finally, the 3D solid model and the flow field simulation model are generated.Comparing with the results of compressor performance simulation and test, a conclusion that the modeling technique is accurate and the error is reasonable is obtained. This technique can realize the re-design of the twisted impeller and the blade diffuser of the complex compressor, overcome the problem of grid division in the twisted impeller basin,and provide the fast channel for the simulation research.The Navier-Stokes equations are used as theoretical support and the two-equation turbulence model is used to analyze the viscous fluid motion. The accuracy of the numerical calculation is verified by comparing with the performance of the compressor.The numerical simulation is carried out by using the finite volume method. The flow field of the compressor is analyzed from the four aspects of meridian flow, impeller, diffuser and volute. The results show that the interaction between the leakage vortex generated in the impeller flow path and the leading edge shock wave causes the flow loss under the blade clearance. The flow loss under the no blade clearance is caused by the wall vortex emerged in the high-speed flow and casing wall and the leading edge shock loss of the blade. The static pressure loss coefficient of the blade diffuser is negatively correlated with the total pressure recovery coefficient. With the increase of the flow rate, the radial velocity of the diffuser is increasing, which causes the axial velocity decreases. It will result in split fluid in the volute does not have enough impetus to quickly discharge volute, and the whirlpool is formed in the tongue under the effect of the high speed and pressure gradient, clogging caused by whirlpool is the main reasons that low the performance of volute.Based on the principle of aerodynamic acoustics, the suitable numerical calculation method of acoustic field for high pressure ratio centrifugal compressor is obtained. The Mohring acoustic analogy method is numerically processed, and the aerodynamic noise and flow radiation noise of the compressor are calculated and analyzed. The results show that the compressor aerodynamic noise which is mainly composed of discrete noise and eddy current noise. Blade noise is the main source in the calculation condition. The sound pressure level of the compressor radiated noise has a greater attenuation than the aerodynamic noise. As the noise radiation efficiency of volute material and air is vary at different frequencies, resulting in the sound pressure level varies at various frequencies.Experimental study on the radiated noise of the compressor and the vibration of the volute structure was carried out. The experimental results show that there is a correlation between the surface vibration of the turbocharger and the radiated noise. The vibration of the volute surface vibration caused by aerodynamic force is the main reason for the radiated noise of the volute. At present, the experimental study on the high pressure ratio centrifugal compressor is less, so, having a good command on the correlation between the vibration of the volute structure and the compressor noise can provide a new idea for the turbocharger noise reduction.Based on the simulation model of the compressor, the aerodynamic noise calculation was carried out by using the acoustic analogy method. Six sets of the volute model of the compressor were established according to the different volute design method. Analysis of aerodynamic noise control of centrifugal compressor with volute structure from the control point of noise sourceBased on the simulation model of the compressor, the aerodynamic noise calculation was carried out by using the acoustic analogy method. Six sets of the volute model of the compressor were established according to the different volute design method. From the control point of noise source, the aerodynamic noise control analysis of centrifugal compressor with volute structure is carried out. Comparison and analysis of different structure designs from three aspects: noise level, isentropic efficiency and Static pressure recovery coefficient. The results showed that under the concept of volute section model 1 yielded the best result, under the concept of tongue analysis model 3 yielded the best result and finally under exit cone analysis model 6 yielded the best results.