Optimization Design Of Electric Turbocharged Centrifugal Compressor With Low Specific Speed

Fuel cell technology is the core of fuel cell vehicle technology,fuel cell system using electric supercharging can improve power density and efficiency,improve water balance performance;The turbocharger of internal combustion engine exhaust gas has a slow response speed and can't increase the pressure at low speed.The low specific speed centrifugal compressor driven by the motor and the fuel cell system have good adaptability,and can also be used to improve the performance of internal combustion engine at low specific speed.In this paper,the centrifugal compressor with low specific speed is simulated and optimized to expand its stable working range,improve pressure ratio and efficiency,and promote its engineering application.The models of centrifugal compressor impeller and volute with low specific speed were established,and the grid was divided and the grid independence was verified.After the numerical simulation calculation,the flow field analysis showed that the circumferential static pressure distortion near the impeller outlet affected the flow in the impeller under off-design conditions.Analyzes the impeller wheel and wheel cover position,blade tip and hub location influence on flow stability,wheel hub and wheel cover location optimization,has improved to the flow of the impeller,and significantly improves the compression ratio and efficiency of the impeller,based on this,in turn,to the blade tip and hub location is optimized,the flow has improved,but the improvement of performance is not obvious.After the impeller was optimized,at the design speed 40,000 r/min,in the medium flow point 0.07 kg/s,the pressure ratio and efficiency were improved by 8.51% and 5.27%,respectively.The effect of volute channel on circumferential static pressure distortion at impeller outlet is discussed.Numerical simulation results show that the circumferential static pressure distortion of the impeller outlet can be suppressed by increasing the volute channel diameter,and the stable working range of the centrifugal compressor can be widened.The larger the volute channel diameter is,the larger the compressor's stable working range will be.However,considering the actual situation,the volute channel cannot be too large,and the improvement of performance is not obvious due to the too large volute channel,the original volute channel diameter of 120% is selected for the volute channel size.Compared with the original channel,the working range of the optimized impeller with stable design speed is widened by 23.53%.In this paper,the flow in the impeller and volute of the centrifugal compressor with low specific speed was analyzed by using the steady numerical simulation calculation,and the centrifugal compressor model with low specific speed was optimized.After the model optimization,the stable working range of the designed centrifugal compressor with low specific speed was improved by 50%,at the flow point was 0.07kg/s,the pressure ratio was improved by 7.14%,and the efficiency was improved by 7.96%.