The Profile Optimization And Numerical Simulation Of High Pressure Ratio Centrifugal Compressor

Generally the axial-centrifugal combined compressor is used on high power-weight ratioturbo-shaft engines as its compressed air system, but internal flow of the centrifugal compressor isvery complex. So the design of high pressure ratio, high efficiency centrifugal compressor isimportant and difficult. The mechanism of different parameters’ influence on the centrifugalcompressor internal flow is great significance to improve its performance.Firstly, the profile optimization methods are presented by numerical simulation and analysis ofKrain impeller. The quantity of the secondary flow can be reduced by increasing the inlet hubincidence, and the quantity of the shock wave can be reduced by decreasing the inlet shroud incidence.Inlet thickness should be reduced to restrain stagnation and local acceleration in transonic centrifugalimpeller, and if the maximum thickness of the blade is located at50%—70%relative arc strengths,the performance of the centrifugal impeller will be better. According to the influence on main bladelode by stagnation and flow blockage, which is caused by splitter blade, a double splitter centrifugalimpeller is pointed out. The isentropic efficiency of new impeller is increased by1.6%, and thepressure ratio equal, but the weight of the impeller can be reduced effectively.Secondly, through numerical simulation on Ziegler impeller with three different vaned diffusers,it can be found that the NACA65vaned diffuser has the highest isentropic efficiency and the widestoperating flow range. However, the double circular blade diffuser can adapt high Ma number flow.On this basis, the solidity of the NACA65vaned diffuser is adjusted, and the conclusion of lowsolidity diffuser can expand the operating flow range is verified. It is concluded that the best solidityvalues should be from0.6to0.85.Finally, through unsteady numerical simulation on Ziegler impeller with two kinds of differentradial gaps of the wedge diffusers by Phase-Lagged Method and Domain Scaling Method, the resultsof the impeller-diffuser unsteady interaction are obtained. After comparison between the numericalresults and the experimental results, it can be found that although they have difference in the value,but have consistent in the trend. Domain Scaling Method is better than Phase-Lagged Method inprecision.