Research On Swept Blade Design Of Transonic Centrifugal Compressor

Turbocharge is the key technology to realize energy conservation and emissions reduction of the internal combustion engine.Centrifugal compressor is the core part of the turbocharge.To improve the transonic centrifugal compressor performance to realize high pressure ratio,high efficiency and wide flow range has always been a research target in the turbomachinery.High pressure ratio causes the transonic flow inside the impeller,and the interaction of the shock wave with the boundary layer and tip leakage flow will further worsen the internal complex flow field and influence the performance of the centrifugal compressor.In modern design of the turbomachinery,swept blade technology is an effective method to reduce the tip leakage loss and achieve better performance.Therefore,to study on the swept blade technology has great significance to the development of transonic centrifugal compressor.This paper studies the swept blade design and numerical simulation of the transonic centrifugal compressor,with the credible numerical method,compares and analyzes different design of main blade sweep,splitter blade sweep and hybrid blade sweep.It leads to the conclusion of the impacts on transonic centrifugal compressor.The effects of different main blade leading edge sweep on transonic centrifugal compressor were studied.Main blade sweep changes the choking mass flow rate of the compressor.With the increase of the sweep angle ? from-20 ° to + 10 °,the blade loading distribution tends to be optimization.The enlarged sweep angle ? weakened the oblique shock wave,passage shock wave and splitter suction surface shock wave,and made a good development of low-momentum flow and leakage flow,which improved the compressor performance.With ? continues to increase,the main blade suction loading reduced,and the radial migration of low-momentum flow and secondary flow enhanced.Which make the flow instability and the performance degradation.The effects of different splitter blade leading edge sweep on transonic centrifugal compressor were studied.The splitter blade sweep hardly affect the choking mass flow rate and oblique shock wave.With the increase of the sweep angle ? from-20 ° to + 10 °,the blade loading is evenly distributed.The tip leakage flow is reduced and deflected from the left channel to the right channel,which improves the flow conditions and the performance of the compressor.With ? continues to increase,passage shock wave and splitter suction surface shock wave enhanced,and the right channel leakage flow and secondary flow increased.Which make the flow instability and the performance degradation.The effects of different main and splitter leading edge hybrid sweep on transonic centrifugal compressor were studied.The influence of non-parallel hybrid sweep with main blade forward sweep(+10°)is similar to splitter swept on compressor performance.And the parallel hybrid sweep has the characteristic of the main blade sweep and the splitter blade sweep.With the increase of sweep angle ? and ? from-20 ° to + 15 °,the main blade loading,the radial migration of flow,the oblique shock wave and the downstream low-momentum flow improved.When the sweep angle continues to increase,the splitter suction surface shock wave enhanced,and the radial migration of flow,the right channel leakage flow and secondary flow increase.The case_MF15SF15 has the best compressor performance in all design cases.The efficiency is higher than the original compressor 1.43%,pressure ratio increased 1.34%.