Numerical Study On The Influence Of Tip Winglet On The Performance Of Centrifugal Compressor

The centrifugal compressor has been applied in many fields due to its simple structure,good manufacturability,and wide stability margin.It has become a researcher to achieve a higher pressure ratio,higher efficiency,and a wider stable working range The focus of our attention.At present,many studies have shown that inside the impeller machinery,the tip leakage vortex caused by the tip clearance is the main source of loss in the compressor.Therefore,how to reasonably control the leakage flow at the compressor gap becomes the research focus.The blade tip winglet technology has attracted attention as one of the geometric modification methods.A large number of scholars have shown that the reasonable layout of the blade tip winglet can effectively control the gap flow.Impact,the main research work is as follows:First of all,this paper studies the blade tip winglet with different installation methods(pressure surface winglet,suction surface winglet)installed under different working conditions with large centrifugal compressor LSCC as the research model,and analyzes its aerodynamic characteristics.The numerical calculation results show that the flow stability margins of the large-scale centrifugal compressor impellers with three widths of pressure surface blade tips under the design gap have been expanded by 1.4%,2.4%,and 3.1%,respectively.An important reason for the impeller stall,the pressure surface winglet's suppression of leakage vortices increases the stability margin.The three different suction surface winglet schemes reduce the stability margin by 0.76%,2.2%,and 15.3%,respectively.The suction surface blade tip winglets have opposite effects on the centrifugal impeller,increasing the leakage vortex strength at the tip Making the impeller unstable in advance.Then,the impeller was numerically calculated under the small gap condition,and it was found that the leakage strength was weakened under the small gap,and the stability range was increased by 12.3%compared with the design gap.The blade tip and wing schemes with different installation methods under the small gap condition were simulated It is calculated that the three pressure surface winglet schemes with different widths reduce the stability margin by 4.38%,6.03%,and 19.25%,respectively.The installation of the pressure surface winglet under a small gap will increase the leakage flow intensity,and the starting position is more In the front,and the leakage flow ruptures near the trailing edge to form more low-speed flow,which induces the impeller stall to advance.The winglets of different suction surfaces have different influences on the stability margin of the impeller.The SW1 scheme reduces the stability margin by 17.21%.The leakage flow near the trailing edge in the flow channel is broken,which affects the flow performance of the flow channel.SW2 and SW3 The scheme has only a small increase in the stability margin,and has little effect on the flow channel.Finally,the numerical simulation of the scheme of adding squealer on the top of the blade tip winglets of different installation methods was performed.After the squealer structure,part of the leakage flow enters the squealer and moves downstream until it flows out of the squealer,which suppresses the generation of leakage vortices,thus expanding the stable range of the impeller.The blade tip squealer is added on the suction surface winglet to increase the impeller stability margin by 4.1%.In addition to the leakage flow flowing into the squealer and improving the leakage vortex strength,a small range of forward suction is formed at the leading edge Is not conducive to fluid circulation,this is why the effect of adding a squealer on the suction surface is not as good as adding a squealer on the pressure surface.