Numerical Study Of The Tip Clearance Flow Of A Transonic Compressor Cascade

For gas turbine engine, the role of the compressor is to increase pressure of air flow by working under the loss of low flow resistance. So, the performance of the compressor is directly related to the efficiency of the engine. And the loss of the tip clearance of compressor can not be ignored. Therefore, it is very important to improve the efficiency of the compressor and enhance the stability of the compressor by taking effective way to reduce the effects caused by clearance leakage.In this paper, the numerical simulation has been carried out to study the straight blade cascade of the transonic compressor with the aid of a commercial computational fluid dynamics. Three-dimensional time-averaged steady state Navier-Stokes equation has been solved by Spalart-Allmars single-equation turbulence model. Second order upwind time advance scheme and the standard near wall function have also been utilized. The grid has been constructed by structure and non-structure hybrid scheme. In this paper, the relative motion of the blade and the casing is considered and the flow velocity and angle of attack are also different. The numerical simulation has been carried out to study a transonic compressor cascade by using blade tip winglet, and to further explore the effects of blade tip winglet at the flow field of cascade top.The numerical simulation of transonic cascade flow field can be obtained: by comparing with the conventional cascade, the results show that blade tip winglet makes the leakage vortex on the surface away from the suction side, and the static pressure's gradient of the casing gradually slowed down along the channel direction. In the export section, the scope of leakage vortex decreases and the core position of leakage vortex shifts from the suction to the pressure along the direction of the pitch, and the high loss region of cascade energy significantly reduces by comparing the cascade of the prototype. These phenomenons show that the installation of suction side winglet can effectively weaken the intensity of tip clearance leakage flow, and the gas dynamic performance of the tip clearance can be effectively improved. But there are advantages and disadvantages with blade tip winglet. The total pressure loss at the cascade exit increases slightly at supersonic mach number. For different angles of attack, the starting point of the leakage vortex at i=2° is migrated to the side of the suction side, and the total pressure loss of the outlet is lower than that of i=98.3°. At the same time, the endwall movement has a certain impact on the leakage of tip clearance.