Experimental Study On Influence Of Blade Tip Geometries On The Tip Clearance Flow Of Compressor Cascade

Tip leakage flow not only produces large tip leakage loss,and the unsteady pressure caused by vortex is closely related to compressor stability.In order to improve the aerodynamic performance of the compressor,it is significant to study the mechanism of secondary flow in the compressor and control it.Based on compressor plane rectangular blade as the research object,this paper focus on investigation of the control mechanism of different tip geometries to tip leakage flow.Firstly,compressor cascade with different geometric parameters and different installation methods of tip winglets have been measured,comparing with original cascade,change of the geometry of the tip clearance flow in a compressor is extremely sensitive,the installation of the tip winglets changes the structure of the blade tip region of flow field,the interaction between tip vortex,thereby improving the compressor cascade aerodynamic performance.For the pressure side winglet case,the tangential momentum of tip leakage flow is reduced;the pressure side winglet manages to displace the tip leakage vortex toward the tip/outer casing corner of the suction side.More low energy fluid is concentrated in the corner area of the suction side of the blade,resulting in the expansion of the high loss area,and the flow undergoes a more underturning near the casing.For the suction side winglet case,the tip leakage vortex moves away from the suction side of the blade and different shapes of the suction side winglet on the control of leakage flow has a certain influence,the influence of different shapes of suction side winglets to the cascade loss is more obvious in the larger gap height.Suction side winglets with different shapes can improve the underturning/overturning phenomenon in the smaller gap height,with the increase of the tip clearance height,the end wall flow undergoes a more underturning gradually.Secondly,on the basis of the tip winglet,and a groove structure is added to the blade tip to study the action mechanism of the control gap leakage in different shapes of the tip-winglet with groove.By studying the flow field of different gap sizes,the results show that the flow field structure of the cascade gap is more complicated due to the structure of the groove,and the vortex structure formed by the tip leakage flow in the groove has a certain influence on the cascade flow field.The circumferential position of the leakage vortex nucleus does not change obviously due to the groove in the cascade.While the strength of the leakage vortices increases and the range of action increases,and the cascade loss increases.The combination of the winglet and the groove aggravates the underturning in the near endwall,the non-uniformity of outlet airflow angle increases.The cascade leakage vortex with suction side winglet and groove is transferred to the position away from the suction side,the strength of leakage vortex is weakened in outlet section.The total pressure loss of the cascade decreases obviously,and the effect is obvious under the higher tip clearance height.Different schemes only improve the underturning/overturning phenomenon in smaller gap height.