Research On The Influence Of Suction On The Aerodynamic Performance Of Planar Diffuser Cascade

The current requirements for air compressors in aerospace high performance engines are becoming more and more demanding,with higher pressure ratios and higher efficiency being demanded.The increase in the pressure ratio makes complex flow phenomena such as the separation of the blade surface and the end-wall boundary layer seriously affect the efficiency of the compressor and hinder the increase in the pressure ratio.As a new type of active control technology,the boundary layer suction technology can remove low energy fluids from the end wall or blade surface,reduce the separation of the corner zone,the flow condition in the cascade is greatly improved,the loss is reduced and the expansion capacity of the compressor is also improved.Therefore,the choice of boundary layer suction technology as a research topic is of great significance.The main research work in this paper is as follows.This paper adopts the computational method of CFD numerical simulation to study the boundary layer suction of DMU-37 on the trans-sonic plane diffusion static leaf cascade.The influence of boundary layer suction on the pneumatic performance and flow field structure of the trans-sonic plane diffusion static leaf cascade at different locations is investigated from the aspects of total pressure loss,streamline,leaf surface static pressure distribution and Mach number distribution,and the optimal location of boundary layer suction is obtained.The paper explores the following aspects.First,the ICEM software was used to perform structured mesh delineation of the leaf grid channels and verify the feasibility of the numerical method.The flow characteristics and loss mechanism of the prototype impeller are investigated,and it is found that the flow up and down of the plane diffuser impeller has excellent symmetry,and the starting position of the angular zone separation is located at about 50%of the suction plane pattern line,and the angle zone separation range is large.Secondly,the end-wall surface-attached layer suction and suction surface-attached layer suction were investigated for the prototype impeller,and the influence of different suction slot locations,different suction flow rates on the performance of the impeller,and changes in the flow field structure were systematically studied.It was found that for the suction scheme of end-wall boundary layer,the suction effect is better near the starting point of corner zone separation,and the corner zone separation is changed from closed separation to open separation,which can significantly reduce the loss of corner zone;when the angle of change,the loss of leaf cascade increases with the increase of the angle of change,and the loss under the positive angle develops rapidly along the direction of leaf height and then stalls.Finally,by combining the best suction scheme for the whole leaf suction surface and different end-wall suction schemes,it was found that the end-wall suction trough corresponding to the best combined suction scheme should be close to the starting point of angular zone separation,and the flow field in the middle of leaf spreading was improved.