Influence Of Casing Treatment On Aerodynamic Characteristics Of Transonic Compressor Rotor

Aero-engines are prone to rotational stall and surge under complex incoming flow conditions.The casing treatment improves the stall margin of the compressor by improving the rotor tip flow and prevents the occurrence of the rotational stall.For the transonic compressor,numerical simulation of three kinds of casing treatment,including single circumferential groove,inclined circumferential multi-groove and reverse blade-angle slot,are carried out.The effects of design parameters such as axial position,depth,width,angle and roughness of the casing treatment slots on the stability of compressor are analyzed.In order to reduce the empirical dependence of the casing treatment design,a research on the proxy model based on axial position was carried out.The research of Rotor37 on circumferential groove casing treatment was carried out,and ten axial positions and three different depths of single circumferential groove were set.By analyzing the difference of tip flow,the variation law that stall margin and peak efficiency vary with design parameters was summarized.It is found that the stall margin is obviously improved when the circumferential groove is located at 10%~20% of the tip axial chord position,and the effectiveness of the shallow groove in the first half of blade tip is better than other groove depths,while the peak efficiency gradually decreases as the groove depth increases.The cross-section change of the circumferential groove affects the aerodynamic characteristics of the compressor.Through qualitative and quantitative analysis of the flow of each circumferential groove,the different effects of radial and inclined circumferential grooves on stall margin are discussed.The results indicate that the effectiveness of incline backward circumferential groove is better than radial form,but the corresponding peak efficiency is reduced.Based on Rotor67 research on the reverse blade-angle slot casing treatment,considering the roughness change of the blade surface,the difference in stall margin is analyzed according to the flow in the slots and the efficiency of casing treatment.The stall margin value of the compressor with smooth blade surface or the rough blade surface is 15.128% and 15.792% respectively,while the change in stall margin is 7.62% and 5.981% respectively.When the surface of the blade is rough,the stall margin value of the compressor is higher,but the amount of change in the stall margin is reduced.The blade surface roughness has a greater impact on peak efficiency than casing treatment.