The Effect Of End-wall Transverse Jet On The Loss Of A High Speed Compressor Cascade

The high-pressure ratio and high-efficient compressor is the guarantee of future advanced aircraft performance.While the pursuit of high pressure ratio will increase the mainstream and transverse pressure gradients,thicken the wall boundary layer and enlarge the effect and range of secondary flow in the cascade.Consequently as the flow separation across the cascade aggravates,the loss increases correspondingly.The secondary flow loss can give rise to aerodynamic unstability phenomena such as surge and stall in severe case.Therefore the major academia research direction is to control flow separation and improve the cascade aerodynamic performance.A new method using transverse end-wall jet is proposed to control the secondary flow in a high speed compressor cascade with an inlet Mach Number of Ma=0.67,which is adopted to numerically simulate schemes of vari ed axial and circumferential locations at different jet angles respectively.In order to determine the optimal scheme,diverse jet slot length and pressure ratio control effects on t he cascade aerodynamic performance have been compared severally.On this basis,it is worth further studying the jet vortex improvements on secondary flow under the condition of various attack angles as well as the end-wall jet control mechanism which suppresses the flow separation in the cascade.Results show that the total pressure loss coefficient reduces firstly and then increases with the end-wall jet due to the axial shift,the augmented circumferential shift which is away from the suction surface as well as the increased skew angle.When chosen the jet slot length of 4mm and the jet pressure ratio of 1.15,the optimal control scheme can be attained at 40% of the blade chord and 10% of the pitch with a skew angle of 40°.Under off-design conditions,all sorts of added endwall jet schemes can reduce total pressure loss signally.Furthermore,the flow performance improvement increases at first then decreases along with an increscent skew angle.Additionally,the generated jet vortex with a certain distance from the suction side shows a potential ability to control the flow separation in the end-wall region by constraining the development of passage vortex,entraining the low energy fluid in the corner region and obstructing the evolution of transverse second flow.Because it is benefited by blowing down the end-wall boundary layer and impeding its circumferential shift with the use of normal and circumferential velocity component correspondingly.There exists an appropriate position that can decrease the cascadde aerodynamic loss dramatically and obtain a maximum relative loss reduction up to 13.9% at the attack angle of 2°.