Influence Of The Trailing Edge Serration On The Aerodynamic Performance Of A High Speed Compressor Cascade

As one of the core components of the aeroengine,the control of the internal flow of the fan/compressor can significantly increase its pressure ratio,reduce losses,and have an important significance for improving the performance of the aeroengine.With the increase of blade load of compressor,the internal flow separation is more serious.The accumulation of low-energy fluid in the boundary layer toward the corner region of suction side causes severe trailing edge vortex shedding and concentrated shedding vortex,which leads to weak mixing,and deteriorated the inlet airflow conditions of the downstream cascade.Therefore,the effective control of secondary flow and corner region separation is of great significance for improving compressor performance.In this paper,based on RANS numerical method,the effect of the trailing edge serration on the aerodynamic performance of a high-speed compressor cascade is investigated.The mechanism of the trailing edge serration as a passive flow control method is analyzed in depth,and the influence of three parameters of serration structure(serration angle ?,chord length ?/H and span position h/H)on the aerodynamic performance of the high-speed cascade is given.At the same time,in order to verify the application scope of the trailing edge serration under the off design conditions,the trailing edge serration cascade with the optimal serration parameter is selected to perform the numerical simulation of off design conditions to verify the applicability of this flow control method.Due to the momentum injection caused by the high-speed jet generated by the serration,as well as the momentum exchange caused by the vortex of the serration jet,the low-energy fluid in the corner region of the cascade obtained new energy.This results in the weakening of concentrated shedding vortex,trailing edge shedding vortex and the weak mixing.Meamwhile,the trailing edge serration located at the proper position could block the transverse secondary flow that migrates from the pressure side of the adjacent blade and plays a role in blocking the radial migration of the low-energy fluid from corner region.Compared with the prototype cascade,after the serration structure is employed on the trailing edge,the wake loss is significantly reduced,and the static pressure coefficient is increased,but the out flow angle is slightly reduced.The three key parameters of the trailing edge serration(serration angle ?,chord length ?/H and span position h/H)are the main factors affecting the aerodynamic performance of the serrated trailing edge cascade.According to the results of this study,the serration structure with angle ?=45° and chord length ?/H=12.5% is located at the spanwise h/H=12.5% from endwall(facing the core region of the low energy fluid)can reduce the total pressure loss coefficient of the cascade reduced by 8.9%,increase the static pressure coefficient by 2.2%,but decrease the out flow angle by 0.93°.The mechanism of the influence of the trailing edge serration on the aerodynamic performance of the cascade is further analyzed from the two different off design conditions of variable incidence and varying Mach number.The results show that the trailing edge serration has a good adaptability,and could improve the aerodynamic performance of the cascade in the range of larger incidence variation and larger range of flow Mach number.When the flow Mach number is Ma=0.5,the total pressure loss coefficient of the cascade can be reduced by 9.3%.Therefore,as a passive flow control method,the trailing edge serration has a strong applicability and application prospects.