Investigations On Effects Of Non-Axisymmetric Endwall And Bowed Blade On Corner Separation In Compressor Stator

The development trend of high thrust-weight ratio,high efficiency and low fuel consumption of aeroengine puts higher requirements on the performance of the compressor.Increasing the single-stage load of the compressor is one of the most effective ways to improve the thrust-weight ratio of the aeroengine.However,with the increase of compressor load,the adverse pressure gradient and transverse pressure gradient in the stator passage will increase,which will lead to the corner separation.As one of the most common complex flow phenomena in high-load compressors,corner separation can cause great harm to the performance and stability of the compressor.Therefore,using effective flow control methods to suppress stator corner separation is of great significance to improve compressor load and thrust-weight ratio of aeroengine.Firstly,the effects of non-axisymmetric endwall and bowed blade on the flow in the stator corner region and its mechanism are investigated by numerical simulation.The numerical results of the non-axisymmetric endwall show that the non-axisymmetric endwall can reduce the accumulation of low-energy fluid in the stator corner region by reducing the backflow at the trailing edge and changing the strength and direction of the passage vortex,thus achieving the purpose of suppressing the corner separation.The non-axisymmetric endwall with an amplitude control factor of 6.5% has the strongest ability to suppress the corner separation,which increases the maximum efficiency of the compressor by 0.71%.The numerical results of the bowed blade show that the radial force caused by the positively bowed blade make the low-energy fluid migrate upward from the blade root,which reduces the accumulation of low-energy fluid in the corner region,thereby weakening or even eliminating the corner separation.As the bowed angle and bowed height increase,the ability of the bowed blade to control the low-energy fluid in the vicinity of the blade root region is stronger.when the bowed angle reaches a certain degree,the concentrated vortex in the stator corner region is eliminated.Secondly,the numerical study on the influence of the combination of bowed stator and non-axisymmetric endwall on the flow in the stator corner region is carried out.The results show that: The ability to suppress corner separation of bowed blade and non-axisymmetric endwall combination is stronger than that of bowed blade.For bowed blade with large separation,the non-axisymmetric endwall can significantly reduce the strength of corner separation.Finally,a multistage low-speed compressor test platform was established to systematically study the effects of bowed blade and non-axisymmetric endwall on the flow in stator corner region.On this basis,the detailed flow field measurement of the straight blade stator is carried out,and the verification experiment of the influence of the bowed blade on the flow in the stator corner region is preliminarily completed.The experimental results reveal the flow field structure and the development of the vortex inside the straight stator passage.It is verified that the bowed blade can effectively reduce the accumulation of low-energy fluid in the endwall region,thus weakening the strength of corner separation and reducing total pressure loss in the tip area.At the 80% relative blade height position,the bowed stator has a 20% reduction in the total pressure loss coefficient of the straight blade.