The Investigation Of The Performance Of Bowed Blades In High-turning Turbine Cascades

In recent years,with the gradual development of aero engine field,the thrust weight ratio of aero-engine increases gradually,and the load of aero turbine increases gradually.Since 1980 s,the main method to improve the turbine load is to increase the turning angle of the turbine blade.The results show that serious flow separation and eddy currents exist in the flow field of high angle and high load turbine cascades.This phenomenon seriously affects the aerodynamic performance of the cascade and the cascade loss play.In order to weaken this loss,it is often used to improve the aerodynamic performance of blades by bending the blade.In this paper,the influence of bowed blades on the flow field structure and aerodynamic performance of cascades is studied based on the CFD method.The influence of the geometric parameters on the aerodynamic parameters is analyzed,and the effect of the bending angle on the vortex structure of the cascade flow field under typical working conditions is discussed,and the cause of the loss is analyzed.Based on the experimental results of the 113 degree plane cascade,this paper verifies the correctness of the turbulence model used by the numerical method,and then verifies the unrelated grid of the original blade type three dimensional cascade.The results show that when the number of grids is 1 million 500 thousand,the number of lattices will not increase the result of the calculation.Combined with the above contents,the reliability of numerical simulation is proved.Secondly,a large number of calculation schemes with different bending height(10%,30%,50%),different bending angles(-30 ~30 degrees)and different punching angles(-9 ~9 degrees)are designed.The three-dimensional modeling of curved blades is carried out by the curved blade modeling program developed by the pneumatic center of Harbin Institute of Technology.The numerical calculation is carried out and the geometric parameters are studied on the cascade.The influence rule of performance parameters(loss coefficient,lag angle,etc.)is also discussed.Finally,the cause of the loss in the flow field is investigated.The research shows that the main source of cascade loss is the separation of flow generated by the interaction between the passage vortex and the trailing edge vortex.