Effect Of Non-axisymmetric Endwall Technique On Aerodynamic Performance Of Turboshaft Turbine Rotor Cascade

With the continuous development of modern military level,the performance requirements of turbine,the core component of aviation gas turbine engine,are becoming more and more stringent.For nearly half a century,high thrust to weight ratio,low fuel consumption,long life and high reliability have always been the development goals of aviation gas turbine engine.High inlet temperature,high speed and high efficiency have become the development goals of turbine.The development goal of high thrust to weight ratio leads to that the number of turbine stages cannot be set too much,otherwise the thrust to weight ratio will decrease.The less number of turbine stages will make the flow field more complex.The development goal of high efficiency requires that the internal flow field of turbine should not be too complex,otherwise the loss will further increase and the efficiency will be reduced.Therefore,how to effectively control the internal loss of turbine has become an urgent problem.In this paper,the turbine rotor cascade of a turboshaft engine is taken as the research object.Firstly,the wind tunnel test of the test cascade is carried out,and the numerical simulation is carried out.The comparison results show that the numerical simulation has high accuracy.Next,the parameters in the numerical simulation results are analyzed in detail.The development and trend of the main vortices in the flow field are obtained,and the loss caused by each vortex is analyzed.Finally,according to the analysis results,the non-axisymmetric endwall is selected to optimize the turbine rotor cascade.Ten kinds of non-axisymmetric endwall with different shapes are constructed by using double control profile method.Ten kinds of non-axisymmetric end walls are divided into three groups according to the modeling characteristics.The wave troughs of the first group of endwall in different circumferential positions are close to the suction surface,and the wave peaks are far away from the pressure surface.In addition,the peak and valley decrease gradually along the axial direction;The wave troughs of the second group of end walls in different circumferential positions are close to the suction surface,and the wave peaks are far away from the pressure surface.In addition,the wave crest and wave trough increase gradually along the axial position;The wave troughs of the third group of end walls are far away from the suction surface at different circumferential positions,and the wave peaks are close to the pressure surface.The simulation results of three groups of non-axisymmetric endwall are compared with those of the prototype cascade under the design condition(isentropic exit Mach number 0.66).According to the results,the influence of different non axisymmetric endwall on the secondary flow and loss in the cascade is analyzed.The results show that the secondary flow in the cascade can be effectively controlled and the loss can be appropriately reduced by only setting an appropriate height of non-axisymmetric endwall near the leading edge.According to the average total pressure loss coefficient of outlet under seven working conditions(isentropic outlet Mach number 0.5,0.58,0.6,0.66,0.7,0.74,0.8),the general characteristics of control loss of end wall with different shapes under different working conditions are analyzed.In the off design condition,the special condition is selected for analysis.The results show that under some conditions,the lower passage vortex with a small climb distance along the spanwise direction will lead to the mixing of the lower passage vortex with the suction surface boundary layer and the lower end wall boundary layer,resulting in the formation of vortices with large vorticity downstream of the trailing edge,resulting in a significant increase in the loss.