Research On The Influence Of Aerodynamic Boundary And Reaction Degree On The Performance Of High Exit Mach Number Turbine

The development of high-performance aero-engine technology is a key technology that countries around the world are vying to pursue and master,and it is related to national security and economic development.High efficiency,light weight and high thrust have become the goal pursued by scientific and technological workers,which will inevitably make the engine turbine blades work under high load,that is,the turbine exhibits transonic motion with high drop pressure ratio and high exit Mach number.At the same time,the turbine inlet temperature will continue to increase,and the key cooling structure of the turbine blade design is indispensable to protect it,extend the life of the turbine,and improve the reliability of the turbine.Therefore,it is very important to study the flow characteristics of single-stage transonic turbine blades with high exit Mach number.Especially in the case of cold air injection,how the cold air affects the flow can be provided more references and basis for the design of this single-stage transonic turbine.First,this paper takes the designed five reaction degree blade profiles as the research object,uses numerical simulation and controls the flow rate and pressure ratio to study the influence of reaction degree selection on the flow of a single-stage high-outlet Mach number transonic turbine.Also change the pressure ratio and speed to analyze the turbine characteristic line.The results show that for the single-stage high-exit Mach number transonic turbine studied in this paper,when the drop pressure is relatively high,no matter whether it is high reaction degree or low reaction degree,there are shock waves in the rotor blades.The change of reaction degree also has a significant effect on the profile pressure distribution.With the increase of reaction degree,the load of the static blade of the aft-loading blade decreases,the moving blade changes from front loading to fore-loading.And the tail shock incident point in the moving blade gradually approached the trailing edge,while the tail shock incident point in the stationary blade gradually approached the leading edge.For the characteristic curve,the flow rate increases with the increase of the pressure ratio until it reaches the critical point,and the efficiency first increases and then decreases with the increase of the pressure ratio.With the increase of the reaction degree,the critical pressure ratio becomes larger,and the efficiency decreases faster at the high pressure ratio.Subsequently,this paper selects two relatively high and low reaction degree blade shapes,and conducts a numerical study in the case of film cooling.Considering the position of the air film hole on the suction surface and the flow rate of the air film hole jetting cold air,the flow characteristics in the flow channel,especially the influence of the wave system structure,are studied.The results show that the changes caused by the changes of these two factors with different reaction degrees and different positions are different,and will have different influence on the intensity and angle of the inner tail shock wave.The cold air position near the upstream of the inner tail shock wave can weaken the reflected wave,and when the air film hole moves downstream,the reflected wave increases again.The change of cold air injection position and cold air volume mainly affects the load of the front and middle of the blade,and also affects the pressure rise of the tail.There is the best position(relative arc length 60%)and the best cold air volume(4.5g/s)which let the pressure rise gentle,the surface shock weaken,and the loss there be reduced.Finally,this paper studies the influence of the total inlet temperature on the aerodynamic performance of the transonic turbine.It also compares the numerical simulation results of the high and low reaction degree blades.The given total inlet temperature changes in a parabolic curve along the blade height,compared with fixed value along the blade.The results show that as the curve opening decreases,the impact on the load is consistent with the high and low reaction degrees,the tip and root loads decrease,and the blade mid-section load increases.In the two reaction degree blade shapes,the disturbance of the cooling air to the main flow are increasing,and the tail shock wave in the flow channel becomes straight and the incident point gradually moves to the trailing edge.Comparing the export parameters,the blade profile with different reaction degrees is affected differently in addition to the export Mach number.For the outlet Mach number,it is relatively uniform and does not change much;For the outlet static pressure,the high reaction degree leaf shape fluctuates in a "W" shape,and the low reaction degree leaf shape shows an inverted "S" shape fluctuation;For the outlet static temperature,high reaction rate The degree leaf shape fluctuates in a "W" shape,and the low reaction degree leaf shape fluctuates in an "S" shape.