Research On Aero-thermal Mechanism By Blended Blade And Endwall Technique Of Turbine Vane

The rapid growth of world economy and today’s environmental consciousness have led to high economical and ecological standards for gas turbines.In this context,a high thermal efficiency is demanded for gas turbines,which is since many years achieved by employing high turbine inlet temperatures.This,however,yields a high thermal loading of e.g.the turbine endwalls.One way to reduce this loading is the application of contoured endwalls between the turbine vanes.By optimizing the geometry of the junction of endwall and blade to control the secondary flow in the region,the purpose of controlling the heat load in the endwall region is achieved.Therefore,this paper will optimize the geometry of the high-pressure turbine endwall rigion.This paper selects one of endwall contouring optimization design,which is a more effective way to meet the designers-that is the BBEW(Blended Blade and Endwall)technique.Its application in the compressor has confirmed that BBEW can effectively control the corner separation.The application of BBEW in turbine is not currently widely used.The load of high-pressure turbine is higher.Expansion of the meridional and secondary flow in turbine is stronger.Which means it is worthwhile to apply BBEW for high-pressure turbine endwall contouring design.Therefore,this paper firstly studies on the adaptability of BBEW in the aerodynamic design of high-load turbine.The effectiveness of BBEW on the high-load turbine was verified by the design of the junction contouring between blade and endwall of the first-stage guide vane of the E~3 model.Numerical simulation results show thatAfter that,this paper carried on the BBEW technique in the project practical application and analyzed the effects of BBEW.By applying the BBEW technique and its optimization method on a realistic high pressure turbine vane,this paper optimized the contouring of blade and endwall junction.Simulation results show that:After optimization,loss of secondary flow was reduced.By analyzing the influence of the flow around the endwall and the loss of the end wall before and after optimization,the design experience of the BBEW technique was further enrichedAt last,this paper studied the influence and optimization of BBEW on the thermal load and film cooling design of the endwall.The state of secondary flow conditions have a direct impact on the film cooling.The heat loading distribution and cooling effects were analyzed before and after optimization of a realistic high pressure turbine vane.Simulation results show that the BBEW technique affected the temperature distribution on the blade surface and the end wall surface,and reduced the average wall temperature of the solid wall surface.The BBEW technique also had an impact on air-cooled design,and increased the coverage area of cold air.