Research On Flow Control In End Zone Of Turbine Cascade For Gas Turbine

The Gas turbine turbines,especially large-meridian expansion turbines,often have a large end zone secondary flow,resulting in large end zone secondary flow loss,which reduces the aerodynamic performance of the turbine and also affects the end zone heat transfer.Brought great difficulties.Therefore,it is very important to adopt effective methods to improve the end zone flow of the turbine,especially the large-meridian expansion turbine,and reduce the end zone flow loss,which is of great significance for improving the aerodynamic heat transfer performance of the existing turbine.Aiming at the large end zone secondary flow loss of typical turbine blades,This article used numerical simulation methods to control the secondary flow in the end zone of the turbine by using Blended Blade and Endwall technique and non-axisymmetric endwall technique Conducted related research.This article first studied the effectiveness of Blended Blade and Endwall technique in turbine aerodynamic optimization.Taking the first stage cascade of the E3 model high-pressure turbine as the research object,different forms of modeling were performed on the stator blades,rotor blades and the lower end walls of the suction surface of the stator and rotor blades,and the Blended Blade and Endwall technique was studied Contribution to reduce end wall aerodynamic loss and improve turbine stage efficiency and power capability.The research results showed that the application of Blended Blade and Endwall technique for high-pressure turbines can effectively increased the low-pressure zone minimal value and reduced the low-pressure area of the turbine end zone,thereby improved the load distribution in this area of the cascade,reducded local flow loss in the end zone,and slightly lifting the turbine.The overall performance of the stage was functional,but at the same time it increased the flow loss at the position of the maximum fusion fillet radius.when the relative radius of the stator blade and the maximum fusion fillet of the rotor blade were 0.16 and 0.19 respectively,the relative axial chord length positions were respectively at 0.47 and 0.80,the overall effect of turbo lifting was the best.At this time,the isentropic efficiency was increased by 0.038%,and the specific power was increased by 0.048%.Secondly,based on the research on the application of E3 high-pressure turbine Blended Blade and Endwall technique,the effect of technique on the flow in the end zone of the large-meridian expansion low-pressure turbine was studied.The research results showed that the application of Blended Blade and Endwall technique to the large-meridian expansion low-pressure turbine vane slightly increased the specific power of the turbine and improved the performance of the turbine stage,but it cannot effectively improved the efficiency of the turbine stage.the Blended Blade and Endwall technique can effectively improved the load distribution in the lower end area and rotor leading edge,and reduced the local flow loss in the cascade local region,but it cannot effectively improved the flow in the upper end area.When the Blended Blade and Endwall technique was applied to the lower end wall of the suction surface of the vane alone,when the relative radius of the maximum fusion fillet was 0.35,and the relative axial chord length position was 0.67,the efficiency and specific power have a maximum value.At this time,the efficiency was consistent with the prototype,and the specific power was increased by 0.059%.Finally,based on the analysis of the vane flow field of the original large-meridian expansion low-pressure turbine stage,non-axisymmetric endwall technique was applied to its upper endwall,and the improvement of the overall aerodynamic performance and local flow of the large-meridian expansion turbine by the non-axisymmetric endwall technique was studied.The research results showed that the non-axisymmetric endwall technique can effectively reduced the lateral pressure gradient in the end region of the cascade,thereby reduced the lateral secondary flow in the cascade channel,reduced the channel vortex loss,and effectively improved the isentropic efficiency and ratio of the turbine stage.At the same time,it also enhanced the horseshoe vortex loss at the leading edge of the cascade and the loss of the trailing edge shedding vortex at the cascade exit.When the radial height change amplitude was 8.6% of the stator blade height and 17.8% of the axial chord length,the efficiency and specific power increased the most,increasing by 0.225% and 0.209% respectively.