Study On The Influence Of Tip Coolant Injection On Turbine Blade Tip Flow And Heat Transfer

The high-pressure turbine rotor blade is a power component of the high-pressure turbine.The leakage flow generated by the blade tip clearance causes the flow loss of the turbine,and the heat transfer between the high-temperature leakage flow and the blade tip wall leads to the turbine rotor blade tip to bear extremely high temperature load,so turbine rotor-blade tip is extremely prone to forming ablation.The rotor blades of modern high-pressure turbines generally employ the squealer-cavity blade tip structure.It is significantly important to study the flow and heat transfer characteristics of the squealer-cavity turbine blade tip,and which under the blade tip cooling jet.In this paper,the numerical simulation method is used to study the flow and heat transfer characteristics of the first stage rotor blade tip of the GE-E~3 high-pressure turbine,in order to provide a reference for the turbine blade tip structure and cooling design.This paper first studies the flow and heat transfer characteristics of the squealer-cavity turbine blade tip,considering the effects of the blade tip clearance height and the squealer cavity depth.The results show that the height of the blade tip clearance and the depth of the squealer cavity have opposite effects on the strength and size of the tip leakage vortex and the upper passage vortex,the leakage vortex core loss,and the static pressure in the tip area.With a small tip clearance,an increase in the depth of the squealer cavity can reduce the flow total pressure loss of the turbine.At the same tip clearance height,the increase in the depth of the squealer cavity can effectively reduce the tip leakage flow rate and the heat transfer between the leakage flow and the blade tip wall surface.In order to further study the influence of the tip cooling jets on the flow and heat transfer characteristics of the squealer-cavity turbine blade tip,different positions and numbers of jet holes are considered.The results show that the positions of the tip jet holes have little effect on the size of the tip leakage vortex and the upper passage vortex,however,for the pressure-side jet on the blade tip,increasing the number of jet holes can make the strength and size of the tip leakage vortex and the upper passage vortex decrease slightly.Tip jets reduce the total pressure loss of the leakage vortex core,but increase the total pressure loss around the leakage vortex core.Tip jets have little effect on reducing turbine flow losses.Compared with the pressure-side jet and the suction-side jet on the tip of the blade,the mid-camber jet on the tip of the blade can obtain the best tip film-cooling effect.Increasing the number of tip jet holes can significantly increase the tip film-cooling effect.