Investigation On Flow And Heat Transfer Characteristics In Trailing Edge Cutback Of Turbine Blade

Modern gas turbines try to approach these high temperatures to improve performance but are limited by the maximum allowable thermal stresses for the blade material.Generally a combination of film cooling and internal convective cooling is utilized to guarantee wall temperatures One of the most critical region of the turbine blade is its trailing edge,which,from an aerodynamic point of view,has to be as thin as possible.This causes an inherent conflict with cooling requirements as in the manufacturing process difficulties ar ise from the integration of internal cooling passages in the thin trailing edge region.At present,cut-back trailing edge are generally used and the structure is stiffened by rib or pin-fin arrays in the cooling passage working as turbulators to enhance the internal convective heat transfer in the cooling passage and protect the blade..Based on this background,Effects of different geometric configurations on the performance of the cooling film are numerically and experimentally investigated.Different shape and size of the ribs are applied,as well as three different configurations representing manufacturing imperfections and wear.The main conclusions are as follows:(1)For the three trailing edges with different shapes,the adiabatic cooling efficiency and heat transfer coefficients show similar change along the flow direction,both of them decrease with the increase of the flow distance and increase with the increase of the blowing ratio at the same wall position.Taking the experimental and numerical result into account,we can find trailing ed ge model B is the best,and model C is the worst.(2)Angle or area have influence on the flow and cooling characteristics.Specifically,the larger angle(or the larger area)shows better cooling effectiveness,lower heat transfer coefficients and less flow loss.(3)When the rib arrays are imperfect,the more serious the damage condition is,the adiabatic cooling efficiency is lower.When the pin fins and the cooling passages are damaged,the cooling effectiveness decreases obviously.And if the pin fins move for some distance,the cooling effectiveness changes a little.