Experimental And Numerical Investigation On Film Cooling With Tabs

Film cooling is used extensively in gas turbine engines for cooling hot components. Traditional film cooling is already incapable to meet the cooling of hot components with hot components of engines in increasingly detrimental situation. Film cooling with tabs is a new kind of cooling technique which effectively improves cooling effect. Three types of tabs with different geometrical configuration, such as triangle,trapezoid and ellipse, were designed and experimental setup of film cooling were established. The infrared camera is used to measure the temperature distribution on the wall. Film cooling efficiency,the convective heat transfer coefficient and discharge coefficient were obtained. Based on Fluent- CFD commercial software, numerical simulation was performed on the heat transfer character of the cooling with tabs. The main research conclusions are the followings:(1) The cooling effectiveness with tabs is enhanced and is much higher than that with no tabs. Blowing ratios are very important influence on the cooling effectiveness. For the different tabs, blowing ratios are different influence on cooling effectiveness at different cooling areas. For the same tabs, the cooling effectiveness is increased with the increases of the film at the same blowing ratio. For the different tabs, the cooling effectiveness with trapezoid tabs is highest and he cooling effectiveness with triangle tabs is lowest at the same blockage ratio, but the cooling effectiveness with trapezoid and triangle tabs is higher than that with no tabs.(2) The tabs are influent on the convective heat transfer coefficient of the film cooling, but the influence of the convective heat transfer coefficient is different at different blockage ratio. Triangle tabs and no tabs of the convective heat transfer coefficient has a little difference at B=0.107 and B=0.214, but the convective heat transfer coefficient with triangle tabs is obviously higher than that with no tabs. The convective heat transfer coefficient with trapezoid and ellipse tabs is bigger than that with no tabs at all blockage ratios, the heat transfer effect with trapezoid tabs is best at B=0.214.(3) The tabs are bigger influent on the discharge coefficient of injection holes. The discharge coefficient of injection holes(Cd) with tabs is decreased with the increases of the blockage ratios. Cd is biggest at no tabs.