Numerical Investigation Of Film Cooling Of Gas Turbine Blades

Effective cooling of high-temperature turbine blade is the key technology to improve the performance and lifetime for gas turbine.Film cooling can separate the high-temperature gas and blade surface,and it is the effective way to blade cooling.The cooling efficiency is affected by the aerodynamics of gas turbine,the geometry of blade and the property of cooling gas.In this study,numerical simulation is carried out to study the film cooling for 3D plate and the first-stage stator blade in a heavy duty gas turbine.Firstly,the film cooling over the 3D plate is numerically simulated with the coupled flow and heat transfer,the effect of aerodynamics parameters,injection angles of cooling gas,hole geometry on the cooling efficiency is investigated,and the variation trend and the reasons are provided.Then,the numerical model is built up for the first-stage stator blade of a heavy-duty gas turbine,the structured grids are adopted to discretize the computational domain.The effect of aerodynamic parameters,such as the blow mass ratio,temperature ratio,on the cooling efficiency is investigated.Because it is difficult to improve the film cooling greatly with single-phase air,the mist cooling is proposed for effective film cooling,i.e.the tiny droplets are mixed into the cooling air.As a great amount of heat is absorbed during mist vaporization,the film cooling efficiency can be improved greatly.Finally,the mist cooling in stator turbine blade is numerically simulated,it is found that the high blowing ratio,and high Reynolds number can improve the cooling efficiency near the film hole,while they have limited effect on the region far from the film hole.The large injection angle for mist cooling can reduce the cooling efficiency,and the expansion hole can improve the cooling efficiency compared with the usual round hole.There is upper limit for cooling efficiency when the temperature ratio is increased.Compared with the single-phase air cooling,the mist cooling can improve the cooling efficiency greatly,furthermore,the increased mass concentration of droplet can lead to the increased cooling efficiency.This study is of great significance for the efficient blade film cooling for heavy-duty gas turbine.