The Research Of Film Cooling Effect About Geometric Construction And Liquid Drop

As an important power plant,gas turbine is widely used in many fields,such as aerospace,ship,vehicle,power station and so on.The turbine blade is an important component of gas turbine,gas film cooling is to prevent the turbine blades during operation are always subjected to high temperature gas cooling technology of erosion,improve film cooling technology can not only prolong the life of turbine blade,but also improve the operation efficiency of gas turbine efficiency.In the course of the study,the effects of film cooling effect are the main flow parameters of cold and hot fluid(blowing ratio,hot and cold fluid temperature,momentum flux ratio),different pass into the cold fluid(cylindrical hole,special-shaped hole,slotted hole etc.).In this paper,based on the structure of slotted hole,the hole structure and the slot structure were changed to study the effect of the slotted conical hole and the four slot structure on the gas film cooling effect.The study found that the film cooling efficiency of cone hole is higher than that of the cylindrical hole;the film cooling effect on both sides of the wall opening slot to improve the inclined transverse and spanwise.In actual operation,the turbine blade is not only affected by high temperature erosion,corrosion by high temperature gas carrying pollutants,pollutant particles in the molten state in high temperature gas.It formed deposition when in contact with the turbine blades,causing thermal barrier coating fracture and fall off,having a certain impact on the film cooling.Aiming at the above problems,this paper studies the effect of deposition on gas film cooling by numerical simulation method;in order to improve the film cooling efficiency,adding a small amount of liquid droplet spray in the cooling gas.The results show that the deposition of pollutants before the film hole decreases the film cooling efficiency of flowing direction,but the effect of film cooling on the wall broad direction is improved.The cooling efficiency of the deposited wall film cooling efficiency is higher than that of the film cooling efficiency without deposition.Considering the effect of the deposition after film hole on the wall film cooling,with the increase of the deposition height,the high value film cooling effect region gradually toward the deposition.The effect of adiabatic film cooling on the lower wall of the wall is decreased.When the droplet is added,with the deposition height increases,the evaporation of the liquid droplet and the lateral diffusion of the wall surface are enhanced,and the coverage area of the film cooling on the wall surface is enlarged.About the influence of the distance from the outlet of the film hole,the distance from the gas film hole determines the position of the cooling gas break away from the wall.The effect of deposition on the film cooling effect of the upstream wall is not very significant.The film cooling effect of lower wall is significantly improved by adding 4.4% droplets in the coolant.