Analysis Of Cooling Performance Of Turbine Blades Based On Improved Correlation Of Film Cooling Efficiency

With the improvement of gas turbine performance,the inlet temperature of the gas turbine is increasing year by year,and the cooling structure of the turbine blade is becoming more and more complicated.Therefore,rapid and accurate thermal analysis of the blade is an important step in the design of the cooling structure.The pipe network method can quickly calculate the complex flow and heat exchange of internal fluid by reducing the dimensionality of the internal cooling structure of the blade.By coupling with the external heat exchange program,it can estimate the external wall surface temperature distribution of the blade before the detailed design of the blade cooling structure,so it can screen different cooling schemes and it is the basis for blade thermal analysis.In this paper,for the application of the pipe network method in blade thermal analysis,the control equations involved in the fluid in the pipe are deduced in detail,and the solution method is introduced.A pipe network program with an elbow model is constructed and compared with the three-dimensional calculation results of the serpentine channel,and it is found that the pressure and temperature changes obtained by the two calculation methods are the same,and the maximum relative errors are 1.8%and 0.97%,respectively.This shows that the pipe network program can be used to calculate the internal fluid flow and heat transfer.Aiming at the outflow of gas film,this paper fits two sets of empirical formulas for calculating the cooling efficiency of the gas film in a single row of cylindrical jet holes.The applicable ranges are0.2≤M≤0.6and0.6<M≤1.2,respectively.Compared with the empirical formula,the fitting accuracy has been improved,and the value ofR~2 has reached more than 0.9,indicating that it has a good fit.Coupling the pipe network program with Fluent and applying it to the Mark II blade thermal analysis calculation.By comparing with experimental data,the feasibility of the pipe network coupling algorithm is verified.The pipe network coupling algorithm is used to predict the temperature of the outer surface of the Mark II blade with a serpentine channel.The temperature distribution trend is basically consistent with the three-dimensional calculation results,and the position of the high temperature area on the outer surface of the blade is predicted.Finally,combined with the empirical formula of film cooling efficiency,the temperature of the gas film outflow was modified,and a pipe network coupling algorithm suitable for gas film outflow was constructed and used to estimate the temperature of the outer wall surface temperature distribution of the Mark II blade with gas film holes,the relative errors of the calculated maximum temperature,minimum temperature and average temperature of the outer surface of the blade and the three-dimensional calculation results are 0.43%,5.5%and0.81%respectively,which provides a basis for rapid screening of cooling schemes...