| Accurate prediction of heat loading and temperature distribution of gas turbine vanes is important to the design of highly efficient cooling scheme and the evaluation of cooling efficiency, which can increase the security and durability. Nowadays, there are two distinct methods to predict the blade temperature distribution, the conventional heat transfer method and the conjugate heat transfer method. Systematic numerical and experimental investigations are performed on the influences of heat transfer coefficient distribution in conventional heat transfer analysis, Biot number in conjugate heat transfer analysis and conjugate effects to film cooling effectiveness. Conjugate heat transfer simulation and analysis of the original closed-loop steam cooling design of a turbine vane is carried out and improvement designs are proposed.Based on the experimental data of the Markâ…¡ vane and the solid heat conduction calculation method, the impact of external surface heat transfer coefficient distribution on the external surface temperature distribution is investigated. The results show that the distributions of external temperature and heat transfer coefficient are closely related. When the heat transfer coefficient is derived from empirical correlations (laminar or turbulent), the predicted temperature distribution differs a lot with experimental data. When the heat transfer coefficient is derived from computation with transitional turbulence model, the predicted temperature is close to the experimental data, and the predicted temperature distribution by using the uniform heat flux boundary gives the best agreement.A linear cascade and a multiple camera imaging and processing system are established. The heat transfer coefficient distribution on the external surface of a vane without film cooling under the first kind boundary condition is measured by using the narrow-band liquid crystal transient single-color capture technology. And the heat transfer coefficient distributions on the external surface of conjugate vane under different Biot numbers are obtained by using the steady-state wide-band liquid crystal technology. The results show that the discrepancy of heat transfer coefficient occurs under different thermal boundary conditions, and the maximum difference occurs at the transition region of the vane suction side.The influences of Biot number and blowing ratio on laterally averaged overall film cooling effectiveness, net film cooling effectiveness, and heat flux of flat plate film cooling are investigated based on conjugate heat transfer simulation. Due to the effect of solid heat conduction, laterally averaged overall cooling effectiveness is higher than adiabatic film cooling effectiveness. The trend of laterally averaged net cooling effectiveness under different blowing ratio is consistent with the adiabatic case, but has lower values. The upstream region of film cooling hole is also cooled by the coolant. There are some locations where the mixture of coolant and main stream is heated by the solid wall. When using the usual definition of heat transfer coefficient in conjugate simulation, the value of heat transfer coefficient may be infinite or zero at specific locations. This indicates the usual definition of heat transfer coefficient is not sufficiently rigorous on the region with both positive and negative heat flux.The guide vane with original closed-loop steam cooling configuration is simulated integrally by using the conjugate heat transfer method, and the cooling efficiency is analyzed. There are several low overall cooling effectiveness regions at the external vane surface. Through the detailed flow and heat transfer analysis of all coolant circuits, the key problem of the original design is found and the corresponding modification designs are proposed. The low overall cooling effectiveness regions for the modified design are suppressed or eliminated, and the reduction of area-averaged temperature on the whole external surface is about14K.
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