Semi-Inverse Design Optimization of Film Cooling Arrangement and Its Prediction of Coolant Amount of HPT Vanes

Abstract

Film cooling design is essential for modern HPT vanes. In this paper, a semi-inverse design optimization (SIDO) method for the film cooling arrangement of HPT vanes is introduced, which is based on a combinatorial optimization algorithm, a 1D heat conduction model and CFD methods. The SIDO method can optimize the total coolant amount of the film cooling structure while ensuring an acceptable metal temperature distribution. The optimization methodology was tested on a 2D vane derived from the 1st stage nozzle of a heavy-duty gas turbine, and the optimization result was validated by the conjugate heat transfer (CHT) CFD simulations. In further study, the SIDO method is applied to predict the optimal (necessary) coolant amount of the vane at various design conditions with different inlet temperature, maximal metal temperature allowed, heat conductivity of TBC, and intensity of internal/film cooling structures. The quantitive results suggested that the inlet temperature and the maximal metal temperature allowed are arbitrary to the necessary coolant amount. Improving film cooling performance is more effective to save coolant compared with internal cooling, especially at higher inlet temperature level. NOMENCLATURE c p Specific heat at constant pressure D Diameter of film hole d Thickness h Convective heat transfer coefficient k Turbulence kinetic energy / Number of sample points on PS & SS M Objective function m Mass flow N Population size (of GA) n Number of candidate holes p Pressure p * Total pressure q Wall heat flux T Temperature T * Total temperature X Streamwise distance x Bit of the design variable Y Spanwise (lateral) distance Greeks η Adiabatic film cooling effectiveness λ Heat conductivity ε Turbulent dissipation rate Subscripts ave Area-averaged c Coolant /