Secondary Air Performance Optimization of a Combined Impingement and Film Cooled Gas Turbine Nozzle Guide Vane

Multi-objective optimization of the film cooled holes for the coupled impingement-film cooled nozzle guide vane is conducted. Two objectives are considered to be minimized: coolant jet exit total temperature and static pressure drop, to assess the trade-off between them. Three-dimensional computationally using SIMPLE algorithm analysis and a k-ω SST turbulence model are used for generating a data base. The plenum mass flow rates and mainstream velocity are considered as the two design variables. The second order polynomial response surface method is chosen to develop the objective function approximation. The multi-objective optimization has been carried out with help of a genetic algorithm and sequential quadratic programing (fminicon) in MATLAB 7.11.0 (R2010b). The Pareto-optimal design points are obtained as the plenum coolant mass flow rate of 0.004kg/s and mainstream velocity of 10m/s. Based on these results, the global minimum coolant jet static pressure drop of 32.5 Pa and global minimum jet exit total temperature of 312K are observed for the film holes of the NGV surface. At these operating conditions, the coupled impingement -film cooled NGV is subjected to its higher safety and durability. This happened due to without cause of hot gas ingestion into the film cooled jets of the typically cooled NGV.