Pre-swirl Vane Geometry Optimization to Improve Discharge Coefficient of Gas Turbine Pre-swirl System

The design of a secondary air system for the air delivery path of a gas turbine cooling system is very crucial because its performance could directly impact on the efficiency and the reliability of turbine cooling system. To meet the desired pre-swirl system performance, the geometry of a vane type pre-swirler was optimized to improve the discharge coefficient by using CFD analysis. Four design variables were selected after sensitivity analysis and the objective function was to maximize the discharge coefficient. The Kriging surrogate model was built and refined iteratively until the difference between predicted point and CFD result was less than 0.1%. The optimized model improved the uniformity of static pressure variation on the cooling path by decreasing converging angle and increasing converging length. As a result, the discharge coefficient of optimized model has a 2.86% increased over the discharge coefficient of the initial model.