Effects of coolant on twisted S₁ stream surface optimization in multi-stage turbine

Multi-stage turbine aerodynamics optimization process was designed with the core of twisted S₁ stream surface optimization, and the effects of film cooling air, trailing edge coolant, endwall coolant were researched on validity and reliability of the twisted S₁ stream surface optimization. This process could advance parallel optimization for multi-stage twisted S₁ stream surface with blade coolant in variety of blade height, which can improve twisted S₁ stream surface optimization reliability. There were three blade coolant plans for a two-stage high pressure turbine: blade body coolant including of film cooling air and trailing edge coolant, film cooling air, without blade coolant, and the design of twisted S₁ stream surface optimization was conducted. The average aerodynamic efficiency of twisted S₁ stream surface increased by 0.20%, 0.38%, 0.07% and turbine aerodynamics efficiency increased by 0.34%, 0.32%, 0.28%, respectively. The optimization reliability was good. After analysis it is concluded that, film cooling air enhances radial secondary flow and then decreases the optimization validity, while trailing edge coolant weakens the negative effect of film cooling air partially. The bottom endwall coolant has more effect on secondary flow near endwall region than top endwall coolant, so the former plays a better positive role on S₁ stream surface optimization.