Research on S₁ stream surface for cooling air mixing and variable thickness flow slice in multi-stage

To reduce the difficulty of aerodynamic design in air-cooled turbine, a set of calculation ideas based on multi-stage air-cooled turbine were presented in consideration of the cooling air mixing, warped S₁ stream surface and variable thickness along with flow passage; the parameterization method program and automatic mesh generation program of warped S₁ stream surface slice with cooling condition were prepared, and the traditional plane slice was modified. Comparative analysis of the difference among the modified plane slice, warped S₁ stream surface slice and three-dimensional calculation was made, and aerodynamic design of a high-pressure turbine with warped S₁ stream surface slice was optimized. The results show that: in comparison with three-dimensional calculation, the maximum gap of mass flow in modified plane slice is up to 22.68%, and 3.58% in warped S₁ stream surface slice; the warped S₁ stream surface slice is closer to three-dimensional calculation on one-dimensional data; blade pressure and Mach number contour distribution of warped S₁ stream surface slice are closer to three-dimensional calculation than that of modified plane slice. After aerodynamic optimization in warped S₁ stream surface slice, compared with original model, the stage efficiency has been increased by 0.41%, while mass flow has only been increased by 0.21%.