The film cooling performance of spiral-channel holes on turbine guide vane

A spiral-channel hole is implemented to heighten the cooling performance of turbine vanes by inducing swirling flow. Numerical simulations examine and compare the film effectiveness and flow structure at four positions. The impact of various factors, such as blowing ratio, hole position, and mainstream Reynolds numbers, on film effectiveness is studied. The spiral-channel hole provides superior cooling effect compared to the cylindrical hole on the suction and pressure sections. When M is 0.5, the coverage range of the spiral-channel hole, where film cooling effectiveness exceeds 0.25, is twice as large as that of the cylindrical hole. The cooling performance difference between the two types of holes is minimal at the leading edge of the turbine vane. The optimal blowing ratio for the spiral-channel hole to achieve maximum cooling performance is 2.0. The groove structure on the inner wall of the spiral-channel hole induces numerous vortices, which deflect the streamlines inside the spiral channel, improving the adhesion of the coolant to the vane surface. The local radial pressure gradient at the outlet suppresses the coolant flow, enhancing its adhesion to the vane surface. The acceleration effect resulting from the streamwise pressure gradient reduces the mixing speed of the fluids. Collectively, these effects enhance the film effectiveness. Increasing Reynolds numbers expands the transverse coverage region of the mixed fluid. But it also lowers the temperature of the cooling film. The dominant impact of Reynolds numbers on film cooling effectiveness depends on which of the above-mentioned factors is most significant.