Leading edge film cooling effectiveness of variable turbine guide vane with different opening degrees
The study on leading edge film cooling characteristics of a variable low-pressure turbine guide vane in a variable cycle engine has been carried out.With 5 typical opening degrees,the pressure coefficient distribution on the surface of the guide vane has been studied by numerical simulation.Subsequently,the influence of opening degree and blowing ratio on the variation of film cooling effectiveness and coverage characteristics has been investigated.The results indicate that the position of the aerodynamic stationary point of the leading edge is shifted towards the pressure side by reducing the opening degree of the adjustable guide vane.As a result,the leading edge coolant air flows more towards the suction side,increasing the cooling efficiency of the suction surface.Furthermore,the reduction of opening degree causes an improvement in the coolant air advection effect on both suction and pressure sides,but the two mechanisms are different.Changing the opening degree has little impact on the optimum blowing ratio of the leading edge film holes,and optimum blowing ratios(M)under different openings are all around M=1.0.Since the stationary line is above film hole row 4 at θ=0°,the blocking effect is significant,reducing the surface average air film cooling efficiency by 13.6%compared to that of openings at θ=5°and-5°.
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