Effect of Inlet Preswirl on the Film Cooling Characteristics of Turbine Vane Surface

Abstract

Conjugate heat transfer (CHT) analyses were conducted to validate the accuracy of numerical method in the prediction of aerodynamic and thermal performance of the film cooled C3X vane. The effect of inlet preswirl on the film cooling performance of the vane surface was investigated, while the Nu and the net heat flux reduction (NHFR) were also calculated to analyze the heat transfer characteristics. In particular, the effects of clocking positions and swirl orientations of the inlet preswirl with varied mass flow ratios of film coolant were studied individually. The results indicate that the inlet preswirl aligned to the vane leading edge (LE) would significantly enhance the heat transfer on the vane surface while the inlet preswirl aligned to the passage would weaken the heat transfer but lead to a nonuniform distribution of Nu. The inlet preswirl aligned to the LE would also seriously affect the flow structure of the showerhead film coolant and do deteriorate to the film cooling performance on the vane surface especially for the suction surface, in contrast, the inlet preswirl aligned to the passage would even improve the film cooling performance under some mass flow rates of film coolant. Moreover, the disadvantage of inlet preswirl to the downstream film cooling performance is almost negligible, while the inlet preswirl is even beneficial to the film coolant coverage under some mass flow rates of coolant in this paper, especially for the suction surface (SS) with a large mass flow rate and the pressure surface (PS) with a small mass flow rate.