Experimental and numerical investigations on film cooling performances with spiral-channel holes for a turbine vane

Abstract

A comprehensive evaluation of the cooling effectiveness of spiral-channel hole in turbine vanes is carried out through a combination of cascade wind tunnel experiments and numerical simulations. The main objectives included: (1) quantifying the aerodynamic performance of vanes at different expansion ratios; (2) assessing the cooling effect under various expansion ratios, secondary flow temperature ratios, and secondary flow rates, while considering the impact of key parameters; and (3) validating the accuracy of CFD method with empirical data. Particularly noteworthy is the comparable performance of spiral-channel hole at a MFR of 4.15% to that of cylindrical hole at an MFR of 6.23%, leading to a 33.39% decrease in coolant usage under the same operational circumstances. With the increase in MFR, the overall cooling effectiveness showed continuous improvement. For an MFR of 8.30%, the averaged overall cooling effectiveness of spiral-channel holes surpassed that of cylindrical holes by 10.80% on the suction surface and 55.12% on the pressure surface. Variations in temperature ratio has a minimal impact on the overall cooling effectiveness. The temperature ratio’s influence is more pronounced on the pressure surface than on the suction surface, and it affect cylindrical holes more than spiral-channel holes. An augmentation in the turbine expansion ratio results in a diminished overall cooling effectiveness. Nevertheless, this effect is mitigated at higher MFRs and higher coolant flow can compensate for the negative impact of increased expansion.