Experimental study on the full-coverage film cooling of fan-shaped holes with a constant exit width

摘要

the present study, the full-coverage film cooling characteristics of the fan-shaped holes with a constant lateral width at the exits are investigated under a wide range of blowing ratio from 0.5 to 7.5. The fan shaped holes with inclination angles of 20, 25 and 30 and expansion angles of 10 and 13 are considered. Adiabatic film cooling effectiveness of the holes is measured using thermo-chromic liquid crystal technology. Meanwhile, the corresponding flow characteristics are illustrated by numerical simulation. Effects of the inclination angle and the expansion angle as well as the blowing ratio on the cooling effectiveness and discharge coefficient of the holes are analyzed. Compared to cylindrical holes, the fan shaped holes have obvious advantages in terms of adiabatic film cooling effectiveness and discharge coefficient. The inclination angle of the fan-shaped hole shows a dominant impact on the separation motion inside the hole, which then governs the vortex structure and the film cooling effectiveness downstream. The row-by-row interaction of the coolant jets, as one of the important features of full-coverage film cooling, normally leads to the weakness of the vortices downstream the holes and therefore the better cooling performance. In order to further quantify the full-coverage film cooling performance and throughflow losses of the holes, correlations of experimental data for area-averaged effectiveness and discharge coefficient are developed. (C) 2019 Elsevier Ltd. All rights reserved.