Experimental study of curvature effects on double-wall laminate cooling structure incorporating impingement hole, pin-fins and slot

The double-wall laminate cooling (DWLC) structures address the conflicting demands of thermal protection, mechanical strength, and weight reduction in modern turbine blades, making them indispensable for advancing gas turbine technology. This study uses transient liquid crystal method to investigate the heat transfer coefficient (h) of target surface on curved DWLC structures incorporating impingement hole, pin-fins and slot, focusing on three types of curvatures (9° concave, 30° convex, and 75° convex). Additionally, this study investigates film cooling effectiveness (FCE) on curved DWLC structures by pressure sensitive paint method, concerning the effects of density ratio (DR) and blowing ratio (M), including impingement Reynolds number (Re_imp) and mainstream Reynolds number (Re_main). Computational fluid dynamics is employed to analyze mechanism. It is found that the h exhibits a multi-peak distribution around the stagnation point. 30° convex and 75° convex achieves higher h compared to 9° concave. The FCE of 9° concave and 30° convex exhibits a spiky distribution, while the FCE of 75° convex shows a U-shaped distribution. When M increases from 0.14 to 0.78, the area-averaged FCE of 9° concave increases the most, by 37.6%. For all curved structures, FCE increases with rising Re_imp and decreases with increasing Re_main. For 30° convex and 75° convex, the area-averaged FCE increases by approximately 0.1 when DR increases from 0.97 to 2. The results obtained in this article provide support for the refined design of cooling structures in the pressure and suction sides of double-wall turbine blades.