Experimental investigation on cutback film cooling with latticework ducts under different crossing angles

With continuously increasing thermal loads in trailing-edge regions of modern high-pressure turbines, cutback film cooling with complex internal cooling structures has become an effective approach for thermal protection. Recent numerical studies on a novel cutback configuration incorporating latticework ducts have shown that swirling jets generated within the latticework ducts can modify film distribution through enhanced spanwise diffusion and jet deflection. Motivated by these findings, the present study provides a systematic experimental investigation of the new configuration and its dependence on geometric parameters. In this study, infrared thermography is utilized to measure the film cooling effectiveness on the cutback surface under five crossing sub-channel configurations and a range of blowing ratios. The results demonstrate that both crossing angle and blowing ratio play critical roles in determining cooling effectiveness and uniformity. Specifically, at a blowing ratio of 0.25, the 60° crossing angle configuration improves the area-averaged effectiveness by 14% compared to the 120° case. Cooling uniformity analysis shows that the asymmetry between the leeward and windward sides is increased as the crossing angle increases. Flow visualizations using stress-blended eddy simulation reveal that jet deflection dominates flow mixing at lower blowing ratios, whereas swirling-induced turbulence governs heat transfer behavior at higher injection. This investigation confirms that smaller crossing angles promote more consistent and efficient film coverage, especially under high blowing conditions. The insights gained from this study offer practical guidance for refining latticework duct architectures to improve trailing-edge film cooling in modern high-pressure turbines.