Discrete slot design for turbine blade tip cooling: A comparative study with continuous slot

The present study investigates the cooling performance of discrete slot configurations on gas turbine blade tip using pressure-sensitive paint (PSP) measurements. The discrete slots, developed as a segmented alternative to continuous slot designs, aim to enhance structural integrity while maintaining effective film cooling. Experimental evaluations were conducted under varying tip gaps (1–3 % of blade span) and coolant mass flow rates (0.3–0.7 % of mainstream flow) to assess local and area-averaged film cooling effectiveness (FCE). The results show that continuous pressure-side (PS) slots consistently outperform discrete PS slots in terms of overall cooling performance, providing more stable and uniform coolant distribution—particularly at lower tip gaps and higher coolant flow rates. In contrast, discrete slots exhibit higher variability in FCE, with pronounced drops in cooling effectiveness between slot segments due to disrupted coolant continuity and intensified interactions with tip leakage flows. However, the increased surface area of the segmented geometry may enhance thermal conduction, partially offsetting the reduced convective performance. Additionally, discrete slots offer potential advantages in structural robustness and manufacturability, particularly with the application of additive manufacturing techniques. These findings contribute to the optimization of blade tip cooling strategies by balancing thermal performance with mechanical and fabrication considerations.