Enhanced Cooling Performance in Turbine Blade Tip U-channel Using Protrusion-V-rib Composite Structure

Improving the cooling effectiveness of turbine blade squealer tip regions under high thermal loads remains a challenge in designing of gas turbines. This study numerically investigates the cooling performance of a novel protrusion-V-rib composite structure applied to the internal U-channel near the blade squealer tip. Eight configurations, including holed/hole free designs and combinations of V-ribs, protrusions and vanes, are evaluated at Re = 10,000-50,000. Key findings show that holed structures enhance heat transfer near holes due to accelerated fluid velocity and increased turbulence, resulting in higher Nusselt number. However, hole free configurations exhibit superior downstream heat transfer (up to 4.14 % improvement) by maintaining coolant mass flow. Complex geometries, particularly the V-Convex design, significantly suppress flow separation and reduce vortex size by promoting fluid disturbance and turbulence. The V-convex structure exhibits the highest Nusselt number and comprehensive thermal performance factor under both constant temperature and constant heat flux boundary conditions, confirming its robustness. The results highlight the trade-off between local heat transfer enhancement (holed structures) and downstream cooling effectiveness (hole-free designs), emphasizing the importance of geometric optimization for blade squealer tip cooling. This work helps understand the composite cooling structures and provides insights for efficient thermal management in applications of hightemperature turbines.