Effect of protrusion shape on film cooling performance for the cylindrical hole embedded in a contoured crater

Abstract

The cratered film-cooling hole is regarded as one of the potential applications with high cooling performance and low cost. This study focuses on the influence of the protrusion shape for the contoured crater embedded in the cylindrical hole. Four protrusion shapes, i.e., arc, rectangle, trapezoid, and triangle, are considered. The cooling effectiveness, flow structure, and aerodynamic loss for the cratered holes at blowing ratios of 0.5-2.5 are obtained using the numerical method with the Shear Stress turbulence model. The numerical results indicate that the arc and triangle protrusion models provide better lateral coolant coverage and higher area-averaged cooling effectiveness at higher blowing ratios, attributed to the ascendant anti-kidney-shaped vortex pair. The rectangle protrusion model provides the lowest area-averaged cooling effectiveness because the kidney-shaped vortex pair dominates the downstream flow field. For the aerodynamic loss, the largest total pressure loss coefficient occurs for the rectangle protrusion model and nearly equivalent values for the other three protrusion models. The contoured cratered holes with arc and triangle protrusions are generally recommended.