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.