In order to explore the film cooling potential of crater holes

numerical simulations are performed to investigate the film cooling characteristics of equal-section crater hole

concentric elliptical crater hole

and two types of rounded corner crater holes proposed on the basis of these two types of crater holes. Cooling efficiency curves are analyzed for four types of crater holes at blowing ratios of 0.5

1.0 and 1.5. The results show that

the crater spreading width of crater holes and crater film holes with rounded corners increases

which is beneficial to spreading coverage of the cooling film. After the crater holes are rounded at three blowing ratios

the Coanda effect strengthenes the ability of the cooling jet to adhere to the wall

and the film cooling efficiency in the near-hole region improves significantly. As the blowing ratio increases

the area-averaged film cooling efficiency after the rounded corner treatment increases by 76%

139% and 155%

respectively

for the equal-section crater hole. The area-averaged film cooling efficiency improves by 18%

27%

and 29%

respectively

for the concentric-elliptical crater hole with rounded corner compared with that of the concentric-elliptical crater hole.