Computational study of film cooling from single and two staggered rows of novel semi-circular cooling holes including coolant plenum

Computational analysis of film cooling effectiveness using novel semi-circular hole shapes with streamwise inclination of 30° has been carried out. Velocity profiles from the separate coolant plenum geometry are used for inlet condition to cooling holes. Realizable k−ε turbulence model with enhanced wall treatment is used for turbulence modeling in simulations. It is observed that coolant jet heights for one row and two staggered rows of semi-circular holes are lower than that for one row of circular holes. The centerline and laterally averaged effectiveness values from a row of semi-circular holes are found almost same as that from a row of circular holes due to the less jet lift-off in semi-circular case. Semi-circular hole utilizes half of the coolant mass required for full circular hole for producing the same blowing ratio, so same level of effectiveness from semi-circular holes as that from full circular holes is great advantage. The centerline and laterally effectiveness values from two staggered rows of semi-circular holes are found much higher than a single row of full circular hole case at all streamwise regions at all blowing ratios tested. Along with centerline effectiveness and laterally averaged effectiveness values, the non-dimensional temperature profiles at ( x/ D, z/ D) = (5.0, 0.0), non-dimensional temperature contours and velocity vectors at plane x/ D = 5.0 are also presented. Counter rotating vortex pairs from row of semi-circular holes are found to be weak and of lower size as compare to that from a row of full circular holes.