Flat Plate Film Cooling with Linear and Curved Round-to-Diffusion Shaped Slots Using PSP Measurement Technique

Abstract

This thesis is an experimental study to examine the effect of different hole shapes and coolant hole trajectory on film cooling effectiveness and discharge coefficient. PSP technique was used to calculate the film cooling effectiveness and film cooling contours. Effect of hole geometry and trajectory was studied at different density ratios and different blowing ratios. Three different density ratios DR=1, DR=1.5 and DR = 2 were used and five blowing ratios from M= 0.5 - 1.5 were used with an increment of 0.25. Diameter of the hole was taken as 4 mm. Three different exit geometries (Round to slot-, Round to annulus, Round to annulus2) were used with linear and projectile trajectories, thus making a total of six test plates.

Results obtained agreed with the general trend of shaped holes. It is interesting to observe that slot shaped exit hole is still a better option than annulus shaped holes. Slot shaped exit hole with projectile trajectory resulted in improved effectiveness with 30-40% increase in span wise effectiveness as compared to its linear slot shaped counterpart. This improved design at DR=2 which corresponds to the actual conditions of a real engine. However round to slot test plate with projectile trajectory has the lowest discharge coefficient implying more pressure requirement for the coolant at the same blowing ratio. Correlation was obtained for a single row different exit shaped holes.