Experiments and simulation of shaped film cooling holes fed by crossflow with rib turbulators
Most studies of turbine airfoil film cooling in laboratories have used relatively large plenums to feed flow into the coolant holes. A more realistic inlet condition for the film cooling holes is an internal crossflow channel. In this study, angled rib turbulators were installed in two geometric configurations inside the internal crossflow channel, at 45° and 135°, to assess the impact on film cooling effectiveness. Film cooling hole inlets positioned in both pre-rib and post-rib locations tested the effect of hole inlet position relative to the rib turbulators. Experiments were performed varying channel velocity ratio and jet to mainstream velocity ratio. These results were compared to the film cooling performance of previously measured shaped holes fed by a smooth internal channel, as well as RANS simulations performed for select cases. The film cooling hole discharge coefficients and channel friction factors were measured for both rib configurations. Spatially-averaged film cooling effectiveness behaves similarly to holes fed by a smooth internal crossflow channel, but hole-to-hole variation due to the obstruction by the ribs was observed.