Large Eddy Simulations of Discrete Hole Film Cooling With Plenum Inflow Orientation Effects

Abstract

Large eddy simulations of film cooling from a discrete hole inclined 35 deg and fed by a plenum chamber are performed at a density ratio of 2 and blowing ratios from 0.5 to 2.0. Cylindrical holes at a length to diameter ratio of 1.75 and 3.5 are simulated issuing into a crossflow at a Reynolds number of approximately 16,000 based on freestream velocity and hole diameter. In addition to the baseline case of vertical inflow into the plenum, flow orientation into the plenum chamber parallel to and perpendicular to the mainstream flow are investigated. The predicted results are validated with reported measurements of the flow field and surface adiabatic effectiveness. Results show that the longer delivery tubes (L/D = 3.5) have higher cooling effectiveness except in the very near field of the coolant hole. The flow orientation in the plenum is demonstrated to have a significant effect on cooling effectiveness and on flow behavior in the delivery tube and downstream of the hole. The perpendicular plenum inflow exhibits the lowest cooling effectiveness, the lowest discharge coefficients, asymmetric jetting behavior, swirl, and a low-velocity core at the exit of the delivery tube. The parallel plenum flow orientation is shown to exhibit the highest cooling effectiveness and discharge coefficients.