Numerical Investigation of Three-Dimensional Plasma Actuation for Improving Film Cooling Effectiveness

We numerically test a horseshoe plasma actuator for film cooling enhancement on a flat plate. We solve three-dimensional plasma governing equations using the finite element based MIG flow code. The electric force density calculated from the plasma governing equations is then employed as a body force density into a finite volume based Navier–Stokes solver with standard turbulence models for controlling the flow. Such electric force influences attachment of the cold jet to the work surface by actively altering the three-dimensional flowfield in the vicinity of the actuator. We consider two problems related to film cooling. The first problem is to understand the influence of a horseshoe plasma actuator on a flowfield where the cooling jet and the bulk flow speeds are of the same order of the flow induced by plasma itself. The second problem is to validate a previously reported film cooling experiment with a single row of round cooling holes issuing at a 35 deg angle on a flat plate, and then predict any improvement due to plasma actuation. For a unit blowing ratio, the results are compared with the published experimental data and other numerical predictions. The numerical results show a progressive improvement of centerline effectiveness as the electric force density is increased from 0 (no force) to (maximum). Specifically, an improvement of effectiveness well above 100% is predicted over the standard baseline design for the latest film cooling technology.