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

摘要

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 8 MN/m~3 (maximum). Specifically, an improvement of effectiveness well above 100% is predicted over the standard baseline design for the latest film cooling technology.