Three-dimensional film cooling on a flat plate with tangential multi-jets

The effects of pitch of five injection slots and of the pressure gradient of the main flow on film cooling effectiveness are theoretically and experimentally discussed. For the experimental study, carbon dioxide was used as a tracer and, mixed with air, was injected from the slots. Film cooling effectiveness was measured by using the analogy between the transfer of heat and mass. The distributions of velocity, concentration, turbulent intensity, and Reynolds shear stress in the boundary layer were measured to determine eddy viscosities and mixing lengths. In the theoretical investigation, Prandtl's mixing length model as determined by the experimental results was introduced, and the three-dimensional boundary layer equations and other fundamental equations were solved numerically using a finite difference scheme in order to obtain the velocity and concentration profiles and the film cooling effectiveness.