Numerical Simulation of Laminar Film Cooling in a Supersonic Boundary Layer using Modeled and Simulated Blowing

Direct numerical simulations are used to investigate the method of film cooling in a laminar flat-plate Mach-2.67 boundary layer. Air is employed as mean-flow and coolant gas and is injected into an adiabatic or isothermal boundary layer through one or two rows of staggered, discrete holes. Previous simulations were performed using a modeled blowing approach, where the mass flux and temperature distribution are prescribed by a 5-order polynomial. This work is dedicated to the simulation of film cooling using additional cylindrical computational domains which represent the blowing channels, enabling a validation of the modeled blowing. It is shown that the temperature modeling plays a significant role for the adiabatic-wall boundary condition. Also, it is demonstrated that for the blowing through two rows of staggered holes the mass-flux through the first row is notably lower than through the second row. Note that the same plenum pressure is assumed for both rows. The holes are acting as obstacles in the flow, leading to an increase of the wall pressure in front of them. As a result, the driving pressure difference between the plenum and the freestream is reduced for the first row.