Effects of Wall-Temperature Conditions on Effusion Cooling in a Supersonic Boundary Layer

Influence of Cooling-Gas Properties on Film-Cooling Effectiveness in Supersonic Flow

“…The numerical results have been compared to and are in very good agreement with experimental investigations; see, e.g., [13], (biglobal) linear stability theory; see, e.g., [33,34], and other numerical simulations; see, e.g., [6,34]. In the following, the extended binary gas-mixture NS3D simulation is compared to 1) an analytical solution of a simple self-diffusion problem, 2) previous air-in-air film-cooling results obtained by experiments and simulations, and 3) foreign-gas film-cooling experiments and other simulations.…”

“…simulations performed without the cooling-gas channel but prescribed mass flux, mass concentration, and temperature at the slit opening in the wall plane, and 2) simulated blowing including the channel flowfield and thus interactions of the main and channel flow; see also [13,14].…”

“…Here, the coolant is injected through a single spanwise slit or row of holes, either by blowing in the (inclined) wall-normal direction (see, e.g., [2][3][4][5][6]) or by wall-parallel blowing through a backward-facing step (see, e.g., [7][8][9][10][11]). When blowing through multiple, uniformly distributed, discrete holes or slits, this is labeled effusion cooling; see, e.g., [12][13][14]. The third method to cool thermally stressed walls is known as transpiration cooling, in which the cooling gas is injected through a porous wall; see, e.g., [15][16][17][18].…”

Numerical Simulation of Film Cooling in Supersonic Flow

“…This section is intended to give a brief overview of the simulation setup, extensive details can be found in the referenced literature. For the DNS we use our in-house code NS3D, which has been used successfully for the calculation of film and effusion cooling in laminar and turbulent supersonic boundary-layer flow [7,9,11,14]. The governing equations for a flow of two mixing, non-reacting calorically perfect gases are the continuity equation, the three momentum equations, the energy equation, and the equation of state, all for the mixture values.…”

“…Here regions of enhanced wall shear exist, increasing locally the heat load at and downstream of the hole sides, by high-speed streaks. The effect is most pronounced for a very cool wall like in shortduration shock-tunnel experiments, but is much weaker for a radiative-adiabatic wall as present in thermal-equilibrium situations [14]. Simple blowing modelling by fixing the blowing distribution at the wall in fast CFD tools has implications: For narrow placed orifices a standard modelling with no knowledge of the actual blowing distribution resulting from included channels and a plenum chamber is inappropriate and indicates a false, too high critical blowing ratio for inducing turbulence tripping by the blowing [9].…”