Experimental and Numerical Investigation of Heat Loads in Separated Nozzle Flow

2-D numerical nozzle flow simulations and cold gas subscale nozzle experiments are conducted to gain a better understanding of the various mechanisms that cause heat loads in nozzles. The 2-D numerical simulations account for non-equilibrium chemistry and show post-combustion with the entrained ambient air but cannot sufficiently explain the wall heat loads observed in the experiments. Obviously, 2-D numerics lack the physics to explain 3-D phenomena. Hence, sub scale cold gas nozzle experiments are chosen to study unsteady and 3-D effects since they are more efficient, more realistic and less costly than unsteady 3-D computations. In addition to the common diagnosis tools an infrared camera is used to visualize wall heat loads. These experiments yield 3-D streamwise structures reminiscent of Görtler vortices which may have a significant effect on the wall heat loads