Experimental Study of Mixing Between a Heated Turbulent Flow and a Cold Airstream Transpirated Through a Porous Wall

Hot air flows along a porous wall, which is submitted to a secondary flow of cold air. Measurements, carried out by hot and cold wires, enable to evaluate the aerothermic characteristics of the turbulent boundary layer. An increase of the blowing rate ensures good average thermal protection effectiveness. However, the average and turbulent aerodynamic properties of the turbulent boundary layer are damaged. The analysis of the results close to the wall shows the existence of thermal intermittencies, which are intensified when the blowing rate goes up. This observation shows a strong interaction between the protective film that is created by the blowing process above the porous wall and the turbulent boundary layer of the main flow.