Influence of a Mixing-Jet on Film Cooling

An experimental analysis of the slot film cooling performance downstream of a mixing jet has been performed. The mixing jet was blown into the main flow at a position five jet diameters downstream of the slot exit. Flow visualizations of the jet and of the cooling film are presented for blowing rates of 1 and 2 with jet momentum rates of 7 and 10. LDV-measurements in the symmetry plane show the strong perturbation acting on the cooling film downstream of the mixing jet injection. Heat transfer coefficients and adiabatic wall effectiveness were determined using electrical heater foils in combination with infrared-thermography. The results clearly show the decrease in film cooling performance in the region downstream of the mixing jet.