Experimental and Numerical Investigations of the Double-Jet Film Cooling Technology

The Double-Jet Film-Cooling (DJFC) technology is invented by the authors and comprises a significant enhancement of the adiabatic film-cooling effectiveness due to the formation of anti-kidney vortices. The DJFC technology places a second ejection hole with compound angle in a double-hole arrangement downstream the first hole. The second hole creates a second jet with another dominating vortex rotating in opposite direction to the first one and then combines both jets to one jet (or double-jet). The basic applicability and function of the DJFC technology has been proven by the numerical studies and testing in a test rig. The comparison of the experimental results of the adiabatic film cooling effectiveness to the numerical results for the same blowing ratio (e. g. M=0.5; M = (rho * C)(c)/ (rho * C)(h)) shows qualitatively similar distributions. However, the experimental results show enhanced mixing-out of the cooling air and, thus, the experimental values of the adiabatic film cooling effectiveness are lower compared to the numerical values.