An Experimental Study Of Natural Gas Jet-Flames In Crossflow With High Hydrogen Admixture At Elevated Pressure Conditions
I. Boxx, J. Pareja, P. Saini
Institut für Verbrennungstechnik, Deutsches Zentrum für Luft-und Raumfahrt, Germany
A series of high hydrogen-content jet flames in crossflow are investigated experimentally using high-speed (10 kHz) stereoscopic particle image velocimetry, dual-plane laser-induced fluorescence of the hydroxyl radical, and OH* chemiluminescence imaging. The flames were fueled with natural gas enriched to 70-, 80-, 90- and 100% H2, by volume at conditions approaching those found in the mixing duct of a modern gas turbine engine, specifically in close confinement, at 7 bars pressure and with a crossflow preheat of 511 K. The measurements indicate the recirculation zone on the leeward side of the jet plays a critical role in stabilization of the lifted jet flame in crossflow. The measurements show that local heat-release from a flame in this region acts as a self-reinforcing feedback mechanism, strengthening the recirculation zone and increasing local residence time there. This, in turn, creates conditions more favorable to flame stabilization. The measurements also showed how close confinement of the JICF by the flow channel walls affects jet-penetration and growth of the counter-rotating vortex pair.