Studies of Blowout of Turbulent Diffusion Flames

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CTS-9905786AbstractThis is an experimental investigation of the mechanisms of jet flame blowout and of the morphology of the reaction zone near blowout. The effects of the dynamics of large-scale structures on flames near blowout is examined. Measurements of the propagation rate of the flame zone relative to the fuel flow are made using simultaneous particle image velocimetry (PIV) and double-pulsed planar laser-induced fluorescence (PLIF). The double-pulsed PLIF images of the CH radical provide information on the motion of the flamefront, while PIV provides information on the fuel velocity in the combustion zone. Assessment of structures at the leading edge of the combustion zone near blowout is made using CH-PLIF. Such visualizations are performed for a variety of flow conditions and downstream positions. The effect of the air coflow velocity on flame blowout is assessed for a variety of fuels such as methane, ethylene, and propane. Further studies are performed to contrast premixedness in the flowfields in near-field lifted flames to far-field flames with an emphasis on the mechanism of lifted diffusion flame stabilization and the transition to blowout.