Investigation of the Elementary Process in Turbulent Combustion

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The turbulent diffusion flame is supposed to be an ensemble of the laminar flamelets which should be strained unsteadily and have positive or negative curvature, and be affected by preferential diffusion. In this study, experimental flame visualization and quantitative detection of temperature and OH concentration were conducted by use of the two-dimensional time-dependent laser Rayleigh scattering and OH laser induced fluorescence methods. Numerical studies were also conducted taking into account detailed chemical kinetics and multi component diffusion to predicted the characteristics of the experimental evidence and revealed the processes dominating the transient behavior of the flame with respect to the flame curvature and flame stretch. Attentions were paid to the effects of the flame stretch, flame curvature, preferential diffusion, unsteadiness and locality of the stretch on the flame temperature and flame extinction.(1) Flames with a controlled steady and unsteady strain were fo … More rmed to investigate the effects of positive and negative strain, flame curvature and unsteadiness on the flame temperature and local extinction by use of the two dimensional temperature detection by Rayleigh scattering.(2) Flames interacted with large scale vortices were formed by acoustic excitation to the fuel flow to investigated the interaction between flame and vortex by the detection of the OH concentration by the laser induced fluorescence together with and temperature detection by Rayleigh scattering paying attention to the local extinction due to the interaction.(3) Numerical simulation was conducted of the flames noted above taking into account multi component diffusion and the detailed chemical dynamics to make clear the interaction of the flame and the fluid dynamics. The large stretch which should induce the local quenching does not necessarily induce the flame quenching due to the unsteadiness and locality. It is also pointed out that the flame extinction is induced by the defect of the fuel or oxidizer interacted with the vortex. Less