THREE DIMENSIONAL SPATIAL CORRELATION OF TEMPERATURE AND VELOCITY IN TUBULENT DIFFUSION FLAME

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Turbulent diffusion flame is widely used in industries. In order to preserve World-wide environment, stable and high speed combustion with low emission is needed. In this research work, flame temperature and gas velocity were measured simultaneously by the system utilizing opto-electronic devices, and three dimensional spatial correlation of turbulence was analyzed for understanding the structure of turbulent diffusion flame.1. Accurate analysis of turbulence spectrum: Two sets of the optical fiber thermometer (OFT) based on the two-color method and two sets of the semiconductor laser 2-focus velocimeter (L2F) were operated simultaneously and these were integrated by a personal computer. Velocity data with non-uniform time interval obtained by L2F were reconstructed by the Karman filter and the correlation-based slotting technique was used for estimating the auto-correlation of turbulence. It was made clear that accurate spectrum could be obtained by the proposed method.2. Spatial corr … More elation of temperature and velocity: The spatial correlation of turbulence of flame temperature and that of gas velocity were obtained accurately by the expanded correlation-based slotting technique. The contour of the temporal- and spatial- correlation of turbulence in a free jet could be related to the mean gas velocity. And, judging from the auto-correlation and spatial correlation of temperature, small thermal eddies of combusting gas seemed to be transferred by the time avenged gas flow to the downstream. Further, the spectrum analysis based on the conditional sampling of the measured temperature and velocity would give an information about temporal- and spatial- correlation of the intermittent combustion region.3. Measurement of near-field structure of jet diffusion flame: The air was supplied to the outer edge of a jet diffusion flame of propane for the formation of a co-axial flame. In case of the lift-of flame, the entrainment was lager than that of the normal flame, and this seemed to lead the increment of entrainment to the hole flame region. Further, from the measurement of flame temperature and soot concentration, it could be deduced that the validity of luminous flame could have some relation to the entrainment of surrounding air. The low validity of luminous flame could be correlated to the reduction of soot concentration in case of the lift-off flame. Less