Visualization of organized structures in buoyant diffusion flames.
Static equidensitometric structures (2 types) and dynamic radiance structures (18 types) are obtained in pool fires of liq. hydrocarbons from flame photograms evaluated with an image anal. computer system. A third kind of structure, the dynamic synchronous structures (9 types), is visualized with a holog. real-time interferometry method. The control parameters of the obsd. structures are the pool diam., the height above the fuel surface, the d. of the fuel vapor, and the volumetric fuel flow rate. The dynamic radiance structures have 4 monoperiodic subprocesses with a frequency of 12 Hz (n-hexane pool fire, d = 4.6 cm) which depend strongly on the pool diam. and show 18 statistical characteristics. The dynamic synchronous structures of the same pool fire show a quasiperiodic region I with 7 sub-processes at 11, 13 and 3 Hz. In a quasiperiodic region II, 8 sub-processes exist at the frequencies 11, 12, 13, 39 and 41 Hz. In addn. there are 17 statistical characteristics. The effects of the obsd. dynamic structures on turbulent exchange processes in pool fires are calcd. and lead to turbulent Prandtl, Schmidt, and Lewis nos. of 0.3-1.
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