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Unified Analysis for Fire Plumes.


pdf icon Unified Analysis for Fire Plumes. (901 K)
Quintiere, J. G.; Grove, B. S.

Combustion Institute, Symposium (International) on Combustion, 27th. Proceedings. Volume 2. August 2-7, 1998, Boulder, CO, Combustion Institute, Pittsburgh, PA, 2757-2766 pp, 1998.

Sponsor:

National Institute of Standards and Technology, Gaithersburg, MD

Keywords:

combustion; fire plumes; flame radiation; temperature; velocity; entrainment; flame height

Abstract:

A unified analysis based on an integral approach is presented for fire plumes involving finite axisymmetric and rectangular sources. The analysis, using Gaussian profiles, obtains the best fits to experimental data found in the literature. Phenomenological constants in the theory are found to give consistent results in that coefficients expected to be numerically similar by theory are found similar among the various data sets. Thorough reviews of the literature data for line and rectangular sources are presented and yield consensus correlations, accordingly. The effect of flame radiation is explicitly included by a radiation fraction that proves to be a significant variable, previously overlooked in experiments. Effective entrainment coefficients for the far-field noncombusting plume are found to be 0.09 to 0.10, and for the flame region about 0.22 for the axisymmetric and rectangle cases as long as D/L > 0.1. For D/L < 0.1, the infinite line gives nearly double the flame entrainment. Generalized results are presented for entrainment rate and flame height in terms of single algebraic equations that span a wide range of Q* or energy release rate values. For low Q* fires, the effect of diameter and line width are important and expressed by the theory but not enough to address dependence involving Grashof and possibly Froude number effects near the origin. Laminar results are also addressed.