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Measurements and Prediction of Fire Induced Flow Field.


pdf icon Measurements and Prediction of Fire Induced Flow Field. (111 K)
Zhou, X. C.; Gore, J. P.; Baum, H. R.

NISTIR 5904; October 1996.

National Institute of Standards and Technology. Annual Conference on Fire Research: Book of Abstracts. October 28-31, 1996, Gaithersburg, MD, 77-78 pp, 1996.

Sponsor:

National Institute of Standards and Technology, Gaithersburg, MD

Available from:

National Technical Information Service
Order number: PB97-153514

Keywords:

fire research; fire science; flow fields; entrainment; pool fires; methanol; heptane; toluene

Abstract:

Motivated by the various application of entrainment rate correlations in fire research and the large uncertainty in the efficacy of existing correlations and experimental data, the first particle Imaging Velocimetry (PIV) based measurements of fire induced flow field around pool fires burning methanol, heptane and toluene were obtained. Air entrainment rates for 15 cm and 30 cm pool fires burning the three different fuels were calculated based on the mean velocity field. The entrainment data for the six fires could be correlated well using the fire Froude number, defined in Ref. 1 as the nondimensional parameter. A kinematic approach for the prediction of the fire induced flow field, following Ref. 2, was extended to the present fires. The driving processes for the entrainment flow, namely the volumetric heat release and the baroclinic vorticity generation, were evaluated based on correlations of buoyant diffusion flame structure in the literature. The predicted entrainment velocities were substantially higher than the measurements but were in qualitative agreement with the data. Based on this, the heat release rate and vorticity correlations used in the analysis were corrected by using a smaller radius for the 1/e point in the elocity profile. The modified predictions were in better agreement with the experimental data. Therefore, further evaluation of the kinematic approach with proper heat release rate and vorticity distributions is warranted.