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Investigation of Fire Impingement on a Horizontal Ceiling.

Investigation of Fire Impingement on a Horizontal
Ceiling.
(3355 K)

You, H. Z.; Faeth, G. M.

NBS GCR 81-304; 83 p. December 1981.

### Sponsor:

National Bureau of Standards, Gaithersburg, MD

### Available from:

National Technical Information Service

Order number: PB82-165838

### Keywords:

ceilings; fire models; fire plumes; heat transfer;
radiation; turbulence

### Abstract:

*
The structure and heat transfer properties of fires and
fire plumes impinging on a horizontal ceiling were
investigated. Profiles of mean velocity, temperature,
composition and mixture fraction were measured.
Turbulence quantities were also measured in the plume,
including longitudinal fluctuations and Reynolds stress.
Other measurements were as follows: convective and
radiative heat fluxes to the ceiling, radiative heat
flux to the surroundings, and flame shape. The
measurements were compared with predications of both
differential and integral models. A k-epsilon-g
differential model was examined for the plume portion of
the flow. This model was originally developed for
forced combusting flows and while it includes buoyancy
affects in the mean equations, the effect of buoyancy on
turbulence quantities is ignored. The prediction of
radiation was simplified, in order to avoid
complications due to the presence of soot, by either
neglecting radiative heat losses entirely or by assuming
that a fixed fraction, 20%, of the energy released by
combustion was lost due to radiation. Integral models
were developed for both the plume and ceiling jet
portions of the flow. Computational conveniene was
emphasized during the construction of these models;
therefore, "top-hat" profiles a flow entrainment
expression, and a mixing-controlled combustion model are
assumed.
*