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Turbulent Penetrative and Recirculating Flow in a Compartment Fire.


pdf icon Turbulent Penetrative and Recirculating Flow in a Compartment Fire. (709 K)
Abib, A. H.; Jaluria, Y.

American Society of Mechanical Engineers (ASME). Heat and Mass Transfer in Fire and Combustion Systems. HTD-Vol. 223. Winter Annual Meeting. November 8-13, 1992, Anaheim, CA, Am. Soc. of Mechanical Engineers, New York, NY, Cho, P.; Quintiere, J., Editor(s)(s), 11-19 pp, 1992.

Sponsor:

National Institute of Standards and Technology, Gaithersburg, MD

Keywords:

compartment fires; turbulent flow; formulations; equations; flow fields; velocity; temperature; zone models; room fires

Abstract:

A numerical study of a turbulent penetrative and recirculating flow induced by the energy input due to a fire at the bottom boundary in a partially open rectangular enclosure is carried out. The compartment with an opening is connected to a long corridor, which opens into a stably stratified environment. The stable stratification that is of interest is a two-layered temperature stratification and is assumed to be due to fire activity in an adjacent enclosure. In this study, attention is focused on the interaction between the cavity and its surrounding ambient medium through the opening. The influence of the stratification parameter is examined in the turbulent flow regime by considering a range of stratification levels for given opening height and initial interface location. It is found that, depending on the stratification parameter, the thermal plume that arises above the fire may never reach the ceiling. Small penetration distances occur at large stratification levels. The flow field reveals a multicellular pattern: a strong main convective cell at the bottom and a weak counter cell at the top. The stable thermal stratification can cause a destruction of the turbulence and may thus lead to reduced mixing in the flow. This results in the relaminarization of the flow in the upper region of the cavity and may significantly affect the transport processes in the enclosure and distort the simplistic concept of two homogeneous gas layers, which forms the basis of zone modeling for compartment fires.