Turbulent Penetrative and Recirculating Flow in a Compartment Fire.
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.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899