Measurements and Predictions of the Velocity Field Induced by Pool Fires.
Measurements and Predictions of the Velocity Field
Induced by Pool Fires.
(564 K)
Zhou, X. C.; Gore, J. P.; Baum, H. R.
NISTIR 6030;
Combustion Institute/Central and Western States (USA)
and Combustion Institute/Mexican National Section and
American Flame Research Committee. Combustion
Fundamentals and Applications. Joint Technical Meeting.
Proceedings. April 23-26, 1995, San Antonio, TX, Gore,
J. P., Editor, 578-583 pp, 1995 AND U.S./Japan
Government Cooperative Program on Natural Resources
(UJNR). Fire Research and Safety. 13th Joint Panel
Meeting. Volume 1. March 13-20, 1996, Gaithersburg,
MD, Beall, K. A., Editor, 201-207 pp, 1997, 1995.
Available from:
National Technical Information Service
(NTIS), Technology Administration, U.S. Department of
Commerce, Springfield, VA 22161.
Telephone:
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Order number: PB97-184204
Keywords:
combustion; pool fires; velocity; entrainment; fluid
flow; equations; flow fields; axial flow
Abstract:
Due to the importance of the air entrainment rate in
determining fire size, radiation properties, and soot
production, various techniques have been applied to its
measurement. The measurement techniques can be roughly
classified into four categories. The first category
involves monitoring of the air flow rate needed to meet
the entrainment requirement of the fire while
maintaining ambient pressure. The second category is to
sample combustion products and solve a set of global
mass balance equations to obtain equivalence ratio and
hence the entrainment rate. The third category involves
measurement of the velocity and the temperature profiles
inside the flame and subsequent calculation of the axial
flow rate by either direct radial integration or
integrations of resulting curve fits. One common
disadvantage of the above three experimental methods is
that information about the details of the entrainment
flow field itself is not obtained. The fourth
measurement category addresses the problem by obtaining
detailed measurements of the flow induced by the fire.
The mean and the fluctuating velocity field around a 7.1
cm tolune pool fire was mapped with a Laser Doppler
Velocimeter (LDV). It was found that the value of the
entrainment rate depends strongly on its definition
implied by the first three measurement categories. In
addition to the experimental work, a few studies
involving analyses and computations of the entrainment
flow field have also been reported. Taylor calculated
the air flow outside a thermal jet originating from a
point source with the assumption that the entrainment
rate is proportional to the jet velocity. Utilizing
published experimental data, Baum and McCaffrey applied
a kinematic approach to predict the flow pattern induced
by unconfined fires. The present paper reports
application and extension of their methodology to the
prediction of the entrainment flow field around 7.1 cm
and 15 cm pool fires burning heptane and toluene.
