VENTCF2: An Algorithm and Associated FORTRAN 77 Subroutine for Calculating Flow Through a Horizontal Ceiling/Floor Vent in a Zone-Type Compartment Fire Model.
VENTCF2: An Algorithm and Associated FORTRAN 77
Subroutine for Calculating Flow Through a Horizontal
Ceiling/Floor Vent in a Zone-Type Compartment Fire
Model.
(2069 K)
Cooper, L. Y.
Fire Safety Journal, Vol. 28, No. 3, 253-287, April
1997.
Keywords:
computer models; building fires; compartment fires; fire
models; mathematical models; vents; zone models
Abstract:
An algorithm and associated FORTRAN 77 subroutine,
called VENTCF2, for calculating the effects on two-layer
compartment fire environments of the quasi-steady flow
through a circular, shallow (i.e., small ratio of depth
to diameter), horizontal vent connecting two spaces is
presented. The two spaces can be either two inside
rooms of a multi-room facility or one inside room and
the outside ambient environment local to the vent. The
flow is determined by consideration of standard
orifice-type flows driven by cross-vent pressure
differences and, when appropriate, the combined
pressure-and buoyancy-driven flows which occur when the
density configuration across the vent is unstable, i.e.,
a relatively cool, dense gas in the upper space overlays
a less dense gas in the lower space. The algorithm
calculates rates of flow exchange between the two spaces
based on previously reported model equations.
Characteristics of the geometry and the instantaneous
environments of the two spaces are assumed to be known
and specified as inputs. Outputs calculated are the
rates and properties of the vent flow at the elevation
of the vent as it enters the top space from the bottom
space. Rates of mass, enthalpy, and products of
combustion extracted by the vent flows from upper and
lower layers of inside room environments and from
outside ambient spaces are determined explicity.
VENTCF2 is an advanced version of the
algorithm/subroutine VENTCF2 in that it includes an
improved theoretical and experimental basis. The
subroutine is completely modular and it is suitable for
general use in two-layer, multi-room, zone-type fire
model computer codes. It has been tested numerically
over a wide range of input variables and the results of
some of these tests are described.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899