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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.
(2808 K)

Cooper, L. Y.

NISTIR 5470; 71 p. August 1994.

### Available from:

National Technical Information Service

Order number: PB94-210127

### Keywords:

computer models; building fires; compartment fires; fire
models; mathematical models; vents; zone models

### Abstract:

*
An algorithm and associated FORTRAN 77 subroutine,
called VENTCF2, is presented 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. 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 description of the flow through the vent is
determined by combing considerations of the
uni-directional-type of flow driven by a cross-vent
pressure difference and, when appropriate, the combined
pressure- and boundary-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. In the algorithm,
calculation of the rates of flow exchange between the
two spaces is 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. The outputs
calculated by the algorithm/subroutine are the rates and
the properties of the vent flow at the elevation of the
vent as it enters the top space from the bottom space
and/or as it enters the bottom space from the top 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 over a wide
range of input variables and these tests are described.
*