- Author
- Cooper, L. Y.
- Title
- Calculation of the Flow Through a Horizontal Ceiling/Floor Vent.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Sponsor
- Naval Research Lab., Washington, DC
- Report
- NISTIR 89-4052, February 1989, 30 p.
- Distribution
- Available from National Technical Information Service
- Keywords
- vents | algorithms | building fires | compartment fires | computer models | computer programs | fire models | pressure differential | pressure effects | zone models | ceiling vents | oxygen concentration
- Abstract
- Calculation of the flow through a horizontal vent located in a ceiling or floor of a multi-room compartment is considered. It is assumed that the environments of the two, vent-connected spaces near the elevation of the vent are of arbitrary relative buoyancy and cross-vent pressure difference. An anomaly of the standard vent flow model is discussed. The problem occurs in practical vent configurations of unstable hydrostatic equilibrium, where, for example, one gas overlays a relatively less-dense gas. In such configurations the cross-vent flow is not uni-directional. Previously published experimental data on a variety of related flow configurations are used to develop a general flow model which does not suffer from the standard model anomaly. The model developed leads to a uniformly valid algorithm, called VENTCL, for horizontal vent flow calcualtions suitable for general use in zone-type compartment fire models. Based on an assumption of total consumption of net oxygen flow rate, the algorithm is used in an example application where steady-state rate-of-burning in a ceiling-vented room is estimated as a function of room temperature, vent area, and oxygen concentration.