NIST Time|NIST Home|About NIST|Contact NIST

HomeAll Years:AuthorKeywordTitle2005-2010:AuthorKeywordTitle

Use of Computer Models to Predict Temperature and Smoke Movement in High Bay Spaces.


pdf icon Use of Computer Models to Predict Temperature and Smoke Movement in High Bay Spaces. (4935 K)
Notarianni, K. A.; Davis, W. D.

NISTIR 5304; 64 p. December 1993.

Sponsor:

National Aeronautics and Space Administration, Greenbelt, MD
General Services Administration, Washington, DC

Available from:

National Technical Information Service
Order number: PB94-145976

Keywords:

computer models; temperature; smoke movement; clean rooms; computational fluid dynamics; detector response; field modeling; fire detection; fire models; forced air flow; fire plumes; fire tests; high bays; response time; sprinkler response

Abstract:

The Building and Fire Research Laboratory (BFRL) was given the opportunity to make measurements during fire calibration tests of the heat detection system in an aircraft hangar with a nominal 30.4 m (100 ft) ceiling height near Dallas, TX. Fire gas temperatures resulting from an approximately 8250 kW isopropyl alchol pool fire were measured above the fire and along the ceiling. The results of the experiments were then compared to predictions from the computer fire models DETACT-QS, FPETOOL and LAVENT. In section A of the analysis conducted, DETACT-QS and FPETOOL significantly underpredicted the gas temperatures. LAVENT at the position below the ceiling corresponding to maximum temperature and velocity provided better agreement with the data. For large spaces, hot gas transport time and an improved fire plume dynamics model should be incorporated into the computer fire model activation routines. A computational fluid dynamics (CFD) model, HARWELL FLOW3D, was then used to model the hot gas movement in the space. Reasonable agreement was found between the temperatures predicted from the CFD calculations and the temperatures measured in the aircraft hangar. In section B, an existing NASA high bay space was modelled using the computational fluid dynamics model. The NASA space was a clean room, 27.5 m (90 ft) high with forced horizontal laminar flow. The purpose of this analysis is to determine how the existing fire detection devices would respond to various size fires in the space. The analysis was conducted for 32 MW, 400 kW, and 40 kW fires.