- Author
-
Hoover, J. B.
|
Tatem, P. A.
- Title
- Application of CFAST to Shipboard Fire Modeling. Part 1. Development of the Fire Specification.
- Coporate
- Naval Research Laboratory, Washington, DC
- Sponsor
- Office of Naval Research, Arlington, VA
- Report
-
NRL/MR/6180-00-8466,
June 26, 2000,
65 p.
- Distribution
- AVAILABLE FROM National Technical Information Service (NTIS), Technology Administration, U.S. Department of Commerce, Springfield, VA 22161. Telephone: 1-800-553-6847 or 703-605-6000; Fax: 703-605-6900; Rush Service (Telephone Orders Only) 800-553-6847; Website: http://www.ntis.gov
- Keywords
-
shipboard fires
|
fire models
|
specifications
|
CFAST
- Identifiers
- CFAST (Consolidated Fire growth And Smoke Transport)
- Abstract
- It is well known that the Navy must reduce shipboard manning requirements while simultaneously maintaining at least the current levels of tolerance to both combat and accidental casualties. Several on-going demonstration projects, such as Damage Control -- Automation for Reduced Manning (DC-ARM) and Reduced Ship-Crew by Virtual Presence (RSVP), attempt to address these issues by increasing the use of automation. The development of advanced damage control modeling techniques supports these efforts by providing improvements in two areas: (a) validation of new ship designs for inherent fire safety; and (b) real-time prediction of fire behavior. In furtherance of these goals, the US Navy has partially funded development, at the National Institute of Standards and Technology (NIST), of the Consolidated Fire Growth and Smoke Transport (CFAST) model. CFAST is already used by the civilian fire protection community to simulate building fires and it has proven useful for building design and post-mortem analysis of fires. The Navy's funding has been directed toward making CFAST more useful for simulation of shipboard fires by adding capabilities for modeling phenomena that are absent from, or of little significance to, building fires. In particular, mass transport through vertical vents (representing hatches and scuttles), energy transport via conduction through decks and an improved radiation transport submodel have been added to CFAST. Work is currently in progress at NIST and the Naval Research Laboratory (NRL) to add (and validate) algorithms for heat conduction through bulkheads. Fire models can be categorized as field or zone models, depending on the level of spatial detail that they provide. Field models typically divide the region of interest into anywhere from several hundred to several million small volumes (cells), the dimensions of which are typically on the order of centimeters. For each cell, the values of a set of variables are tracked as a function of time. The variables that are calculated include the temperature, pressure and species concentrations. Each variable is represented as a time variant vector field (hence the name field model). Field models are very slow -- it is not unusual to require hours of super computer time to simulate fractions of a second of real time, even for physically small systems. This is partly due to the large number of cells involved, which require a correspondingly large number of calculations, and partly due to the need to use partial differential equations to represent both time and spatial variations.