Two-Room Structural Fire Calculations with the FDS Computer Code for Smoke and Heat Detector Response

Abstract

The application of Fire Dynamics Simulator FDS code to two-room structural fires with smoke detectors and heat detectors is described. The code solves the time-dependent partial differential equations PDEs on a 3-D grid system covering the interior of the structure. Results therefore permit properties like velo cities, temperature, species, etc to vary throughout the 3-D space, and indeed models for fire growth and development are included to permit fire development that depends on the local items available for burning. The fine details of the interior environment can be ac commodated within the model. A series of applications are described, and results are vividly illustrated th at show the volume, temperature and location of combustion product species evolving from the fire. The influence of open and closed exterior door to the outside on the simulation results of a tworoom structure has been studied. Ultra-fast , fast and medium fires are considered. Smoke detector activation is via the four parameter Cleary model using local velocity and optical density of the nearby smoke. Activation times are obtained and discussed for smoke detectors located in many places. In each ro om, 16 smoke detectors are located sequentially on the side wall, 3 smoke detectors located just above the doorway, and another smoke detector located top-dead-center on the ceiling. Similarly, the activation times of 18 heat detectors, 5 each on the side wall, 3 just above the doorway and another at the top-deadcenter are studied. These are the exact same lo cations as used with the smoke detectors. Heat detector activation times, based on their positions and their controlling parameters, are calculated for the same specified fires as was used with the smoke detectors.