Developing detector siting rules from computational experiments in spaces with complex geometries

Abstract

Abstract The National Institute of Standards and Technology (NIST) is conducting a 4-year research project wherein a computational fluid dynamics (CFD) computer code is utilized to map temperature, flow velocities, and particle densities in spaces with complex ceiling geometries. Through parametric variation of independent variables for the fire and the space, the number and location of smoke or thermal sensors required to assure response prior to a critical fire size is determined. The first year addressed horizontal ceilings with open beams or joists, and the second year adds sloped ceilings. In addition to the geometric studies, several special studies have been conducted. These include detection of low energy fires (as low as 100 W), stratification of fire gases in spaces with a vertical thermocline which exceeds the plume temperature, and obstructions which do not come, completely to the ceiling. A unique method of relating the response of detectors to the predicted conditions has been developed which can be utilized with any CFD model or with experimental data. The data analysis is being used to produce siting rules for inclusion directly into existing codes. The paper will review the results of the first 2 years of the project and present some thoughts on the potential for these techniques to greatly improve the technical basis for the utilization of fire sensors in complex installations.