NUMERICAL SIMULATION OF FIRE SPREAD ON POLYURETHANE FOAM SLABS | NIST
Computational Fluid Dynamics (CFD) models are used extensively by fire protection engineers for performance based design and forensic analysis. The equations of motion describing the gas phase are relatively well known and the approximations in the various gas phase sub-models have been extensively studied. However, coupling of the gas phase and the condensed phase to describe flame spread over a burning solid, has proven to be difficult to model. This is due to a lack of understanding of the underlying physical phenomena that take place during the decomposition of the solid as well as poor characterization of the fundamental material properties that control the burning process. The overall goal of this project is to improve the capability of the fire models to predict flame spread over materials that typically burn in a compartment fire. In this paper, we attempt to simulate fire growth and spread on 10 cm thick slabs of polyurethane foam. A multi-layered, multi-material model was developed to simulate flame spread, and material properties were obtained from various small scale experiments. Model predictions were compared with large scale experiments on polyurethane foam slabs, ignited on one edge. Results indicate that the model is capable of qualitatively predicting the observed trends in heat release rate, flame spread rate and heat fluxes measured in the experiments. This report will describe the progress that has been made to date on modeling fire growth and spread on polyurethane foam slabs and the comparison of these results with experimental data.
Effects of Thickness and Ignition Location on Flame Spread Rates in Furniture Calorimeter Tests of Polyurethane Foam
Furniture calorimeter tests of polyurethane foam specimens were conducted to determine the effects of ignition location and specimen thickness on measured flame spread rates. These measurements were made using a new procedure that measured flame areas using infrared video records. Furniture calorimeter tests were conducted using specimens with thicknesses ranging between 2.5 cm and 10 cm, which were ignited in either the centre or on one edge. Flame spread rates increased with foam thickness, and flame spread rates in centre ignition tests were quicker than in edge ignition tests. These flame spread measurements will be used in a model, along with heat release rate data from cone calorimeter tests of the same foam, in order to predict heat release rates in furniture calorimeter tests of polyurethane foam slabs.
Measurements of Water Density and Drop Size Distributions of Selected Esfr Sprinklers
Characteristics of single sprinkler sprays for two Early Suppression Fast Response (ESFR) sprinklers were investigated. The water density, drop size and velocity distributions were measured at an elevation 2.85 m (9 ft 4 in.) below the sprinkler deflector for two water discharge pressures, 1.72 bar (25 psig) and 3.45 bar (50 psig). Measurements began at 0.61 m (2 ft) from the sprinkler axis and extended to near spray boundary. For every 0.61 m (2 ft) increment, the measurements were performed for 10 azimuthal angles with 45 degree intervals. The drop size and velocity distributions were measured with a PMS (Particle Measuring Systems, Inc.) optical imaging probe which can measure drop size ranging from 0.1 to 6.2 mm with a resolution of 0.1 mm.The results of the water density measurements indicate that the water densities for the two sprinkler models diminish with increasing radial distance from the sprinkler axis. Based on the local measured density data, the gross density distributions in term of volume...