Wildland
FIRES
A single wildland fire can result in over a billion dollars in damages and pose risks to firefighters working to contain the fire and communities near the wildland fire - urban interface (WUI). As our climate continues to evolve and conditions change, wildland fires are becoming an ever present risk to communities all over the world. Our research focuses on characterizing and developing a deeper understanding of how wildland fires spread and the risks of wildland fires on communities. The goal of the research is to reduce the dangers wildland fires pose by improving fire prevention methods and providing the fire service with science-based resources.
Time sequence of ember ignition of denim insulation. Here a single ember was created and dropped on the denim test specimen. Once ignition was observed, the fire was suppressed. The finale post-test denim test specimen is also shown. During the test, air was flown over the test specimen in the top to bottom direction with respect to the images above.
A wide range of typical flame-retardant (FR) and nonflame-retardnant (NFR) attic insulations were tested at different flow conditions. The image to the right shows a) FR denim, b) NFR denim, c) FR cellulose, d) NFR cellulose, e) polyurethane foam, f) extruded polystyrene, and g) expanded polystyrene
Comparison of heat release rate (HRR) of ember-sized branches from different sections of little bluestem plants measured using the cone calorimeter. Ornamental plants, such as little bluestem, used for home landscaping is another possible driver for fire spread at the WUI.
Project:
FIRE SPREAD
at the WILDLAND-
URBAN
INTERFACE
Researchers: Savannah Wessies and Michael Chang
​
Wildfire embers are one of the dominant fire spread elements in wildfire growth, and have been associated with the ignition of homes at the wildland-urban interface (WUI). The main focus of this research is to study the fire resilience of one of the most vulnerable areas of homes at the WUI---the attic space. An experimental procedure was developed to create consistent embers, that were then transported onto various flame retarded attic insulation materials. The ignition behavior was observed for the materials over a range of air flow rates blowing over the fuel bed, as well as with different ember geometries. In order to better understand the ignition behavior of the materials, flammability testing was performed using oxygen consumption (cone) calorimetry and thermogravimetric analysis (TGA), while results from non-flame retarded samples were used to highlight the effects of flame retardants.
Project:
GRASSLAND
FIRES
Researchers: Kristopher Overholt, Jan-Michael Cabrera, Andrew Kurzawski, Matthew Koopersmith
Understanding of the physics and fire dynamics of grassland fueled fire is critical in predicting fire behavior and developing mitigation strategies. In this study, little bluestem (Schizachyrium scoparium) grass was chosen as the grassland fuel due to its prevalent coverage in the Texas area and its relevance to grassland fires in Texas. Experimental characterization included intermediate-scale experiments to characterize the mass loss rates, heat release rates (HRRs), and flame heat fluxes of burning little bluestem plants at various moisture contents. Experiments included single plant tests, multiple plant tests with no forced flow/wind, and multiple plant tests in which a forced flow was directed over the plants to simulate wind. The burning characteristics of single plants and fire spread between multiple plants was observed. The computational tool, Wildland-Urban Interface Fire Dynamics Simulator (WFDS), was also used to model the experiments using both the prescribed HRR model and the particle-based fuel element model.
Burn testing of little bluestem plants (top). Measurements of heat flux and mass loss were made to characterize effects of fuel moisture content (FMC). The relationship between relative humidity and FMC of little bluestem (bottom). Symbols show experimental data and lines show proposed models
Little bluestem exhibits three stages of burning (right): Stage (1) upward flame spread and evaporation of fuel moisture in the plant, Stage (2) steady burning of the entire plant, Stage (3) burning of only the bunch section of the plant due to burn-out of the stalk section