Mechanical and Civil Engineering Seminar

Title: "Identifying Source Terms of Firebrand Generation for Models of Fire Spread in Wilderness and Urban Areas"

Abstract: Better understanding the formation of firebrands is critical to improving the ability to predict and ultimately mitigate risks associated with fire spread via spot fires. This talk reports findings about firebrand generation characteristics and firebrand source terms, across laboratory, tree-, and structure-scales. During laboratory-scale studies, dowels and natural samples were burned in a vertical wind tunnel. The species, moisture content, diameter, crossflow temperature, and crossflow velocity were varied. A factorial study with the time to generate a firebrand as the dependent variable showed that the diameter of the sample has the largest effect on the time required to generate a firebrand. It was observed that natural samples of Douglas-fir took roughly 50% longer to generate a firebrand than corresponding dowel samples. During tree-scale studies, over 100 roughly 3 m tall trees were burned. Firebrands generated were collected in trays filled with water and on fire resistant fabrics. It was found that both the number of firebrands (collected in the water) and char marks (observed on the fabric) are significantly dependent on the fuel species. Douglas-fir generated the most firebrands per kilogram of mass loss. More recently, entire structures have been burned and estimates of the total numbers of firebrands produced quantified. The composition of the siding has a notable impact on firebrand production and characteristics, but the size of the structure has little effect. These "source terms" for firebrand production are needed to inform physics-based models.

Bio: Dr. David Blunck is the former Associate Dean for Undergraduate Programs in the College of Engineering at Oregon State University and is a Professor in the School of Mechanical, Industrial, and Manufacturing Engineering. He established the Combustion, Ignition, Radiation and Energy (CIRE) Laboratory and co-founded the Propulsion Laboratory. His research focuses on combustion processes for wildfire and propulsion applications. As a result, his research ranges from studying smoldering combustion (which burns at mm/s) to detonations (which burn at 1 km/s). In 2026 he was named an Outstanding Mechanical Engineering Graduate from Purdue University, in 2015 he was named the AIAA Pacific Northwest Section Young Engineer of the Year and in 2016 he received an ONR Young Investigator Award for combustion research. Prior to joining OSU (in 2013) he was the lead investigator in fundamental combustor research at Air Force Research Laboratory (2010 – 2013) and a graduate research assistant at Purdue University (2005-2010). During his time at AFRL, Dr. Blunck's was the recipient of a Simpson Team Award (2013) and was nominated for a Presidential Early Career Award from the Propulsion Directorate (2011). At Purdue University, Dr. Blunck conducted studies of infrared radiation emissions from exhaust plumes and flames. He received a Department of Homeland Security Fellowship (2007 – 2010), was named the Outstanding Graduate Student for the School of Mechanical Engineering (2010) and received the Graduate Student Excellence Award from the University (2010). He received a Bachelor of Science degree from Brigham Young University in 2005. Dr. Blunck has authored over 140 peer-reviewed or conference publications, 2 sections in books, and has provided nearly 50 invited presentations.