X-ray Measurements to Understand the Science of Fire Spread by Ember Transport
Please note that Zoom participation requires a SUNET ID. Non-Stanford attendees should contact Derek Fong (dfong@stanford.edu) for access.
This seminar is part of the fall 2023/2024 Wildland Fire Seminar Series, co-sponsored by the Bill Lane Center for the American West, Precourt Institute for Energy, Stanford Sustainability Data Science, and Woods Institute for the Environment. In the series, we will hear from a spectrum of researchers, decision makers, and industry experts on some important issues and challenges related to wildland fires.
The series continues Tuesday, Nov. 28 with a talk by Mattias Ihme, professor of mechanical engineering and photon science at Stanford.
Abstract
The severity and frequency of large wildfires have increased significantly in the past two decades, which is largely attributed to poor forest management and climate change but also to growing population and human activities in the wildland-urban interface. The main mechanisms for the spread of wildfires are direct flame impingement, radiation, and firebrand showers. Firebrands are hot airborne particles that are generated from burning vegetation and flammable materials. Firebrands have been identified as a main source of wildfire-spread disasters and were found to be responsible for the loss of more than half of the buildings in fires. Therefore, understanding the fundamental physical processes underlying the ember combustion is therefore increasingly relevant. In particular, accurate experimental measurements are critical to guide our understanding of fuel consumption. However, because of the multiphase nature of biomass combustion, the release of smoke, and the requirement for optical access in traditional diagnostic techniques, acquiring detailed experimental measurements remains challenging.
This presentation provides an overview of recent development of 3D X-ray computed tomography (CT) to experimentally investigate smoldering and combustion of solid fuel particles. By temporally resolving the surface recession of solid fuel material, the local consumption rates are extracted at the micro-meter spatial resolution. By diluting the ambient flow with Krypton, the X-ray measurements enable simultaneous estimations of the 3D gas-phase temperature field. Using these high-resolution measurements, we discuss effects of air dilution, heating rate, and biomass properties on smoldering and combustion processes. These measurements provide unique insights on the pore-scale structural changes occurring during the primary pyrolysis and subsequent char devolatilization, allowing for further investigations of state-of-the-art models of smoldering.
WILDLAND FIRE SEMINAR SERIES
Fall Quarter 2023-24
Tuesdays s at 12:30 p.m. - Seminars via Zoom
October 3: Understanding the wildfire insurance challenge in California: from individual structures to the global reinsurance market
Michael Wara, Doerr School of Sustainability
October 10: Fire as a social-ecological system
Maria Santos, University of Zurich
October 17: Firetech: Using technology to address our wildfire crisis
Bill Clerico, Convective Capital
October 24: The Importance, Challenges, and Opportunities for Enabling Aerial Firefighting in Degraded Visual Environments
Mark Bathrick, Bathrick Aviation Consulting
October 31: Evolution of PG&E Wildfire Mitigation Efforts – 2019 to 2023
Andy Abranches, PG&E
November 7: Fueling fires: wildfire mitigation and wildfire behavior
Georgia Scarr, Bill Lane Center for the American West
November 14: Nonprofits and wildfire. The evolution of the Santa Clara County FireSafe Council: From hazardous fuels reduction to technology leader
Seth Schalet, Santa Clara County FireSafe Council
November 28: X-ray measurements to understand the science of fire spread by ember transport
Matthias Ihme, Department of Mechanical Engineering
December 5: Translating First Responder Expertise – Enhancing university wildfire management and communications
Luisa Rapport, Stanford Emergency Services
This seminar series is co-sponsored by The Bill Lane Center for the America West, Woods Institute for the Environment, Center for Sustainability Data Science, and the Wildland Fire Challenge.