Novel Sloping Wind Tunnel Experiments and Adaptive Mesh Simulations of Fine-Scale Combustion for Physics-Based Models of Wildland Fire
Dr. Peter Hamlington | University of Colorado, Boulder
The objective of the project is to develop an improved physics-based computational capability for reliably predicting fine- to landscape-scale wildland fire behavior, including realistic estimates of particulate matter emissions and ember production, for different fuel and environmental conditions. This development will be based on insights obtained from controlled and heavily instrumented sloping wind tunnel experiments, along with complementary adaptive mesh numerical simulations, for different fuel types, moisture contents, wind speeds, and slopes. More specific objectives of the project are to: 1. Implement a multi-diagnostic suite to enable simultaneous measurements of velocity, ember production, gas phase and surface temperature, and particulate and gas phase emissions for parametric studies of wildland fuel pyrolysis and combustion. 2. Characterize and understand wildland fire behavior, emissions, and ember production at scales from roughly 1 meter (m) to below 1 millimeter (mm) using advanced measurement techniques and adaptive mesh simulations in a novel sloping wind tunnel. 3. Extend advanced diagnostic techniques to enable temporally and spatially resolved in situ field measurements, and develop subgrid-scale (SGS) models for landscape-scale simulations. 4. Characterize and understand wildland fire behavior, emissions, and ember production at scales from roughly 1 m up to 1 kilometer (km) using advanced measurement techniques and landscape-scale simulations with new SGS models for a series of prescribed field burns. This effort heavily leverages tools developed as part of a previous Strategic Environmental Research and Development Program (SERDP) project (RC-2642) involving four of the current team members that was focused on fuel pyrolysis, ignition, and combustion at sub-meter scales.
The research team will use particle image velocimetry, gas chromatography with mass spectrometry, and novel mid-infrared dual frequency comb laser diagnostics to study flame spread, emissions, and ember production in a one-of-a-kind variable slope wind tunnel. Cutting-edge adaptive mesh computational tools will be used to perform companion high-resolution simulations of the wind tunnel experiments. Insights obtained from these studies will be used to develop new physics-based SGS models for landscape-scale simulations of fire spread. In the last two years of this project, select experimental diagnostics and the new computational models will be tested in the field for a series of prescribed burns across a range of scales and conditions.
The proposed simulations and experiments will enable the development of improved SGS models for landscape-scale simulations and advanced field-deployable diagnostic techniques which will, in turn, increase the capability of fire managers to predict wildland fire behavior and emissions during prescribed burns on Department of Defense (DoD) lands. The range of experiments and simulations in this project will allow us to study fire structure and dynamics over a broad scale range (from roughly 1 mm up to 1 km), and the new landscape-scale model is intended to provide reliable predictions of fire behavior on DoD lands.