BYU's "flames on wheels" provides new fire behavior info

HERRIMAN — Even as the Machine Gun fire continues to ravage thousands of wildland acres, a multimillion-dollar study, in which Brigham Young University was tapped to participate, is shedding new information on how quickly brush fires can advance and what affects their behavior.

While old assumptions rested on the premise that a higher moisture content in vegetation can slow a fire's pace, BYU chemical engineering professor Thomas Fletcher and his team of students learned that's not always the case.

"Once a fire gets going, it doesn't matter if you have wet leaves or bone-dry plants," Fletcher said. "A big enough fire can ignite leaves, even though there may still be some moisture in the vegetation."

A recent article by Fletcher in the International Journal of Wildland Fire described how a leaf can burn, even with up to 50 percent of its moisture present. This previously unknown fact, according to Fletcher, has "serious ramifications" for existing fire behavior models, which can mistakenly factor in the additional time it takes for a leaf's moisture to evaporate.

The information comes after nine years, seven peer-reviewed articles, dozens of presentations and piles of charred leaves produced in a simulated "fire front" in a lab — the only arrangement of its kind.

The simulation is created by pumping a gas mixture into what looks like a small lunar rover. The top of the rover is covered with porous material that allows gas to escape in a steady fashion, creating a uniform, 1,800-degree flame when lit. Using a small pulley, the rover becomes "flames on wheels" as it ambles toward varying kinds of leaves and bushes, simulating the approach of a wildfire. Fletcher said the goal is to improve three aspects of fire modeling: the impact of moisture on fires, how wind affects flame and how flame spreads through shrubs.

The effort is part of a $13 million federal research program designed to study ways to manage vegetation in the Great Basin, using controlled burns and other strategies to reduce catastrophic fires.

BYU's portion was $1.4 million, with the entire project being funded by the Joint Fire Services program, which is administered by the Bureau of Land Management, the U.S. Forest Service, the National Park Service and other federal agencies.

The result of the project is also intended to guide vegetation management in a multistate effort that includes Oregon, Idaho, Nevada and Utah.

e-mail: amyjoi@desnews.com