Flamelets and Wavelets: An EDA

• Activity Number: 306
• Type: Contributed
• Date/Time: Tuesday, August 6, 2013 : 8:30 AM to 10:20 AM
• Sponsor: Section on Statistics and the Environment
• Author(s): David Brillinger*+ and Mark Finney
• Companies: University of California, Berkeley and Missoula Fire Sciences Laboratory
• Keywords: EDA ; fire ; linear array ; stacking ; velocity ; wavelets

Abstract

The heat transfer processes that produce a spreading wildfire are still unclear. Recent experimental research by the United States Forest Service may offer some insight to the fine-scale flame contacts that occur just before a fuel particle ignites. In the experiment, fuel is comprised of an array of cardboard elements cut with a laser-engraver to resemble 'combs' of 2mm tines 0.1m tall. The fuel elements are arranged in rows separated by 1cm. The entire bed of fuel is approximately 1 meter wide and 4 meters long and placed in a wind tunnel with 0.5 m/s wind speed. The fuel bed is lit at one end and the flames move along the bed. Thirty-two thermocouples are placed 1.2 cm apart in the fire spread direction and measure the changing temperatures every 1/500th of a second which range from room temperature to over 1200C. It is of interest to estimate the velocity with which the flames move along the bed and more importantly to model the temperature behavior leading into ignitions. Of particular interest is characterizing the apparent 'pulsing' behavior of the temperature time series. Statistical tools include: include: spectrogram, cross-correlation, wavelet analysis.