Abstract

The paper reports visualization of the flow of smoke over a flat surface inside of a low-speed wind tunnel. A heating plate flush mounted on the wind tunnel floor simulated a spreading line fire that produces uniform heat flux under constant wind speed condition. A paper-thin cloth was soaked with commercially available Vaseline and placed on top of the heating plate; when it is heated, it produced thick white smoke, ideal for flow visualization. Two sides and top of the wind tunnel were made of a trans- parent acrylic sheet that enabled LED and laser sheet light illumination of the flow. A still camera with a full-frame CMOS sensor was used to record time-series images of illuminated smoke flow patterns from different angles. From these images, the following four flow structures were identified: organized horizontal vortex flows, weak vortex flow interactions, strong vortex flow interactions (also described as the ‘transition regime’), and, turbulent flows. Previously developed scaling laws on forest fires were applied to find similarity in flow structures created by the current small-scale convective heat-transfer experiments and the USDA’s mid-scale wind tunnel fire experiments.

Document Type

Article

Publication Date

11-2018

Notes/Citation Information

0010-2180/© 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Digital Object Identifier (DOI)

https://doi.org/10.1016/j.combustflame.2018.08.014

Funding Information

This study was sponsored by a grant (17-CS-11221637-099) from USDA Forest Service, Missoula, MT. We also acknowledge that the current work is a continuation of a long history of work per- formed by USDA Forest Service scientists and collaborators and part of a larger national effort to better understand wildland fires which is focused within the research branch of the USDA Forest Service.

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