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International Journal of Wildland Fire International Journal of Wildland Fire Society
Journal of the International Association of Wildland Fire
RESEARCH ARTICLE

Interactions of non-intersecting oblique lines of fire burning in surface fuels in a combustion wind tunnel with and without wind

Andrew L. Sullivan https://orcid.org/0000-0002-8038-8724 A * and William Swedosh https://orchid.org/0000-0002-6071-8300 B
+ Author Affiliations
- Author Affiliations

A CSIRO, GPO Box 1700, Canberra, ACT 2601, Australia.

B CSIRO, Private Bag 10, Clayton South, Vic. 3169, Australia.

* Correspondence to: Andrew.Sullivan@csiro.au

International Journal of Wildland Fire 32(12) 1741-1757 https://doi.org/10.1071/WF23075
Submitted: 19 May 2023  Accepted: 15 September 2023  Published: 10 October 2023

© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of IAWF.

Abstract

Background

High-intensity wildfires are often characterised by the interaction of multiple coalescing fires. Previously, results of investigation of obliquely intersecting lines of fire in a ‘V’ configuration in dry eucalypt forest litter were reported.

Aim

This article reports on investigation of the behaviour of separated non-intersecting lines of fire in the absence and presence of wind.

Methods

Experiments in the CSIRO Pyrotron combustion wind tunnel investigated interactions of lines of fire of 800 and 1500 mm lengths located at incident angles of 30° and 45° and separated at the closest point by 150 mm.

Key results

The behaviour of separated fires in wind was fundamentally different to that of fires burning in no wind and previous non-separated fires, sustaining separation for some time and distance before merging.

Conclusions

Although all fires showed evidence of interactions, the strength of interaction was greater in larger fires with more energetic flames, suggesting a key influence of the magnitude and rate of release and transfer of heat to unburnt fuels.

Implications

Future research should focus on quantifying contributions of aspects such as fuel combustibility and bulk density that contribute to and determine the convecto–radiative interactions of fires so such behaviour can be predicted a priori.

Keywords: combustion, eucalypt litter, fire behaviour, junction fires, Pyrotron, wildfire, wildland fire, wind tunnel.

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