Effects of Wind on Heat Transfer and Spread of Different Fire Lines Across a Pine Needle Fuel Bed

ABSTRACT

In this work, a series of surface fire experiments are performed to investigate the effect of wind velocity on the surface fire behaviors over a pine needle fuel bed under nine wind velocities (0/0.25/0.5/0.75/1/1.5/2/2.5/3 m/s) and three fuel loads (0.2/0.5/0.8 kg/m²). The essential parameters are obtained and analyzed, including flame length, flame angle, flame spread rate, and heat flux. The main valuable conclusions have been drawn: (1) Under no or low wind velocity, the flame tilts in the direction of the burned fuel, and the fire line shows a linear shape; whereas as the wind velocity increases, the flame gradually shifts toward the unburned fuel and the fire line is observed to be curved. (2) Flame angle decreases with increasing wind velocity and is not sensitive to fuel load, while flame length, heat transfer, and fire spread rate increase with increasing wind velocity and fuel load. Moreover, the empirical flame length and fire spread rate models are proposed considering the wind velocity and fuel load. (3) The modified model of radiation heat flux for surface fire spread under wind conditions taking different fire line shapes into account, is developed, and the predicted values are in good agreement with the experimental data. This paper’s results can help better understand the fire spread and controlling mechanism of surface fire under wind velocity conditions.

KEYWORDS:

• Surface fire
• wind velocity
• fuel load
• rate of spread
• radiation heat flux

Acknowledgements

This work was supported by National Key R&D Program of China (No.2022YFC3005704) and National Natural Science Foundation of China (NSFC) (Grant No. 52108478), and the Sichuan Science and Technology Program (Grant No. 2021YFS0327 and 2022YFS0533). The authors declare that there is no conflict of interest regarding the publication of this paper.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by National Key R&D Program of China (No.2022YFC3005704) and National Natural Science Foundation of China (NSFC) (Grant No. 52108478), and the Sichuan Science and Technology Program (Grant No. 2021YFS0327 and 2022YFS0533).