ARTICLE IN PRESS JID: PROCI [m;November 9, 2016;7:0] Available online at www.sciencedirect.com Proceedings of the Combustion Institute 000 (2016) 1–8 www.elsevier.com/locate/proci Pool fre fame base drag behavior with cross fow in a sub-atmospheric pressure Longhua Hu a,∗ , Xiaolei Zhang a , Michael A. Delichatsios b,∗∗ , Long Wu a , Chen Kuang a a State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230026, China b FireSERT, School of Built Environment, University of Ulster, Newtownabbey BT37 0QB, Northern Ireland, UK Received 3 December 2015; accepted 20 June 2016 Available online xxx Abstract This paper investigates the effect of cross fow of air on fame base drag in pool fres in sub-atmospheric pressure, where no data is available, by combining the effects of these two factors: sub-atmospheric pres- sure and cross fow. Experiments were carried out using heptane and acetone as fuels for 10–25 cm square pool fres where the cross fow was provided by a wind tunnel built in Lhasa city-Tibet (64 kPa) as well as correspondingly by a wind tunnel in Hefei city (100 kPa). Additional larger scale experiments were also con- ducted with 45 cm, 60 cm and 70 cm square pool fres in Hefei city. The evolution of fame base drag length as a function of cross fow air speed was quantifed. The fame base drag length was found to be larger in the sub-atmospheric pressure than that in normal pressure, indicating higher risk of causing fre spread to nearby fuel at the ground level. Previous correlations based on a wind Froude number are not in agreement with each other. In addition, they do not include all the physics and they do not account for the effect of the pressure change on fame base drag length. A new theoretical approach is proposed accounting for the relation of wind force with the buoyancy of the fame and the interaction of wind with the total heat release rate from the fre. It follows that three independent dimensionless quantities are introduced: the (inverse) fre source Froude number owing to fame buoyancy, the total buoyancy–wind interaction number and the ratio of fuel vapor density near the fuel surface to the air density. This theory allows us to develop and validate a correlation for fame base drag length to account for pressure effect and for generalizing the existing relations for fame base drag. © 2016 by The Combustion Institute. Published by Elsevier Inc. Keywords: Pool fre; Cross fow; Sub-atmospheric pressure; Flame base drag length; Froude number ∗ Corresponding author. Fax: +86 551 63601669. ∗∗ Corresponding author. Fax: +44 (0) 28 90368726. E-mail addresses: hlh@ustc.edu.cn (L. Hu), m.delichatsios@ulster.ac.uk (M.A. Delichatsios). 1. Introduction Flame base drag is a special phenomenon of pool fres in cross fow of air [1–8] (Figs. 1 and 2). Due to the high risk of igniting the combustible downstream nearby by the fame base drag, its http://dx.doi.org/10.1016/j.proci.2016.06.139 1540-7489 © 2016 by The Combustion Institute. Published by Elsevier Inc. Please cite this article as: L. Hu et al., Pool fre fame base drag behavior with cross fow in a sub-atmospheric pressure, Proceedings of the Combustion Institute (2016), http://dx.doi.org/10.1016/j.proci.2016.06.139