Investigation of surface fire spread in the presence of fire break with variable slope angles
In order to investigate the effect of slope angle on surface fire spread and arrangement of fire break,a slope-adjustable forest surface fire spread experimental setup was built.Six different slope angles(0°,10°,15°,20°,25°,30°)and four different fire break widths(10 cm,20 cm,30 cm,40 cm)were considered and the fire behaviors like surface fire spread were experimentally studied.The fuels used in these experiments were dead pine needles collected in Southwest China,where forest fires occurred frequently.It is found that during the surface fire spread in front of the fire break,as the slope increases,the flame gradually tilts from burned fuel toward the unburned area,and the fire spread rate,flame length and heat flux characteristic values increase,while the flame angle decreases.Moreover,a model of surface fire radiation heat flux under the slope condition is established and the model agrees well with the experimental data of radiation heat flux.Meanwhile,according to the ignition result of the fuel after the fire break,the effect of the fire break can be divided into effective and inactive.When the fire break is effective,the fuel surface temperature and heat flux after the fire break are significantly reduced;while when the fire break is inactive,the fuel surface temperature and heat flux after the fire break are not significantly different from those before the fire break.The fuel surface temperature and heat flux after the fire break decrease with the increase of the width of the fire break.The fuel surface temperature and heat flux after the fire break increase with the increase of the slope.Therefore,this study can help to better understand the surface fire spreading characteristics under slope conditions and the mechanism of the ignition of the fuel behind the fire break.
safety engineeringsurface fire spreadslope anglefire breakfire behavior
万方数据
维普
