低重力下典型固体燃料的火焰特征及燃烧速率

Flame Characteristics and Burning Rate of Typical Solid Fuel Under Reduced Gravity

利用实验时间为2.2,s,低重力水平为10-2,g0简易实验系统,对易升华典型固体燃料试样从常重力到低重力环境过渡的瞬态燃烧过程进行了实验研究,考察了火焰形态、火焰亮度和温度以及燃料试样燃烧速率受重力水平影响的变化趋势.结果表明,随着重力水平的变化,火焰从常重力环境中的湍流扩散火焰,过渡为低重力环境中的层流火焰,火焰高度、亮度和温度以及燃烧速率都随重力水平的下降而降低.由于进入低重力状态后,常重力燃烧诱导的空气流动并没有完全消失,观察到了逆风侧火焰温度、火焰平均亮度,以及燃烧速率因气流作用而回升的现象,这种现象会使低重力环境中的火灾复杂性和危害性增强.

Experiments were carried out in a simplified drop system,which can provide a simulated reduced gravity period of about 2.2 s and a residual gravity of 10-2,g0.The transitional behaviors of flame shape,average flame lumi-nance,flame temperature and combustion rate of fuel sample under normal to reduced gravity condition have been investigated.The results show that flame transforms from diffusive turbulent flame under normal gravity to laminar flame under reduced gravity.Flame height,average flame luminance,flame temperature and combustion rate of fuel decrease under reduced gravity.Because of the residual air movement induced by combustion under normal grav-ity,the rise in upwind flame temperature,luminance and combustion rate has been observed,which may make the fires under reduced gravity more complicated and hazardous.