不同重力下薄燃料表面火焰传播的相似性

Comparability of Flame Spread over Thin Solid Fuel Surface Under Different Gravities

利用数值模拟方法,研究了不同重力下有限空间内薄燃料表面逆风传播火焰的相似性.结果表明,通道高度的变化,通过影响通道间的流场和壁面的热损失,来影响通道内燃料表面的火焰传播,因此用水平窄通道模拟微重力下大空间内的火焰传播,只能得到定性相似但定量差别较大的结果,这与他人的实验结果一致.在微重力和常重力下的窄通道中,当Grashof准数足够小时(200可以作为一个定性参考值),其中的自然对流基本可以忽略,不同重力下窄通道中的火焰传播过程基本相似.

The comparability of opposed-flow flame spread over thin solid fuels in finite spaces in different gravities was numerically simulated. The results show that the variation of the channel height affects the velocity profile of flow field in the channel and heat loss at the wall of the channel, and further, flame spread over solid fuels in the finite spaces. Therefore, using a horizontally narrow channel in normal gravity to simulate flame spread in large space in microgravity can only yield qualitatively similar but quantitatively different results. Which is consistent with the previous experimental results. In the process of flame spread in the narrow channel in normal gravity and microgravity, when Grashof number is low enough（200 can be taken as a qualitative reference value ） , natural convection can be ignored and flame spread processes in different gravities will be comparable.