高热壁油气热爆燃实验研究

Experiment analysis of gasoline-air mixture deflagration under the condition of hot wall

设计了高热壁油气热爆燃实验系统,对地下受限空间油气混合物在高热壁条件下的热爆燃现象进行研究,获得了油气热爆燃过程中测点的温度和各成分体积分数变化历程,以及热起燃过程的时序照片。根据实验结果,讨论了油气混合物热爆燃的着火方式、着火条件及着火延滞期规律。结果表明,高热壁条件下,密闭坑道内的油气混合物的着火温度高于自燃点近80 K。高热壁周围极大的温度梯度是着火温度远高于自燃点的原因之一。热壁条件下油气混合物引燃过程分为缓慢氧化阶段、快速氧化段和着火段3个阶段。热壁着火的延迟期在实验条件下相当长,着火方式以热壁表面油气点燃为起点。

This paper is aimed to introduce a special experiment system designed by the author to make experiments on gasoline-air mixture deflagration in the confined undergrotmd space surrotmded by hot walls. As a result of our experiments, we have realized a great change in temperature and concentration measuring points in the course of gasoline-air mixture deflagration with a set of pictures of auto-ignition taken in the research process. In accordance with the result of our experiments, we have renewed our arguments in the manner, condition and arrearage time of the self-ignition in detail with the conventional ideas in this way. The results of our experiments also enable us to make the following conclusion： the self-ignition temperature of gasoline-air mixture in the confined underground space proves much higher than the spontaneous combustion temperature of gasoline, which may get to 773 K under the experimental conditions. We believe that it is most likely that the abrupt temperature grad in the tunnel and hot wall that has led to the abrupt change of gasoline composition. In addition, the ignition time of gasoline-air mixture in the confined underground space can be divided into three stages, namely, slow oxidation, quick oxidation, and the ignition. The boundary between the slow oxidation and quick oxidation should be the temperature of gasoline spontaneous combustion, however, the arrearage time of deflagration can be long under the experimental conditions, and the ignition area of gasoline-air mixture usually begins with a point on the hot wall and then quickly spread to the whole wall areas at a tremendous speed of propagation to all the parts of the tunnel.