不同分支坑道分布形式及分布位置对油气爆炸超压特性的影响

为探索洞库支坑道不同分布形式及分布位置对坑道内油气爆炸超压特性的影响，在控制容积、初始油气浓度以及点火能不变的情况下，开展了不同支坑道分布形式及分布位置条件下油气的爆炸超压特性实验，重点对最大超压、最大超压时间、超压上升速率、爆炸强度指数等主要超压特性参数进行了分析。结果表明：密闭容器内坑道的分布形式及分布位置对容器内油气爆炸超压特性有显著影响。相对布置形式下最大超压、最大超压上升速率、爆炸强度指数均小于一字排开和交错布置，达到最大超压和最大超压上升速率的时间也有所延后。3种不同分支坑道分布位置下，最大爆炸超压上升速率和爆炸强度指数由大到小依次为：远离点火端、靠近点火端、沿主坑道均匀分布。分支坑道距离点火端越远，爆炸强度指数越大, 分支坑道距离点火端越近，达到最大爆炸超压上升速率的时间越提前。

Effects of distribution form and location of different branch tunnels on overpressure characteristics of ventedgasoline-air mixture explosion in closed vessels

The branch structure of the tunnel significantly affects the overpressure characteristics of combustible gas explosions in confined space. However, most of previous studies involved explosions in branch vessels were limited to single branch structure, effects of the distribution form and location of the branch structure were rarely considered. In order to explore the influence of various branch distribution forms and locations on overpressure characteristics of vented gasoline-air mixture explosion in closed vessels, the experiments were carried out using three kinds of branch tunnel distribution forms (linear/staggered/symmetrical) and three kinds of branch tunnel locations (near to the spark plug/far from the spark plug/evenly distributed along the main tunnel), under the condition of the same tunnel volume (0.24 m3), initial fuel volume concentration (1.2%) and ignition energy (5 J). The maximum explosion overpressure p_max, the time to reach maximum explosion overpressure, the maximum rates of pressure rise (dp/dt)_max, and the deflagration index K_G were examined. Moreover, the effects of distribution form and location of branch tunnels on overpressure characteristics were discussed. Results show that explosion overpressure characteristics are strongly influenced by branch tunnels' distribution form and location. In terms of the symmetrical distribution, the maximum explosion overpressure, the maximum rates of pressure rise, and the deflagration index K_G are the lowest among the three types of distribution forms of branch tunnel. Linear and staggered distributions have similar overpressure characteristics, whose explosion overpressure, maximum rates of pressure rise, deflagration index K_G are 1.14, 1.52 and 1.52 times of those in the symmetrical situation respectively. Time to reach the maximum explosion overpressure and time to reach the maximum rates of pressure rise in the symmetrical situation are delayed, which are 1.31 and 1.30 times of those in the linear and staggered situations respectively. The maximum rates of pressure rise and the deflagration index K_G descend in the following distribution locations: far from the spark plug, near to the spark plug, evenly distributed along the main tunnel. The results indicate that the farther the branch tunnel from the ignition end, the larger the explosion intensity index, and the closer the branch tunnel from the ignition end, the earlier the time to reach the maximum explosion overpressure rising rate.