局部开口受限空间油气爆燃的超压瞬变与火焰行为

开展了油气在局部开口受限空间内油气爆燃的实验研究，获得了不同初始浓度下油气爆燃超压及火焰特性。研究结果表明：内场有两个超压峰值，外场仅有一个，开口处出现负压区。内外最大超压大小基本相同，均由外部爆燃形成。随着浓度的升高，超压先增后减，最大超压对应初始浓度为1.88%。火焰的传播过程分为3个阶段，火焰的形态、颜色、各阶段持续时间、直径、平均速度均受初始浓度的影响。随着初始浓度升高，火焰从淡蓝色层流光滑火焰变为亮黄色褶皱火焰，层流传播阶段和加速变形阶段的持续时间先增后减，溃散熄灭阶段的持续时间增加。火球直径与浓度的关系可用三次多项式描述，火焰平均速度随时间的变化可用二次多项式描述。随着开口率的升高，爆燃超压和火焰速度逐渐减小，火球直径先增大后减小。

Overpressure transients and flame behaviors of gasoline-air mixture deflagration in confined space with local opening

Experiments on gasoline-air mixture deflagration in the confined space with a local opening was carried out. Overpressure transients and flame behaviors under different concentration were acquired and the results showed that:there were two overpressure peaks inside the vessel but only one outside the vessel, and negative pressure zone was formed near the opening. The maximum value of internal and external overpressure were the same and both of them were caused by external deflagration. The value of overpressure peak showed the trend of first increasing and then decreasing with the increase of concentration, and the concentration corresponding to maximum overpressure peaks was 1.88%. The process of flame propagation could be divided into three stages, and the flame shape, color, duration of each stage, diameter of external fireball and average flame speed were dominated by initial concentration. With the increase of the concentration, the blue laminar flame with smooth front was changed into bright yellow flame with wrinkled front, and the duration of laminar propagating stage as well as accelerating and distorting stage showed the same trend of first increasing and then decreasing, but the duration of extinguishing stage showed a decreasing trend. The relationship between the diameter of fireball and concentration could be fitted by cubic polynomial, and the flame speed of 1st and 2nd stage could be fitted by quadratic polynomial. With the increase of opening ratio, the pressure peaks and flame speed of 2nd stage showed a decreasing trend, and the diameter of fireball showed a first increasing and then decreasing trend.