微小空间内丙烷/空气火焰传播特性与加氢爆燃实验

摘要

在内径150 mm的圆盘狭缝微型燃烧室内,实验探讨了在常温常压下,不同当量比的丙烷/空气预混气以及掺氢的丙烷/空气混合气在电火花点火后向外传播的特性,通过高速摄影方法获得了在狭缝间距为2.0、2.5、3.0、5.0 mm时微燃烧室内的火焰传播形态.实验中观察到火焰传播存在光滑、皱褶和断裂三种火焰锋面形态.当量比的增加和狭缝间距的减小会使火焰更容易发生褶皱.随着火焰的传播,火焰半径逐渐增大,火焰传播速度整体呈下降趋势.火焰传播速度随着间距的减小先增大后减小,在间距3 mm时最大.因为壁面散热的影响,微尺度效应在降低火焰传播速度和增加火焰不稳定性方面具有重要作用.掺入氢气能提高预混气的火焰传播速度,在间距2.5 mm的微燃烧腔中还观察到了爆燃现象.%An experimental study on the characteristics of propane/air and propane/hydrogen/air flame propagation,at ambient temperature and pressure,was carried out in a narrow-gapped micro-chamber shaped like a disk and 150 mm in diameter,which was ignited by a spark igniter;photographs of the flame propagation were obtained with a high-speed camera at a gap distance of 2.0,2.5,3.0 and 5.0 mm,respectively;and the flame was observed to be smooth,wrinkled,and broken.As the flame equivalence ratio increases or the height of the gap decreases,the flame wrinkles occur earlier.The flame speed in the micro-chamber was slightly lower than that in the conventional-scale chamber,and it gradually decreased as the flame radius increased.As the gap height decreased,the flame propagation speed increased at first and then decreased,reaching the maximum at the gap height of 3 mm in the micro-chamber.As the heat loss increased,the micro scale effects played an important role in reducing the flame speed and enhancing the flame instability.Addition of hydrogen raised the flame propagation speed,and led to the detonation observed in the micro-chamber at a gap width of 2.5 mm.