Propagation mechanisms of supersonic combustion waves
Propagation mechanisms of supersonic combustion waves
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超音速燃烧波的传播机制
DOI：
10.1016/j.proci.2014.08.002
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
G. Ciccarelli
中科院分区：
文献类型：
--
作者：
M. Kellenberger;G. Ciccarelli
利用高速纹影摄影技术研究了超声速燃烧波在有障碍通道中的传播。实验是在一个2.54厘米宽7.82厘米高的通道与等距1.91厘米高的栅栏型障碍物安装在顶部和底部表面进行的。在8-30 kPa的初始压力范围内用化学计量的氢-氧混合物进行试验。高速摄像表明，燃烧波在准爆轰传播区的传播是非常复杂的，涉及耦合的局部爆炸，并不是所有的涉及爆轰起爆。对于最具反应性的混合物（d/λ> 6.5），持续的爆轰通过通道传播，由于障碍物周围的衍射而有所减弱。对于反应性较低的混合物（6.5 >d/λ> 2），爆轰传播是间歇性的，其中爆轰由于障碍物周围的衍射而失败，然后在两个横向激波碰撞后在通道中心线处重新引发。横向冲击波起源于在顶部和底部障碍物表面的冲击反射之后立即形成的爆震。爆轰起爆发生在拐角处，在那里的通道壁和障碍物满足，作为激波聚焦的结果，并传播到火焰前面的未燃烧的气体。对于λ< 2的混合物，波的传播取决于激波从障碍物对（顶部和底部）反射的结果。如果冲击波从障碍物对的反射在障碍物表面处引发爆炸，则所产生的两个横向冲击波的碰撞在每个障碍物之后的通道中心线处产生局部爆炸，导致平均铅冲击速度大致等于产品的等压声速。如果激波反射不导致障碍物表面处的气体点燃，则所产生的传播处于扼流火焰状态。
The propagation of a supersonic combustion wave in an obstructed channel is investigated using high-speed schlieren photography. Experiments were carried out in a 2.54 cm wide by 7.82 cm tall channel with equally spaced 1.91 cm tall fence-type obstacles mounted on the top and bottom surfaces. Tests were carried out with stoichiometric hydrogen–oxygen mixtures over an initial pressure range of 8–30 kPa. The high-speed video shows that combustion wave propagation in the quasi-detonation propagation regime is very complex involving coupled local explosions, not all of which involve detonation initiation. For the most reactive mixtures (d/λ> 6.5) a sustained detonation propagates through the channel with some weakening due to diffraction around obstacles. For less reactive mixtures (6.5 >d/λ> 2) detonation propagation is intermittent, where the detonation fails due to diffraction around the obstacles and then is re-initiated at the channel centerline following the collision of two transverse shock waves. The transverse shock wave originates from a detonation that forms immediately following shock reflection off the top and bottom obstacle faces. Detonation initiation occurs at the corner, where the channel wall and obstacle meet, as a result of shock focusing and propagates into the unburned gas ahead of the flame. For mixtures whered/λ< 2, the wave propagation is governed by the outcome of the shock reflection off the obstacle pair (top and bottom). If shock reflection off the obstacle pair initiates an explosion at the obstacle face, the collision of the resulting two transverse shock waves produces a local explosion at the channel centerline after each obstacle resulting in an average lead shock velocity roughly equal to the isobaric speed of sound of the products. If shock reflection does not result in ignition of the gas at the obstacle face, the resulting propagation is in the choked flame regime.