On the Mechanism of Rapid Flame Propagation in a Rotating Flow

从涡爆机理上解释了旋转流动中火焰的快速传播，认为低密度热燃烧气体被强制卷入高密度未燃烧气体混合物中。第一年，研究了火焰速度与旋转气体速度之间的关系，指出理论不能定量地解释结果。在明年,压力分布在火焰前锋是exaimed证实的理论压力的火焰被认为是低于背后的火焰,因为离心力弱热燃烧气体的低密度,因此,旋转轴上的压力不能减少与环境压力,而离心力强未燃烧气体的密度高,因此,旋转轴上的压力变得比环境压力低得多。结果，火焰后面的压力比火焰前面的压力要高。采用高响应微差压力计和瞬态存储器，测量了火焰在旋转混合物中传播的压力分布。为了比较，还测量了火焰在静止可燃混合物和非旋转混合物流中传播的压力分布。结果表明，正如理论预测的那样，火焰前面的压力小于火焰后面的压力。然而，火焰速度仅为预测速度的一半或三分之一。今年的额外实验证实了这一点。第一年的研究结果发表在《宇航进展》杂志上，去年的研究结果将发表在《燃烧科学与技术》杂志上。

The rapid flame propagation in a rotating flow is explained on the vortex bursting mechanism, in which it is considered that the hot burned gas of low density is forcibly involved into the unburned gas mixture of high density. In the first year, the relation between the flame speed and the rotating gas speed was examined and it was pointed out that quantitatively the theory could not explain the results.In the next year, the pressure distribution across the flame front was exaimed to substantiate the theory in which the pressure ahead of the flame is assumed to be lower than that behind the flame, because the centrifugal force is weak in the hot burned gas of low density, and hence, the pressure on the axis of rotation cannot be decreased much as compared with the ambient pressure, whereas the centrifugal force is strong in the unburned gas of high density, and hence, the pressure on the axis of rotation becomes much lower than the ambient pressure. Resultingly, the pressure behind the flame becomes higher than the pressure ahead of the flame.Using a high-response, micro-diffential manometer and a transient memory, the pressure distribution was measured for the flame propagating in a rotating mixture. For comparison, the pressure distribution was also measured for the flames propagating in a quiescent combustible mixture and in a non-rotating mixture stream. The results show that, as the theory predicts, the predicts, the pressure ahead of the flame is lower than the pressure behind the flame. However, it is shown that the flame apeed is only one half or one third the predicted speed. This is confirmed by the additonal experiments this year. The results obtained in the first year have been published in Progress in Astronautics and Aeronautics, and those in the last year will appear in Combustion Science and Technolgy.