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On the Mechanism of Rapid Flame Propagation in a Rotating Flow

旋转流中火焰快速传播机理研究

基本信息

批准号：
03650172
负责人：
ISHIZUKA Satoru
金额：
$ 1.28万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

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.

本文用涡破裂机理解释了旋转气流中火焰的快速传播，认为低密度的热燃气被强制卷入高密度的未燃气混合物中。第一年考察了火焰速度与旋转气体速度的关系，指出理论不能定量地解释这一结果，第二年考察了火焰前缘的压力分布，以证实火焰前缘压力低于火焰后缘压力的理论。因为离心力在低密度的热的已燃烧气体中较弱，因此与环境压力相比，旋转轴上的压力不能降低很多，而离心力在高密度的未燃烧气体中较强，因此，旋转轴上的压力变得比环境压力低得多。采用高响应微差压计和瞬态存储器测量了旋转混合物中火焰传播的压力分布。为了比较，还测量了在静止的可燃混合物和在非旋转的混合物流中传播的火焰的压力分布。结果表明，正如理论预测的那样，火焰前方的压力低于火焰后方的压力。然而，它表明，火焰apeed只有一半或三分之一的预测速度。这一点在今年的实验中得到了证实。第一年获得的结果已发表在《宇航学进展》上，最后一年的结果将发表在《燃烧科学与技术》上。