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Study on The Flame Behaviors in A Centrifugal Acceleration Environment of Solid Vortex

固体涡流离心加速环境下火焰行为研究

基本信息

批准号：
01550180
负责人：
ONO Shinsuke
金额：
$ 1.28万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1991
项目状态：
已结题

项目摘要

Flame propagation in a swirl flow shows complicated behaviors due to the intense turbulence accompanied by the swirl. In this study, by making use of the rotary combustion device which rotates with mixture in it, the real effects of the rotating flow environments on the flame behaviors are investigated. The experimental results make clear that the enhanced combustion by the swirl cannot always be realized because of the rapid motion of a flame kernel toward the center and the laminarization of turbulent flame front in the intense rotating flow. The experimental results are summarized as follows :(1)A rapid expansion of the burned gas ignited at the vessel center may suppress the growth of flame due to disturbance caused by a mechanical non-equilibrium existing between unburned and burned gas, and may cause a flame extinction, depending on the condition.(2)In the case of the ignition near the vessel wall, flame quickly moves to the vessel center and the flame zone develops more than for the central ignition. But, the laminatization of the turbulent flame zone soon appears to follow the similar process to the central ignition. Although the extinction radius becomes larger than that for the central ignition, the extinction time(burnig period)still remains approximately the same as that for the central ignition.(3)The extinction limit seems to be determined by the relative relation between a flame propagation speed and a flame convection speed. The extinction tendency becomes considerable with the increase of the ratio, Vc/Vf.(4)With the exception of the influence of the rotation speed, the degree of influence considerably depends on the preheat zone thickness, the burning velocity, and the lewis number that are related to the flame structure.

由于旋流伴随着强烈的湍流，旋流中的火焰传播表现出复杂的行为。在本研究中，通过利用其中含有混合物旋转的旋转燃烧装置，研究旋转流动环境对火焰行为的真实影响。实验结果表明，由于火焰核心向中心的快速运动以及强烈旋转流中湍流火焰锋的层流化，旋流强化燃烧并不总是能够实现。实验结果总结如下：（1）在容器中心点燃的已燃气体的快速膨胀可能会抑制由于未燃烧气体和已燃烧气体之间存在的机械不平衡引起的扰动而引起的火焰的生长，并可能导致火焰熄灭，具体取决于条件。（2）在靠近容器壁点火的情况下，火焰快速移动到容器中心，并且火焰区比中心区域发展得更多点火。但是，湍流火焰区域的分层很快似乎遵循与中心点火类似的过程。虽然熄灭半径变得比中心点火的更大，但是熄灭时间（燃烧周期）仍然与中心点火的大致相同。（3）熄灭极限似乎由火焰传播速度和火焰对流速度之间的相对关系决定。随着Vc/Vf比的增大，熄灭趋势变得相当大。(4)除转速的影响外，影响程度很大程度上取决于预热区厚度、燃烧速度以及与火焰结构有关的路易斯数。