Simulating microgravity in small diffusion flames by using electric fields to counterbalance natural convection
Simulating microgravity in small diffusion flames by using electric fields to counterbalance natural convection
复制标题
通过使用电场来平衡自然对流来模拟小扩散火焰中的微重力
DOI：
10.1098/rspa.2001.0929
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
F. J. Weinberg
中科院分区：
文献类型：
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作者：
B. A. Strayer;Jonathan D. Posner;D. Dunn;F. J. Weinberg
在微重力下进行燃烧研究的一个主要动机是没有浮力驱动的流动。为了在实验室中实现等效的微浮力条件，我们使用电场驱动的火焰离子产生的风来平衡局部对流。这种台式微重力模拟的目的是促进广泛的光学和激光诊断，可以探测小的扩散火焰的结构，而没有相当大的实验障碍和微重力落塔或飞行试验所涉及的费用。在初步实验中，一个临时的（秒的顺序）微浮力平衡点实现了整个火焰，这是，然而，只适合于瞬时记录，受到振荡和干扰的随机对流在实验室中，以及火焰结构的逐渐变化。本文描述了一个本地化的稳态平衡条件，允许在延长的时间内，我们已经实现了适当的修改电极配置的迭代测量。为了证明这一方法，一个小的非预混甲烷-空气毛细管火焰的温度场的电场控制下，探测全息干涉术和相干反斯托克斯拉曼光谱，以帮助理解平衡的稳态，离子形成率也进行了测量，与正常的浮力情况下进行比较。与适当的电场，毛细管火焰的温度测量显示的温度梯度的减少密切接近一个纯粹的扩散热分布，如预期将导致从抑制局部浮力驱动的对流。
A principal motivation for combustion research in microgravity is the absence of buoyancy–driven flows. To accomplish an equivalent microbuoyant condition in the laboratory, we use flame–ion generated winds driven by electric fields to balance local convection. The object of such bench–top microgravity simulation is to facilitate a wide range of optical and laser diagnostics that can probe the structure of small diffusion flames without the considerable experimental obstacles and costs involved in microgravity drop tower or flight tests. In preliminary experiments, a temporary (of the order of seconds) microbuoyant point of balance was achieved for the entire flame, which was, however, suitable only for instantaneous recording, being subject to oscillations and disturbance by random convection currents in the laboratory as well as gradual changes in flame structure. This paper describes a localized steady–state balance condition, permitting iterative measurements over extended time periods, which we have achieved by appropriate modifications of the electrode configuration. To demonstrate this methodology, the temperature field of a small non–premixed methane–air capillary flame under electric field control is probed with holographic interferometry and coherent anti–Stokes Raman spectroscopy.To help understand the steady state of balance, rates of ion formation were also measured for comparison with the normal buoyancy case. With the appropriate electric field, the temperature measurements of the capillary flame show a reduction in the temperature gradient closely approximating to a purely diffusive thermal profile, such as would be expected to result from inhibition of the local buoyancy–driven convection.