Diffusion flames and their flickering motions related with Froude numbers under various gravity levels
Diffusion flames and their flickering motions related with Froude numbers under various gravity levels
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DOI：
10.1016/s0010-2180(00)00154-1
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发表时间：
2000-10-01
影响因子：
4.4
通讯作者：
Arai, M
中科院分区：
文献类型：
--
作者：
Sato, H;Amagai, K;Arai, M
研究了不同重力水平下扩散火焰中与弗劳德数和斯特劳哈数相关的燃烧现象。燃料射流的弗劳德数由重力水平、喷嘴直径、燃料性质和燃料流量控制。人工重力由离心机产生，其水平从1 G到14 G不等。另一方面，微重力条件由落塔形成。 CH4、C3H8 和 CH4 + C3H8 (54:46 mol%) 用作测试燃料。在直径0.5至10.0毫米的喷嘴上观察到多种扩散火焰。火焰长度通过 Altenkirch 等人提出的无量纲参数进行测量和关联。利用它们的参数，得到如下经验方程：L-f/d = 0.58 Re-0.667 Fr-0.089，其中L-f是平均火焰长度，d是喷嘴直径，其中Re是雷诺数（5小于或等于Re小于或等于570），Fr是弗劳德数（4.2 X 10(-4)小于或等于Fr小于或等于5.3×10(3))。由于实验的重力水平是通过弗劳德数来解释的，因此该方程可以表示不同重力水平（低重力和高重力条件）下的火焰长度。此外，还测量了不同重力水平（1.0-5.0 G）下的闪烁频率。在较宽的燃料喷射速度范围内（从 0.03 m/s 到 36.2 m/s），闪烁频率通过弗劳德数耦合的两个关系相关。一种关系是对于低弗劳德数条件，St 与 Fr-0.50 成比例，另一种关系是对于高弗劳德数条件，St 与 Fr-0.41 成比例。这意味着低电平和高电平的弗劳德数是闪烁频率的划分标准，并且这两个方程表达的闪烁运动以不同的方式受到浮力的影响。 (C) 2000 年，燃烧研究所。
Combustion phenomena related to Froude number and Strouhal number were investigated in diffusion flames under various gravity levels. The Froude number of the fuel jet was controlled by gravity level, diameter of the nozzle, fuel properties, and fuel how rate. Artificial gravity was created by a centrifuge and its level was varied from 1 G to 14 G. On the other hand, microgravity condition was formed by a drop tower. CH4, C3H8 and CH4 + C3H8 (54:46 mol %) were used as the test fuels. Many kinds of diffusion flames were observed on nozzles ranging in diameter from 0.5 to 10.0 mm. Flame lengths were measured and correlated by a dimensionless parameter which was proposed by Altenkirch et al. Using their parameter, an empirical equation was obtained as follows: L-f/d = 0.58 Re-0.667 Fr-0.089, where L-f was the average flame length and d was nozzle diameter, where Re is the Reynolds number (5 less than or equal to Re less than or equal to 570) and Fr is the Froude number (4.2 X 10(-4) less than or equal to Fr less than or equal to 5.3 X 10(3)). Since gravity levels of experiments were accounted for via the Froude number, this equation could express the flame lengths at various gravity levels (low- and high-gravity conditions). Also, flickering frequencies under various gravity levels (1.0-5.0 G) were measured. Over a wide range of fuel jet velocity (from 0.03 m/s to 36.2 m/s), flickering frequencies were correlated by two relations coupled through the Froude number. One relation was St proportional to Fr-0.50 for low Froude number conditions, and the other was St proportional to Fr-0.41 for high Froude number conditions. It meant that the Froude numbers of the low and high levels were dividing criteria for the flickering frequencies, and that flickering motions expressed by these two equations were affected by buoyancy in different ways. (C) 2000 by The Combustion Institute.