THE EFFECT OF CHARGE EMISSION FROM ELECTRIFIED LIQUID CONES
THE EFFECT OF CHARGE EMISSION FROM ELECTRIFIED LIQUID CONES
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DOI：
10.1017/s0022112092002829
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发表时间：
1992-10-01
影响因子：
3.7
通讯作者：
DELAMORA, JF
中科院分区：
文献类型：
--
作者：
DELAMORA, JF
泰勒解释说，在带电的液体界面中，稳定锥体的形成是电张力和毛细张力之间的平衡，其中静电势随距离锥体尖端的距离r而变化，约为r1/2。虽然Taylor关于锥体形成的起始电压依赖于液体表面张力和锥体尺寸的预测与观察到的趋势一致，但他关于锥体半角α只能取α = α (T) = 49.3度的结论却不一致。对于高导电性流体，通过计算从锥尖发出的液滴的空间电荷，建立了一个不受这种悖论影响的更一般的理论，其势也具有遵循泰勒r1/2定律的显著特性。在这个公式中，半角α的锥形半月板的顶点发出角均匀的对向同轴半角α的锥形喷雾，β和喷雾电流I都是固定的函数；即beta = beta(a), I = 2pigammaKqG(alpha)，其中Kq和q分别为液滴的电迁移率和总电荷。在含有5% H2SO4和1-辛醇的实验中，观察到的喷雾近似圆锥形，顶点接近半月板尖端。实测和预测的β (α)关系在46°>°>°32°范围内是合理一致的，在这个范围内，液体锥是稳定的，喷雾是可见的，尽管数据明显低于理论曲线。预测的喷雾电流I与初步实验结果也基本吻合。该分析既不适用于具有显著惯性的大液滴喷雾，也不适用于真空中的液体锥。
The formation of stable cones in electrified liquid interfaces was explained by Taylor as a balance between electrical and capillary tensions, where the electrostatic potential varies as phi approximately r1/2 with the distance r from the cone tip. Although Taylor's predictions for the dependence of the onset voltage for cone formation on the liquid surface tension gamma and the cone dimensions agree with observed trends, his conclusion that the cone semiangle alpha can only take the value alpha = alpha(T) = 49.3-degrees does not. A more general theory free from this paradox is constructed for highly conducting fluids by accounting for the space charge of the droplets emanating from the cone apex, whose potential has the remarkable property of also obeying Taylor's r1/2 law. In this formulation, where the apex of a conical meniscus of semiangle alpha emits an angularly uniform opposed coaxial Conical spray of Semiangle pi - beta, both beta and the spray current I turn out to be fixed as functions of alpha; namely, beta = beta(a), and I = 2pigammaKqG(alpha), where Kq and q are the droplet's electrical mobility and total charge, respectively. In experiments with 5% H2SO4 in 1-octanol, the observed sprays are approximately conical with an apex nearly touching the meniscus tip. The measured and predicted beta(alpha) relations are in reasonable agreement in the range 46-degrees > alpha > 32-degrees, where the liquid cone is stable and the spray is visible, though the data fall clearly below the theoretical curve. The predicted spray current I is also in rough agreement with preliminary experiments. The analysis applies neither to sprays of large droplets with significant inertia, nor to liquid cones in vacuo.