On the breakup of spiralling liquid jets
On the breakup of spiralling liquid jets
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DOI：
10.1017/jfm.2018.956
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发表时间：
2019-01
影响因子：
3.7
通讯作者：
Yuan Li;G. M. Sisoev;Y. Shikhmurzaev
中科院分区：
文献类型：
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作者：
Yuan Li;G. M. Sisoev;Y. Shikhmurzaev
在离心力的作用下，从旋转装置的喷射螺旋出的液滴的产生被认为是在入口处引入的小扰动的情况。接近入口，在那里的干扰可以被视为小，他们的传播被发现是定性类似的波传播的直喷拉伸的外部体力（如重力）。色散方程对基流有相同的参数依赖性，但基流当然是不同的。进一步向下的射流，在那里的扰动的幅度变得有限，并最终导致液滴形成，流动似乎是相当复杂的。如图所示，对于液滴产生的规则/周期性过程，对应于入口处的频率的波长随着波沿着拉伸射流向下传播而增加，通常不确定所产生的液滴的体积，而是确定主液滴和跟随主液滴的卫星液滴的体积之和。形成主液滴的总体积的比例取决于液滴在射流中产生的距离，即取决于入口扰动的大小。主液滴的体积被发现是一个线性函数的未扰动射流的半径评估的点，在那里的下降脱离射流。必须通过使用在Shikhmurzaev和Sisoev（J. Fluid Mech.，第819卷，2017年，pp. 352-400）。讨论了液滴形成过程的非线性动力学特性。
The generation of drops from a jet spiralling out of a spinning device, under the action of centrifugal force, is considered for the case of small perturbations introduced at the inlet. Close to the inlet, where the disturbances can be regarded as small, their propagation is found to be qualitatively similar to that of a wave propagating down a straight jet stretched by an external body force (e.g. gravity). The dispersion equation has the same parametric dependence on the base flow, but the base flow is, of course, different. Further down the jet, where the amplitude of the disturbances becomes finite and eventually resulting in drop formation, the flow appears to be quite complex. As shown, for the regular/periodic process of drop generation, the wavelength corresponding to the frequency at the inlet, increasing as the wave propagates down the stretching jet, determines, in general, not the volume of the resulting drop but the sum of volumes of the main drop and the satellite droplet that follows the main one. The proportion of the total volume forming the main drop depends on how far down the jet the drops are produced, i.e. on the magnitude of the inlet disturbance. The volume of the main drop is found to be a linear function of the radius of the unperturbed jet evaluated at the point where the drop breaks away from the jet. This radius, and the corresponding velocity of the base flow, have to be found simultaneously with the jet’s trajectory by using a jet-specific non-orthogonal coordinate system described in detail in Shikhmurzaev & Sisoev (J. Fluid Mech., vol. 819, 2017, pp. 352–400). Some characteristic features of the nonlinear dynamics of the drop formation are discussed.