论文标题
泰勒 - 库特流中的分散液滴调制湍流阻力调制：分散相粘度的影响
Turbulence drag modulation by dispersed droplets in Taylor-Couette flow: the effects of the dispersed phase viscosity
论文作者
论文摘要
湍流中的分散相可以从几乎不粘的流体到高粘性流体不等。通过更改分散液滴相的粘度，我们通过实验研究了分散液滴的变形性如何影响湍流乳液的全局运输量。采用了不同种类的硅油来产生粘度比，$ζ$，范围从$ 0.53 $到$ 8.02 $。液滴音量分数为$ ϕ $，从0 \％到10 \％，间距为2 \％。通过归一化摩擦系数$ c_ {f，ϕ}/c_ {f，ϕ = 0} $量化的全局传输数量显示，由于液滴的消失有限尺寸效应，对湍流强度的依赖性较弱。有趣的事实是，随着$ζ$的增加，$ c_ {f，ϕ}/c_ {f，ϕ = 0} $首先增加，然后饱和到与刚性粒子悬架相似的高原值。通过执行图像分析，从液滴变形性的方面解释了这种阻力修饰，这是导致液滴的分裂和聚结效应。液滴尺寸分布的统计数据表明，随着$ζ$的增加，界面张力引起的稳定效应变得很大，并且纯粹的惯性分解过程占主导地位。沿系统的径向方向的液滴分布的测量显示出散装的聚类效应，这可以归因于液滴的不可忽略的合并效应。发现随着$ζ$的增加，可以抑制液滴聚合作用，从而影响界面张力对总应力的贡献，并考虑到观察到的乳液流变学。
The dispersed phase in turbulence can vary from almost inviscid fluid to highly viscous fluid. By changing the viscosity of the dispersed droplet phase, we experimentally investigate how the deformability of dispersed droplets affects the global transport quantity of the turbulent emulsion. Different kinds of silicone oil are employed to result in the viscosity ratio, $ζ$, ranging from $0.53$ to $8.02$. The droplet volume fraction, $ϕ$, is varied from 0\% to 10\% with a spacing of 2\%. The global transport quantity, quantified by the normalized friction coefficient $c_{f,ϕ}/c_{f,ϕ=0}$, shows a weak dependence on the turbulent intensity due to the vanishing finite-size effect of the droplets. The interesting fact is that, with increasing $ζ$, the $c_{f,ϕ}/c_{f,ϕ=0}$ first increases and then saturates to a plateau value which is similar to that of the rigid particle suspension. By performing image analysis, this drag modification is interpreted from the aspect of droplet deformability, which is responsible for the breakup and coalescence effect of the droplets. The statistics of the droplet size distribution show that, with increasing $ζ$, the stabilizing effect induced by interfacial tension comes to be substantial and the pure inertial breakup process becomes dominant. The measurement of the droplet distribution along the radial direction of the system shows a bulk-clustering effect, which can be attributed to the non-negligible coalescence effect of the droplet. It is found that the droplet coalescence effect could be suppressed as the $ζ$ increases, thereby affecting the contribution of interfacial tension to the total stress, and accounting for the observed emulsion rheology.
