Poor mixing in the clear liquid layer above the cloud height has been reported by several authors. This study uses LDV measurements to quantify turbulence above the cloud using a liquid level of 1.5 T to remove the barrier of a free surface at H = T. A D = T/3, down-pumping PBT was used at an off-bottom clearance of C = T/3. Three slurries were tested at impeller speeds 0.8, 1, and 1.2N_js. The change in turbulence was quantified using the normalized root mean square (RMS) of the fluctuating velocity summed and averaged over each radial traverse. A significant difference between the fluctuating values of the cloud height—minimum, average, and maximum—was observed. The turbulence decays until the maximum cloud height. Beyond that, it remains constant and near zero. The effects of both particle size and solids concentration prove to be important.

中文翻译：

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搅拌罐中浓浆悬浮液中高于云层高度的湍流阻尼

几位作者报告了云层高度上方透明液体层的混合不良。本研究使用 LDV 测量来量化云层上方的湍流，使用 1.5 T 的液位去除H  =  T 时自由表面的障碍。A D  =  T / 3，在C  =  T / 3的离底间隙处使用向下泵送 PBT 。在 0.8、1 和 1.2 N _{js 的}叶轮速度下测试了三种浆料. 湍流的变化使用归一化的波动速度的均方根 (RMS) 来量化，并在每个径向横越上求和和平均。观察到云高度的波动值（最小值、平均值和最大值）之间存在显着差异。湍流衰减直到最大云高。除此之外，它保持不变并且接近于零。粒度和固体浓度的影响被证明是重要的。