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首页> 外文期刊>Minerals Engineering >Numerical and experimental investigation of single phase flow characteristics in stirred tanks using Rushton turbine and flotation impeller
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Numerical and experimental investigation of single phase flow characteristics in stirred tanks using Rushton turbine and flotation impeller

机译：使用Rushton涡轮和浮选叶轮的搅拌槽内单相流动特性的数值和实验研究

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In this study, computational fluid dynamics (CFD) simulations are used to investigate turbulent single phase flow characteristics in lab-scale stirred tanks with different geometric variations. Water at standard conditions is used as operating fluid. Rushton turbine (RT) and flotation impeller (Fl) are used to agitate the fluid leading to turbulent flows in the tank. For Fl, impeller diameter, d, is varied and three sizes corresponding to d values of 75, 100, and 150 mm are considered. Additionally, for 75 and 100 mm FI, off-bottom clearance, C, is varied from 100 (D/3) to 60 mm (D/5). The impeller based Reynolds number, Re, ranged from 29,000 to 120,000. CFD results are compared with LDA data from the literature for RT and in-house PIV data for Fl. CFD predictions for Fl are found to match experimental measurements satisfactorily with accurate prediction of flow transition at lower C. The normalized flow properties are observed to be invariant with Re for both impellers in fully turbulent regime. Mean flow characteristics for FI suggests that the flow is characterized by strong radial and tangential velocities close to impeller with peak values along disc level. Turbulence kinetic energy profiles close to impeller are characterized by two peaks suggesting development of trailing vortex which is further verified using swirling strength visualization. For FI with diameter equal to 100 mm, flow transition in which mean flow changes from radial flow (double loop) to axial-type (single loop) flow is observed when C is reduced. Both PIV measurements and CFD simulation are able to predict this transition accurately. Using both torque on rotating parts and volume averaged dissipation rate of turbulence kinetic energy, power numbers are calculated for both impellers. The axial-type flow at smaller clearance is marked by significant drop in power number value. (C) 2015 Elsevier Ltd. All rights reserved.
机译：在这项研究中，使用计算流体动力学（CFD）模拟来研究具有不同几何变化的实验室规模搅拌罐中的湍流单相流动特性。标准条件下的水用作工作流体。 Rushton涡轮（RT）和浮选叶轮（F1）用于搅动导致罐中湍流的流体。对于F1，改变叶轮直径d，并考虑与d值分别为75、100和150mm的三种尺寸。此外，对于75毫米和100毫米FI，底下间隙C从100（D / 3）到60 mm（D / 5）不等。基于叶轮的雷诺数Re从29,000到120,000。将CFD结果与来自文献的RT的LDA数据和针对F1的内部PIV数据进行比较。发现F1的CFD预测与实验测量值令人满意地匹配较低温度下的流动转变的准确预测。对于在完全湍流状态下的两个叶轮，对于Re，观察到归一化的流动特性对于Re是不变的。 FI的平均流量特性表明，该流量的特征是靠近叶轮的径向和切向速度很强，峰值沿圆盘水平。靠近叶轮的湍流动能曲线的特征是两个峰值，表明出现了尾涡，并通过涡旋强度可视化进一步证实了这一点。对于直径等于100 mm的FI，当C减小时，观察到平均流量从径向流（双回路）变为轴向型（单回路）的流动过渡。 PIV测量和CFD模拟都能够准确预测这种转变。使用旋转部件上的扭矩和湍流动能的体积平均耗散率，可计算两个叶轮的功率数。轴向间隙较小的轴向流量以功率数值的显着下降为标志。 （C）2015 Elsevier Ltd.保留所有权利。

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