Data on the mixing of non-Newtonian fluids by a Rushton turbine in a cylindrical tank

The paper focuses on the data collected from the mixing of shear thinning non-Newtonian fluids in a cylindrical tank by a Rushton turbine. The data presented are obtained by using Computational Fluid Dynamics (CFD) simulation of fluid flow field in the entire tank volume. The CFD validation data for this study is reported in the research article ‘Numerical investigation of hydrodynamic behavior of shear thinning fluids in stirred tank’ (Khapre and Munshi, 2015) [1]. The tracer injection method is used for the prediction of mixing time and mixing efficiency of a Rushton turbine impeller.


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The paper focuses on the data collected from the mixing of shear thinning non-Newtonian fluids in a cylindrical tank by a Rushton turbine. The data presented are obtained by using Computational Fluid Dynamics (CFD) simulation of fluid flow field in the entire tank volume. The CFD validation data for this study is reported in the research article 'Numerical investigation of hydrodynamic behavior of shear thinning fluids in stirred tank'   [1]. The tracer injection method is used for the prediction of mixing time and mixing efficiency of a Rushton turbine impeller. & 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Experimental features
For simulation, the Ansys 13 is used to solve the continuity, momentum and species transport equations. A known concentration of a tracer which has same physical property of working fluid is injected in tank for mixing time prediction. The sliding mesh approach is applied for calculation of the mixing time in tank. The strain and vorticity tensors are calculated from simulated flow field inside a tank.

Rourkela, India
Data accessibility With this article

Value of the data
The data help to predict the performance of a Rushton turbine in a cylindrical tank in terms of mixing efficiency.
It provides significant information about the mixing time in the transition and turbulent flow zone. It is also useful to explore the nature of the fluid flow and dispersive mixing efficiency inside the tank.

Data
In this article, the data generated on mixing of shear thinning non-Newtonian fluids by a Rushton turbine in a cylindrical tank is reported. The data is obtained using CFD simulation of whole tank. The validation of this study is found in [1]. The data presented herein showed some significant information about the mixing time and dispersive mixing efficiency of a Rushton turbine. We include figures and tables containing quantitative and qualitative information on the mixing time and its dispersive efficiency.

Tank geometry studied
The baffled cylindrical tank with a Rushton turbine to agitate non-Newtonian fluids is shown in Fig. 1a [2]. The detailed cylindrical tank dimensions are given in Table 1. Fig. 1b depicted the detail of locations in a tank where the tracer is injected (P 5 ) and concentrations of the tracer is collected (P 1 -P 4 ) with time to finding out the mixing time of the tank.  The rheological properties of the shear thinning non-Newtonian fluids are given in Table 2 [2], where K and n is the consistency index and flow behavior index, respectively.

Mixing time
The mixing time in the tank is determined by plotting curves between the simulation predicted tracer concentration and time. The impeller rotations are kept constant at 180 rpm. The detailed experimental and CFD simulation method for estimating the mixing time is given in the literature [3,4], respectively. A tracer is injected initially at midpoint of bottom surface of the tank, i.e., at location P 5 and the concentrations at remaining cells are initialized to zero. Numerically the concentrations at locations P 1 -P 4 are collected with time and the respective non-dimensional traction concentration distributions are presented in Fig. 2. The effect of impeller on fluid flow decreases as move from locations P 1 to P 4 . The mixing time, t m , increases from the locations P 1 -P 4 at all the impeller speeds irrespective of the flow behavior index (n). It is also seen that the impeller rotations has the huge effect on the mixing time.
The calculated mixing time, t m is multiplied by the impeller rotations, N to obtain the nondimensional mixing time, Nt m . The chosen range of the impeller rotations make sure that the Reynolds number of fluid flow is either in transition or in the turbulent flow state. The distributions of the non-dimensional mixing time with the impeller speed are illustrated in Fig. 3. The figure shows that the nature of distribution of the Nt m is dependent on the mixing study location and the distribution of the non-dimensional mixing time is scattered in nature.

Dispersive mixing efficiency
The mixing efficiency in terms of dispersive mixing efficiency ðα DME Þ is defined as [5,6] α DME ¼ where _ γ is the rate of strain tensor and ω ¼ 1=2 ∇v À ∇v ð Þ T h i is the vorticity tensor.
For α DME ¼ 0, a rotational flow and no effective mixing occur, For α DME ¼ 0:5, a simple shear flow, and. For α DME ¼ 1, a dispersive flow. Fig. 4 illustrates the distribution of α DME for the Rushton turbine impeller. The figure shows that the average α DME is little more than 0.5 for all impeller rotations and flow behavior indexes. Thus, the flow inside the stirred tank is a simple shear flow.

Transparency document. Supporting material
Transparency data associated with this article can be found in the online version at: http://dx.doi. org/10.1016/j.dib.2016.08.023.