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Numerical Simulation and Analysis of Power Consumption and Metzner-Otto Constant for Impeller of 6PBT

Chinese Journal of Mechanical Engineering 2014年第3期27卷 635-640页

作者： luan deyu CHEN Qiao ZHOU Shenjie School of Mechanical and Electrical Engineering Qingdao University of Science and Technology School of Mechanical Engineering Shandong University

Majority of non-Newtonian fluids are pseudoplastic with shear-thinning property, which means that the viscosity will be different in different parts of the stirred tank. In such mixing process, it is difficult to predict accurately the power consumption and mean shear rate for designing novel impeller. Metzner-Otto method is a widely accepted method to solve these questions in mixing non-Newtonian fluids. As a result, Metzner-Otto constant will become a key factor to achieve an optimum way of economical mixing. In this paper, taking glycerine and xanthan gum solutions as research system, the power consumption, stirred by the impeller composed of perturbed six-bent-bladed turbine （6PBT） with differently geometrical characteristics in a cylindrical vessel, is studied by means of computational fluid dynamics （CFD）. The flow is modeled as laminar and a multiple reference frame （MRF） approach is used to solve the discretized equations of motion. In order to determine the capability of CFD to forecast the flow process, the torque test experiment is used to measure the glycerine solution power consumption. The theological properties of the xanthan gum solutions are determined by a Brookfleld rheometer. It is observed that the power consumption predicted by numerical simulation agrees well with those measured using torque experiment method in stirring glycerine solution, which validate the numerical model. Metzner-Otto constant is almost not correlated with the flow behavior index of pseudoplastic fluids. This paper establishes the complete correlations of power constant and Metzner-Otto constant with impeller geometrical characteristics through linear regression analysis, which provides the valuable instructions and references for accurately predicting the power consumption and mean shear rate of pseudoplastic fluids in laminar flow, comparatively.

关键词： impeller composed of perturbed six-bent-bladed trbine pseudoplastic fluids power constant Metzner-Otto constant

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Chaotic characteristics of pseudoplastic fluid induced by 6PBT impeller in a stirred vessel

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Chinese Journal of Chemical Engineering 2019年第2期27卷 293-297页

作者： deyu luan Yiming Chen Hong Wang Yue Wang Xing Wei College of Electromechanical Engineering Qingdao University of Science and Technology

Xanthan gum solutions with different mass concentrations were used to study the chaotic characteristics induced by the impeller of perturbed six-bent-blade turbine(6 PBT) in a stirred vessel. Based on the velocity time series obtained by the experiment of particle image velocimetry(PIV), with the software MATLAB(R2016a), the distributions of the largest Lyapunov exponent(LLE) and Kolmogorov entropy(K entropy) of the system, as two important parameters for characterizing the chaotic degree, were investigated respectively. Results showed that both of the LLE and K entropy increased with the increasing speed at the beginning. As the speed was up to 200 r·min-1, the two parameters reached the maximal values meanwhile, corresponding to 0.535 and 0.834, respectively, which indicated that the chaotic degree of the flow field was up to the highest level. When the speed was increased further, both of the LLE and K entropy decreased on the contrary, which meant that the chaotic degree was decreasing. It was also observed that the chaotic characteristics of flow field were hardly affected by the fluid rheology and the detecting positions. The research results will enhance the understanding of the chaotic mixing mechanism and provide a theoretical reference for optimizing impeller structure.

关键词： Chaos Pseudoplastic fluids Largest Lyapunov exponent (LLE) Kolmogorov entropy (K entropy) Particle image velocimetry (PIV) 6PBT impeller

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Study on gas–liquid flow characteristics in stirred tank with dual-impeller based on CFD-PBM coupled model

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Chinese Journal of Chemical Engineering 2021年第10期34卷 63-75页

作者： Songsong Wang Qiuxiang Bu deyu luan Ying Zhang Longbin Li Zhaorui Wang Wenhao Shi College of Electromechanical Engineering Qingdao University of Science and TechnologyQingdao 266061China

Study on gas–liquid flow in stirred tank with two combinations of dual-impeller(six-bent-bladed turbine(6BT)+six-inclined-blade down-pumping turbine(6 ITD),the six-bent-bladed turbine(6BT)+six-inclinedblade up-pumping turbine(6ITU))was conducted using computational fluid dynamics(CFD)and population balance model(PBM)(CFD-PBM)coupled *** local bubble size was captured by particle image velocimetry(PIV)*** gas holdup,bubble size distribution and gas–liquid interfacial area were explored at different conditions through numerical *** results showed that the 4 mm bubbles accounted for the largest proportion of 33%at the gas flow rates Q=0.76 m^(3)·h^(-1) and 22%at Q=1.52 m^(3)·h^(-1) for combined impeller of 6BT+6ITU,while the bubbles of 4.7 mm and 5.5 mm were the largest proportion for 6BT+6ITD combination,i.e.25%at Q=0.76 m^(3)·h^(-1) and 22%at Q=1.52 m^(3)·h^(-1),respectively,which indicated that 6BT+6ITU could reduce bubble size effectively and promote gas *** addition,the gas holdup around impellers was increased obviously with the speed compared with gas flow *** it was concluded that 6ITU impeller could be more conductive to the bubble dispersion with more uniform bubble size,which embodied the advantages of 6BT+6ITU combination in gas–liquid mixing.

关键词： Gas-liquid two-phase flow Gas holdup Gas-liquid interfacial area Bubble Coupling algorithm of CFD-PBM

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螺旋角对六分型螺旋折流板换热器换热性能的影响

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石油化工设备技术 2024年第3期45卷 22-26,I0002页

作者：张翔赵承志佀闻胡志刚栾德玉青岛科技大学山东青岛266061 青岛畅隆重型装备有限公司山东青岛266000

为探究螺旋角对六分型螺旋折流板换热器换热性能的影响,采用数值模拟的方法,以液态水为工作介质,对六分型螺旋折流板换热器在不同流量下的换热性能进行研究,分析螺旋角变化对于传热系数和换热综合性能的影响。结果表明:随着螺旋角的增大... 详细信息

为探究螺旋角对六分型螺旋折流板换热器换热性能的影响,采用数值模拟的方法,以液态水为工作介质,对六分型螺旋折流板换热器在不同流量下的换热性能进行研究,分析螺旋角变化对于传热系数和换热综合性能的影响。结果表明:随着螺旋角的增大,换热管沿轴向的表面热流密度逐渐减小,壳程传热系数和压降也随之减小;换热综合性能指标h s/Δp和h s/Δp 1/3随螺旋角增大而增大,而在螺旋角β=25°的条件下,h s/Δp和h s/Δp 1/3显著下降。由此可知,选择较大螺旋角能够获得较好的换热性能。上述研究结果可为六分型螺旋折流板换热器的工程应用提供参考。

关键词：螺旋折流板换热器螺旋角数值模拟传热

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直叶涡轮及斜四叶桨搅拌槽层流流场的数值分析

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石油炼制与化工 2011年第4期42卷 50-56页

作者：田华栾德玉中国石化催化剂上海分公司上海201507 山东大学机械工程学院

采用计算流体力学(CFD)方法,对直叶圆盘涡轮桨(Rushton)和斜四叶桨(PBT)搅拌槽流场进行研究。利用Laminar层流模型对其在甘油中产生的流场进行数值计算,得到四种形式的搅拌桨以恒定转速200r/min在搅拌槽内转动时所产生的流场结构,对比... 详细信息

采用计算流体力学(CFD)方法,对直叶圆盘涡轮桨(Rushton)和斜四叶桨(PBT)搅拌槽流场进行研究。利用Laminar层流模型对其在甘油中产生的流场进行数值计算,得到四种形式的搅拌桨以恒定转速200r/min在搅拌槽内转动时所产生的流场结构,对比分析轴向、径向和切向的速度矢量图、速度云图以及速度分布曲线,比较所需的搅拌功率。结果表明:Rushton桨的搅拌效果优于PBT桨,但能量损耗较高;不同倾角的PBT桨具有类似的流动特性。

关键词：直叶圆盘涡轮桨斜四叶桨搅拌槽层流模型数值分析

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错位六弯叶桨搅拌假塑性流体流场宏观不稳定性数值模拟

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化工学报 2018年第5期69卷 1999-2006页

作者：栾德玉魏星陈一鸣青岛科技大学机电工程学院山东青岛266061

采用分离涡模型,对错位六弯叶(6PBT)搅拌槽内流场结构和宏观不稳定性(MI)进行了数值模拟。工作介质分别选用去离子水和不同质量分数的黄原胶水溶液,并将水的速度场分布与PIV实验结果进行了比较。通过采集监测点的速度时间序列,结合MATLA... 详细信息

采用分离涡模型,对错位六弯叶(6PBT)搅拌槽内流场结构和宏观不稳定性(MI)进行了数值模拟。工作介质分别选用去离子水和不同质量分数的黄原胶水溶液,并将水的速度场分布与PIV实验结果进行了比较。通过采集监测点的速度时间序列,结合MATLAB软件编程,计算得到流场宏观不稳定频率的变化。结果表明:流场结构和速度矢量的计算值与PIV实验数据吻合较好,分离涡模型的计算结果可靠;提高转速,槽内假塑性流体MI频率峰值增大,脉动强度提高,当转速达到225 r·min-1时,MI频率特征消失,频谱图呈现谱带现象,意味着流场进入混沌;流体的流变性对MI没有影响,MI现象是流体流动的共有特征。

关键词：错位六弯叶搅拌器假塑性流体宏观不稳定性分离涡模型

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错位六弯叶桨搅拌假塑性流体的洞穴变化

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机械工程学报 2012年第16期48卷 152-157页

作者：栾德玉周慎杰陈颂英青岛科技大学机电工程学院青岛266061 山东大学机械工程学院济南250061

预测洞穴大小及其变化规律对于剪切变稀的假塑性流体搅拌至关重要。利用计算流体力学(Computational fluid dynamics,CFD)模拟方法,对错位六弯叶桨搅拌黄原胶水溶液所形成的洞穴效应进行研究,确定较为适宜的洞穴边界速度,得到洞穴形状... 详细信息

预测洞穴大小及其变化规律对于剪切变稀的假塑性流体搅拌至关重要。利用计算流体力学(Computational fluid dynamics,CFD)模拟方法,对错位六弯叶桨搅拌黄原胶水溶液所形成的洞穴效应进行研究,确定较为适宜的洞穴边界速度,得到洞穴形状、直径及高径比随表观雷诺数Re*的变化情况,并进行搅拌功率的试验验证。结果表明,模拟计算得到的功率值与试验测量值吻合较好,表明建立的层流模型正确;洞穴形状呈现圆柱形的变化规律,符合圆柱形洞穴模型(EN模型)的描述;Dc/D-NpRey的变化规律和洞穴高径比的变化均与流体流变性无关,当Dc

关键词：错位六弯叶搅拌器假塑性流体洞穴表观黏度

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