非牛顿流体气液两相流的实验研究与数值模拟

发布时间：2018-03-14 07:09

本文选题：计算流体力学　切入点：非牛顿流体　出处：《华东理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：搅拌反应器在化工领域应用广泛,本文以多层桨搅拌反应器为研究对象,对不同溶液中的气液两相流进行了实验研究与数值模拟。考察了CMC浓度、桨型组合、通气量和搅拌转速对通气功率、气含率和体积氧传质系数的影响。结果表明,在相同操作条件下,随着CMC浓度的增加气含率和体积氧传质系数减小；下压组合桨的气含率高于上翻组合桨,功率消耗受粘度影响小；BTD+2HDTd组合桨体积氧传质系数高于BTD+2KSXd。综合考虑,BTD+2HDTd组合桨的传质和混合特性最佳。考察了气体分布器对CMC介质中通气功耗和气含率的影响,得出微孔分布器比圆环分布器更有利于气体分散。研究结果为工业反应器的设计与放大提供了基础数据,具有一定的参考价值。对新型组合桨BTD+2HDTd进行了单相模拟,计算得到的功率准数与搅拌功率略高于实验值,偏差最大不超过5%。对于气液两相流的模拟采用CFD和PBM耦合求解。采用多重参考系法和SST湍流模型计算,采用默认的曳力模型模拟的气含率较低,改用修正的Symmetric曳力模型得到的总体气含率和功率消耗与实验结果基本吻合。此外,模拟还得到了大量实验条件下难以测量的局部信息,如宏观流场、表观粘度分布、气含率分布等,直观地探究了反应器内的流体混合状态。
[Abstract]:Agitator is widely used in chemical industry. In this paper, the gas-liquid two-phase flow in different solution is studied and numerically simulated. The concentration of CMC and the combination of impeller are investigated. The effects of aeration volume and stirring speed on ventilation power, gas holdup and volumetric oxygen mass transfer coefficient. The results show that under the same operating conditions, the gas holdup and volume oxygen mass transfer coefficient decrease with the increase of CMC concentration. The gas holdup of lower pressure combined propeller is higher than that of upturned combined propeller. Power consumption is affected by viscosity. The volumetric oxygen mass transfer coefficient of BTD 2HDTd combined propeller is higher than that of BTD 2KSXd. considering the optimum mass transfer and mixing characteristics of BTD 2HDTd combination propeller, the effect of gas distributor on ventilation power consumption and gas holdup in CMC medium is investigated. It is concluded that the microporous distributor is more favorable for gas dispersion than the ring distributor. The results provide the basic data for the design and amplification of the industrial reactor and have certain reference value. The single-phase simulation of a new type of combined propeller BTD 2HDTD is carried out. The calculated power standard and stirring power are slightly higher than the experimental values, and the maximum deviation is not more than 5. The simulation of gas-liquid two-phase flow is solved by CFD and PBM coupling. The multi-reference system method and the SST turbulence model are used to calculate the two-phase flow. The gas holdup simulated by the default drag model is relatively low, and the total gas holdup and power consumption obtained by using the modified Symmetric drag model are in good agreement with the experimental results. In addition, a great deal of local information which is difficult to measure under the experimental conditions is obtained by the simulation. For example, macroscopic flow field, apparent viscosity distribution, gas holdup distribution and so on, the fluid mixing state in the reactor was investigated intuitively.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.72

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