Effects of drag model and turbulence model on simulation of air-lift internal-loop reactor

doi:10.11949/j.issn.0438-1157.20170830

Abstract

Abstract:

The influence of drag models and turbulence models on the hydrodynamic parameters in an air-lift internal-loop reactor is evaluated. Drag models determine the existence of gas in downcomer, and drag models and turbulence models jointly determine the accuracy of the simulation of gas holdup. Using uniform size bubbles, the Schiller-Naumann, Tomiyama, Grace and Ishii-Zuber drag models are only suitable for lower superficial gas velocity, and there is no gas in downcomer. The capability of DBS-Local drag model was confirmed. Compared with the other four drag models, only DBS-Local drag model can predict the existence of gas in downcomer. DBS-Local drag model combining with the standard k-ε mixture turbulence model can well predict gas holdup, and combining with RNG k-ε dispersed turbulence model can better predict liquid velocity.

Key words: CFD, internal-loop reactor, gas-liquid flow, drag model, turbulence model, gas holdup

摘要：

研究了曳力模型和湍流模型对气升式内环流反应器流体力学参数的影响，进一步证实了DBS-Local曳力模型在气升式内环流反应器中的适用性。结果表明：曳力模型决定了是否可以模拟出下降管中的气体；而曳力模型和湍流模型共同作用，决定了气含率模拟结果的准确性。Schiller-Naumann、Tomiyama、Grace、Ishii-Zuber这4种曳力模型均无法预测出下降管含气这一现象，而DBS-Local曳力模型能够模拟出下降管中的气体。DBS-Local曳力模型与standard k-ε mixture湍流模型组合，对气含率的预测值与实验值较为接近，而与RNG k-ε dispersed湍流模型组合，对轴向液速的预测值与实验值更为接近。

关键词: 计算流体力学, 内环流反应器, 气液两相流, 曳力模型, 湍流模型, 气含率

CLC Number:

TQ021.1

ZHANG Jiabao, CUI Lijie, YANG Ning. Effects of drag model and turbulence model on simulation of air-lift internal-loop reactor[J]. CIESC Journal, 2018, 69(1): 389-395.

张佳宝, 崔丽杰, 杨宁. 曳力模型和湍流模型对内环流反应器数值模拟的影响[J]. 化工学报, 2018, 69(1): 389-395.

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