Abstract
Bubble flow can be simulated by the two-fluid model and the multi-fluid model based on the Eulerian method. In this paper, the gas phase was further divided into several groups of dispersed phases according to the diameter by using the Eulerian-Eulerian (E-E) multi-fluid model. The diameters of bubbles in each group were considered to be the same, and their distributions were reorganized according to a specific probability density function. The experimental data of two kinds of bubble flow with different characteristics were used to verify the model. With the help of the open-source CFD software, OpenFOAM-7.x (OpenFOAM-7.0, produced by OpenFOAM foundation, Reading, England), the influences of the group number, the probability distribution function, and the parameters of different bubble diameters on the calculation results were studied. Meanwhile, the numerical simulation results were compared with the two-fluid model and the experimental data. The results show that for the bubble flow with the unimodal distribution, both the multi-fluid model and the two-fluid model can obtain the distribution of gas volume fraction along the pipe radius. The calculation results of the multi-fluid model agree with the experimental data, while those of the two-fluid model differ greatly from the experimental data, which verifies the advantage of the multi-fluid model in calculating the distribution of gas volume fraction in the polydisperse bubble flow. Meanwhile, the multi-fluid model can be used to accurately predict the distribution of the parameters of each phase of the bubble flow if the reasonable bubble diameter distribution is provided and the appropriate interphase force calculation model is determined.
Highlights
The gas-liquid two-phase flow is a kind of fluid flow that exists widely in different industries such as energy, water conservancy, and chemical industry
The experimental data of the gas volume fraction were captured by a metal grid sensor equipped with an electrode, which has been widely used in the study of the flow pattern of gas–liquid bubble flow and of the distribution of gas volume fraction in vertical pipes
The results show that the two-fluid model cannot be used to accurately predict the distribution of the gas volume fraction along the radius in the polydisperse bubble flow
Summary
The gas-liquid two-phase flow is a kind of fluid flow that exists widely in different industries such as energy, water conservancy, and chemical industry. The classical E-E two-fluid model is commonly used to describe the movement of bubble flow. This model treats the gas phase as a single phase and takes the average bubble diameter as that of the whole [1,2]. This method is effective only when the gas volume fraction is low, the turbulence effect is small, and the bubble diameter is uniform [3,4,5]. It is not appropriate to use the two-fluid model to describe the bubble flow in this condition, because the movement of bubbles with polydispersity and the forces on them are different
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