COMPARISON OF MODELS FOR DRAG AND NON-DRAG FORCES FOR GAS-LIQUID TWO-PHASE BUBBLY FLOW

摘要

In this study, we have compared the effect of various interfacial forces such as drag, lift, wall lubrication and turbulent dispersion force. We analyze the contribution of these forces on numerical predictions of radial gas void fraction distribution, interfacial area concentration, and gas and liquid velocity profile. A CFD model has been developed for the prediction of radial distribution of gas void fraction and interfacial area concentration in a vertical pipe. For the development of this CFD code, the experimental data were taken from the available literature. The experimental conditions are, pipe diameter of 48.3-51.2 mm, wide range of superficial liquid velocity 0.405-2.607 m/s, and gas superficial velocity 0.0111-1.275 m/s, and wide range of bubble diameters 2.5-9.3 mm. The void fractions vary from 1.89% to 25.7%. Based on the experimental data available in the literature, three cases of low bubble Reynolds number (Re_b ≈ 29), medium (Re_b ≈ 880), and high (Re_b ≈ 15,132), at the inlet have been selected. Different interfacial force models differ in the prediction of radial distribution of gas void fraction and interfacial area concentration. Based on the results obtained for comparison of interfacial forces, the Grace drag model, Tomiyama lift and wall lubrication model, and Burns turbulent dispersion force model were found to provide the best agreement with the experimental data.