大口径管内気液二相流の界面抗力モデルと数値解析

抄録

As the two-phase flow regime evolves from bubbly to slug flows along the flow direction in a vertical large diameter pipe, the void fraction increases first in the bubbly flow region, then decreases in the transitional region, and finally increases again in the slug flow region. The N-shaped profile of void fraction was numerically analyzed by using the one-dimensional two-fluid model. Its interfacial drag model was modified by including constitutive equations of C₀ and V_gj developed by Shen et al. [2] for evolving two-phase flow from bubbly to slug flows in a large diameter pipe. The numerical calculation predicted well the N-shaped profile of the measured axial void fraction distribution from the present experiments. The predicted average gas and liquid velocities indicated that the average gas velocity increased significantly and the average liquid velocity decreased slightly when the void profile is N-shaped one. The phenomenon can be attributed to the formation and development of large bubbles of pipe size.