抄録
To design and operate the two-phase flow equipments, local liquid velocity and each bubble velocities are required. The most drastic velocity transformation appears at the entrance region of a conduit. Thus we computed the two-phase flow velocities including their fluctuations and the void fraction distribution by using the HSMAC method. We assumed the flow is bubble flow and flow domain is rectangular with square cross-section. For the initial condition, calculated domain is filled with water, liquid velocity is uniform and the void fraction is uniform. After the flow domain is filled with bubbles, outlet boundary velocity and void fraction are used for the inlet boundary. Free flow out condition is used for the outlet boundary. The other wall boundaries are non-slip conditions. Re assumed as 3000 and the calculated domain was divided to 30x30x30.
The velocity distribution is on the developing flow, thus both liquid and bubble velocities tended to move to the center of cross-section, but the local velocity at the arbitrary position on the cross-section was fluctuated randomly. The bubble velocity distribution was similar to that of liquid. Void fraction showed complex distribution and it seems bubbles made a cluster in spite of almost uniform distribution at the inlet boundary. The velocity fluctuations, pressure distribution and void fraction varied with time and a position of the flow direction. Direction of local velocity changes at random to orderly then at random along the x direction periodically.
