The lance is a critical component of the bottom-blowing pool melting process,
and its placement has an important impact on the pool?s gas-liquid two-phase
flow. In this study, a mathematical model of the bottom-blowing process is
established, and the flow pattern, trajectory, wake vortex, and velocity of
bubbles under four lance spacings are simulated. Results show that there are
three basic bubble flow patterns appear in the flow field: bubbles coalesce
before leaving the nozzle (Pattern I), bubbles coalesce after leaving the
nozzle (Pattern II), and no coalescence during the rise of bubbles (Pattern
III). The bubble pattern varies from Pattern I to Pattern III with the
increase in lance spacing. The intensity of the influence of the wake vortex
on the bubbles decreases. The Q (The Q is the second Galilean invariant of
the velocity gradient tensor ?v.) value of the wake vortex is small, but the
vortex structural distribution is complex. Moreover, there is a large
velocity difference between gas and liquid at the beginning of gas
injection, but the velocity difference between them decreases after gas
injection, so the average turbulent kinetic energy in the pool initially
increases sharply, and then approaches dynamic equilibrium. The top and
bottom velocities of the bubbles are consistent, and the velocity
fluctuation is orderly. Moreover, the greater the lance spacing is, the
greater the disturbance in the pool is. The mixing effect of D = 0.2 m is
the best among the four spacings.