磁-流场耦合气-固流化床气含率的模拟

Simulation of Gas Holdup in a Gas-Solid Fluidized Bed with Magnetic and Fluid Fields

在内径0.16 m、高2.0 m的磁-流场耦合气-固流化床内,以空气为气相、掺杂铁粉的纳米SiO_2(平均粒径16 nm和48nm)为固相,应用Fluent软件将磁场模型与Fluent软件中的传统模型结合,模拟研究磁-流场耦合气-固流化床内磁场强度对局部气含率、平均气含率和轴向压力波动均方根的影响规律。模拟结果表明,随磁场强度的增加,局部气含率和平均气含率均增大,局部气含率径向分布的非均匀性增大;在一定磁场强度下,随颗粒粒径的增大,局部气含率及其径向分布的非均匀性均增大;在低磁场强度作用下,床内的局部气含率变化明显,多处出现大气泡;在高磁场强度作用下,床中局部气含率变得较均匀;随磁场强度和床层轴向高度的增加,床层内局部压力波动均方根增大。

The effects of magnetic field intensity in a gas-solid fluidized bed with inner diameter of 0.16 m and height of 2.0 m, in which a magnetic field coupled with a fluid field using air as gas phase and iron doped silica powder as solid phase, on the radial distribution of local gas holdup, the average gas holdup and the root mean square（RMS） of bed axial pressure drop were investigated by the combination of magnetic field model with traditional model in the Fluent sol, ware. The results show that the local and average gas holdups, and the nonuniformity of the radial distribution of the local gas holdup increased with increasing the magnetic field intensity. The local gas holdup and the nonuniformity increased with increasing the particle diameter at certain magnetic field intensity. The local gas holdup was changed significantly and some big bubbles appeared at low magnetic field intensity. However, the local gas holdup became uniform at high magnetic field intensity. RMS of the local bed pressure drop increased with increasing the magnetic field intensity and the axial height of the bed.