Abstract Flow behavior of top-gas jet and particles is simulated by means of gas-solids two-fluid model incorporating the kinetic theory of granular flow (KTGF) in a top-gas jet bubbling fluidized bed. The RNG k-e model is used to model gas turbulence of the top-gas jet. The effects of the top-jet gas velocity and fluidizing gas velocity on distributions of volume fractions and velocities of gas and particles are evaluated, and the results are quantified in terms of top-gas jet penetration length. Numerical simulations show that the fluidized gas-particle mixture along bed height is divided into three regions as (a) the top-gas jet region in the freeboard, (b) the concentrating region near the bed surface and (c) the diluting region near the bottom in terms of the axial distribution of solids volume fraction. By increasing the top-jet gas velocity, particles circulate through the down-flow at the center from the concentrating region to the diluting region and the up-flow near the walls from bottom to bed surface along bed height. The distributions of volume fraction and velocity of gas and particles considerably change with the variation of top-jet gas velocities. Moreover, the top-gas jet penetration length with the change of top-jet gas velocity and fluidizing gas velocity is identified and discussed.

中文翻译：

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气粒鼓泡流化床顶气射流流动行为数值模拟

摘要 采用气固二流模型，结合颗粒流动力学理论(KTGF)，在顶气射流鼓泡流化床中模拟了顶气射流和颗粒的流动行为。RNG ke 模型用于模拟顶气射流的气体湍流。评估了顶部射流气体速度和流化气体速度对气体和颗粒的体积分数和速度分布的影响，并根据顶部气体射流穿透长度对结果进行了量化。数值模拟表明，流化气颗粒混合物沿床层高度分为三个区域：(a) 干舷顶部气体射流区，(b) 靠近床面的浓缩区和 (c) 靠近床层的稀释区在固体体积分数的轴向分布方面的底部。通过增加顶部喷射气体速度，颗粒通过中心的下降流从浓缩区到稀释区和沿床高从底部到床面的靠近壁的上升流循环。气体和颗粒的体积分数和速度分布随顶喷气体速度的变化而显着变化。此外，还确定并讨论了顶气射流穿透长度随顶射气速度和流化气速度的变化。