气力输送系统中加速区气固两相流动特性的研究

Research on gas-solid two-phase flowing characteristics of accelerating zone in pneumatic conveying system

对气力输送系统中具有不同初始状态的固粒群在加速区的气固两相流动进行了数值模拟.气流场采用修正的k-ε湍流模型进行计算,利用相间滑移数值方法(IPSA)求解全流场的Navier-Stokes方程,并推导求解了在时间模式和空间模式下具有不同初始速度的固粒群的运动解析关系.通过分析解析关系和数值模拟结果发现,初始气固速度比与固粒加速区的运动高度相关,但与稳定运动无关;最终运动速度取决于摩擦条件和悬浮运动速度;加速区固粒作变加速运动;初始速度比决定了中心区加速度;近壁区变速运动与初始速度比和壁面摩擦相双因素有关.

Gas-solid two-phase flow with different initial state in accelerating zone of pneumatic conveying system was simulated. Inter-phase-slip algorithm (IPSA) was used to solve Navier-Stokes equations, while turbulence was considered with modified k-Ε model. The equations of particles velocities with different initial velocities were deduced for both the temporal model and the spatial model. The analysis of the equations and the simulation results shows that the particle motion in the acceleration zone has close relation with the initial velocity ratio of gas and particles, which is not true when the particle motion is stable; that the particles velocity in stable state depends on the friction condition and the suspend velocity; that the acceleration rate of particles in acceleration zone is variable; that the particles velocity in the center of acceleration zone only depends on the initial velocity ratio of gas and particles; that the initial velocity ratio of gas and particles and the friction condition are the double factors affecting the particles velocity near the pipe wall.