摘要
对气体相湍动能采用修正的k-ε二方程模型,颗粒相湍动动能采用颗粒动力学方法,考虑两相间的相互作用,发展建立了水平管气力输送的数学物理模型和计算方法。该模型能计算颗粒相压力、粘性系数、扩散系数、导热系数、颗粒温度等流体力学特性参数。用文献实验得到的压降和转捩速度验证了所建模型和计算方法的正确性。就水平管中圆柱坐标系下典型的三维悬浮气力输送过程进行了初步数值研究,得到了管道沿程压降、平均气体速度、平均颗粒速度和平均颗粒浓度的变化、以及输送方向上不同截面处的颗粒浓度分布。结果表明:在给定的输送条件下,颗粒在管中并不总是维持同样的悬浮状态,在入口和快速加速度段,悬浮颗粒易集中于管中心区域,从加速段到恒速段,悬浮颗粒逐渐向管底沉降;颗粒浓度在管截面上有两种分布状态。为进一步利用该法研究气力输送打下了基础。
Based on the modified k-ε model for gas phase and the kinetic theory for granular flow, and taking the interaction between fluid and particles into account, a locally averaged three-dimensional gas-particle two-fluid flow model for horizontal pneumatic conveying pipe was built up, and the relevant numerical algorithm and computational code were developed consequently. The model makes it possible to calculate the macroscopic behaviors of the two-fluid flow, such as effective pressure, effective viscosity and shear viscosity of particle phase. The pressure drop and saltation velocity predicted by the model are in good agreement with the experimental data from literature. A typical horizontal pneumatic conveying was simulated, and the change of pressure drop, the mean gas velocity, the mean particle volume fraction along the horizontal pipeline and the particle volume fraction distributions over the cross.sections were obtained. The results show that the suspended particles tend to be concentrated in a region near the pipe center in the inlet and quick acceleration section, but it will be gradually deposited to the bottom of the pipe from the section of acceleration to the stabilized one under given conditions. The distribution of the particle volume fraction over the cross-section has two different styles and it changes from one style to another with the flow along the pipe. This work sets a foundation for the extensive study on horizontal pneumatic conveying by using the above method.
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2006年第3期331-337,共7页
Journal of Chemical Engineering of Chinese Universities
基金
中国石化总公司资助项目(X599015)。
关键词
气力输送
两相流动
双流体模型
数值模拟
horizontal pneumatic conveying
two-phase flow
two-fluid model
numerical simulation
