Numerical evaluation of turbulence models for dense to dilute gas-solid flows in vertical conveyor

• Published in: Particuology 2012-10, Vol.10 (5), p.553-561
• Main Authors: Azizi, Salar, Mowla, Dariush, Ahmadi, Goodarz
• Format: Article
• Language: English
• Subjects: Kinetic theory; Numerical modeling; TFM; Turbulence; Vertical gas–solid flow; 垂直管; 密集; 数值计算; 气体速度; 湍流模型; 稀释气; 输送机; 长度计算
• ISSN: 1674-2001; 2210-4291
• DOI: 10.1016/j.partic.2011.12.006

A two-fluid model （TFM） ofmultiphase flows based on the kinetic theory and small frictional limit boundary condition of granular flow was used to study the behavior of dense to dilute gas-solid flows in vertical pneumatic conveyor. An axisymmetric 2-dimensional, vertical pipe with 5.6 m length and 0.01 m internal diameter was chosen as the computation domain, same to that used for experimentation in the literature. The chosen particles are spherical, of diameter 1.91 mm and density 2500 kg/m3. Turbulence interaction between the gas and particle phases was investigated by Simonin＇s and Ahmadi＇s models and their numerical results were validated for dilute to dense conveying of particles. Flow regimes transition and pressure drop were predicted. Voidage and velocity profiles of each phase were calculated in radial direction at different lengths of the conveying pipe. It was found that the voidage has a minimum, and gas and solid velocities have maximum values along the center line of the conveying pipe and pressure drop has a minimum value in transition from dense slugging to dilute stable flow regime. Slug length and pressure fluctuation reduction were predicted with increasing gas velocity, too. It is shown that solid phase tur- bulence plays a significant role in numerical prediction of hydrodynamics of conveyor and the capability of particles turbulence models deDends on tuning parameters of sliD-wall boundarv condition.