Numerical evaluation of turbulence models for dense to dilute gas–solid flows in vertical conveyor--颗粒学报PARTICUOLOGY

Azizi, S., Mowla, D., & Ahmadi, G. (2012). Numerical evaluation of turbulence models for dense to dilute gas–solid flows in vertical conveyor. Particuology, 10(5), 553–561. https://doi.org/10.1016/j.partic.2011.12.006

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

Salar Azizi ^a, Dariush Mowla ^a *, Goodarz Ahmadi ^b

a Chemical Engineering Department, School of Chemical and Petroleum Engineering, Shiraz University, Shiraz 71345-1789, Iran
b Department of Mechanical and Aeronautical Engineering, Clarkson University, Potsdam, NY 13699-5725, USA

10.1016/j.partic.2011.12.006

Volume 10, Issue 5, October 2012, Pages 553-561

Received 4 August 2011, Revised 15 October 2011, Accepted 19 December 2011, Available online 21 June 2012.

E-mail: dmowla@shirazu.ac.ir

Highlights

► Two-fluid model with small frictional limit boundary condition of granular flow was used.

► Turbulence interaction between gas and particle phases was investigated by Simonin's and Ahmadi's models.

► Capability of particle turbulence models was studied for dense to dilute gas–solid flows in vertical conveyor.

Abstract

A two-fluid model (TFM) of multiphase 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 turbulence plays a significant role in numerical prediction of hydrodynamics of conveyor and the capability of particles turbulence models depends on tuning parameters of slip-wall boundary condition.

Graphical abstract

Keywords

Vertical gas–solid flow; TFM; Kinetic theory; Turbulence; Numerical modeling

文章导读