Research on coal particle carrying out in unsteady flow field of rod pumped well annulus

Key words:  annulus  moving boundary  unsteady flow field  dynamic mesh  coal particle  clean out

Abstract:

The annulus between rod and tube in sucker rod pumped well has a moving boundary due to the rod 's periodic motion, which makes the two-phase flow of coal particle and water become a complicated transient problem. The dynamic mesh theory was adopted to handle the grid node 's movement both on the boundary and in the flow field. The high quality grid can be obtained using this method, which is beneficial to precisely solving the unsteady flow field. The mathematical model of solid-liquid two-phase flow was solved by SIMPLEC method based on unstructured grid. The coal particle 's velocity and concentration were acquired, then the mass flow rates at the inlet and outlet of annulus were gained and the integrals for flux in different working conditions were computed. The results show that the coal particle emission is influenced by the rod 's periodic motion disturbance, which makes the coal particle clean out change with different stroke and rate of pump, while the pump output volume is a constant. The clean out difference increases while the coal particle diameter increases and the pump output volume decreases, and the maximum difference value is 29%.