Investigation of two phase particle-suspended flow in a horizontal channel

• Main Authors: Ching-Mao Chang, 張景貿
• Other Authors: Reiyu Chein
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/76943683899679875113

碩士 === 國立中興大學 === 機械工程學系 === 88 === Abstract The major goal of the present study is to investigate the effect of density ratio on the motion of particles that suspended in a flow. Two extreme cases of particle suspended flows, the gas-solid particle flow and the liquid-bubble flow are investigated numerically in the present study. The two-phase system is assumed to be sufficient dilute and therefore the carrier and particle phase can be solved independently. In the carrier phase, a numerical model based on streamfunction-vorticity formulation is employed for obtaining the velocity and vorticity field. The particle motion is obtained by integrating its equation of motion. The two-phase flow system is restricted to be laminar and inside a horizontal channel with a block mounted on the lower surface of the channel. In the gas-solid particle flow, it is found that the traditionally defined Stokes number is the major control parameter of solid particle motion in the flow. Density ratio plays insignificant role in the particle motion. For reducing Reynolds number of the flow field, it is found that gravity effect becomes important resulting early particle deposition on the lower wall of the channel. In the liquid-bubble channel flow, it is found that the major control parameters of bubble motion are the bubble Stokes number and Reynolds number Re of flow field. For low Re, it is found that bubble exhibits oscillatory trajectories for small values of . The bubble follows the streamlines of the flow field as increasing. For large Reynolds number, the oscillatory trajectories of bubble are still can be found, however, with longer period due to the effect of the flow velocity. It is found oscillating bubble trajectories are caused by the vorticity lift force that acting on bubble. The bubble motion in a channel with surface-mounted block is also examined. The oscillatory trajectories can also be found for small values. While increases, the bubble trajectories become complicated due to the reasons of existence of recirculation zones and complicated vorticity variation in the flow field. The bubble may be entrapped into the recirculation zone for certain values of .