ABSTRACT:

An experimental investigation is conducted to investigate effects of particle size and concentration on pressure gradient or drag in a 2phase vertically upward hydraulic transport of silica sand particles for 2-phase water-particle mixture flows in a pipe. The particles are in 3 sizes: 8–10, 30–40 and 80–100 mesh in size (2.36–2.00, 0.6∼0.425, 0.180–0.150 mm) and irregular or rough in surface shape, the concentration ranges 2.2∼9.3%, and the flow loop is made of a clear PVC pipe 2.54 cm in diameter. Pressure drops and average flow rates were measured in the Reynolds number range of 104 < Re < 105. The present results of the particle-water mixture flows show that contrary to the conventional perception of "non-Newtonian-type" drag reduction for the pipe flows of fine particles, the present experiment within the measurement range revealed that the pressure gradient of the present 100-mesh fine sand particles increased over the measured Re range, as compared to the larger 8–10 and 30–40 mesh sands. This is contrary in the case of for 80–100 mesh sands to the trend that the larger particles, the larger the drag or pressure gradient also for 80–100 mesh sands.

INTRODUCTION

The present experiment investigates the effects of particle size and concentration on pressure gradient or drag in 2-phase flows of silica sands in water for vertical upward hydraulic transport. Shape effects of particles on pressure gradient were previously reported by Chung et al. (1998 and 1999). The present result is one of a series of experiments of solid particle-water mixtures in a I-in (2.54-cm)-diameter flow loop. Conventional perception of fine particle flows in water, but without defining the size range of the fine solid particles, has been that there may be non-Newtonian-type drag reduction for the pipe flows of fine particles.

This content is only available via PDF.
You can access this article if you purchase or spend a download.