Abstract
In a spiral tube twisted with a constant pitch in relation to the axis, a swirling flow occurs when fluids flow in the tube. Solid particles in multiphase flows are mixed by the swirling flow. It has been established from the experimental results that the values of the critical velocity and the pressure loss decrease in comparison with these values in a circular pipe. Thus, the hold up phenomena of the multiphase flow does not occur in the spiral tube under a low velocity range. This review presents, the experimental data of the pressure drop and the velocity distribution of the single phase flow in the spiral tube, and the experimental results of the hydraulic and the pneumatic conveyance test of solid particles, respectively. It is pointed out that in practical application, the spiral tube presents a very useful method for preventing the holdup phenomenon in a transport pipeline for the hydraulic or pneumatic conveyance of highly concentrated solid particles.
