Slurry transport of very large particles at high line speeds
S.A. Miedema (TU Delft - Offshore and Dredging Engineering)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
In slurry transport there are many models for fine, medium and coarse particles, based on the assumption that the particles are still small compared to the pipe diameter. However, when the particle size is not small compared to the pipe diameter (up to 25% of the pipe diameter) the models do not give a good prediction of the hydraulic gradient. The existing models assume suspended flow at high line speeds, but the question is, will there still be suspension in this case. Yagi, Vlasak, Ravelet and others carried out experiments with very large particles and describe the phenomena occurring, but do not give a physical or mathematical model for this case. At low line speeds the physics of the slurry transport can be described with the 2LM or 3LM models (Wilson, Doron, etc.), but at high line speeds these models are not sufficient. Will there be (pseudo) homogeneous transport at high line speeds or will there still be a sort of sliding bed (sliding flow)? How does the sliding friction coefficient behave? How does the slip velocity behave? Is there still a Limit Deposit Velocity? To answer these questions the available experimental data from literature is investigated. This paper shows a collection of experimental data from literature of different authors, shows the general trends and a model for very coarse particles at high line speeds. © BHR Group Hydrotransport 20.