Author(s): J. Krupicka; V. Matousek
Linked Author(s): Vaclav Matousek
Keywords: No Keywords
Abstract: Pipeline transport of settling slurries occurs in many industrial applications. Sometimes, slurry pipelines are operated at flow velocities low enough to enable stationary bed formation at the bottom of the pipe. In such a case the surface of the deposit affects flow resistance. The frictional pressure drop is a measure of the flow resistance and it can be predicted only if the hydraulic roughness of the top of the deposit is determined. The fact that the top of the bed is sheared off due to the applied high shear stress makes the determination of the roughness difficult. Only few experimental works devoted to flow under the described conditions can be found in literature. Recently, the authors proposed an empirical formula for the hydraulic roughness of an eroded bed. The formula was based on the data available at the time. In autumn 2008, new experiments were carried out for flows of two very different sand fractions (median particle size of0. 22 mm, 0. 38 mm respectively) in the 100-mm pipe loop of the Institute of Hydrodynamics. The experimental results confirmed that the proposed formula works well within a broad range of grain sizes. The paper discusses the structure of the proposed formula and its validity in the light of the new experimental results.
Year: 2010