Abstract
Herein there are theoretical dispositions on the conditions of the fluid flow and sand transportation within a wide range of rates. The results of some exploratory research on the sand transport in specially designed laboratory and production benches, including a platform with interchangeable modular polymer elements having an artificial rough surface, have been presented. The ranges of the experiment procedure have been established to create the turbulence zones, where the tray inner surfaces are of various texture in the form of obstacles of different height. The technique has been presented for carrying out experiments on large-size benches with modular pipe elements based on the use of photo and film equipment, as well as a set of devices for determining rates, filling and slopes. The results of hydraulic experiments on modeling the process of vortex formation in the flow in the trays with artificial roughness are presented. The ability of the flow to move sand dunes in the trays with an alternative texture of the inner surface has been studied, and the design data of the quantitative assessment of the transporting ability of the flow depending on various factors has been given.
Highlights
During transportation of a double-phase water flow containing a significant concentration of suspended solids, four flow regimes can be observed depending on the liquid flow rate [1, 2]
The above mentioned four fluid flow modes were the result of the study of alluvial river channels [3]
The trays made an integral part of the experimental small-sized hydraulic unit developed by the authors of the article [14]
Summary
During transportation of a double-phase water flow containing a significant concentration of suspended solids, four flow regimes can be observed depending on the liquid flow rate [1, 2]. At low fluid flow rates the sand deposits and forms a dense and displacementresistant sediment layer at the bottom of the pipe. With a bigger flow rate the sand begins to move in the form of a thin layer over the compacted sediment. At the further rate increase the compacted sediments, which have been accumulated at the bottom, begin to disintegrate into slowly flowing dune-type formations, which can increase both in area and volume in the form of vortex zones. When the rate grows up to the self-cleaning (critical) one, the sand particles almost completely pass into a suspended state in the fluid flow. As to the gravity drainage networks this was one of the basic elements for the study of transport processes in wastewater containing suspended solids. If we formulate briefly, the first parameter characterizing the nascent motion of sediment particles on the tray surface of pipelines is called the Shields number, the second is the gravity, the third is the filling and the fourth is the viscosity
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