Solid-liquid Two-phase Flow of Mixed Particles in Vortex Pump Based on CFD-DEM
Abstract
In order to explore the mechanism of solid liquid two phase flow in the folded-blade vortex pump, based on the computational fluid dynamics-discrete element method (CFD-DEM) coupling algorithm, the rapeseed and soybean particles were mixed in equal proportion, and the solid-liquid two-phase flow numerical simulation and experimental research of the vortex pump were carried out under different flow conditions and volume concentrations. The internal flow law and particle distribution characteristics of the folded blade vortex pump were also studied. Under the condition of small flow rate, the rotating reflux length in the inlet pipe was longer, and the disturbance to the inlet flow was greater. As the flow rate was increased, the reflux length of the inlet pipe was decreased gradually. With the increase of flow rate, the number of vortices on the front surface of the impeller was increased first and then decreased, and gradually gathered towards the turning point. The particles in the pump were affected by the combined action of circulating flow and through flow. The particles in the center of the inlet pipe were mainly affected by the through flow, directly passing through the vaneless cavity and impacting the impeller inlet. The particles near the pipe wall were greatly affected by the circulating flow. The particle distribution in the leafless cavity showed that the concentration in the center was the highest, the concentration in the middle was decreased gradually with the increase of the outer diameter, and the concentration in the outer edge was increased slightly. The number of particles in the front half of the impeller was significantly less than that in the rear half of the impeller. The particles moved along the folding edge of the first section of blade, and began to separate at the folding point, and no longer followed the folding edge of the second section. Under different working conditions, the pump inlet had different degrees of rotational reflux, resulting in a decrease in the inlet flow area. The existence of circulating flow made the particles in the vaneless cavity and the inlet pipe fully rotated, the pumping capacity was enhanced, and the blockage was not easy to occur.
Keywords: centrifugal pump, CFD-DEM coupling algorithm, folded blade mixed particle, high-speed photography experiment of inlet rotating backflow
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