Instability analysis of solid-liquid two-phase flow in impeller channel of vortex pump
Due to the particularity of the structure and the density difference between the solid and liquid phases,some instability characteristics are present in the vortex pump during the transportation of the solid-liquid two-phase medium.Based on the Particle model,this paper uses ANSYS CFX to carry out unsteady numerical simulation of various working conditions of vortex pump conveying different solid phase volume fractions at different flow rates under rated speed.The solid phase distribution,pressure pulsation and radial force in the impeller channel are analyzed,so as to deeply understand the internal instability of the impeller.The results show that,in terms of solid phase distribution,at Cv=5％ volume fraction,the solid phase distribution in the impeller channel is uniform at 0.8Qd and 1.0Qd flow rates,and the 1.2Qd distribution is not uniform;at Cv=10％ volume fraction,the distribution is uniform at 0.8Qd flow rate,and non-uniform at 1.0Qd and 1.2Qd flow rates.At Cv=20％ volume fraction,the distribution is uniform at 0.8Qd and 1.2Qd flow rates,and the distribution of 1.0Qd is not uniform.In a rotation cycle of Cv=20％ and 1.0Qd,there is always a strip solid phase distribution area inside the impeller,and its rotation speed lags behind the impeller rotation speed.In terms of pressure pulsation,at 1.0Qd flow rate,with the increase of solid volume fraction,the amplitude fluctuation of pressure coefficient at each monitoring point gradually becomes larger;the amplitude at the blade frequency of the monitoring point in the post-shrinking cavity is basically unchanged,and the amplitude at the shaft frequency of the monitoring point in the impeller flow channel gradually increases.At the volume fraction of Cv=20％,with the increase of flow rate,the amplitude fluctuation of pressure coefficient at each monitoring point increases first and then decreases,and the amplitude at the blade frequency of the monitoring point in the post-shrinking cavity gradually increases.In terms of radial force,under the same solid volume fraction,the radial force gradually increases with the increase of flow rate;under different solid volume fractions,with the increase of volume fraction,the radial force fluctuation at 0.8Qd flow rate is small,the fluctuation at 1.0Qd flow rate gradually increases,and the fluctuation at 1.2Qd flow rate gradually decreases.
vortex pumpsolid-liquid two-phasepressure pulsationradial force
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