Experimental study on large particle solid-liquid two-phase flow in a centrifugal pump

Abstract: As important equipment for solid material transportation, solid-liquid two-phase flow pump has been widely used in many fields and the medium was complex and diverse. Therefore, the internal flow characteristics, particle motion and collision of the solid-liquid two-phase flow in the pump have always been the focus of research. At present, the pump with small-scale solid phase has been studied well, but research on the mechanism of coarse particle solid-liquid two-phase flow in the pump is still insufficient. A single-stage single-suction cantilever centrifugal pump was selected as the research object and the high-speed photographic test method was used in the paper to study the movement rules on large diameter spherical particles in the solid-liquid two-phase flow pump, the ability to pass the pump and the collision law between the particles and the tongue. Through the processing of the test results by Motion Studio and MATLAB software, the movement laws of particles with different diameters and volume fractions in the solid-liquid two-phase pump was obtained. The experiment results indicated that the relative motion trajectories of spherical particles with different diameters all have a tendency to move toward the back of the blade at the impeller inlet. During the movement, it gradually deviates from the back of the blade and approaches the pressure side of the next blade. When the particle diameter is 6 mm, the relative motion trajectory is the longest, and when the particle diameter is 8 mm, the relative motion trajectory is the shortest. The passing pump time of spherical particles with different diameters mainly concentrated between 0.25-0.55 s. The average passing pump time of particles with diameters of 8 mm and 10 mm decreases by 15.15% and 11.03% respectively compared with that of particles with diameters of 6 mm. The relative motion trajectories of the three volume fractions of particles in the impeller basically coincide with each other, and they also tend to close to the back of the blade at the inlet of the impeller. With the passage of time, the particles gradually approach from the back of the blade to the pressure side of the next blade. But at the impeller outlet area, the particle outlet position is closest to the blade pressure surface when the volume concentration is 3%, the position where the particle flows out the impeller is farthest from the blade pressure surface when the volume concentration is 1%. The passing pump time of spherical particles with different volume fractions is mainly concentrated between 0.35-0.55 s. The average passing pump time of particles with the volume fraction is 3% and 5% increased by 4.38% and 3.21% respectively compared with that when the volume fraction of particles is 1%. When the volume fraction of particles is 1%, 3% and 5%, the collision probability between particles and tongue is 0.5%, 0.69% and 0.9% respectively. When the particle diameter was 6 mm, 8 mm and 10 mm, the probability of particle collision in the tongue region is 0.69%, 0.63% and 0.55% respectively. The research results can provide a reference for the structural design and anti-wear research of large particle two-phase flow pump.