| Open impeller slurry pump is widely used in the transportation of solid slurry or solid-liquid two-phase flow with crystalline particles in petrochemical,power and smelting industries because of its good non-clogging performance.Owing to the existence of the axial clearance between the open impeller and the pump shell,the leakage flow from the working surface to the back surface is generated under the influence of the pressure difference between the blade working fa ce and the back surface.The interaction between the leakage flow of the axial clearance and the main flow of the impeller forms a complex two-field clearance flow field structure,which leads to the decrease of pump efficiency and the aggravation of wear and tear.In this paper,the axial clearance flow field of the impeller of the open impeller slurry pump is analyzed,expecting to provide some theoretical support for the optimization of hydraulic performance and wear characteristics of the slurry pump.In this study,LCF100/350 slurry pump is taken as the research object,and DPM solid-liquid two-phase flow model is applied to simulate the internal flow field of open impeller slurry pump with axial clearance.The hydraulic performance and wear characteris tics of slurry pump are analyzed,and the main conclusions are as follows:1)On the suction side of the blade,the leakage flow caused by the axial clearance of the impeller interacts with the mainstream to form a leakage vortex,of which a local low pressure zone is created in the center.With the increase of flow rate,the strength of leakage vortices behind the blade surface decreases and the area of local low pressure region decreases gradually due to the weakening of pressure difference between the blade working face and the back surface.In the axial clearance area at the top of the blade pressure surface,the flow into the axial clearance is coupled with the mainstream to form an angular vortex at t he top of the pressure surface and the shape of the angular vortex is elliptical.2)In the axial clearance region of impeller,the fluid flows along the direction of impeller rotation from the high pressure region with larger radius to the low pressure region with smaller radius,and its trajectory is gene rally spiral.In the watershed near the tongue separation,the pretty strong local secondary flow structure is created for the influence of the secondary flow,which is caused by the tongue separation.The tongue has a great influence on the performance of the pump.3)The flow field structure obtained by solid-liquid two-phase flow simulation is basically the same as that obtained by pure liquid flow simulation.The strong vorticity is produced in the axial clearance of impeller due to leakage flow.The vorticity close to the side of the leakage vortices pump is larger under the influence of the interaction between the leakage vortices and the mainstream and along the axial direction entering the impeller,and the vorticity decreases gradually.4)Under the action of the spiral leakage flow structure in the axial clearance of impeller,the distribution of wear intensity on the suction side of pump body is spiral,which is completely consistent with the actual wear condition.With the increase of particle size,the wear distribution of the front pump chamber has little change,but under the action of secondary flow in the tongue separation area,the wear intensity increases sharply with the increase of particle size.5)In the solid-liquid two-phase flow field,the existence of particles reduces the pump head and efficiency to a certain extent.With the increase of particle size,the density and area of solid particles deposited on suction surface and hub position gradually increase,and the wear area of blades increases,especially in the hub area of rear cover plate.The distribution of particle deposition density on impeller and pump wall is positively correlated with the distribution of wear strength,and the variation law with particle size is basically the same. |
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