| Screw centrifugal pump is a kind of trash pump which mainly transports two-phase media flow with particle and easy tangles solid.And the impeller is a triple helix impeller, number of blades is small. Because of the different structure form of its impeller, its internal flow is different from traditional centrifugal pump. Pulp is mainly a mixture of fiber and water, whose has Bingham fluid characteristics. Then only the overcome the shear stress, it can flow like Newtonian fluid. And close as the same as Newtonian fluid. During the flow, the forces between fibers and winding way are more complicated. Now a lot of paper mills use screw centrifugal pump to transport fluid with long fibers and high concentration of pulp, depending on its special advantages, but its efficiency is low, only about 60%. And now our countries are also strong advocates in conveying middle&high concentration pulp in order to save water. Under these conditions, re-design screw centrifugal pump is necessary to satisfy the market and social needs. The pulp is opaque, so it can't be observed by visualization method. In order to clarify flow pattern of the pulp in the screw centrifugal pump and verify the design performance, steady numerical simulation in single blade helicon centrifugal model is done through the use of CFD software. And the simulation result is in comparison with experiment. The concrete work and the main conclusions are shown as following:Present domestic and international research states on the screw centrifugal pump were summarized briefly, a design method was described, and on this basis of design parameters the impeller and pump body were designed. Finished three-dimensional modeling for the screw centrifugal pump and internal flow channel solid model meshing by Pro/ENGINEER Wildfire3.0.CFD software FLUENT was used, by selecting the RNG k-εturbulent model, respectively, with water and 10% of the concentration of pulp suspension as a medium for solid-liquid two-phase flow, for numerical simulation of internal flow in the pump, and its internal three-dimensional flow, pressure and speed distribution results were compared. A prototype was made through the model, on the bedstand for the overall performance of the pump was experimented, and the data with simulation results were compared with the calculation. In both medium conditions, similar to the internal flow pattern, pressure and velocity is uniform, but only there are differences in numerical size. Vortexes and circumrotatory fluid are born in the impeller and the body, made a turbulent flow. The vortex move when the flux grows up. Part of the vortex move in the body, the other move to the hub from the body. Vortexes are in the different situation on the both medium conditions. Because of the pulp fiber concentrate on the flange, its flow condition is different from the water, when the pulp out of the impeller. While the two-phase flow, under the low flux, a vortex is produced in pump exit, nothing about single phase flow. But it disappears while the flux grows. Under the design operation condition, while single phase flow head is on the high side, the error of the sample pump head and design requirement is 13.41%, above the experimental data 1.99%, the error of two-phase flow head respectively is 5.75%and 4.89%. The efficiency of the numerical simulation exceeds the test date:68.25%by water,70.43%by pulp, prototype test date is 66.03%, which is tower above the design requirements one percent. It supplies the gist of theory and experiment for the optimize design of screw centrifugal pump.
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