Numerical Simulation Study On The Internal Flow Field Of Dredging Pump

Centrifugal mud pump is the most crit7ical component of cutter suction dredgerslurry transport system. As to the numerical simulation of flow field in the centrifugalpump, domestic and foreign scholars have studied the influence of various parameterson the flow field, such as number of blades, exit angle of blade, outlet width of blade.These studies focused primarily on improving the design level of centrifugal pump,but the problems during the manufacture and operation process draw little attention.The inner wall of dredging pumps after casted is non-smooth, and the impeller andvolute wear will occur after running for some time. That will make dredgingefficiency decreased. At present, scholars have studied the influence of volute wallroughness on centrifugal pump performance, but nobody has studied on the influenceof macro-roughness. In this paper, the inner flow field of cabin mud pump JF212-45-90was simulated when transporting pure water and solid-liquid two-phase flow, thenthe internal flow characteristics coupled with the external characteristics of the wornand unworn pump have been analyzed.In this paper, gambit is used to mesh the three-dimensional model of the flowchannel which is modeled by Pro/E, and then the internal flow was simulated byFluent. The relative parameters, including the RNG k-ε viscous model, SIMPLEalgorithm and First Order Wind discretization were set in Fluent. First of all, theinternal flow field was simulated on the flow rates that were0.8Qopt、1.0Qoptand1.2Qopt when transporting water. On the basis of that simulation, the solid-liquid two-phase flow was simulated on the9flow rates that were0.2Qopt、0.4Qopt、0.6Qopt、0.8Qopt、1.0Qopt、1.1Qopt、1.2Qopt、1.3Qopt and1.4Qopt. Finally, under the assumption that the inner wall of the volute was worn,these nine simulations were done again.In this paper, simulation results were analyzed. Analysis of the distribution ofvelocity and pressure in the volute and impeller when transporting pure waterfound that the distribution in the impeller is non-axial symmetry. The absolutevelocity and total pressure are increasing along the impeller radial direction. Near the tongue between the impeller and the volute outlet position appeared reflux,which sparked a certain scale vortex in the corresponding position. Face side ofthe blade head and the negative pressure area in the turning point of impeller inletarea prone to cavitation in low flow rates. The parameters of solid phase have animportant impact on its own distribution. The average absolute velocity and totalpressure on the center section of the impeller outlet edge are cyclical, and theyreach a maximum value in the leaf edge. The total pressure and absolute velocityhas a minimum value near the volute tongue. With the volume concentration anddiameter of the solid phase increase, the total pressure and absolute velocitydecreased. The opposite is that the total pressure rises when the concentrationand diameter increase. The simulation of the worn pump uses the spherical capbody as a physical mode of pits. When the radical value of the spherical cap bodyreach82mm，the head reduces10m in the design flow rate. And in the other flowrate, the head, power, efficiency all decline.