| As the power equipment of sludge backflow,sludge reflux pump has the characteristics of large flow and low head,and is widely used in municipal engineering,sewage treatment and other industries.The liquid transported is a solid-liquid two-phase flow,the solid particle diameter is less than 2mm,but the liquid contains a large number of fibers and impurities,easy to wound or attached to the impeller,resulting in the unstable operation of the sludge reflux pump,mainly in the operation accompanied by severe vibration noise and unit load too large equipment can't continue to operate and so on.The main work and research results of this paper are as follows:1)In view of the low efficiency of sludge reflux pump and the poor backflow effect of sludge,the hydraulic design method of the impeller of the axial flow pump is carried out,and a new type of sludge reflux pump impeller is obtained.2)Based on the hybrid mesh of polyhedron and prismatic grids,a numerical calculation of the sludge reflux pump is carried out,and the lift and efficiency of the pump are predicted.Through the design of the special experiment device for sludge reflux pump,the paper compares the flow-head curve to find out the accuracy of the numerical simulation of the sludge reflux pump.3)The whole performance of the sludge reflux pump is improved by designing the Segmental guide vane and the twisted guide vane respectively.By means of numerical simulation to analyze the performance of the sludge reflux pump of 3 kinds of guide vanes,it is found that the Twisted Guide vane scheme can greatly improve the head and efficiency of the sludge reflux pump,and the head and efficiency are increased by 8.7% and 9.1% respectively under the design condition.Moreover,the distorted guide vanes better improve the flow of the guide vane,reduce the impact loss of the liquid flow on the guide vane,and improve the overall performance of the sludge reflux pump.4)Based on the method of linear back-sweep,the effect of the swept blades on the performance of the sludge reflux pump was studied by numerical simulation.Through the analysis of the external characteristics and internal flow field of the sludge reflux pump with different swept blades,with the increase of the blade sweep,the head curve and shaft power curve of the sludge reflux pump are shifted downward,and the greater the drift of the blade is the more obvious,but the efficiency curve does not follow the change of grazing angle.Under the design condition,the efficiency of the sludge reflux pump with sweep as 20o is the largest,the efficiency is 2.8% higher than that of the prototype blade,and the efficiency of the sludge reflux pump with sweep as 60o is the lowest and the efficiency is reduced by 2.6%.At the same time,with the increase of the sweep,the radius of the impeller is increased and the radial velocity of the blade edge increases.5)The internal flow of the sludge reflux pump is complicated unsteady flow,so the unsteady calculation of the sludge reflux pump is carried out to study the pressure fluctuation characteristics of the back-swept sludge reflux pump.The results show that with the increase of sweep,the swept blades decrease the amplitude of pressure fluctuation at the frequency of the 60o,and the amplitude of the pressure fluctuation of the swept blades is about 50% of that of the prototype blade,and the back-swept blades can improve the operation stability of the sludge reflux pump. |
PDF Full Text Request