Investigation On Partial Emission Pump With Super-low Specific Speed

As the rapid development of petrochemical industry and the fertilizer and pharmaceutical industries,more and more pumps with little flow are needed and the partial flow pump is a kind of new centrifugal pump with little flow and high head. Compared with the ordinary centrifugal pump,the structure of the partial flow pump is simple and its flux-head curve is relatively flat in a given work scope.The theoretical system of the partial flow pump is dispersion,so its hydraulic design method has limitation.The theories,hydraulic design method and performance characteristic of the partial flow pump are elaborated on the base of existing results of the research in this paper.Through numerical calculation and test design research,the reliability of the hydrodynamic calculation that predict the partial flow pump with conventional speed is discussed in this paper.Base on the numerical simulation by CFD,the relationship of flow field and external performance is set up.The influences of impeller diameter,throat area and vanes number on the pump performance,head coefficient and flow coefficient are the main investigative parameters.Through numerical simulation and analysis we draw the conclusion as follows:1.Parameter(Q=3m³/h,H=260m,n=2900rpm),under the condition of the D₃/D₂=1.1,the head of the partial flow pump's increased with the increasing of the impeller's diameter in a certain range.The efficiency changes from high to low, appearing extreme value.2.Under the same condition,with increasing of the impeller diameter,coefficient of the head and the flow also increased,but increscent value is small and the both of the changes are not linear.So variation discipline of the flow coefficient and head coefficient is determined by a number of parameters.3.Only change the throat diameter,in a certain scope(d₀=8mm～12mm),the head and the efficiency of the partial flow pump increased with the throat diameter increasing.At the same time,with the throat diameter increasing,the head coefficient increased and the flow coefficient decreased.4.Only change the number of impeller blades,in a certain scope(z=8～12),the head and the efficiency of the partial flow pump are increasing with the throat diameter increasing.This is because the using of more blades will reduce vane's back flow zone. The circle rate increased with the increasing number of blades,and then the head coefficient is also increased.Flux coefficient is increased with the average flow rate of the volute throat increasing.