Research On Internal Flow Structure And Energy Conversion Of Vortex Pump In Solid-liquid Two-phase Flow

With the development of social industrialization,it is often necessary to transport solid-liquid mixtures in industrial and agricultural activities such as coal,water conservancy dredging,environmental protection,etc.,which has high requirements for the non-clogging performance of the pump.As one of the multi-phase transportation machinery,it has been widely used in these industries.At present,most researches on vortex pumps are based on assumptions and numerical simulations,and the effects of media parameters and blade types on vortex pumps are mostly based on the research level of special performance.Compared with other pump types,the main disadvantage of the vortex pump is its low efficiency.According to the needs of the team,the 150WX-200-20 type vortex pump was selected as the research object.The test was indirectly verified by the accuracy of numerical simulation.The numerical simulation was mainly used to study the vortex pump and its hydraulic design.With the establishment of the three-dimensional model,it is divided into two parts: the impeller domain and the volute domain,and the unstructured mesh is divided.Numerical simulation of the solid-liquid two-phase flow field in the vortex pump with six solid phase volume fractions and four blade types under different working conditions.The Eulerian two-fluid model was selected for the solid-liquid two-phase flow,and the RNG k-?model was used as turbulent The model uses fluid dynamics theory to perform steady calculations on the pump,and the results of solid and liquid phase vectors,velocity streamlines,and vorticity are calculated.Numerical simulations and tests of the same-vane model pumps under single-phase media under full operating conditions were conducted,and the error between the calculated external characteristics results was less than 6%,which indirectly verified the reliability of the numerical simulation.First,the simulation results of the single-phase and solid-liquid two-phase flow under the design conditions are analyzed,and the flow rules of the solid and liquid phases in the pump under the two-phase flow are compared.The conclusions are as follows: There is an axial vortex.The geometric characteristics of the axial vortex between the blades in the two phases are more regular than in the single phase.The flow velocity of the solid phase out of the rim under the two phases is much greater than the liquid phase flow velocity in the two phases or single phase.Participating in the vortex motion,the main flow is entrapped by the liquid phase.After the hydraulic impact or impeller contact,the vector change of the medium is much larger than that of the liquid phase.The liquid interacting with the solid phase also follows therelative solid phase.The shape and scale of the vortex structure formed inside the solid phase will reduce the strength of the vortex during single-phase flow and suppress the increase of the vortex size of the secondary circulation.The effects of solid phase parameters on the internal flow structure of the pump were studied,and the evolution process of the circulating flow was analyzed.The geometric characteristics of the circulating flow were expressed by the position and shape coefficients.The conclusions are as follows: The main flow form of the medium in the impeller domain of the vortex pump is The hydraulic impact caused by the rotation of the impeller is accompanied by the axial vortex generated by the medium exchanged with the circulating flow caused by the rapid flow of the medium.When and only when the vortex core position is close to but does not enter the impeller domain,the pump reaches the high efficiency point.On this basis,the standard deviation of the shape factor on each shaft section is the smallest,and a flow model of the vortex pump is established on this basis.Intuitively expressed the relationship between solid phase parameters and internal flow structure;finally,on the basis of the above research,the factor of the blade type was added,and starting from the flow structure of the impeller domain,it was concluded that the blade type had more influence on the circulating flow than the solid phase The larger the parameter,the flow state of the medium flowing out of the impeller domain directly affects the flow of the circulating flow,which is related to the flow law of the medium in the flow path between the blades.The performance of the folded blade is the best,and the performance of the curved blade is the worst.Based on the research in this paper,the relationship between the circulating flow and the external characteristics of the vortex pump under solid-liquid two-phase flow can lay the foundation for the subsequent analysis of other flow structures and performance prediction in the flow field,and the energy conversion and optimization of the research pump The structure of the pump has important significance.