The vortex pump is suitable for salt solution transportation. But the salt-out flow mechanism in the pump has not been understood fully. Salt-out layer formation and growth rate are closely related to crystal particle...The vortex pump is suitable for salt solution transportation. But the salt-out flow mechanism in the pump has not been understood fully. Salt-out layer formation and growth rate are closely related to crystal particle motion and concentration distribution. Study on the particle hydrodynamic characteristics in the pump volute becomes a key problem, because the crystal particles are mainly distributing in this zone after they enter the pump. Phase Doppler particle analyzer（PDPA） is used to measure the two-phase flow field in a model pump volute to get more understanding about the salt-out phenomenon. The crystal particle velocities are obtained in all three peripheral, radial and axial directions. Particle size and particle number density（PND） measurements are also performed in the experiment. Results are presented and discussed along the radial direction under different pump operating conditions, as well as various axial measurement positions. It is found that particle velocity gradient of peripheral component varies with the pump discharge. There is a turning point of relation between peripheral velocity component and discharge. Radial flow velocity curves look like a saddle shape and velocity magnitudes are changing greatly with the discharge. The non-equilibrium velocity feature between liquid and solid phase on this direction is also remarkable. Particles flow into the impeller at radial position R〈I, and the axial velocity component increases in this region. The particle size curve shows an open-up parabola distribution. The largest particles are distributing near the casing peripheral wall. As flow rate increases, accordingly PND increases. It also grows up in the axial-outward direction towards the suction cover. Crystal particle aggregation phenomenon can be revealed from the analysis of particle size and PND distribution, and the aggregation region is determined as well. Research results are helpful for optimal design of this kind of pump preventing salt-out.展开更多
The momentum flow exchange between the impeller and side channel produces highly turbulent flows in side channel pumps.The turbulent flows feature complex patterns of vortex structures that are partly responsible for ...The momentum flow exchange between the impeller and side channel produces highly turbulent flows in side channel pumps.The turbulent flows feature complex patterns of vortex structures that are partly responsible for the dissipation of energy losses and unsteady pressure pulsations.The concept of turbulent flows in side channel pumps requires a reliable vortex identification criterion to capture and predict the effects of the vortex structures on the performance.For this reason,the current study presents the application of the new Ω-criterion to a side channel pump model in comparison with other traditional methods such as Qand λ2 criteria.The 3D flow fields of the pump were obtained through unsteady Reynolds-averaged Navier-Stokes(RANS)simulations.Comparative studies showed that the Ω-criterion identifies the vortex of different intensities with a standard threshold,Ω=0.52.The Q and λ2 criteria required different thresholds to capture vortex of different intensities thus leads to subjective errors.Comparing theΩ-criterion intensity on different planes with the entropy losses and pressure pulsation,the longitudinal vortex plays an important role in the momentum exchange development which increases the head performance of the pump.However,the rate of exchange is impeded by the axial and radial vortices restricted in the impeller.Therefore,the impeller generates the highest entropy loss and pressure pulsation intensities which lower the output efficiency.Finally,the findings provide a fundamental background to the morphology of the vortex structures in the turbulent flows which can be dependent upon for efficiency improvement of side channel pumps.展开更多
In order to study the mechanism of the vortex generation at the bottom of the pump sump below the flare tube,twenty pressure pulsation monitoring points were arranged at the bottom of the pump sump below the flare tub...In order to study the mechanism of the vortex generation at the bottom of the pump sump below the flare tube,twenty pressure pulsation monitoring points were arranged at the bottom of the pump sump below the flare tube,and the pressure fluctuation experiments were carried out under different flow conditions.The experimental results show that the frequency of pressure fluctuation at the bottom of the pump sump is twice of the rotational frequency of the impeller blade.The vortex below the flare tube is easy to generate under the large flow conditions and mainly concentrates at the right front position below the flare tube.The position of the vortex occurring is corresponding to the position of the low-pressure region below flare tube.展开更多
In order to study influence of tongue clearance on the hydraulic performance of double support vortex pump,three dimensional flow model with symmetric variable size tongue clearance was established by changing section...In order to study influence of tongue clearance on the hydraulic performance of double support vortex pump,three dimensional flow model with symmetric variable size tongue clearance was established by changing section parameter of tongue clearance,and applied to numerically simulate the steady inner flow in a vortex pump based on fixed working conditions and impeller through ANSYS FLUENT.The numerical results show the influence of tongue channel with two sections(non-uniform and uniform sections)on flow field characteristics in vortex pump.Firstly,the variation of tongue channel section changes the vortex structure distribution in circumferential flow channel.Specifically the spiral forward vortex structure in the circumferential direction shifts to large radius side with increasing tongue width.Secondly,the circumferential velocity gradient and axial pressure gradient both diminish with the increase of the tongue section,and the inlet/outlet pressure difference and velocity distribution also reduce with increasing tongue channel section.Finally,for vortex pump with non-uniform section of tongue channel,the head diminishes and the efficiency remains constant approximately with the increase of the tongue width,while the head and the efficiency both diminish for uniform section of tongue channel.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 50476068)Jiangsu Provincial Postgraduate Cultivation Innovation Project of China (Grant No. CX07B_093z)
文摘The vortex pump is suitable for salt solution transportation. But the salt-out flow mechanism in the pump has not been understood fully. Salt-out layer formation and growth rate are closely related to crystal particle motion and concentration distribution. Study on the particle hydrodynamic characteristics in the pump volute becomes a key problem, because the crystal particles are mainly distributing in this zone after they enter the pump. Phase Doppler particle analyzer（PDPA） is used to measure the two-phase flow field in a model pump volute to get more understanding about the salt-out phenomenon. The crystal particle velocities are obtained in all three peripheral, radial and axial directions. Particle size and particle number density（PND） measurements are also performed in the experiment. Results are presented and discussed along the radial direction under different pump operating conditions, as well as various axial measurement positions. It is found that particle velocity gradient of peripheral component varies with the pump discharge. There is a turning point of relation between peripheral velocity component and discharge. Radial flow velocity curves look like a saddle shape and velocity magnitudes are changing greatly with the discharge. The non-equilibrium velocity feature between liquid and solid phase on this direction is also remarkable. Particles flow into the impeller at radial position R〈I, and the axial velocity component increases in this region. The particle size curve shows an open-up parabola distribution. The largest particles are distributing near the casing peripheral wall. As flow rate increases, accordingly PND increases. It also grows up in the axial-outward direction towards the suction cover. Crystal particle aggregation phenomenon can be revealed from the analysis of particle size and PND distribution, and the aggregation region is determined as well. Research results are helpful for optimal design of this kind of pump preventing salt-out.
基金Supported by National Natural Science Foundation of China(Grant Nos.51809121,51879121)China Postdoctoral Science Foundation(Grant No.2021M701535).
文摘The momentum flow exchange between the impeller and side channel produces highly turbulent flows in side channel pumps.The turbulent flows feature complex patterns of vortex structures that are partly responsible for the dissipation of energy losses and unsteady pressure pulsations.The concept of turbulent flows in side channel pumps requires a reliable vortex identification criterion to capture and predict the effects of the vortex structures on the performance.For this reason,the current study presents the application of the new Ω-criterion to a side channel pump model in comparison with other traditional methods such as Qand λ2 criteria.The 3D flow fields of the pump were obtained through unsteady Reynolds-averaged Navier-Stokes(RANS)simulations.Comparative studies showed that the Ω-criterion identifies the vortex of different intensities with a standard threshold,Ω=0.52.The Q and λ2 criteria required different thresholds to capture vortex of different intensities thus leads to subjective errors.Comparing theΩ-criterion intensity on different planes with the entropy losses and pressure pulsation,the longitudinal vortex plays an important role in the momentum exchange development which increases the head performance of the pump.However,the rate of exchange is impeded by the axial and radial vortices restricted in the impeller.Therefore,the impeller generates the highest entropy loss and pressure pulsation intensities which lower the output efficiency.Finally,the findings provide a fundamental background to the morphology of the vortex structures in the turbulent flows which can be dependent upon for efficiency improvement of side channel pumps.
基金Supported by the National Natural Science Foundation of China （50576088, 20706049） and Zhejiang Provincial Key Science Foundation （2006C21064, 2007C21067）.
基金China Nature Science Funds(51279173)“The 12th Five-year”Key Project of National Science and Technology Support Plan(2015BAD20B01)Jiangsu Water Conservancy Science and Technology Project(2017031)
文摘In order to study the mechanism of the vortex generation at the bottom of the pump sump below the flare tube,twenty pressure pulsation monitoring points were arranged at the bottom of the pump sump below the flare tube,and the pressure fluctuation experiments were carried out under different flow conditions.The experimental results show that the frequency of pressure fluctuation at the bottom of the pump sump is twice of the rotational frequency of the impeller blade.The vortex below the flare tube is easy to generate under the large flow conditions and mainly concentrates at the right front position below the flare tube.The position of the vortex occurring is corresponding to the position of the low-pressure region below flare tube.
基金the National Natural Science Foundation of China(No. 51575420)the Local Service Special Project of the Education Department of Shaanxi Province, China (No. 14 JF011)+1 种基金the Special Fund Project of Major Science and Technology Innovation of Shaanxi Province, China (No. 2017ZKC0124, No. 2018TP-17)Xi’an Science and Technology project, China (No. 201805032YD10CG16(5)) for the support
文摘In order to study influence of tongue clearance on the hydraulic performance of double support vortex pump,three dimensional flow model with symmetric variable size tongue clearance was established by changing section parameter of tongue clearance,and applied to numerically simulate the steady inner flow in a vortex pump based on fixed working conditions and impeller through ANSYS FLUENT.The numerical results show the influence of tongue channel with two sections(non-uniform and uniform sections)on flow field characteristics in vortex pump.Firstly,the variation of tongue channel section changes the vortex structure distribution in circumferential flow channel.Specifically the spiral forward vortex structure in the circumferential direction shifts to large radius side with increasing tongue width.Secondly,the circumferential velocity gradient and axial pressure gradient both diminish with the increase of the tongue section,and the inlet/outlet pressure difference and velocity distribution also reduce with increasing tongue channel section.Finally,for vortex pump with non-uniform section of tongue channel,the head diminishes and the efficiency remains constant approximately with the increase of the tongue width,while the head and the efficiency both diminish for uniform section of tongue channel.
