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
Underground mining requires lot of water pumping to surface which increases cost. Because of safety, support, ventilation and environment costs underground mines are closing down gradually all over the world. This inn...Underground mining requires lot of water pumping to surface which increases cost. Because of safety, support, ventilation and environment costs underground mines are closing down gradually all over the world. This innovative paper is based on method studies by computer programming with realistic data. With development of electronic control systems, coal water slurry mix can be remote controlled for transport to surface Separator-bunker. Main consumers need powdered coal/mineral like thermal power stations, for feeding to Fuel Burners of boilers, generating power or in steel plants for feeding into coke ovens to make hard coke for charging into Blast Furnaces for making pig iron. Feed for coal washeries also require crushed coal and output of washed coal as slurry can be sent to coke ovens of steel plants directly. Production from mine faces should be taken through lump-breaker and conveyed to a mixing chamber, near panel sump, from where adequate capacity slurry pump will propel up to pit-top. The projected financial benefit can be several millions of Rupees per year, as compared to road, rail conveyor or winders is shown, by run of a computer program in Java, with realistic cost figures from mines.展开更多
A comprehensive 3D turbulent CFD study has been carried out to simulate a Low-Head(LH)vertical Direct Chill(DC)rolling ingot caster for the common magnesium alloy AZ31.The model used in this study takes into account t...A comprehensive 3D turbulent CFD study has been carried out to simulate a Low-Head(LH)vertical Direct Chill(DC)rolling ingot caster for the common magnesium alloy AZ31.The model used in this study takes into account the coupled laminar/turbulent melt flow and solidification aspects of the process and is based on the control-volume finite-difference approach.Following the aluminum/magnesium DC casting industrial practices,the LH mold is taken as 30 mm with a hot top of 60 mm.The previously verified in-house code has been modified to model the present casting process.Important quantitative results are obtained for four casting speeds,for three inlet melt pouring temperatures(superheats)and for three metal-mold contact heat transfer coefficients for the steady state operational phase of the caster.The variable cooling water temperatures reported by the industry are considered for the primary and secondary cooling zones during the simulations.Specifically,the temperature and velocity fields,sump depth and sump profiles,mushy region thickness,solid shell thickness at the exit of the mold and axial temperature profiles at the center and at three strategic locations at the surface of the slab are presented and discussed.展开更多
This study aims to analyze the development of small-scale irrigation using shallow groundwater in Nahouri province (south-central Burkina Faso). The methodological approach adopted was essentially based firstly on sem...This study aims to analyze the development of small-scale irrigation using shallow groundwater in Nahouri province (south-central Burkina Faso). The methodological approach adopted was essentially based firstly on semi-structured surveys with producers who have adopted sump technology and the monitoring of groundwater level using the installed piezometers and secondly on geophysical prospection. Results obtained show that market gardening is mainly a family activity practiced on plots of 0.20 ha with a predominance of pepper cultivation occupying about 75% of cultivated areas. It was also highlighted that this agricultural activity faces several constraints that delay its development. These include: lack of water, land insecurity, small and fragmented farms and difficulty in selling products when they are put on local markets at the very same time as significant price drops. This problem is accentuated by the perishable nature of these market garden products. Despite these limiting factors, there is some satisfaction considering the income earned by farmers, most of whom are able to meet their primary needs. This work made it possible to conclude that even in zones which are not sedimentary formations, it is possible to mobilize groundwater, at a reasonable depth for agricultural purposes, without much effort to practice additional irrigation, knowing that evaporation carries harm to the use of dams.展开更多
In this article, a numerical model forthree-dimensional turbulent flow in the sump of the pumpstation was presented. A reasonable boundary condition for the flow in the sump with several water intakes at different flo...In this article, a numerical model forthree-dimensional turbulent flow in the sump of the pumpstation was presented. A reasonable boundary condition for the flow in the sump with several water intakes at different flowrates was proposed. The finite volume method was employed tosolve the governing equations with the body fitted gridgenerated by the multi-block grid technique. By using theFluent software, the fluid flow in a model sump of the pumpstation was calculated. Compared with the experimental result,the numerical result of the example is fairly good.展开更多
Numerical simulations of 3D turbulent flow in a large-bore axial-flow pump coupled with half-elbow suction sump were perlbrmed by using CFD approach. The numerical model and velocity and pressure distributions in enti...Numerical simulations of 3D turbulent flow in a large-bore axial-flow pump coupled with half-elbow suction sump were perlbrmed by using CFD approach. The numerical model and velocity and pressure distributions in entire flow passage were presented. The obvious backflow in half-elbow suction sump and strong flow nonuniformity at suction sump outlet were observed, whereas these phenomena were not observed in existing studies performed for a separate suction sump by either experimental or numerical approach. This result indicates that the interaction between half-elbow suction sump and impeller has significant effect on the flow distribution in the pump passage. The change of pump efficiency caused by the interaction was discussed,展开更多
Vortices in the flow of a pump sump present an important problem in pump station operation. In the present study, the flow patterns in two model pump sumps with specially designed structures are analyzed using the p...Vortices in the flow of a pump sump present an important problem in pump station operation. In the present study, the flow patterns in two model pump sumps with specially designed structures are analyzed using the particle image velocimetry (PIV) technique. The data is analyzed to reveal a number of parameters including the internal flow field with velocity distribution, the streamline distribution, and the turbulent kinetic energy. The analysis certifies that a modified pump with added T-type baffle below the sump exhibits good performance for realistic working conditions.展开更多
The dynamics of air entrainment and suppression schemes in a pump sump are investigated. Four different turbulence models(standard k-ε model, realizable k-ε model, renormalization group(RNG) k-ε model and shear-str...The dynamics of air entrainment and suppression schemes in a pump sump are investigated. Four different turbulence models(standard k-ε model, realizable k-ε model, renormalization group(RNG) k-ε model and shear-stress transport(SST) k-ω model) and the volume of fluid(VOF) multiphase model are employed to simulate the three-dimensional unsteady turbulent flow in a pump sump. The dynamic processes of air entrainment are simulated under conditions of relatively high discharge and low submergence; the mechanism of air entrainment is discussed in detail. Then suppression means for air entrainment is adopted by placing a circular plate on the intake pipe at three different heights. The results show: the position and structure of the free-surface vortices, sidewall-attached vortices, back wall-attached vortices, and floor-attached vortices calculated by SST k-ω turbulence model agree well with the experimental data. The two main contributors for air entrainment are pressure difference and vortex strength. By placing a circular plate in the middle of the intake pipe under water, air entrainment is suppressed because vortex strength is reduced.展开更多
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.
文摘Underground mining requires lot of water pumping to surface which increases cost. Because of safety, support, ventilation and environment costs underground mines are closing down gradually all over the world. This innovative paper is based on method studies by computer programming with realistic data. With development of electronic control systems, coal water slurry mix can be remote controlled for transport to surface Separator-bunker. Main consumers need powdered coal/mineral like thermal power stations, for feeding to Fuel Burners of boilers, generating power or in steel plants for feeding into coke ovens to make hard coke for charging into Blast Furnaces for making pig iron. Feed for coal washeries also require crushed coal and output of washed coal as slurry can be sent to coke ovens of steel plants directly. Production from mine faces should be taken through lump-breaker and conveyed to a mixing chamber, near panel sump, from where adequate capacity slurry pump will propel up to pit-top. The projected financial benefit can be several millions of Rupees per year, as compared to road, rail conveyor or winders is shown, by run of a computer program in Java, with realistic cost figures from mines.
文摘A comprehensive 3D turbulent CFD study has been carried out to simulate a Low-Head(LH)vertical Direct Chill(DC)rolling ingot caster for the common magnesium alloy AZ31.The model used in this study takes into account the coupled laminar/turbulent melt flow and solidification aspects of the process and is based on the control-volume finite-difference approach.Following the aluminum/magnesium DC casting industrial practices,the LH mold is taken as 30 mm with a hot top of 60 mm.The previously verified in-house code has been modified to model the present casting process.Important quantitative results are obtained for four casting speeds,for three inlet melt pouring temperatures(superheats)and for three metal-mold contact heat transfer coefficients for the steady state operational phase of the caster.The variable cooling water temperatures reported by the industry are considered for the primary and secondary cooling zones during the simulations.Specifically,the temperature and velocity fields,sump depth and sump profiles,mushy region thickness,solid shell thickness at the exit of the mold and axial temperature profiles at the center and at three strategic locations at the surface of the slab are presented and discussed.
文摘This study aims to analyze the development of small-scale irrigation using shallow groundwater in Nahouri province (south-central Burkina Faso). The methodological approach adopted was essentially based firstly on semi-structured surveys with producers who have adopted sump technology and the monitoring of groundwater level using the installed piezometers and secondly on geophysical prospection. Results obtained show that market gardening is mainly a family activity practiced on plots of 0.20 ha with a predominance of pepper cultivation occupying about 75% of cultivated areas. It was also highlighted that this agricultural activity faces several constraints that delay its development. These include: lack of water, land insecurity, small and fragmented farms and difficulty in selling products when they are put on local markets at the very same time as significant price drops. This problem is accentuated by the perishable nature of these market garden products. Despite these limiting factors, there is some satisfaction considering the income earned by farmers, most of whom are able to meet their primary needs. This work made it possible to conclude that even in zones which are not sedimentary formations, it is possible to mobilize groundwater, at a reasonable depth for agricultural purposes, without much effort to practice additional irrigation, knowing that evaporation carries harm to the use of dams.
基金Project supported by the Shanghai Leading Academic Discipline Project(Grant No: Y0103).
文摘In this article, a numerical model forthree-dimensional turbulent flow in the sump of the pumpstation was presented. A reasonable boundary condition for the flow in the sump with several water intakes at different flowrates was proposed. The finite volume method was employed tosolve the governing equations with the body fitted gridgenerated by the multi-block grid technique. By using theFluent software, the fluid flow in a model sump of the pumpstation was calculated. Compared with the experimental result,the numerical result of the example is fairly good.
基金Project supported by the National Nature Science Foundation of China (Grant Nos: 10372114, 50479008 and 90510007) and Program for New Century Excellent Talents in Universities of China (Grant No: NCET-04-0133).
文摘Numerical simulations of 3D turbulent flow in a large-bore axial-flow pump coupled with half-elbow suction sump were perlbrmed by using CFD approach. The numerical model and velocity and pressure distributions in entire flow passage were presented. The obvious backflow in half-elbow suction sump and strong flow nonuniformity at suction sump outlet were observed, whereas these phenomena were not observed in existing studies performed for a separate suction sump by either experimental or numerical approach. This result indicates that the interaction between half-elbow suction sump and impeller has significant effect on the flow distribution in the pump passage. The change of pump efficiency caused by the interaction was discussed,
文摘Vortices in the flow of a pump sump present an important problem in pump station operation. In the present study, the flow patterns in two model pump sumps with specially designed structures are analyzed using the particle image velocimetry (PIV) technique. The data is analyzed to reveal a number of parameters including the internal flow field with velocity distribution, the streamline distribution, and the turbulent kinetic energy. The analysis certifies that a modified pump with added T-type baffle below the sump exhibits good performance for realistic working conditions.
基金supported by the National Natural Science Foundation of China(Grant No.51422906)
文摘The dynamics of air entrainment and suppression schemes in a pump sump are investigated. Four different turbulence models(standard k-ε model, realizable k-ε model, renormalization group(RNG) k-ε model and shear-stress transport(SST) k-ω model) and the volume of fluid(VOF) multiphase model are employed to simulate the three-dimensional unsteady turbulent flow in a pump sump. The dynamic processes of air entrainment are simulated under conditions of relatively high discharge and low submergence; the mechanism of air entrainment is discussed in detail. Then suppression means for air entrainment is adopted by placing a circular plate on the intake pipe at three different heights. The results show: the position and structure of the free-surface vortices, sidewall-attached vortices, back wall-attached vortices, and floor-attached vortices calculated by SST k-ω turbulence model agree well with the experimental data. The two main contributors for air entrainment are pressure difference and vortex strength. By placing a circular plate in the middle of the intake pipe under water, air entrainment is suppressed because vortex strength is reduced.
