Primary breakup in a liquid-liquid pintle injector element at different radial jet velocities is investigated to elucidate the impingement morphology,the formation of primary breakup spray half cone angle,the pressure...Primary breakup in a liquid-liquid pintle injector element at different radial jet velocities is investigated to elucidate the impingement morphology,the formation of primary breakup spray half cone angle,the pressure distribution,the liquid diameter distribution,and the liquid velocity distribution.With a sufficient mesh resolution,the liquid morphology can be captured in a physically sound way.A mushroom tip is triggered by a larger radial jet velocity and breakup happens at the tip edge first.Different kinds of ligament breakup patterns due to aerodynamic force and surface tension are captured on the axial sheet.A high pressure core is spotted at the impinging point region.A larger radial jet velocity can feed more disturbances into the impinging point and the axial sheet,generate stronger vortices to promote the breakup process at a longer distance,and form a larger spray half cone angle.Because of the re-collision phenomenon the axial sheet diameter does not decrease monotonically.The inner rim on the axial sheet shows a larger diameter magnitude and a lower velocity magnitude due to surface tension.This paper is expected to provide a reference for the optimum design of a liquid-liquid pintle injector.展开更多
Fluid-structure interaction(FSI)of gas-liquid two-phase fow in the horizontal pipe is investigated numerically in the present study.The volume of fluid model and standard k-e turbulence model are integrated to simulat...Fluid-structure interaction(FSI)of gas-liquid two-phase fow in the horizontal pipe is investigated numerically in the present study.The volume of fluid model and standard k-e turbulence model are integrated to simulate the typical gas-liquid two-phase fow patterns.First,validation of the numerical model is conducted and the typical fow patterns are consistent with the Baker chart.Then,the FSI framework is established to investigate the dynamic responses of the interaction between the horizontal pipe and gas-liquid two-phase fow.The results show that the dynamic response under stratified fow condition is relatively flat and the maximum pipe deformation and equivalent stress are 1.8 mm and 7.5 MPa respectively.Meanwhile,the dynamic responses induced by slug fow,wave fow and annular fow show obvious periodic fuctuations.Furthermore,the dynamic response characteristics under slug flow condition are maximum;the maximum pipe deformation and equivalent stress can reach 4mm and 17.5 MPa,respectively.The principal direction of total deformation is different under various flow patterns.Therefore,the periodic equivalent stress will form the cyclic impact on the pipe wall and affect the fatigue life of the horizontal pipe.The present study may serve as a reference for FSI simulation under gas-liquid two-phase transport conditions.展开更多
The investigation of the melting behaviors of the molten salt at micron scale during the melting process is critical for explaining the solid-liquid phase transition mechanism.In this paper,a novel experimental system...The investigation of the melting behaviors of the molten salt at micron scale during the melting process is critical for explaining the solid-liquid phase transition mechanism.In this paper,a novel experimental system and analysis method were proposed to study the melting process with three heating rates in the range of1-10℃/min of the solar salt at micron scale.The solid-liquid boundary morphology and phase transition kinetics of molten salt particles were focused on.Meanwhile,the correlations between liquid fraction,temperature and time under different heating rates were studied.The solid-liquid boundary morphology was depicted by the visualized experimental set-up,and the instantaneous liquid volume fraction during the non-isothermal phase transition was obtained.Then,the correlation between temperature and liquid volume fraction was proposed to reveal the evolution of the solid-liquid boundary with temperature at different heating rates.Furthermore,the non-isothermal phase transition kinetic equation was established by introducing a constant parameter(V_(a,b)),and more kinetic parameters such as 1g V_(a,b) and-lg V_(a,b)/b were studied.The results showed that the exponent b is not sensitive to the heating rate with a range of 3-5 for solar salt particles.However,the heating rate influences the value of V_(a,b) and presents a positive relationship.Besides,the non-isothermal phase transition kinetic equations at different heating rates in the range of 1-10℃/min can be quickly predicted by the proposed improved experimental test method.This study could fill the research insufficiency and provide significant guidance for future research on the solid-liquid transition mechanism of molten salts at micron scale.展开更多
By simulating test and study in laboratory, the structure and performance offrothing generator were determined. The relative curves between the frothing volume and gas velocityof foaming net, supplying liquid volume a...By simulating test and study in laboratory, the structure and performance offrothing generator were determined. The relative curves between the frothing volume and gas velocityof foaming net, supplying liquid volume and the content of foaming agent were obtainedrespectively. There were an optimum gas-velocity of foaming net, an optimum supplying liquid volumeand an optimum content of foaming agent under the condition of the given material quality and shapeof foaming net and spraying form. The spraying froth is of a great assistance in collectingrespirable dust.展开更多
Liquid sloshing is a kind of very complicated free surface flow and exists widely in many fields.In order to calculate liquid sloshing damping precisely a volume of fluid method based on finite volume scheme is used t...Liquid sloshing is a kind of very complicated free surface flow and exists widely in many fields.In order to calculate liquid sloshing damping precisely a volume of fluid method based on finite volume scheme is used to simulate free surface flows in partly filled cylindrical containers.A numerical method is pre-sented to simulate the movement of the free surface flow,in which a piecewise linear interface con-struction scheme and an unsplit Lagrangian advection scheme instead of Eulerian advection scheme are used.The damping performance of liquid sloshing in cylindrical containers under fundamental sloshing mode is investigated.There are four factors determining the surface-wave damping:free surface,boundary-layer,interior fluid and contact line.In order to study different contributions from these four factors to whole damping,several examples are simulated.No-slip and slip wall boundary conditions on both side wall and bottom wall of the cylindrical containers are studied to compare with the published results obtained by solving Stokes equations.In the present method the first three main factors can be considered.The simulation results show that the boundary-layer damping contribution increases while the interior fluid damping contribution decreases with increase of Reynolds number.展开更多
Single argon bubble dynamics in liquid steel under Ruhrstahl-Heraeus(RH)vacuum conditions were simulated using the volume of fluid method,and the ideal gas law was used to consider bubble growth due to heat transfer a...Single argon bubble dynamics in liquid steel under Ruhrstahl-Heraeus(RH)vacuum conditions were simulated using the volume of fluid method,and the ideal gas law was used to consider bubble growth due to heat transfer and pressure drop.Additional simulation with a constant bubble density was also performed to validate the numerical method,and the predicted terminal bubble shape and velocity were found to agree with those presented in the Grace diagram and calculated by drag correlation,respectively.The simulation results under RH conditions indicate that the terminal bubble shape and velocity cannot be reached.The primary bubble growth occurs within a rising distance of 0.3 m owing to heating by the high-temperature liquid steel;subsequently,the bubble continues to grow under equilibrium with the hydrostatic pressure.When the initial diameter is 8-32 mm,the bubble diameter and rising velocity near the liquid surface are 80-200 mm and 0.5-0.8 m/s,respectively.The bubble rises rectilinearly with an axisymmetric shape,and the shape evolution history includes an initial sphere,(dimpled)ellipsoid,and spherical cap with satellite bubbles.展开更多
基金supported by the National Natural Science Foundation of China(No.11572346)。
文摘Primary breakup in a liquid-liquid pintle injector element at different radial jet velocities is investigated to elucidate the impingement morphology,the formation of primary breakup spray half cone angle,the pressure distribution,the liquid diameter distribution,and the liquid velocity distribution.With a sufficient mesh resolution,the liquid morphology can be captured in a physically sound way.A mushroom tip is triggered by a larger radial jet velocity and breakup happens at the tip edge first.Different kinds of ligament breakup patterns due to aerodynamic force and surface tension are captured on the axial sheet.A high pressure core is spotted at the impinging point region.A larger radial jet velocity can feed more disturbances into the impinging point and the axial sheet,generate stronger vortices to promote the breakup process at a longer distance,and form a larger spray half cone angle.Because of the re-collision phenomenon the axial sheet diameter does not decrease monotonically.The inner rim on the axial sheet shows a larger diameter magnitude and a lower velocity magnitude due to surface tension.This paper is expected to provide a reference for the optimum design of a liquid-liquid pintle injector.
基金the National Natural Science Foundation of China(No.51779143)the Oceanic Interdisciplinary Program of Shanghai Jiao Tong University(No.SL2020ZD101)the Cultivation of Scientific Research Ability of Young Talents of Shanghai Jiao Tong University(No.19X100040072)。
文摘Fluid-structure interaction(FSI)of gas-liquid two-phase fow in the horizontal pipe is investigated numerically in the present study.The volume of fluid model and standard k-e turbulence model are integrated to simulate the typical gas-liquid two-phase fow patterns.First,validation of the numerical model is conducted and the typical fow patterns are consistent with the Baker chart.Then,the FSI framework is established to investigate the dynamic responses of the interaction between the horizontal pipe and gas-liquid two-phase fow.The results show that the dynamic response under stratified fow condition is relatively flat and the maximum pipe deformation and equivalent stress are 1.8 mm and 7.5 MPa respectively.Meanwhile,the dynamic responses induced by slug fow,wave fow and annular fow show obvious periodic fuctuations.Furthermore,the dynamic response characteristics under slug flow condition are maximum;the maximum pipe deformation and equivalent stress can reach 4mm and 17.5 MPa,respectively.The principal direction of total deformation is different under various flow patterns.Therefore,the periodic equivalent stress will form the cyclic impact on the pipe wall and affect the fatigue life of the horizontal pipe.The present study may serve as a reference for FSI simulation under gas-liquid two-phase transport conditions.
基金supported by the National Natural Science Foundation of China (No.51821004 and No. 51876061)。
文摘The investigation of the melting behaviors of the molten salt at micron scale during the melting process is critical for explaining the solid-liquid phase transition mechanism.In this paper,a novel experimental system and analysis method were proposed to study the melting process with three heating rates in the range of1-10℃/min of the solar salt at micron scale.The solid-liquid boundary morphology and phase transition kinetics of molten salt particles were focused on.Meanwhile,the correlations between liquid fraction,temperature and time under different heating rates were studied.The solid-liquid boundary morphology was depicted by the visualized experimental set-up,and the instantaneous liquid volume fraction during the non-isothermal phase transition was obtained.Then,the correlation between temperature and liquid volume fraction was proposed to reveal the evolution of the solid-liquid boundary with temperature at different heating rates.Furthermore,the non-isothermal phase transition kinetic equation was established by introducing a constant parameter(V_(a,b)),and more kinetic parameters such as 1g V_(a,b) and-lg V_(a,b)/b were studied.The results showed that the exponent b is not sensitive to the heating rate with a range of 3-5 for solar salt particles.However,the heating rate influences the value of V_(a,b) and presents a positive relationship.Besides,the non-isothermal phase transition kinetic equations at different heating rates in the range of 1-10℃/min can be quickly predicted by the proposed improved experimental test method.This study could fill the research insufficiency and provide significant guidance for future research on the solid-liquid transition mechanism of molten salts at micron scale.
基金This work was financially supported by the National Natural Science Foundation of China, No.50174004
文摘By simulating test and study in laboratory, the structure and performance offrothing generator were determined. The relative curves between the frothing volume and gas velocityof foaming net, supplying liquid volume and the content of foaming agent were obtainedrespectively. There were an optimum gas-velocity of foaming net, an optimum supplying liquid volumeand an optimum content of foaming agent under the condition of the given material quality and shapeof foaming net and spraying form. The spraying froth is of a great assistance in collectingrespirable dust.
基金Supported by the National Natural Science Foundation of China(Grant No.10532010)
文摘Liquid sloshing is a kind of very complicated free surface flow and exists widely in many fields.In order to calculate liquid sloshing damping precisely a volume of fluid method based on finite volume scheme is used to simulate free surface flows in partly filled cylindrical containers.A numerical method is pre-sented to simulate the movement of the free surface flow,in which a piecewise linear interface con-struction scheme and an unsplit Lagrangian advection scheme instead of Eulerian advection scheme are used.The damping performance of liquid sloshing in cylindrical containers under fundamental sloshing mode is investigated.There are four factors determining the surface-wave damping:free surface,boundary-layer,interior fluid and contact line.In order to study different contributions from these four factors to whole damping,several examples are simulated.No-slip and slip wall boundary conditions on both side wall and bottom wall of the cylindrical containers are studied to compare with the published results obtained by solving Stokes equations.In the present method the first three main factors can be considered.The simulation results show that the boundary-layer damping contribution increases while the interior fluid damping contribution decreases with increase of Reynolds number.
基金supported by the National Natural Science Foundation of China(Grant No.52104321)the Natural Science Foundation of Chongqing,China(Grant No.CSTB2023NSCQ-MSX0871)the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJQN202101404).
文摘Single argon bubble dynamics in liquid steel under Ruhrstahl-Heraeus(RH)vacuum conditions were simulated using the volume of fluid method,and the ideal gas law was used to consider bubble growth due to heat transfer and pressure drop.Additional simulation with a constant bubble density was also performed to validate the numerical method,and the predicted terminal bubble shape and velocity were found to agree with those presented in the Grace diagram and calculated by drag correlation,respectively.The simulation results under RH conditions indicate that the terminal bubble shape and velocity cannot be reached.The primary bubble growth occurs within a rising distance of 0.3 m owing to heating by the high-temperature liquid steel;subsequently,the bubble continues to grow under equilibrium with the hydrostatic pressure.When the initial diameter is 8-32 mm,the bubble diameter and rising velocity near the liquid surface are 80-200 mm and 0.5-0.8 m/s,respectively.The bubble rises rectilinearly with an axisymmetric shape,and the shape evolution history includes an initial sphere,(dimpled)ellipsoid,and spherical cap with satellite bubbles.
