The growing demand for ocean space has generated significant interest in multi-body floating systems,where gap resonance in confined regions plays a critical role in ensuring the safety of offshore operations.This stu...The growing demand for ocean space has generated significant interest in multi-body floating systems,where gap resonance in confined regions plays a critical role in ensuring the safety of offshore operations.This study develops a numerical tank model using the Smoothed Particle Hydrodynamics(SPH)method,implemented through the open-source code DualSPHysics,to investigate hydrodynamic resonance in a twin-floater system and to examine the influence of internal tank sloshing on its hydrodynamic characteristics.The hydrodynamic behavior of the gap flow between a fixed twin-floater system in the numerical tank is validated through systematic comparison with experimental data.Subsequently,the wave-induced motions and forces on a twin-floater system are compared with those on a single floater.Furthermore,the effects of internal tank sloshing on the hydrodynamic response of the twin-floater system are explored.A parametric study is conducted to analyze the influence of incident wave frequency on floater motion and tank sloshing dynamics.The results show that the presence of an internal tank can significantly reduce pitch motion and vertical forces on the floating body,while exerting minimal influence on heave motion and horizontal forces.The findings provide new insights into the hydrodynamic performance of twin-floater systems and their interaction with internal sloshing phenomena.展开更多
This paper investigates the coupling characteristics of variable mass tank sloshing and ship motion.A full nonlinear numerical model of variable mass tank sloshing-external wave-ship motion coupling is established.Fir...This paper investigates the coupling characteristics of variable mass tank sloshing and ship motion.A full nonlinear numerical model of variable mass tank sloshing-external wave-ship motion coupling is established.Firstly,the coupled motion characteristics of tank sloshing and simplified hull in beam sea are compared,the time history of dimensionless roll angle agrees well with experimental results,and the accuracy of the numerical model is verified.Secondly,the effects of wave excitation and ship speed on the coupled characteristics of Korea Research Institute of Ships and Ocean Engineering very large crude carrier(KVLCC)tank sloshing and ship motion are discussed,and the influence of liquid filling rate on ship heave motion and pitch motion is discussed emphatically.The results show that during the tank filling,the sloshing pressure in the tank increases steadily,and the growth rate is positively correlated with the filling rate.At the same time,the ship pitch motion is less affected by tank sloshing,while the ship heave motion is evidently affected by tank sloshing.展开更多
In recent years,tuned liquid dampers(TLDs)have attracted significant research interest;however,overall progress has been limited due to insufficient understanding of the mechanisms governing sloshing-induced loads.In ...In recent years,tuned liquid dampers(TLDs)have attracted significant research interest;however,overall progress has been limited due to insufficient understanding of the mechanisms governing sloshing-induced loads.In particular,it remains unclear whether the water in aqueducts—common water-diversion structures in many countries—can serve as an effective TLD.This study investigates the generation mechanisms of sloshing loads during the first-order transverse resonance of water in a U-shaped aqueduct using a two-dimensional(2D)numerical model.The results reveal that,at the equilibrium position,the free surface difference between the left and right walls,the horizontal force on the aqueduct,and the fluctuating component of the vertical force all reach their maxima,with energy predominantly stored as potential energy.At the maximum displacement position,the surface difference and horizontal force drop to zero,while the fluctuating vertical force attains its minimum and energy shifts primarily to kinetic form.At this stage,static pressure is governed solely by the vertical convective acceleration,whereas at equilibrium it is closely linked to both the free surface difference and vertical local acceleration of the water.This dynamic energy exchange generates vertical force oscillations even when the free surface appears nearly symmetric.展开更多
In the process of stage separation of recoverable liquid launch vehicles,because of the large amount of residual fuel in the storage tanks,the influence of liquid sloshing on separation safety must be considered.Consi...In the process of stage separation of recoverable liquid launch vehicles,because of the large amount of residual fuel in the storage tanks,the influence of liquid sloshing on separation safety must be considered.Considering calculation simplicity and operation practicability,the Moving Pulsating Ball Model(MPBM)of large amplitude liquid sloshing is introduced into the calculation of launch vehicle stage separation.Combining the dynamic equation of the model with the energy relationship during"breathing movement",the formula calculating the force of liquid on the rigid body is derived.Compared with the calculations of commercial CFD calculation software,the accuracy of MPBM model is verified.Then,all the external forces and moments are applied to the rigid body of the stages,so that the translational and rotational dynamic equations of the stages are obtained respectively.According to the relative position of the two stages,the geometric shape of the interstage section and the engine of the second stage,the minimum clearance in the separation process can be decided to guarantee that the separation process is safe.展开更多
Predicting the response of liquefied natural gas(LNG)contained in vessels subjected to external waves is extremely important to ensure the safety of the transportation process.In this study,the coupled behavior due to...Predicting the response of liquefied natural gas(LNG)contained in vessels subjected to external waves is extremely important to ensure the safety of the transportation process.In this study,the coupled behavior due to ship motion and liquid tank sloshing has been simulated by the Smoothed-Particle Hydrodynamics(SPH)method.Firstly,the sloshing flow in a rectangular tank was simulated and the related loads were analyzed to verify and validate the accuracy of the present SPH solver.Then,a three-dimensional simplified LNG carrier model,including two prismatic liquid tanks and a wave tank,was introduced.Different conditions were examined corresponding to different wave lengths,wave heights,wave heading angles,and tank loading rates.Finally,the effects of liquid tank loading rate on LNG ship motions and sloshing loading were analyzed,thereby showing that the SPH method can effectively provide useful indications for the design of liquid cargo ships.展开更多
The production of hydrogen on offshore platform can decrease reliance on the power grid,mitigate transmission losses of electricity,and diminish investment costs for subsea cables.In this study,the hydrodynamic perfor...The production of hydrogen on offshore platform can decrease reliance on the power grid,mitigate transmission losses of electricity,and diminish investment costs for subsea cables.In this study,the hydrodynamic performances of platforms equipped with two types of tanks separately are evaluated and are comprehensively compared with each other.The Volume of Fluid(VOF)two-phase flow model and the Shear−Stress Transport(SST)k−omega turbulence model are applied to simulate the motion responses of the C-type and Moss-type tanks under the same excitation force of platform based on the time-frequency response results of platforms.Comparisons are made among the shape of the liquid hydrogen surface,variations of the wall pressures,changes of the gas-liquid temperatures,and the pressure drop phenomena induced by phase changes inside the tanks.The results indicate that the interaction between wave-induced excitation force and sloshing force from tanks can either increase or decrease the amplitude of platform’s motion.Meanwhile,the thermodynamic responses of liquid hydrogen sloshing inside the tanks correlate positively with the dynamic behavior.Compared with Moss-type tanks,the sloshing of liquid hydrogen in C-type tanks is more intense,accompanied by jetting and breaking wave phenomena.For the C-type tanks,the substantial increase in interfacial area significantly enhances phase change condensation and heat transfer,leading to the rapid decline in temperature and pressure inside the tanks.The results of this study can provide valuable insights for the future design of floating hydrogen storage platform and the selection of tanks on the platform.展开更多
The spiral-wound heat exchanger(SWHE) is the primary low-temperature heat exchanger for large-scale LNG plants due to its high-pressure resistance, compact structure, and high heat exchange efficiency. This paper stud...The spiral-wound heat exchanger(SWHE) is the primary low-temperature heat exchanger for large-scale LNG plants due to its high-pressure resistance, compact structure, and high heat exchange efficiency. This paper studied the shell-side heat and mass transfer characteristics of vapor-liquid two-phase mixed refrigerants in an SWHE by combining a multi-component model in FLUENT software with a customized multicomponent mass transfer model. Besides, the mathematical model under the sloshing condition was obtained through mathematical derivation, and the corresponding UDF code was loaded into FLUENT as the momentum source term. The results under the sloshing conditions were compared with the relevant parameters under the steady-state condition. The shell-side heat and mass transfer characteristics of the SWHE were investigated by adjusting the component ratio and other working conditions. It was found that the sloshing conditions enhance the heat transfer performance and sometimes have insignificant effects. The sloshing condition is beneficial to reduce the flow resistance. The comprehensive performance of multi-component refrigerants has been improved and the improvement is more significant under sloshing conditions, considering both the heat transfer and pressure drop.These results will provide theoretical support for the research and design of multi-component heat and mass transfer enhancement of LNG SWHE under ocean sloshing conditions.展开更多
Sloshing experiment is crucial to determine the reaction performance of regeneration columns on an offshore floating platform.A novel type of column motion simulating device and a Marine Predator Algorithm-based Slidi...Sloshing experiment is crucial to determine the reaction performance of regeneration columns on an offshore floating platform.A novel type of column motion simulating device and a Marine Predator Algorithm-based Sliding Mode Controller(MPA-SMC)are proposed for such sloshing experiments.The simulator consists of a Stewart platform and a steel framework.The Stewart platform is located at the column's center of gravity(CoG)and supported by the steel framework.The platform's hydraulic servo system is controlled by a sliding mode controller with parameters optimized by MPA to improve robustness and precision.A numerical sloshing experiment is conducted using the proposed device and controller.The results show that the novel motion simulator has lower torque during the column sloshes,and the proposed controller performs better than a well-tuned PID controller in terms of target tracking precision and anti-interference capability.展开更多
The sloshing in a tank with a specific geometric shape containing fluid was modeled numerically to reduce its effects by applying a porous medium to the tank wall.The thickness and position of the porous layer and the...The sloshing in a tank with a specific geometric shape containing fluid was modeled numerically to reduce its effects by applying a porous medium to the tank wall.The thickness and position of the porous layer and the geometric shape of the tank were investigated as the main parameters to select an optimal approach to reduce the effects of sloshing.Different fluid tank filling percentages(H_(w)/H_(tot)) were evaluated.Results indicate that performance at H_(w)/H_(tot)=0.33 and two tank modes with and without a porous environment layer have the greatest impact on reducing sloshing.A thickness of 30 cm and placement on the side walls are determined to be the ideal thickness and location of the porous layer.A porous layer with a thickness(t)relative to the tank length at the middle(L_(m)),t L_(m)=0.1 applied to the side walls of the tank effectively reduces the pressure by 65%.This study provided suggestions for the aspect ratio of a chamfered tank designed against sloshing.展开更多
This study aimedto investigatethe spatiotemporal variation of hydrodynamic variables around a sphere rigidlyϐixed to the bottom of a sloshing tank.The experimental measurement of the variations of dynamic variables ar...This study aimedto investigatethe spatiotemporal variation of hydrodynamic variables around a sphere rigidlyϐixed to the bottom of a sloshing tank.The experimental measurement of the variations of dynamic variables around a body in a sloshing tank requires non‑intrusive measurements that are usually expensive and sometimes inappli‑cable.Therefore,the numerical model could serve as a cost‑effective tool for such problems.A two‑stage analysis was conducted.In theϐirst stage,an experimental study was carried out in a testing system comprising a water tank with uniaxial freedom of movement constructed on a monorail operated by a computer‑controlled step motor.The primary objective of the experiments was to generate reliable data for calibrating the numerical model.During the experiments,the tank’s movements were recorded using an accelerometer and ultrasonic sensors with a sampling frequency of 200 Hz for each.The accelerometer and ultrasonic sensor data were used to impose the motion of the sloshing tank into a Reynolds‑Averaged Navier‑Stokes(RANS)‑based numerical model.The video recordings,which comprised temporalϐluctuations of the water surface,were used to calibrate the Model 1.Once theϐirst numerical model was calibrated based on water surface level records using image processing methods,the second numerical model was constructed to accommodate a rigid spherical body with a 17 mm diameter connected to the bottom of the sloshing tank. The initial and boundary conditions used in the second numerical model were identical to those used in the ϐirst model to measure the spatiotemporal ϐluctuations of the surrounding spherical body’s kinematic and dynamic variables, respectively. The ϐindings revealed that sloshing motion exerts a signiϐicant impact on the boundary layer separation process around the sphere. It was also witnessed that the stage of the sloshing motion controls the temporal lag between the pressure, velocity and water surface level.展开更多
Different Baffle designs usable in cylindrical and elliptical storage tanks carried by trucks often used for transporting inflammable liquid materials in Cameroon are investigated to evaluate their safest fluid sloshi...Different Baffle designs usable in cylindrical and elliptical storage tanks carried by trucks often used for transporting inflammable liquid materials in Cameroon are investigated to evaluate their safest fluid sloshing damping response during emergency braking where the magnitude of sloshing waves are the greatest.The uncontrolled fluid sloshing creates thrust on the walls of the tanks usually felt externally on the truck carrying the tank and capable of hindering driver’s effort to maintain steer ability and improve on safety during critical braking moments.The study first passes through COMSOL,to expose the safest margin of each Baffle type at instantaneous fluid pressure wave propagation initiated at a single phase to reflect sloshing in the storage tank during an emergency braking by the truck carrying the tank.The vivid results can be seen in the domain of Acoustic Iso-surface Pressure response;but also acoustic Pressure and Sound pressure response are seen automatically.Secondly,through an experimental finding in which fluid is forced to pass through each Baffle and the resistance to fluid flow is a measured as it’s the Baffle’s damping ability.Either,the fluid is lost through the Baffle and by determination of the surface load exerted on each Baffle due to the reaction of the residual fluid acting on the surface of each Baffle after some of it is Lost,the individual sloshing damping abilities are exposed.By comparing the Experimental outcome with the computational response obtained,an ideal Baffle design is proposed for cylindrical and elliptical tanks and considered to respond to abrupt braking more effciently.The application of the Baffle designs with an average multiple holes rather than the usual face centered proved to be more effcient in fluid sloshing as they provide a more uniformly distributed damping pressure during fluid sloshing in the tank thereby reducing the magnitude of forward thrust that can be created by the conventional Baffle type during emergency braking hence contributing to improving safety.Mindful of the human,material and environmental damages that an accident involving mobile petroleum storage tanks can course,this study is therefore of great significance for design optimization by petroleum storage tank manufacturing companies in Cameroon.展开更多
Base d on fluid velocity potential, an ALE finite element formulation for the analysi s of nonlinear sloshing problems has been developed. The ALE kinemat ical description is introduced to move the computational mesh...Base d on fluid velocity potential, an ALE finite element formulation for the analysi s of nonlinear sloshing problems has been developed. The ALE kinemat ical description is introduced to move the computational mesh independently of f luid motion, and the container fixed noninertial coordinate system is employed to establish the governing equations so that the mesh is needed to be updated in this coordinate system only. This leads to a very simple mesh moving algorithm which makes it easy to trace the motion of the moving boundaries and the free su rface without producing undesirable distortion of the computational mesh. The fi nite element method and finite difference method are used spacewise and timewise , respectively. A numerical example involving either forced horizontal oscillati on or forced pitching oscillation of the fluid filled container is presented to illustrate the effectiveness and the robustness of the method. In additi on, this work can be extended for the fluid structure interaction problems.展开更多
The analogy between the wave equation of liquid and the Navier equations of structural elasticity is examined in detail. By introducing appropriate parameters, the structural counterpart of the liquid sloshing model c...The analogy between the wave equation of liquid and the Navier equations of structural elasticity is examined in detail. By introducing appropriate parameters, the structural counterpart of the liquid sloshing model can be easily built. Therefore, the dynamic analysis of liquid sloshing can be reduced to that of structural elasticity, and the existing FEM structural analysis computer programs can be applied to liquid sloshing analysis without any modification. The present method also reveals the internal relationship between liquid sloshing and structural vibration. The effectiveness and reliability of the method is illustrated by the numerical example.展开更多
The performance of dual perforated floating plates in a rectangular tank is investigated based on the model tests under different external excitations for different filling rates.It is found that dual perforated float...The performance of dual perforated floating plates in a rectangular tank is investigated based on the model tests under different external excitations for different filling rates.It is found that dual perforated floating plates in the tank can remarkably mitigate violent resonant sloshing responses compared with the clean tank,especially when the external excitation frequency is in the vicinity of the first-order resonant frequency.Next,the parametric studies based on different filling rates and external excitation amplitudes are performed for the first-order resonant frequencies.The presence of dual perforated floating plates seldom shifts the sloshing natural frequencies.Further,dual perforated floating plates change the sloshing modes from the standing-wave mode in the clean tank to the Utube mode,which can arise from the sloshing reduction to some extent.展开更多
Sloshing is a common phenomenon in nature and industry, and it is important in many fields, such as marine engineering and aerospace engineering. To reduce the sloshing load on the side walls, the topology optimizatio...Sloshing is a common phenomenon in nature and industry, and it is important in many fields, such as marine engineering and aerospace engineering. To reduce the sloshing load on the side walls, the topology optimization and optimal control methods are used to design the shape of the board, which is fixed in the middle of the tank. The results show that the new board shape, which is designed via topology optimization, can significantly reduce the sloshing load on the side wall.展开更多
A sloshing mitigation concept taking advantage of floating layers of solid foam elements is proposed in the present study. Physical experiments are carried out in a liquid tank to investigate the hydrodynamic mechanis...A sloshing mitigation concept taking advantage of floating layers of solid foam elements is proposed in the present study. Physical experiments are carried out in a liquid tank to investigate the hydrodynamic mechanism of this concept. Effects of the foam-layer thickness, excitation amplitude, and excitation frequency on the sloshing properties are analyzed in detail. It is found that the floating layers of solid foam elements do not evidently affect the fundamental natural sloshing frequency of the liquid tank evidently among the considered cases. At the resonant condition, the maximum wave height and dynamic pressure are greatly reduced as the foam-layer thickness increases. Higher-order pressure components on the tank side gradually vanish with the increase of the foam-layer thickness. Cases with different excitation amplitudes are also analyzed. The phenomenon is observed when the wave breaking in the tank can be suppressed by solid foam elements.展开更多
An approach based on equivalent mechanics theory and computational fluid dynamics （CFD） technology is proposed to estimate dynamical influence of propellant sloshing on the spacecraft. A mechanical model is estab- l...An approach based on equivalent mechanics theory and computational fluid dynamics （CFD） technology is proposed to estimate dynamical influence of propellant sloshing on the spacecraft. A mechanical model is estab- lished by using CFD technique and packed as a ＂sloshing＂ block used in spacecraft guidance navigation and control （GNC） simulation loop. The block takes motion characteristics of the spacecraft as inputs and outputs of pertur- bative force and torques induced by propellant sloshing, thus it is more convenient for analyzing coupling effect between propellant sloshing dynamic and spacecraft GNC than using CFD packages. An example demonstrates the accuracy and the superiority of the approach. Then, the deducing process is applied to practical cases, and simulation results validate that the proposed approach is efficient for identifying the problems induced by sloshing and evaluating effectiveness of several typical designs of sloshing suppression.展开更多
This paper aims at finding a proper way to estimate sloshing severity.First,the concept of sloshing severity RAO(SSR) is introduced,and the wave elevation on the liquid free surface is chosen as an initial index for t...This paper aims at finding a proper way to estimate sloshing severity.First,the concept of sloshing severity RAO(SSR) is introduced,and the wave elevation on the liquid free surface is chosen as an initial index for the rough prediction of sloshing severity.Then,compared with experimental data from a 3 D regular model test,this index is adjusted and a new index is generated.One step further,sloshing severity under irregular sea states can be achieved by nonlinear combinations of the new index.For validation,the same model tank is tested under a set of irregular sea conditions,and peak pressures and impulse areas are taken as comparison standards.It is found that both numerical and experimental results show a similar tendency of sloshing severity.As a real ship application on the new index,the sloshing severity of a liquefied natural gas floating production storage and offloading(LNG-FPSO) is predicted under a low filling condition.Besides,the ship motion responses with and without sloshing effects are considered for the calculation of severity.From the present observation,this proposed methodology and generated new index is expected to be applicable to the selection of severe sea states for sloshing loads analysis.展开更多
A meshless numerical simulation method, the moving-particle semi-implicit method （MPS） is presented in this paper to study the sloshing phenomenon in ocean and naval engineering. As a meshless method, MPS uses parti...A meshless numerical simulation method, the moving-particle semi-implicit method （MPS） is presented in this paper to study the sloshing phenomenon in ocean and naval engineering. As a meshless method, MPS uses particles to replace the mesh in traditional methods, the governing equations are discretized by virtue of the relationship of particles, and the Poisson equation of pressure is solved by incomplete Cholesky conjugate gradient method （ICCG）, the free surface is tracked by the change of numerical density. A numerical experiment of viscous liquid sloshing tank was presented and compared with the result got by the difference method with the VOF, and an additional modification step was added to make the simulation more stable. The results show that the MPS method is suitable for the simulation of viscous liquid sloshing, with the advantage in arranging the particles easily, especially on some complex curved surface.展开更多
A liquid sloshing experimental rig driven by a wave-maker is designed and built to study liquid sloshing problems in a rectangular liquid tank with perforated baffle. A series of experiments are conducted in this expe...A liquid sloshing experimental rig driven by a wave-maker is designed and built to study liquid sloshing problems in a rectangular liquid tank with perforated baffle. A series of experiments are conducted in this experimental rig to estimate the free surface fluctuation and pressure distribution by changing external excitation frequency of the shaking table. An in-house CFD code is also used in this study to simulate the liquid sloshing in three-dimensional （3D） rectangular tank with perforated baffle. Good agreements of free surface elevation and pressure between the numerical results and the experimental data are obtained and presented. Spectral analysis of the time history of free surface elevation is conducted by using the fast Fourier transformation.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52271316 and 12302314)the Science and Technology Project in Guangzhou(No.2024A04J9886).
文摘The growing demand for ocean space has generated significant interest in multi-body floating systems,where gap resonance in confined regions plays a critical role in ensuring the safety of offshore operations.This study develops a numerical tank model using the Smoothed Particle Hydrodynamics(SPH)method,implemented through the open-source code DualSPHysics,to investigate hydrodynamic resonance in a twin-floater system and to examine the influence of internal tank sloshing on its hydrodynamic characteristics.The hydrodynamic behavior of the gap flow between a fixed twin-floater system in the numerical tank is validated through systematic comparison with experimental data.Subsequently,the wave-induced motions and forces on a twin-floater system are compared with those on a single floater.Furthermore,the effects of internal tank sloshing on the hydrodynamic response of the twin-floater system are explored.A parametric study is conducted to analyze the influence of incident wave frequency on floater motion and tank sloshing dynamics.The results show that the presence of an internal tank can significantly reduce pitch motion and vertical forces on the floating body,while exerting minimal influence on heave motion and horizontal forces.The findings provide new insights into the hydrodynamic performance of twin-floater systems and their interaction with internal sloshing phenomena.
基金supported by the China Postdoctoral Science Foundation(Grant No.2024M763646)the China University of Petroleum(East China)Independent Innovation Research Project(Science and Engineering)-Youth Fund(Grant No.24CX06062A)+2 种基金the Postdoctoral Fellowship Program(Grade C)of China Postdoctoral Science Foundation(Grant No.GZC20250181)the Qingdao Natural Science Foundation(Grant No.25-1-1-66-zyyd-jch)Shandong Provincial Key Laboratory of Ocean Engineering(Grant No.kloe202504).
文摘This paper investigates the coupling characteristics of variable mass tank sloshing and ship motion.A full nonlinear numerical model of variable mass tank sloshing-external wave-ship motion coupling is established.Firstly,the coupled motion characteristics of tank sloshing and simplified hull in beam sea are compared,the time history of dimensionless roll angle agrees well with experimental results,and the accuracy of the numerical model is verified.Secondly,the effects of wave excitation and ship speed on the coupled characteristics of Korea Research Institute of Ships and Ocean Engineering very large crude carrier(KVLCC)tank sloshing and ship motion are discussed,and the influence of liquid filling rate on ship heave motion and pitch motion is discussed emphatically.The results show that during the tank filling,the sloshing pressure in the tank increases steadily,and the growth rate is positively correlated with the filling rate.At the same time,the ship pitch motion is less affected by tank sloshing,while the ship heave motion is evidently affected by tank sloshing.
基金Science and Technology Planning Project of Sichuan Province with Grant No.2023YFS0429supported by Science and Technology Project of China Road and Bridge Corporation with Grant No.P2220447+1 种基金supported by Foundation of Xinjiang Institute of Engineering 2024(Grant No.2024xgy072605)supported by Sichuan Natural Science Foundation Project(Grant No.2024NSFSC0162).The numerical calculations in this study have been done on Hefei advanced computing center.
文摘In recent years,tuned liquid dampers(TLDs)have attracted significant research interest;however,overall progress has been limited due to insufficient understanding of the mechanisms governing sloshing-induced loads.In particular,it remains unclear whether the water in aqueducts—common water-diversion structures in many countries—can serve as an effective TLD.This study investigates the generation mechanisms of sloshing loads during the first-order transverse resonance of water in a U-shaped aqueduct using a two-dimensional(2D)numerical model.The results reveal that,at the equilibrium position,the free surface difference between the left and right walls,the horizontal force on the aqueduct,and the fluctuating component of the vertical force all reach their maxima,with energy predominantly stored as potential energy.At the maximum displacement position,the surface difference and horizontal force drop to zero,while the fluctuating vertical force attains its minimum and energy shifts primarily to kinetic form.At this stage,static pressure is governed solely by the vertical convective acceleration,whereas at equilibrium it is closely linked to both the free surface difference and vertical local acceleration of the water.This dynamic energy exchange generates vertical force oscillations even when the free surface appears nearly symmetric.
基金supported by the National Natural Science Foundation of China(Nos.12132002,12202044)。
文摘In the process of stage separation of recoverable liquid launch vehicles,because of the large amount of residual fuel in the storage tanks,the influence of liquid sloshing on separation safety must be considered.Considering calculation simplicity and operation practicability,the Moving Pulsating Ball Model(MPBM)of large amplitude liquid sloshing is introduced into the calculation of launch vehicle stage separation.Combining the dynamic equation of the model with the energy relationship during"breathing movement",the formula calculating the force of liquid on the rigid body is derived.Compared with the calculations of commercial CFD calculation software,the accuracy of MPBM model is verified.Then,all the external forces and moments are applied to the rigid body of the stages,so that the translational and rotational dynamic equations of the stages are obtained respectively.According to the relative position of the two stages,the geometric shape of the interstage section and the engine of the second stage,the minimum clearance in the separation process can be decided to guarantee that the separation process is safe.
基金the National Natural Science Foundation of China(No.52271316)the Guangdong Basic and Applied Basic Research Foundation(No.2023A1515030262).
文摘Predicting the response of liquefied natural gas(LNG)contained in vessels subjected to external waves is extremely important to ensure the safety of the transportation process.In this study,the coupled behavior due to ship motion and liquid tank sloshing has been simulated by the Smoothed-Particle Hydrodynamics(SPH)method.Firstly,the sloshing flow in a rectangular tank was simulated and the related loads were analyzed to verify and validate the accuracy of the present SPH solver.Then,a three-dimensional simplified LNG carrier model,including two prismatic liquid tanks and a wave tank,was introduced.Different conditions were examined corresponding to different wave lengths,wave heights,wave heading angles,and tank loading rates.Finally,the effects of liquid tank loading rate on LNG ship motions and sloshing loading were analyzed,thereby showing that the SPH method can effectively provide useful indications for the design of liquid cargo ships.
基金supported by the National Natural Science Foundation of China(Grant No.51979130).
文摘The production of hydrogen on offshore platform can decrease reliance on the power grid,mitigate transmission losses of electricity,and diminish investment costs for subsea cables.In this study,the hydrodynamic performances of platforms equipped with two types of tanks separately are evaluated and are comprehensively compared with each other.The Volume of Fluid(VOF)two-phase flow model and the Shear−Stress Transport(SST)k−omega turbulence model are applied to simulate the motion responses of the C-type and Moss-type tanks under the same excitation force of platform based on the time-frequency response results of platforms.Comparisons are made among the shape of the liquid hydrogen surface,variations of the wall pressures,changes of the gas-liquid temperatures,and the pressure drop phenomena induced by phase changes inside the tanks.The results indicate that the interaction between wave-induced excitation force and sloshing force from tanks can either increase or decrease the amplitude of platform’s motion.Meanwhile,the thermodynamic responses of liquid hydrogen sloshing inside the tanks correlate positively with the dynamic behavior.Compared with Moss-type tanks,the sloshing of liquid hydrogen in C-type tanks is more intense,accompanied by jetting and breaking wave phenomena.For the C-type tanks,the substantial increase in interfacial area significantly enhances phase change condensation and heat transfer,leading to the rapid decline in temperature and pressure inside the tanks.The results of this study can provide valuable insights for the future design of floating hydrogen storage platform and the selection of tanks on the platform.
基金funded by the National Natural Science Foundation of China(No.51806236,No.51806239)the Fundamental Research Funds for the Central Universities(No.2015XKMS059)+1 种基金Shaanxi Postdoctoral Fund Project(No.2018BSHEDZZ56)Foundation of Key Laboratory of Thermo-Fluid Science and Engineering(Xi'an Jiaotong University),Ministry of Education(No.KLTFSE2017KF01)。
文摘The spiral-wound heat exchanger(SWHE) is the primary low-temperature heat exchanger for large-scale LNG plants due to its high-pressure resistance, compact structure, and high heat exchange efficiency. This paper studied the shell-side heat and mass transfer characteristics of vapor-liquid two-phase mixed refrigerants in an SWHE by combining a multi-component model in FLUENT software with a customized multicomponent mass transfer model. Besides, the mathematical model under the sloshing condition was obtained through mathematical derivation, and the corresponding UDF code was loaded into FLUENT as the momentum source term. The results under the sloshing conditions were compared with the relevant parameters under the steady-state condition. The shell-side heat and mass transfer characteristics of the SWHE were investigated by adjusting the component ratio and other working conditions. It was found that the sloshing conditions enhance the heat transfer performance and sometimes have insignificant effects. The sloshing condition is beneficial to reduce the flow resistance. The comprehensive performance of multi-component refrigerants has been improved and the improvement is more significant under sloshing conditions, considering both the heat transfer and pressure drop.These results will provide theoretical support for the research and design of multi-component heat and mass transfer enhancement of LNG SWHE under ocean sloshing conditions.
文摘Sloshing experiment is crucial to determine the reaction performance of regeneration columns on an offshore floating platform.A novel type of column motion simulating device and a Marine Predator Algorithm-based Sliding Mode Controller(MPA-SMC)are proposed for such sloshing experiments.The simulator consists of a Stewart platform and a steel framework.The Stewart platform is located at the column's center of gravity(CoG)and supported by the steel framework.The platform's hydraulic servo system is controlled by a sliding mode controller with parameters optimized by MPA to improve robustness and precision.A numerical sloshing experiment is conducted using the proposed device and controller.The results show that the novel motion simulator has lower torque during the column sloshes,and the proposed controller performs better than a well-tuned PID controller in terms of target tracking precision and anti-interference capability.
文摘The sloshing in a tank with a specific geometric shape containing fluid was modeled numerically to reduce its effects by applying a porous medium to the tank wall.The thickness and position of the porous layer and the geometric shape of the tank were investigated as the main parameters to select an optimal approach to reduce the effects of sloshing.Different fluid tank filling percentages(H_(w)/H_(tot)) were evaluated.Results indicate that performance at H_(w)/H_(tot)=0.33 and two tank modes with and without a porous environment layer have the greatest impact on reducing sloshing.A thickness of 30 cm and placement on the side walls are determined to be the ideal thickness and location of the porous layer.A porous layer with a thickness(t)relative to the tank length at the middle(L_(m)),t L_(m)=0.1 applied to the side walls of the tank effectively reduces the pressure by 65%.This study provided suggestions for the aspect ratio of a chamfered tank designed against sloshing.
文摘This study aimedto investigatethe spatiotemporal variation of hydrodynamic variables around a sphere rigidlyϐixed to the bottom of a sloshing tank.The experimental measurement of the variations of dynamic variables around a body in a sloshing tank requires non‑intrusive measurements that are usually expensive and sometimes inappli‑cable.Therefore,the numerical model could serve as a cost‑effective tool for such problems.A two‑stage analysis was conducted.In theϐirst stage,an experimental study was carried out in a testing system comprising a water tank with uniaxial freedom of movement constructed on a monorail operated by a computer‑controlled step motor.The primary objective of the experiments was to generate reliable data for calibrating the numerical model.During the experiments,the tank’s movements were recorded using an accelerometer and ultrasonic sensors with a sampling frequency of 200 Hz for each.The accelerometer and ultrasonic sensor data were used to impose the motion of the sloshing tank into a Reynolds‑Averaged Navier‑Stokes(RANS)‑based numerical model.The video recordings,which comprised temporalϐluctuations of the water surface,were used to calibrate the Model 1.Once theϐirst numerical model was calibrated based on water surface level records using image processing methods,the second numerical model was constructed to accommodate a rigid spherical body with a 17 mm diameter connected to the bottom of the sloshing tank. The initial and boundary conditions used in the second numerical model were identical to those used in the ϐirst model to measure the spatiotemporal ϐluctuations of the surrounding spherical body’s kinematic and dynamic variables, respectively. The ϐindings revealed that sloshing motion exerts a signiϐicant impact on the boundary layer separation process around the sphere. It was also witnessed that the stage of the sloshing motion controls the temporal lag between the pressure, velocity and water surface level.
文摘Different Baffle designs usable in cylindrical and elliptical storage tanks carried by trucks often used for transporting inflammable liquid materials in Cameroon are investigated to evaluate their safest fluid sloshing damping response during emergency braking where the magnitude of sloshing waves are the greatest.The uncontrolled fluid sloshing creates thrust on the walls of the tanks usually felt externally on the truck carrying the tank and capable of hindering driver’s effort to maintain steer ability and improve on safety during critical braking moments.The study first passes through COMSOL,to expose the safest margin of each Baffle type at instantaneous fluid pressure wave propagation initiated at a single phase to reflect sloshing in the storage tank during an emergency braking by the truck carrying the tank.The vivid results can be seen in the domain of Acoustic Iso-surface Pressure response;but also acoustic Pressure and Sound pressure response are seen automatically.Secondly,through an experimental finding in which fluid is forced to pass through each Baffle and the resistance to fluid flow is a measured as it’s the Baffle’s damping ability.Either,the fluid is lost through the Baffle and by determination of the surface load exerted on each Baffle due to the reaction of the residual fluid acting on the surface of each Baffle after some of it is Lost,the individual sloshing damping abilities are exposed.By comparing the Experimental outcome with the computational response obtained,an ideal Baffle design is proposed for cylindrical and elliptical tanks and considered to respond to abrupt braking more effciently.The application of the Baffle designs with an average multiple holes rather than the usual face centered proved to be more effcient in fluid sloshing as they provide a more uniformly distributed damping pressure during fluid sloshing in the tank thereby reducing the magnitude of forward thrust that can be created by the conventional Baffle type during emergency braking hence contributing to improving safety.Mindful of the human,material and environmental damages that an accident involving mobile petroleum storage tanks can course,this study is therefore of great significance for design optimization by petroleum storage tank manufacturing companies in Cameroon.
文摘Base d on fluid velocity potential, an ALE finite element formulation for the analysi s of nonlinear sloshing problems has been developed. The ALE kinemat ical description is introduced to move the computational mesh independently of f luid motion, and the container fixed noninertial coordinate system is employed to establish the governing equations so that the mesh is needed to be updated in this coordinate system only. This leads to a very simple mesh moving algorithm which makes it easy to trace the motion of the moving boundaries and the free su rface without producing undesirable distortion of the computational mesh. The fi nite element method and finite difference method are used spacewise and timewise , respectively. A numerical example involving either forced horizontal oscillati on or forced pitching oscillation of the fluid filled container is presented to illustrate the effectiveness and the robustness of the method. In additi on, this work can be extended for the fluid structure interaction problems.
文摘The analogy between the wave equation of liquid and the Navier equations of structural elasticity is examined in detail. By introducing appropriate parameters, the structural counterpart of the liquid sloshing model can be easily built. Therefore, the dynamic analysis of liquid sloshing can be reduced to that of structural elasticity, and the existing FEM structural analysis computer programs can be applied to liquid sloshing analysis without any modification. The present method also reveals the internal relationship between liquid sloshing and structural vibration. The effectiveness and reliability of the method is illustrated by the numerical example.
基金This study is financially supported by Hainan Provincial Natural Science Foundation of China(Grant No.519MS026)Scientific Research Foundation of Hainan University(Grant No.KYQD(ZR)1878).
文摘The performance of dual perforated floating plates in a rectangular tank is investigated based on the model tests under different external excitations for different filling rates.It is found that dual perforated floating plates in the tank can remarkably mitigate violent resonant sloshing responses compared with the clean tank,especially when the external excitation frequency is in the vicinity of the first-order resonant frequency.Next,the parametric studies based on different filling rates and external excitation amplitudes are performed for the first-order resonant frequencies.The presence of dual perforated floating plates seldom shifts the sloshing natural frequencies.Further,dual perforated floating plates change the sloshing modes from the standing-wave mode in the clean tank to the Utube mode,which can arise from the sloshing reduction to some extent.
基金Project supported by the National Natural Science Foundation of China(Nos.11572350,11372068,and 11602051)the National Key Basic Research and Development Program of China(No.2014CB744104)
文摘Sloshing is a common phenomenon in nature and industry, and it is important in many fields, such as marine engineering and aerospace engineering. To reduce the sloshing load on the side walls, the topology optimization and optimal control methods are used to design the shape of the board, which is fixed in the middle of the tank. The results show that the new board shape, which is designed via topology optimization, can significantly reduce the sloshing load on the side wall.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51709038,51679036 and51739010)the Project funded by China Postdoctoral Science Foundation(Grant No.2018M630289)the Open Foundation of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering(Grant No.2016490111)
文摘A sloshing mitigation concept taking advantage of floating layers of solid foam elements is proposed in the present study. Physical experiments are carried out in a liquid tank to investigate the hydrodynamic mechanism of this concept. Effects of the foam-layer thickness, excitation amplitude, and excitation frequency on the sloshing properties are analyzed in detail. It is found that the floating layers of solid foam elements do not evidently affect the fundamental natural sloshing frequency of the liquid tank evidently among the considered cases. At the resonant condition, the maximum wave height and dynamic pressure are greatly reduced as the foam-layer thickness increases. Higher-order pressure components on the tank side gradually vanish with the increase of the foam-layer thickness. Cases with different excitation amplitudes are also analyzed. The phenomenon is observed when the wave breaking in the tank can be suppressed by solid foam elements.
基金Innovation Foundation of Aerospace Science and Technology(CASC200902)~~
文摘An approach based on equivalent mechanics theory and computational fluid dynamics （CFD） technology is proposed to estimate dynamical influence of propellant sloshing on the spacecraft. A mechanical model is estab- lished by using CFD technique and packed as a ＂sloshing＂ block used in spacecraft guidance navigation and control （GNC） simulation loop. The block takes motion characteristics of the spacecraft as inputs and outputs of pertur- bative force and torques induced by propellant sloshing, thus it is more convenient for analyzing coupling effect between propellant sloshing dynamic and spacecraft GNC than using CFD packages. An example demonstrates the accuracy and the superiority of the approach. Then, the deducing process is applied to practical cases, and simulation results validate that the proposed approach is efficient for identifying the problems induced by sloshing and evaluating effectiveness of several typical designs of sloshing suppression.
文摘This paper aims at finding a proper way to estimate sloshing severity.First,the concept of sloshing severity RAO(SSR) is introduced,and the wave elevation on the liquid free surface is chosen as an initial index for the rough prediction of sloshing severity.Then,compared with experimental data from a 3 D regular model test,this index is adjusted and a new index is generated.One step further,sloshing severity under irregular sea states can be achieved by nonlinear combinations of the new index.For validation,the same model tank is tested under a set of irregular sea conditions,and peak pressures and impulse areas are taken as comparison standards.It is found that both numerical and experimental results show a similar tendency of sloshing severity.As a real ship application on the new index,the sloshing severity of a liquefied natural gas floating production storage and offloading(LNG-FPSO) is predicted under a low filling condition.Besides,the ship motion responses with and without sloshing effects are considered for the calculation of severity.From the present observation,this proposed methodology and generated new index is expected to be applicable to the selection of severe sea states for sloshing loads analysis.
基金the National Natural Science Foundation under Grant No.50579035
文摘A meshless numerical simulation method, the moving-particle semi-implicit method （MPS） is presented in this paper to study the sloshing phenomenon in ocean and naval engineering. As a meshless method, MPS uses particles to replace the mesh in traditional methods, the governing equations are discretized by virtue of the relationship of particles, and the Poisson equation of pressure is solved by incomplete Cholesky conjugate gradient method （ICCG）, the free surface is tracked by the change of numerical density. A numerical experiment of viscous liquid sloshing tank was presented and compared with the result got by the difference method with the VOF, and an additional modification step was added to make the simulation more stable. The results show that the MPS method is suitable for the simulation of viscous liquid sloshing, with the advantage in arranging the particles easily, especially on some complex curved surface.
基金supported by the China Postdoctoral Science Foundation(Grant No.2012M511192)the National Natural Science Foundation of China(Grant Nos.51209080 and 51061130547+5 种基金Open Fund of State Key Laboratory of Coastaland Off shore Engineering(Grant No.LP1207the Open Fund of State Key Laboratory of Hydraulics and Mountain River Engineering(Grant No.1213)Qing Lan Project and 333 Project of Jiangsu Province(Grant No.BRA2012130)the Fundamental Research Funds for the Central Universities(Hohai University,Grant No.2012B06514the 111 Project(Grant No.B12032)Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120181110084)
文摘A liquid sloshing experimental rig driven by a wave-maker is designed and built to study liquid sloshing problems in a rectangular liquid tank with perforated baffle. A series of experiments are conducted in this experimental rig to estimate the free surface fluctuation and pressure distribution by changing external excitation frequency of the shaking table. An in-house CFD code is also used in this study to simulate the liquid sloshing in three-dimensional （3D） rectangular tank with perforated baffle. Good agreements of free surface elevation and pressure between the numerical results and the experimental data are obtained and presented. Spectral analysis of the time history of free surface elevation is conducted by using the fast Fourier transformation.
