Every day,an NDT(Non-Destructive Testing)report will govern key decisions and inform inspection strategies that could affect the flow of millions of dollars which ultimately affects local environments and potential ri...Every day,an NDT(Non-Destructive Testing)report will govern key decisions and inform inspection strategies that could affect the flow of millions of dollars which ultimately affects local environments and potential risk to life.There is a direct correlation between report quality and equipment capability.The more able the equipment is-in terms of efficient data gathering,signal to noise ratio,positioning,and coverage-the more actionable the report is.This results in optimal maintenance and repair strategies providing the report is clear and well presented.Furthermore,when considering tank floor storage inspection it is essential that asset owners have total confidence in inspection findings and the ensuing reports.Tank floor inspection equipment must not only be efficient and highly capable,but data sets should be traceable and integrity maintained throughout.Corrosion mapping of large surface areas such as storage tank bottoms is an inherently arduous and time-consuming process.MFL(magnetic flux leakage)based tank bottom scanners present a well-established and highly rated method for inspection.There are many benefits of using modern MFL technology to generate actionable reports.Chief among these includes efficiency of coverage while gaining valuable information regarding defect location,severity,surface origin and the extent of coverage.More recent advancements in modern MFL tank bottom scanners afford the ability to scan and record data sets at areas of the tank bottom which were previously classed as dead zones or areas not scanned due to physical restraints.An example of this includes scanning the CZ(critical zone)which is the area close to the annular to shell junction weld.Inclusion of these additional dead zones increases overall inspection coverage,quality and traceability.Inspection of the CZ areas allows engineers to quickly determine the integrity of arguably the most important area of the tank bottom.Herein we discuss notable developments in CZ coverage,inspection efficiency and data integrity that combines to deliver an actionable report.The asset owner can interrogate this report to develop pertinent and accurate maintenance and repair strategies.展开更多
Corrosion behavior of low-alloy steel was investigated in simulated cargo oil tank （COT） bottom plate service environment （10% NaCl solution, pH = 0.85）. The corrosion behavior of inclusion was studied by in-situ ...Corrosion behavior of low-alloy steel was investigated in simulated cargo oil tank （COT） bottom plate service environment （10% NaCl solution, pH = 0.85）. The corrosion behavior of inclusion was studied by in-situ scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）. It was found that pitting corrosion was inclined to occur around the place where inclusions exist. After initial corrosion, an area of 10-20μm in diameter was formed as a cireinate cathode around the edge of inclusion. MnS inclusion dissolved in the simulated COT corrosion solution before low-alloy steel matrix, and pitting was formed at the place where MnS dissolved. TiO2 inclusion dissolved in the simulated COT corrosion solution after low alloy steel matrix, and pitting was formed at the place where steel matrix dissolved. The corrosion tended to occur at the area where the curvature radius of inclusion is smaller. The size of round TiO2 inclusions had little influence on corrosion behavior in this certain environment.展开更多
To analyze the bottom slope's effect on the sloshing liquid in floating liquefied natural gas(FLNG)membrane tanks,a simulation model is built and applied to describe the liquid behavior in a sloshing container.The...To analyze the bottom slope's effect on the sloshing liquid in floating liquefied natural gas(FLNG)membrane tanks,a simulation model is built and applied to describe the liquid behavior in a sloshing container.The free surface motion is simulated by the volume-of-fluid method and the standard k-εturbulence model.Experimental data and numerical results from references are used to validate the accuracy of the proposed simulation model.To study the influence of the sloped bottom on the liquid sloshing,different slope sizes and filling ratios are numerically simulated at the lowest natural frequency.The results reveal that the natural frequency can be determined by the average peak values of hydrodynamic parameters.The natural frequency and pressure loading on the tank walls decrease with the increase in the slope size.The peak pressure on the wall decreases by 5.45 kPa with the increase in the slope ratio from 5%to 20%.However,the relationship between the peak pressure and slope ratio is more significant with lower filling rates.Liquid behavior is more stable and independent with the change of the slope structure at a high filling rate(60%).The results of numerical simulation and modeling are expected to provide reference data for the design and operation of the FLNG system.展开更多
Water tank experiments were carried out to investigate the thermal convection due to the bottom heating in an asymmetrical valley under neutral and stably stratified approach flows with the Particle Image Velometry (P...Water tank experiments were carried out to investigate the thermal convection due to the bottom heating in an asymmetrical valley under neutral and stably stratified approach flows with the Particle Image Velometry (PIV) visualization technique. In the neutral stratification approach flow, the ascending draft induced by bottom heating is mainly located in the center of the valley in calm ambient wind. However, with ambient wind flow, the thermal convection is shifted leeward, and the descending draft is located on the leeward side of the valley, while the ascending draft is located on the windward side. The descending draft is minorly turbulent and organized, while the ascending draft is highly turbulent. With the increase of the towing speed, the descending and ascending drafts induced by the mechanical elevation begin to play a more dominant role in the valley flow, while the role of the thermal convection in the valley airflow becomes limited. In the stable stratification approach flow, the thermal convection is limited by the stable stratification and no distinct circulation is formed in calm ambient wind. With ambient wind, agravity wave appears in the upper layer in the valley. With the increase of the ambient wind speed, a gravity wave plays an important role in the valley flow, and the location and intensity of the thermal convection are also modulated by the gravity internal waves. The thermal convection has difficulty penetrating the upper stable layer. Its exchange is limited between the air in the upper layer and that in the lower layer in the valley, and it is adverse to the diffusion of pollutants in the valley.展开更多
The minimum fluid velocity to maintain particles just suspendedwas deduced, and the theoretical analysis shows that the minimumvelocity is influenced by the properties of the solid and liquid, notby the operational co...The minimum fluid velocity to maintain particles just suspendedwas deduced, and the theoretical analysis shows that the minimumvelocity is influenced by the properties of the solid and liquid, notby the operational conditions. For justification, the local minimumvelocity at the bottom of the tank was measured by a bi- electrodeconductivity probe, in a square-sectioned stirred tank (0.75m×0.75×1.0m) with the glass beads-water system. The experiments showed thatthe fluid velocities for the same suspension state were identicaldespite that the power Dissipated per unite mass was not the sameunder different configuration and operation. Both theoreticalanalysis And experimental results indicate that the off-bottomsuspension is controlled by the local fluid flow over the bottom Ofthe stirred tank.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
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
As a key storage facility, the structural safety of large oil tanks is directly related to the stable operation of the energy system. The static pressure caused by the change of liquid level is one of the main loads i...As a key storage facility, the structural safety of large oil tanks is directly related to the stable operation of the energy system. The static pressure caused by the change of liquid level is one of the main loads in the service process of storage tanks, which determines the structural deformation and damage risk. To explore the structural deformation properties under the change of liquid levels and provide a theoretical basis for the prevention and control of damage risk, this paper systematically analyzes the mechanical response of storage tanks under the pressures induced by different liquid levels based on the shell theory. Combined with the finite element software COMSOL, the radial displacement and stress-strain distribution under different liquid levels are simulated to verify the accuracy and effectiveness of the proposed theoretical model. The increase in liquid level and radius aggravates the radial deformation and makes the risk point move up, while the increase in wall thickness can effectively reduce the deformation response. Suggestions on the monitoring zone and damage risk prevention measures have also been given to instruct the safe operation of oil tanks. The research provides theoretical support for the optimization design of storage tank structures, the construction of advanced structural health monitoring system and the prevention and control of damage risk.展开更多
Cold air is one key factor affecting the freezing process of ice tanks.The volume of fluid method is employed to simulate the freezing process of water in an ice tank with cold air inlets.The temperature field distrib...Cold air is one key factor affecting the freezing process of ice tanks.The volume of fluid method is employed to simulate the freezing process of water in an ice tank with cold air inlets.The temperature field distribution in the ice tank is calculated.The temperature field at different typical instants are compared.The main characteristics of the freezing process in an ice tank driven by cold air are analyzed.The influence of the number of cold air inlets on the freezing process is investigated.The numerical results show that with increasing the number of cold air inlets,the temperature field becomes more uniform.The inlet velocity of cold air has a great influence on the generation of ice.This work can serve for the design of the ice tank and control of the freezing process.展开更多
Fractal theory provides a new strategy for equipment design.In this work,we propose a novel H-like fractal(HLF)impeller to improve the uniformity of the distribution of hydrodynamics in stirred tanks.The impellers are...Fractal theory provides a new strategy for equipment design.In this work,we propose a novel H-like fractal(HLF)impeller to improve the uniformity of the distribution of hydrodynamics in stirred tanks.The impellers are constructed by replacing two vertical blades or four legs with two or four H-like subblades by fractal iterations,respectively.Flow characteristics including velocity and turbulent kinetic energy(TKE)distributions,vortices,power number,are predicted by large eddy simulation.Compared with Rushton turbine(RT)impeller when H/T=1(or dual RTs when H/T=1.5,triple RTs when H/T=2),the HLF impeller can produce a flow field with more uniform distributions of larger velocities and TKE level.The impeller with more fractal iteration times can further improve the distribution uniformity of hydrodynamics in the case of high H/T.Power analysis shows that this is mainly due to the improved energy utilization efficiency by the fractal structure design.展开更多
This study focused on realizing Sustainable Development Goal(SDG)6 for inclusive clean water and sanitation;in particular Target 6.3,which aims to reduce untreated wastewater by 2030 while promoting circular wastewate...This study focused on realizing Sustainable Development Goal(SDG)6 for inclusive clean water and sanitation;in particular Target 6.3,which aims to reduce untreated wastewater by 2030 while promoting circular wastewater reuse and recycling globally.The main objective was to assess the adequacy and efficiency of communal septic tank systems in informal settlements while helping local planners and authorities in their decision-making regarding Target 6.3.Quantitative and qualitative approaches were employed with secondary data from previous researchers,and primary data were collected from field surveys,observations,and interviews with members of the local community.The research was delimited to two village administrative divisions known as Rukun Warga(Village Administrative Division,RW):RW 7 and RW 8 of Lebak Siliwangi Kampung in Coblong District,Bandung,West Java,Indonesia.The findings were also compared with situations in other informal settlements in Brazil,Bangladesh,and Nairobi.The results indicated the inadequacy of communal septic tanks in informal settlements due to factors such as substandard system design,limited support and communication between authorities and residents,and the gap between septic tank availability and capacity vis-a-vis demand.Other limiting factors included limited land availability and irregular geomorphology,the latter of which affected the siting and operation of septic tanks due a lack of room for upgrades or expansion in response to continuous population growth.These findings illustrate the need to complement communal septic systems with flexible centralized or decentralized systems to achieve Target 6.3 of SDG 6.展开更多
Leveraging big data signal processing offers a pathway to the development of artificial intelligencedriven equipment.The analysis of fluid flow signals and the characterization of fluid flow behavior are of critical i...Leveraging big data signal processing offers a pathway to the development of artificial intelligencedriven equipment.The analysis of fluid flow signals and the characterization of fluid flow behavior are of critical in two-phase flow studies.Significant research efforts have focused on discerning flow regimes using various signal analysis methods.In this review,recent advances in time series signals analysis algorithms for stirred tank reactors have been summarized,and the detailed methodologies are categorized into the frequency domain methods,time-frequency domain methods,and state space methods.The strengths,limitations,and notable findings of each algorithm are highlighted.Additionally,the interrelationships between these methodologies have also been discussed,as well as the present progress achieved in various applications.Future research directions and challenges are also predicted to provide an overview of current research trends in data mining of time series for analyzing flow regimes and chaotic signals.This review offers a comprehensive summary for extracting and characterizing fluid flow behavior and serves as a theoretical reference for optimizing the characterization of chaotic signals in future research endeavors.展开更多
The existing deep-sea sediment plume tests are mostly under small-scale static water and rarely under large-scale flowing water conditions.In this study,large-scale tank experiments of flowing water were designed and ...The existing deep-sea sediment plume tests are mostly under small-scale static water and rarely under large-scale flowing water conditions.In this study,large-scale tank experiments of flowing water were designed and conducted to investigate the morphological characteristics and concentration evolution of the sediment plumes under different discharge rates(Q)and initial sediment concentrations(c).Viscosity tests,resuspension tests and free settling tests of the sediment solution with different c values were performed to reveal the settling mechanism of the plume diffusion process.The results show that the plume diffusion morphology variation in flowing water has four stages and the plume concentration evolution has three stages.The larger the Q,the smaller the initial incidence angle at the discharge outlet,the larger the diffusion range,the poorer the stability and the more complicated the diffusion morphology.The larger the c,the larger the settling velocity,the faster the formation of high-concentration accumulation zone,the better the stability and the clearer the diffusion boundary.The research results could provide experimental data for assessing the impact of deep-sea mining on the ocean environment.展开更多
This paper proposes a differential-fatness-based active disturbance rejection control(ADRC)for high-speed steering control of tracked tank systems.Firstly,a high-speed steering model is established by considering the ...This paper proposes a differential-fatness-based active disturbance rejection control(ADRC)for high-speed steering control of tracked tank systems.Firstly,a high-speed steering model is established by considering the lateral component of the centrifugal force acting on the tank on the basis of modeling and analyzing the dynamic model of the low-speed steering system.Secondly,we propose a differential-flatness ADRC approach by converting the under-actuated system to a fully driven flat one.Moreover,we prove the differential flatness of the steering system,which facilitates a two-channel ADRC development.Finally,we show that both the states of the flat system and the original under-actuated system can track the reference trajectory.On the external interference condition,the system is observed to re-track the target signal within 2 s.展开更多
On June 20,the 7th China-Latin America and Caribbean Think Tank Forum was held in Beijing.The forum carried the theme“Working Together to Build a China-LAC Community with a Shared Future.”Assistant Foreign Minister ...On June 20,the 7th China-Latin America and Caribbean Think Tank Forum was held in Beijing.The forum carried the theme“Working Together to Build a China-LAC Community with a Shared Future.”Assistant Foreign Minister Miao Deyu attended the opening ceremony and delivered remarks.Leonel Caraballo Maqueira,Vice President of the Cuban Diplomatic Academy,and Martin Charles,Ambassador of Dominica to China and Representative of the Latin American and Caribbean Diplomatic Corps in China,attended the meeting and delivered speeches.展开更多
The improved Intermig impeller has been used in the seed precipitation tank in China, which could enhance the mixing and suspension of Al(OH)3 particles and the power consumption declined largely. The flow field, soli...The improved Intermig impeller has been used in the seed precipitation tank in China, which could enhance the mixing and suspension of Al(OH)3 particles and the power consumption declined largely. The flow field, solids hold-up, cloud height, just off-bottom speed and power consumptions were investigated in solid-liquid mixing system with this new type of impeller by CFD and water experiment methods. Compared with the standard Intermig impeller, the improved one coupled with specially sloped baffles could promote the fluid circulation, create better solids suspension and consume less power. Besides lower impeller off-bottom clearance is good for solid suspension and distribution. The just-off-bottom speed was also determined by a power number criterion. Meanwhile, the predicted results were in good agreement with the experimental data.展开更多
文摘Every day,an NDT(Non-Destructive Testing)report will govern key decisions and inform inspection strategies that could affect the flow of millions of dollars which ultimately affects local environments and potential risk to life.There is a direct correlation between report quality and equipment capability.The more able the equipment is-in terms of efficient data gathering,signal to noise ratio,positioning,and coverage-the more actionable the report is.This results in optimal maintenance and repair strategies providing the report is clear and well presented.Furthermore,when considering tank floor storage inspection it is essential that asset owners have total confidence in inspection findings and the ensuing reports.Tank floor inspection equipment must not only be efficient and highly capable,but data sets should be traceable and integrity maintained throughout.Corrosion mapping of large surface areas such as storage tank bottoms is an inherently arduous and time-consuming process.MFL(magnetic flux leakage)based tank bottom scanners present a well-established and highly rated method for inspection.There are many benefits of using modern MFL technology to generate actionable reports.Chief among these includes efficiency of coverage while gaining valuable information regarding defect location,severity,surface origin and the extent of coverage.More recent advancements in modern MFL tank bottom scanners afford the ability to scan and record data sets at areas of the tank bottom which were previously classed as dead zones or areas not scanned due to physical restraints.An example of this includes scanning the CZ(critical zone)which is the area close to the annular to shell junction weld.Inclusion of these additional dead zones increases overall inspection coverage,quality and traceability.Inspection of the CZ areas allows engineers to quickly determine the integrity of arguably the most important area of the tank bottom.Herein we discuss notable developments in CZ coverage,inspection efficiency and data integrity that combines to deliver an actionable report.The asset owner can interrogate this report to develop pertinent and accurate maintenance and repair strategies.
基金Item Sponsored by National Science and Technology Major Project of the Ministry of Science and Technology of China(2011ZX05016-004)National Key Technology Research and Development Program of the Ministry of Science and Technology of China(2011BAE25B00)
文摘Corrosion behavior of low-alloy steel was investigated in simulated cargo oil tank （COT） bottom plate service environment （10% NaCl solution, pH = 0.85）. The corrosion behavior of inclusion was studied by in-situ scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）. It was found that pitting corrosion was inclined to occur around the place where inclusions exist. After initial corrosion, an area of 10-20μm in diameter was formed as a cireinate cathode around the edge of inclusion. MnS inclusion dissolved in the simulated COT corrosion solution before low-alloy steel matrix, and pitting was formed at the place where MnS dissolved. TiO2 inclusion dissolved in the simulated COT corrosion solution after low alloy steel matrix, and pitting was formed at the place where steel matrix dissolved. The corrosion tended to occur at the area where the curvature radius of inclusion is smaller. The size of round TiO2 inclusions had little influence on corrosion behavior in this certain environment.
基金The National Natural Science Foundation of China(No.51905093)the Natural Science Foundation of Jiangsu Province for Young Scholars(No.BK20180392)。
文摘To analyze the bottom slope's effect on the sloshing liquid in floating liquefied natural gas(FLNG)membrane tanks,a simulation model is built and applied to describe the liquid behavior in a sloshing container.The free surface motion is simulated by the volume-of-fluid method and the standard k-εturbulence model.Experimental data and numerical results from references are used to validate the accuracy of the proposed simulation model.To study the influence of the sloped bottom on the liquid sloshing,different slope sizes and filling ratios are numerically simulated at the lowest natural frequency.The results reveal that the natural frequency can be determined by the average peak values of hydrodynamic parameters.The natural frequency and pressure loading on the tank walls decrease with the increase in the slope size.The peak pressure on the wall decreases by 5.45 kPa with the increase in the slope ratio from 5%to 20%.However,the relationship between the peak pressure and slope ratio is more significant with lower filling rates.Liquid behavior is more stable and independent with the change of the slope structure at a high filling rate(60%).The results of numerical simulation and modeling are expected to provide reference data for the design and operation of the FLNG system.
基金This research was supported by the National Natural Science Foundation of China under Grant Nos.40105003 and 4001161948partly supported by the Chinese Academny of Sciences Projct KZCX-201.
文摘Water tank experiments were carried out to investigate the thermal convection due to the bottom heating in an asymmetrical valley under neutral and stably stratified approach flows with the Particle Image Velometry (PIV) visualization technique. In the neutral stratification approach flow, the ascending draft induced by bottom heating is mainly located in the center of the valley in calm ambient wind. However, with ambient wind flow, the thermal convection is shifted leeward, and the descending draft is located on the leeward side of the valley, while the ascending draft is located on the windward side. The descending draft is minorly turbulent and organized, while the ascending draft is highly turbulent. With the increase of the towing speed, the descending and ascending drafts induced by the mechanical elevation begin to play a more dominant role in the valley flow, while the role of the thermal convection in the valley airflow becomes limited. In the stable stratification approach flow, the thermal convection is limited by the stable stratification and no distinct circulation is formed in calm ambient wind. With ambient wind, agravity wave appears in the upper layer in the valley. With the increase of the ambient wind speed, a gravity wave plays an important role in the valley flow, and the location and intensity of the thermal convection are also modulated by the gravity internal waves. The thermal convection has difficulty penetrating the upper stable layer. Its exchange is limited between the air in the upper layer and that in the lower layer in the valley, and it is adverse to the diffusion of pollutants in the valley.
文摘The minimum fluid velocity to maintain particles just suspendedwas deduced, and the theoretical analysis shows that the minimumvelocity is influenced by the properties of the solid and liquid, notby the operational conditions. For justification, the local minimumvelocity at the bottom of the tank was measured by a bi- electrodeconductivity probe, in a square-sectioned stirred tank (0.75m×0.75×1.0m) with the glass beads-water system. The experiments showed thatthe fluid velocities for the same suspension state were identicaldespite that the power Dissipated per unite mass was not the sameunder different configuration and operation. Both theoreticalanalysis And experimental results indicate that the off-bottomsuspension is controlled by the local fluid flow over the bottom Ofthe stirred tank.
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.
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 Fundamental Research Funds for the Central Universities(No.lzujbky-2024-05)Innovation Foundation of Provincial Education Department of Gansu(2024B-005)+1 种基金Scientific Department of Gansu(24CXGA083,24CXGA024,JK2024-28,JK2024-32,23CXJA0007)Industrial Support Plan Project of Provincial Education Department of Gansu(2025CYZC-003 and CYZC-2024-10).
文摘As a key storage facility, the structural safety of large oil tanks is directly related to the stable operation of the energy system. The static pressure caused by the change of liquid level is one of the main loads in the service process of storage tanks, which determines the structural deformation and damage risk. To explore the structural deformation properties under the change of liquid levels and provide a theoretical basis for the prevention and control of damage risk, this paper systematically analyzes the mechanical response of storage tanks under the pressures induced by different liquid levels based on the shell theory. Combined with the finite element software COMSOL, the radial displacement and stress-strain distribution under different liquid levels are simulated to verify the accuracy and effectiveness of the proposed theoretical model. The increase in liquid level and radius aggravates the radial deformation and makes the risk point move up, while the increase in wall thickness can effectively reduce the deformation response. Suggestions on the monitoring zone and damage risk prevention measures have also been given to instruct the safe operation of oil tanks. The research provides theoretical support for the optimization design of storage tank structures, the construction of advanced structural health monitoring system and the prevention and control of damage risk.
基金the Key Technologies Research and Development Program(No.2022YFE0107000)the National Natural Science Foundation of China(No.52171259)。
文摘Cold air is one key factor affecting the freezing process of ice tanks.The volume of fluid method is employed to simulate the freezing process of water in an ice tank with cold air inlets.The temperature field distribution in the ice tank is calculated.The temperature field at different typical instants are compared.The main characteristics of the freezing process in an ice tank driven by cold air are analyzed.The influence of the number of cold air inlets on the freezing process is investigated.The numerical results show that with increasing the number of cold air inlets,the temperature field becomes more uniform.The inlet velocity of cold air has a great influence on the generation of ice.This work can serve for the design of the ice tank and control of the freezing process.
基金the financial support from the National Natural Science Foundation of China(22078058)。
文摘Fractal theory provides a new strategy for equipment design.In this work,we propose a novel H-like fractal(HLF)impeller to improve the uniformity of the distribution of hydrodynamics in stirred tanks.The impellers are constructed by replacing two vertical blades or four legs with two or four H-like subblades by fractal iterations,respectively.Flow characteristics including velocity and turbulent kinetic energy(TKE)distributions,vortices,power number,are predicted by large eddy simulation.Compared with Rushton turbine(RT)impeller when H/T=1(or dual RTs when H/T=1.5,triple RTs when H/T=2),the HLF impeller can produce a flow field with more uniform distributions of larger velocities and TKE level.The impeller with more fractal iteration times can further improve the distribution uniformity of hydrodynamics in the case of high H/T.Power analysis shows that this is mainly due to the improved energy utilization efficiency by the fractal structure design.
文摘This study focused on realizing Sustainable Development Goal(SDG)6 for inclusive clean water and sanitation;in particular Target 6.3,which aims to reduce untreated wastewater by 2030 while promoting circular wastewater reuse and recycling globally.The main objective was to assess the adequacy and efficiency of communal septic tank systems in informal settlements while helping local planners and authorities in their decision-making regarding Target 6.3.Quantitative and qualitative approaches were employed with secondary data from previous researchers,and primary data were collected from field surveys,observations,and interviews with members of the local community.The research was delimited to two village administrative divisions known as Rukun Warga(Village Administrative Division,RW):RW 7 and RW 8 of Lebak Siliwangi Kampung in Coblong District,Bandung,West Java,Indonesia.The findings were also compared with situations in other informal settlements in Brazil,Bangladesh,and Nairobi.The results indicated the inadequacy of communal septic tanks in informal settlements due to factors such as substandard system design,limited support and communication between authorities and residents,and the gap between septic tank availability and capacity vis-a-vis demand.Other limiting factors included limited land availability and irregular geomorphology,the latter of which affected the siting and operation of septic tanks due a lack of room for upgrades or expansion in response to continuous population growth.These findings illustrate the need to complement communal septic systems with flexible centralized or decentralized systems to achieve Target 6.3 of SDG 6.
基金the National Natural Science Foundation of China(22078030)the National Key Research and Development Project(2019YFC1905802,2022YFB3504305)+1 种基金the Joint Funds of the National Natural Science Foundation of China(U1802255,CSTB2022NSCQ-LZX0014)the Key Project of Independent Research Project of State Key Laboratory of Coal Mine Disaster Dynamics and Control(2011DA105287-zd201902).
文摘Leveraging big data signal processing offers a pathway to the development of artificial intelligencedriven equipment.The analysis of fluid flow signals and the characterization of fluid flow behavior are of critical in two-phase flow studies.Significant research efforts have focused on discerning flow regimes using various signal analysis methods.In this review,recent advances in time series signals analysis algorithms for stirred tank reactors have been summarized,and the detailed methodologies are categorized into the frequency domain methods,time-frequency domain methods,and state space methods.The strengths,limitations,and notable findings of each algorithm are highlighted.Additionally,the interrelationships between these methodologies have also been discussed,as well as the present progress achieved in various applications.Future research directions and challenges are also predicted to provide an overview of current research trends in data mining of time series for analyzing flow regimes and chaotic signals.This review offers a comprehensive summary for extracting and characterizing fluid flow behavior and serves as a theoretical reference for optimizing the characterization of chaotic signals in future research endeavors.
基金supported by the Major Project of Hunan Natural Science Foundation,China(No.2021JC0010)the National Natural Science Foundation of China(No.51274251)。
文摘The existing deep-sea sediment plume tests are mostly under small-scale static water and rarely under large-scale flowing water conditions.In this study,large-scale tank experiments of flowing water were designed and conducted to investigate the morphological characteristics and concentration evolution of the sediment plumes under different discharge rates(Q)and initial sediment concentrations(c).Viscosity tests,resuspension tests and free settling tests of the sediment solution with different c values were performed to reveal the settling mechanism of the plume diffusion process.The results show that the plume diffusion morphology variation in flowing water has four stages and the plume concentration evolution has three stages.The larger the Q,the smaller the initial incidence angle at the discharge outlet,the larger the diffusion range,the poorer the stability and the more complicated the diffusion morphology.The larger the c,the larger the settling velocity,the faster the formation of high-concentration accumulation zone,the better the stability and the clearer the diffusion boundary.The research results could provide experimental data for assessing the impact of deep-sea mining on the ocean environment.
基金supported by the National Natural Science Foundation of China(62422305,62373049).
文摘This paper proposes a differential-fatness-based active disturbance rejection control(ADRC)for high-speed steering control of tracked tank systems.Firstly,a high-speed steering model is established by considering the lateral component of the centrifugal force acting on the tank on the basis of modeling and analyzing the dynamic model of the low-speed steering system.Secondly,we propose a differential-flatness ADRC approach by converting the under-actuated system to a fully driven flat one.Moreover,we prove the differential flatness of the steering system,which facilitates a two-channel ADRC development.Finally,we show that both the states of the flat system and the original under-actuated system can track the reference trajectory.On the external interference condition,the system is observed to re-track the target signal within 2 s.
文摘On June 20,the 7th China-Latin America and Caribbean Think Tank Forum was held in Beijing.The forum carried the theme“Working Together to Build a China-LAC Community with a Shared Future.”Assistant Foreign Minister Miao Deyu attended the opening ceremony and delivered remarks.Leonel Caraballo Maqueira,Vice President of the Cuban Diplomatic Academy,and Martin Charles,Ambassador of Dominica to China and Representative of the Latin American and Caribbean Diplomatic Corps in China,attended the meeting and delivered speeches.
基金Projects(50974035,51074047)supported by the National Natural Science Foundation of ChinaProject(2010AA03A405)supported by the High-tech Research and Development Program of China
文摘The improved Intermig impeller has been used in the seed precipitation tank in China, which could enhance the mixing and suspension of Al(OH)3 particles and the power consumption declined largely. The flow field, solids hold-up, cloud height, just off-bottom speed and power consumptions were investigated in solid-liquid mixing system with this new type of impeller by CFD and water experiment methods. Compared with the standard Intermig impeller, the improved one coupled with specially sloped baffles could promote the fluid circulation, create better solids suspension and consume less power. Besides lower impeller off-bottom clearance is good for solid suspension and distribution. The just-off-bottom speed was also determined by a power number criterion. Meanwhile, the predicted results were in good agreement with the experimental data.
