The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volu...The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volume force. The motion equation of fluid and the hydrokinetics equations of rotating pipe were described in the Cartesians coordinates. The equations showed that the solutions to hydrokinetics equations of rotating pipe in the crossed electric and magnetic electromagnetic field were highly complicated and numerical calculations were also astronomical. The pressure distribution and temperature distribution of one dimension were solved using the electromagnetic equations set. The results showed that the fluid in rotating pipe was in the asymmetrical pressure field and temperature field because it was in the energy exchange and thermo-electrical coupling course. The primary characteristic of flow course could be expressed using the proposed hydrokinetics equations.展开更多
In this article,a hybrid energy storage system powered by renewable energy sources is suggested,which is connected to a grid-tied electric vehicle charging bay(EVCB)in Sarawak and is examined for its techno-economic e...In this article,a hybrid energy storage system powered by renewable energy sources is suggested,which is connected to a grid-tied electric vehicle charging bay(EVCB)in Sarawak and is examined for its techno-economic effects.With a focus on three renewable energy sources,namely hydrokinetic power,solar power,and hydrogen fuel cells,the study seeks to minimize reliance on the electrical grid while meeting the growing demand from the growing electric vehicle(EV)infrastructure.A hybrid renewable energy storage system that combines solar power,hydrogen fuel cells,hydrokinetic power,and the grid was simulated and analyzed.The system design leverages Kuching,Sarawak's unique geographical and renewable source profile,including abundant hydro and solar potential as well as supportive regional energy policies,to optimize economic and environmental performance.The findings showed that the technoeconomic evaluation of the hydrogen storage-integrated EVCB system in Kuching,Sarawak,demonstrates promising performance under current market conditions.The system successfully meets charging demand while generating an annual profit of approximately$5l,104.30 through excess energy sales to the grid.Hydrokinetic power dominates generation,contributing 81.4%of the total output,with the hydrogen fuel cell adding a modest 2.84%.The system achieves a cost of electricity of$0.0617/kWh and a Levelized Cost of Hydrogen of approximately$7.33/kg,confirming its economic feasibility.With a total investment of approximately$2.43 million,the hydrogen storage subsystem represents the largest cost share at 55.2%($1.34 million).A high renewable fraction of 97.2%enhances the system's sustainability,which is further supported by significant annual emissions reductions of approximately 102,209 kg of carbon dioxide,8.48 kg of sulfur dioxide,and 43.1 kg of nitrogen oxides.These results demonstrate that the proposed hybrid EVCB exhibits excellent economic and environmental sustainability,making it a viable option for Sarawak's sustainable electric vehicle charging infrastructure.展开更多
We present a series of large-eddy simulations to systematically investigate the impact of debris accumulation onthe hydrodynamics and power production of a utility-scale marine hydrokinetic(MHK)turbine under variousde...We present a series of large-eddy simulations to systematically investigate the impact of debris accumulation onthe hydrodynamics and power production of a utility-scale marine hydrokinetic(MHK)turbine under variousdebris loads lodged on the upstream face of the turbine tower.The turbine blades are modeled using turbineresolving,actuator line,and actuator surface methods.Moreover,the influence of debris on the flow field iscaptured by directly resolving individual logs and employing a novel debris model.Analyzing the hydrodynamicseffects of various debris accumulations,we show that an increase in the density of debris accumulation leads tomore flow bypassing beneath the turbine blade.This,in turn,reduces the flow momentum that reaches theMHK blades at the lower depths,inducing significant fluctuation in power production.Further,it is shown thatdebris-induced turbulent fluctuations contribute to significant variability in the MHK turbine’s power production.展开更多
This paper presents a similitude and computational analysis of the performance of a scaled-down model of a paddle wheel style hydrokinetic generator device used for generating power from the flow of a river. The paddl...This paper presents a similitude and computational analysis of the performance of a scaled-down model of a paddle wheel style hydrokinetic generator device used for generating power from the flow of a river. The paddle wheel dimensions used in this work are one-thirtieth scale of the full-size paddle wheel. The reason for simulating the scaled-down model was to prepare for the testing of a scaled-down physical prototype. Computational Fluid Dynamics using ANSYS Fluent 14.0 software was used for the computational analysis. The scaled-down dimensions were used in the simulations to predict the power that can be generated from the scaled size model of the paddle wheel, having carried out similitude analysis between the scaled down size and its full-size. The dimensionless parameters employed in achieving similitude are the Strouhal number, power coefficient, and pressure coefficient. The power estimation of the full-size was predicted from the scaled size of the paddle wheel based on the similitude analysis.展开更多
Savonius hydrokinetic turbine is a kind of turbine set which is suitable for low-velocity conditions.Unlike conventional turbines,Savonius turbines employ S-shaped blades and have simple internal structures.Therefore,...Savonius hydrokinetic turbine is a kind of turbine set which is suitable for low-velocity conditions.Unlike conventional turbines,Savonius turbines employ S-shaped blades and have simple internal structures.Therefore,there is a large space for optimizing the blade geometry.In this study,computational fluid dynamics(CFD)numerical simulation and genetic algorithm(GA)were used for the optimal design.The optimization strategies and methods were determined by comparing the results calculated by CFD with the experimental results.The weighted objective function was constructed with the maximum power coefficient Cp and the high-power coefficient range R under multiple working conditions.GA helps to find the optimal individual of the objective function.Compared the optimal scheme with the initial scheme,the overlap ratioβincreased from 0.2 to 0.202,and the clearance ratioεincreased from 0 to 0.179,the blade circumferential angleγincreased from 0°to 27°,the blade shape extended more towards the spindle.The overall power of Savonius turbines was maintained at a high level over 22%,R also increased from 0.73 to 1.02.In comparison with the initial scheme,the energy loss of the optimal scheme at high blade tip speed is greatly reduced,and this reduction is closely related to the optimization of blade geometry.As R becomes larger,Savonius turbines can adapt to the overall working conditions and meet the needs of its work in low flow rate conditions.The results of this paper can be used as a reference for the hydrodynamic optimization of Savonius turbine runners.展开更多
Hydrokinetic energy is a promising technology to harness predictable renewable energy from free-flowing water,tides and ocean currents.Many studies have been conducted by researchers and engineers to find out ways to ...Hydrokinetic energy is a promising technology to harness predictable renewable energy from free-flowing water,tides and ocean currents.Many studies have been conducted by researchers and engineers to find out ways to enhance the performance of the hydrokinetic turbine.The current paper reports the experimental study of using hydrophobic coating as an alternative way to improve the performance of hydrokinetic turbine.A hydrophobic coating can lower the friction drag of a surface that is in contact with liquid.For hydrokinetic turbine blade,reduction in friction drag may allow a blade section to have a better lift/drag ratio and have its efficiency improved.In this study,a formula to predict the pattern of drag reduction over a hydrophobic surface has been derived.Two hydrophobic coatings were applied on NACA 63418 hydrofoils and their performances were tested.It was found that NACA 63418 hydrofoil with the hydrophobic coatings had its drag reduced by an average of 3%−4.0%.When the coatings were applied on a 350 mm diameter three-bladed turbine,the maximum increment of rotational speed of the turbine was found to be 2.5%.The performance of the two coatings against marine fouling was also investigated.The weight of plate with and without the coatings increased by 10%and 100%,respectively.展开更多
The rate of electrification in rural areas in Zambia is very low, currently standing at less than 5% despite having abundant flowing water resources. Hydrokinetic technology is an alternative among other promising tec...The rate of electrification in rural areas in Zambia is very low, currently standing at less than 5% despite having abundant flowing water resources. Hydrokinetic technology is an alternative among other promising technologies for rural area electrification because of availability of abundant flowing Rivers and low population in rural settlement. In this paper, the author designed and numerically simulated a circular arc blade hydrokinetic turbine system. The design power for the horizontal axis hydrokinetic turbine was 3 kW at water velocity of 3 m/s with the tip speed ratio of 2.5, angle of attack of 10 degrees and power coefficient of 0.4. In this work, a numerical simulation was employed to characterize and develop the horizontal axis hydrokinetic turbine. The prototype circular arc blade horizontal axis hydrokinetic turbine was tested in one of stream in Zambia and the results were compared with the numerical simulation results.展开更多
The application of marine current turbines for electricity generation could offer a distinct advantage over other renewable energy sources due to the regular and predictable nature of this resource. This paper details...The application of marine current turbines for electricity generation could offer a distinct advantage over other renewable energy sources due to the regular and predictable nature of this resource. This paper details the application of Analytical Hierarchy Process (AHP) as a possible tool for decision makers to better understand the environment and the impacts of the marine current turbines. The best areas for generating energy from the currents were found using a tridimensional model (TELEMAC3D). In addition to applying the energy conversion module, these regions were also evaluated for energy production, which was then applied to the AHP. Several databases (Transmission and Transport, Socioeconomic, Conservation Units, Endangered Species and Geological Information) were compared to minimize decision deviation. The results showed the viability of the northern region of the Southern Brazilian Shelf (SBS) as a possible area to harvest energy from the currents, as much of the studied region was limited by human activities in the coastal zone and sensitive biological resources.展开更多
The computer simulation is an important method for hydrokinetic hammer design. Various kinds of simulation measures with their technical characters and applications being taken during the computer aided design are enu...The computer simulation is an important method for hydrokinetic hammer design. Various kinds of simulation measures with their technical characters and applications being taken during the computer aided design are enumerated. Computer simulation supports plenty of valuable references to the designer. Each type of simulation process is used to explore the exact aspect of the performance of hydrokinetic hammer and each type of simulation method has its own excellences and deficiencies. Thus the integrative simulation methods based on modem computational technology are brought forward to obtain the perfect capability of the whole product. Along with the development of computer hardware and software, various kinds of platforms have been provided to different simulation methods that can be carried out with distinct working flows. The jet flow element is the core part of the hydrokinetic hammer. We can build the ideal simulation model of it by means of CFD （ computational fluid dynamics） technology. On the other hand, to set up the digital model of piston and hammer, the best way is to build the virtual prototype using automatic dynamic analysis of mechanical system. As a result of the argumentation, we think the technique of Virtual Prototype and CFD are the prime way to process the combined computer simulation for hydrokinetic hammer,展开更多
Wastewater disposal through the dumping of spoil and sludge into the river,lake,or ocean is typically in the form of a sediment-laden jet.The inorganic and organic solids from the effluent settling close to the source...Wastewater disposal through the dumping of spoil and sludge into the river,lake,or ocean is typically in the form of a sediment-laden jet.The inorganic and organic solids from the effluent settling close to the source often result in the formation of sludge banks which can have a damaging effect on the marine ecosystem.Therefore,predicting the transport and deposition of sediment-laden wastewater jet flows has been a focus of intense research for decades.In this paper,we discussed the fundamental understanding of sediment-laden jets and the progress made in their predictions.We also highlighted some of the pertinent research challenges revealed by the previous studies and identified some key research issues that need to be addressed to achieve sustainable marine wastewater disposal in the face of increasing river,lake,and marine pollution.展开更多
The environmental effects of hydrokinetic turbines are still under investigation,reflecting the emerging status of this technology.This study investigates the interaction between hydrokinetic rotor wakes and fish swim...The environmental effects of hydrokinetic turbines are still under investigation,reflecting the emerging status of this technology.This study investigates the interaction between hydrokinetic rotor wakes and fish swimming,revealing insights into fish biomechanics in complex flows and assessing the environ-mental implications of marine energy solutions.We conducted numerical simulations with the URANS approach and k−ω−SST turbulence closuremodeltopredictthree-dimensionalturbulent flowinthe OpenFOAM software.The hydrokinetic rotor wake was simulated employing the actuator line method,providing a computationally efficient alternative to full geometry simulations.For accurate replication of the motion of a fish-like tuna(Thunnus atlanticus),dynamic adaptive mesh discretization was employed.The results offer a comparative analysis of fish swimming performance within the wake rotor,particularly when immersed in the tip blade vortex,contrasted with scenarios where fish swim in undisturbed flow conditions.The analysis encompasses three-dimensional wake structures,force generation,efficiency,and equilibrium states(balancing drag and thrust)across varying Swimming numbers(Sw).Key findings in-clude the enhanced attachment of the leading-edge vortex due to the caudal fin’s interaction with the tip blade vortex,resulting in improved auto-propulsive force production;a reduced tail stride frequency observed in fish swimming downstream of the rotor to achieve longitudinal force balance compared to unperturbed flow;and transverse hydrodynamic forces pushing fish radially away from the wake’s influ-ence zone,potentially mitigating the risk of collision with turbine blades.展开更多
With the global demand for more electricity,and for that electricity to be produced using low-carbon generation,a turbine was designed to extract energy from underutilised flows.The mechanism by which the turbine oper...With the global demand for more electricity,and for that electricity to be produced using low-carbon generation,a turbine was designed to extract energy from underutilised flows.The mechanism by which the turbine operates makes it highly demanding to represent using mesh-based numerical schemes,resulting in a need to investigate alternative methods.The Smoothed Particle Hydrodynamics(SPH)software,DualSPHysics,utilising the Chrono solid body solver,was used to represent the turbine as a free body in a 2-D environment allowing for evaluation of the free-spin velocity to be assessed.The aim of this being to ascertain the applicability of SPH to the modelling of vertical axis turbines with multiple moving parts,and also develop an understanding of the design itself.The model was found to compare favourably with lab results,showing that a vertical axis turbine may be represented in this fashion.The resilience of the device,a design driver and previously untested mode,was assessed by considering post-damage scenarios.From this,future flume study and parallel numerical modelling can guide this or other vertical axis turbines towards improved performance.展开更多
The hydrokinetic energy of river current,as one of the essential and widespread renewable energies,is difficult to be harvested in low flow velocity and shallow water areas.In this work,a three-dimensional(3D)fully-en...The hydrokinetic energy of river current,as one of the essential and widespread renewable energies,is difficult to be harvested in low flow velocity and shallow water areas.In this work,a three-dimensional(3D)fully-enclosed triboelectric nanogenerator(FETENG)with bionic fish-like structure for harvesting hydrokinetic energy is reported,which is comprised of the triboelectric powergeneration unit,bionic fish-like structure and connection unit.Through the bionic structure,the FE-TENG realizes zero head power generation in shallow water with low flow velocity.What’s more,the effect of external excitations and bionic structures on the electrical performance are systematically studied in this work.The FE-TENG can generate peak power density of 7 and 0.36 W/m^(3)respectively under the simulated swing state with frequency of 1.25 Hz and simulated river current with flow velocity of 0.81 m/s.In practical applications,due to the 3D fully-enclosed design,the FE-TENG immersed in water for 35 days demonstrates excellent immersion durability with undiminished electrical performance.Therefore,the work proposes an efficient method realizing zero head power generation,and provides a good candidate for long-term service in the river current.展开更多
文摘The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volume force. The motion equation of fluid and the hydrokinetics equations of rotating pipe were described in the Cartesians coordinates. The equations showed that the solutions to hydrokinetics equations of rotating pipe in the crossed electric and magnetic electromagnetic field were highly complicated and numerical calculations were also astronomical. The pressure distribution and temperature distribution of one dimension were solved using the electromagnetic equations set. The results showed that the fluid in rotating pipe was in the asymmetrical pressure field and temperature field because it was in the energy exchange and thermo-electrical coupling course. The primary characteristic of flow course could be expressed using the proposed hydrokinetics equations.
基金Swinburne University of Technology Sarawak Campus and Birmingham City University.
文摘In this article,a hybrid energy storage system powered by renewable energy sources is suggested,which is connected to a grid-tied electric vehicle charging bay(EVCB)in Sarawak and is examined for its techno-economic effects.With a focus on three renewable energy sources,namely hydrokinetic power,solar power,and hydrogen fuel cells,the study seeks to minimize reliance on the electrical grid while meeting the growing demand from the growing electric vehicle(EV)infrastructure.A hybrid renewable energy storage system that combines solar power,hydrogen fuel cells,hydrokinetic power,and the grid was simulated and analyzed.The system design leverages Kuching,Sarawak's unique geographical and renewable source profile,including abundant hydro and solar potential as well as supportive regional energy policies,to optimize economic and environmental performance.The findings showed that the technoeconomic evaluation of the hydrogen storage-integrated EVCB system in Kuching,Sarawak,demonstrates promising performance under current market conditions.The system successfully meets charging demand while generating an annual profit of approximately$5l,104.30 through excess energy sales to the grid.Hydrokinetic power dominates generation,contributing 81.4%of the total output,with the hydrogen fuel cell adding a modest 2.84%.The system achieves a cost of electricity of$0.0617/kWh and a Levelized Cost of Hydrogen of approximately$7.33/kg,confirming its economic feasibility.With a total investment of approximately$2.43 million,the hydrogen storage subsystem represents the largest cost share at 55.2%($1.34 million).A high renewable fraction of 97.2%enhances the system's sustainability,which is further supported by significant annual emissions reductions of approximately 102,209 kg of carbon dioxide,8.48 kg of sulfur dioxide,and 43.1 kg of nitrogen oxides.These results demonstrate that the proposed hybrid EVCB exhibits excellent economic and environmental sustainability,making it a viable option for Sarawak's sustainable electric vehicle charging infrastructure.
基金supported by the United States Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Water Power Technologies Office (WPTO) (Grant No.DEEE0009450)the National Science Foundation (Grant No.2233986)
文摘We present a series of large-eddy simulations to systematically investigate the impact of debris accumulation onthe hydrodynamics and power production of a utility-scale marine hydrokinetic(MHK)turbine under variousdebris loads lodged on the upstream face of the turbine tower.The turbine blades are modeled using turbineresolving,actuator line,and actuator surface methods.Moreover,the influence of debris on the flow field iscaptured by directly resolving individual logs and employing a novel debris model.Analyzing the hydrodynamicseffects of various debris accumulations,we show that an increase in the density of debris accumulation leads tomore flow bypassing beneath the turbine blade.This,in turn,reduces the flow momentum that reaches theMHK blades at the lower depths,inducing significant fluctuation in power production.Further,it is shown thatdebris-induced turbulent fluctuations contribute to significant variability in the MHK turbine’s power production.
文摘This paper presents a similitude and computational analysis of the performance of a scaled-down model of a paddle wheel style hydrokinetic generator device used for generating power from the flow of a river. The paddle wheel dimensions used in this work are one-thirtieth scale of the full-size paddle wheel. The reason for simulating the scaled-down model was to prepare for the testing of a scaled-down physical prototype. Computational Fluid Dynamics using ANSYS Fluent 14.0 software was used for the computational analysis. The scaled-down dimensions were used in the simulations to predict the power that can be generated from the scaled size model of the paddle wheel, having carried out similitude analysis between the scaled down size and its full-size. The dimensionless parameters employed in achieving similitude are the Strouhal number, power coefficient, and pressure coefficient. The power estimation of the full-size was predicted from the scaled size of the paddle wheel based on the similitude analysis.
基金funded by National Natural Science Foundation of China,Grant Number 52079142.
文摘Savonius hydrokinetic turbine is a kind of turbine set which is suitable for low-velocity conditions.Unlike conventional turbines,Savonius turbines employ S-shaped blades and have simple internal structures.Therefore,there is a large space for optimizing the blade geometry.In this study,computational fluid dynamics(CFD)numerical simulation and genetic algorithm(GA)were used for the optimal design.The optimization strategies and methods were determined by comparing the results calculated by CFD with the experimental results.The weighted objective function was constructed with the maximum power coefficient Cp and the high-power coefficient range R under multiple working conditions.GA helps to find the optimal individual of the objective function.Compared the optimal scheme with the initial scheme,the overlap ratioβincreased from 0.2 to 0.202,and the clearance ratioεincreased from 0 to 0.179,the blade circumferential angleγincreased from 0°to 27°,the blade shape extended more towards the spindle.The overall power of Savonius turbines was maintained at a high level over 22%,R also increased from 0.73 to 1.02.In comparison with the initial scheme,the energy loss of the optimal scheme at high blade tip speed is greatly reduced,and this reduction is closely related to the optimization of blade geometry.As R becomes larger,Savonius turbines can adapt to the overall working conditions and meet the needs of its work in low flow rate conditions.The results of this paper can be used as a reference for the hydrodynamic optimization of Savonius turbine runners.
基金financially supported by the Natural Science Foundation of Hunan Province(Grant No.2019JJ50644).
文摘Hydrokinetic energy is a promising technology to harness predictable renewable energy from free-flowing water,tides and ocean currents.Many studies have been conducted by researchers and engineers to find out ways to enhance the performance of the hydrokinetic turbine.The current paper reports the experimental study of using hydrophobic coating as an alternative way to improve the performance of hydrokinetic turbine.A hydrophobic coating can lower the friction drag of a surface that is in contact with liquid.For hydrokinetic turbine blade,reduction in friction drag may allow a blade section to have a better lift/drag ratio and have its efficiency improved.In this study,a formula to predict the pattern of drag reduction over a hydrophobic surface has been derived.Two hydrophobic coatings were applied on NACA 63418 hydrofoils and their performances were tested.It was found that NACA 63418 hydrofoil with the hydrophobic coatings had its drag reduced by an average of 3%−4.0%.When the coatings were applied on a 350 mm diameter three-bladed turbine,the maximum increment of rotational speed of the turbine was found to be 2.5%.The performance of the two coatings against marine fouling was also investigated.The weight of plate with and without the coatings increased by 10%and 100%,respectively.
文摘The rate of electrification in rural areas in Zambia is very low, currently standing at less than 5% despite having abundant flowing water resources. Hydrokinetic technology is an alternative among other promising technologies for rural area electrification because of availability of abundant flowing Rivers and low population in rural settlement. In this paper, the author designed and numerically simulated a circular arc blade hydrokinetic turbine system. The design power for the horizontal axis hydrokinetic turbine was 3 kW at water velocity of 3 m/s with the tip speed ratio of 2.5, angle of attack of 10 degrees and power coefficient of 0.4. In this work, a numerical simulation was employed to characterize and develop the horizontal axis hydrokinetic turbine. The prototype circular arc blade horizontal axis hydrokinetic turbine was tested in one of stream in Zambia and the results were compared with the numerical simulation results.
文摘The application of marine current turbines for electricity generation could offer a distinct advantage over other renewable energy sources due to the regular and predictable nature of this resource. This paper details the application of Analytical Hierarchy Process (AHP) as a possible tool for decision makers to better understand the environment and the impacts of the marine current turbines. The best areas for generating energy from the currents were found using a tridimensional model (TELEMAC3D). In addition to applying the energy conversion module, these regions were also evaluated for energy production, which was then applied to the AHP. Several databases (Transmission and Transport, Socioeconomic, Conservation Units, Endangered Species and Geological Information) were compared to minimize decision deviation. The results showed the viability of the northern region of the Southern Brazilian Shelf (SBS) as a possible area to harvest energy from the currents, as much of the studied region was limited by human activities in the coastal zone and sensitive biological resources.
基金Project of State 863 Program(No.2006AA06A109-3-2-1)
文摘The computer simulation is an important method for hydrokinetic hammer design. Various kinds of simulation measures with their technical characters and applications being taken during the computer aided design are enumerated. Computer simulation supports plenty of valuable references to the designer. Each type of simulation process is used to explore the exact aspect of the performance of hydrokinetic hammer and each type of simulation method has its own excellences and deficiencies. Thus the integrative simulation methods based on modem computational technology are brought forward to obtain the perfect capability of the whole product. Along with the development of computer hardware and software, various kinds of platforms have been provided to different simulation methods that can be carried out with distinct working flows. The jet flow element is the core part of the hydrokinetic hammer. We can build the ideal simulation model of it by means of CFD （ computational fluid dynamics） technology. On the other hand, to set up the digital model of piston and hammer, the best way is to build the virtual prototype using automatic dynamic analysis of mechanical system. As a result of the argumentation, we think the technique of Virtual Prototype and CFD are the prime way to process the combined computer simulation for hydrokinetic hammer,
基金funded by the National Natural Science Foundation of China(Grant Nos.51979076,52211530103)the Research Funds for the Central Universities(Grant No.B200204017)the Belt and Road Special Foundation of the State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering(Grant No.2021491911).
文摘Wastewater disposal through the dumping of spoil and sludge into the river,lake,or ocean is typically in the form of a sediment-laden jet.The inorganic and organic solids from the effluent settling close to the source often result in the formation of sludge banks which can have a damaging effect on the marine ecosystem.Therefore,predicting the transport and deposition of sediment-laden wastewater jet flows has been a focus of intense research for decades.In this paper,we discussed the fundamental understanding of sediment-laden jets and the progress made in their predictions.We also highlighted some of the pertinent research challenges revealed by the previous studies and identified some key research issues that need to be addressed to achieve sustainable marine wastewater disposal in the face of increasing river,lake,and marine pollution.
文摘The environmental effects of hydrokinetic turbines are still under investigation,reflecting the emerging status of this technology.This study investigates the interaction between hydrokinetic rotor wakes and fish swimming,revealing insights into fish biomechanics in complex flows and assessing the environ-mental implications of marine energy solutions.We conducted numerical simulations with the URANS approach and k−ω−SST turbulence closuremodeltopredictthree-dimensionalturbulent flowinthe OpenFOAM software.The hydrokinetic rotor wake was simulated employing the actuator line method,providing a computationally efficient alternative to full geometry simulations.For accurate replication of the motion of a fish-like tuna(Thunnus atlanticus),dynamic adaptive mesh discretization was employed.The results offer a comparative analysis of fish swimming performance within the wake rotor,particularly when immersed in the tip blade vortex,contrasted with scenarios where fish swim in undisturbed flow conditions.The analysis encompasses three-dimensional wake structures,force generation,efficiency,and equilibrium states(balancing drag and thrust)across varying Swimming numbers(Sw).Key findings in-clude the enhanced attachment of the leading-edge vortex due to the caudal fin’s interaction with the tip blade vortex,resulting in improved auto-propulsive force production;a reduced tail stride frequency observed in fish swimming downstream of the rotor to achieve longitudinal force balance compared to unperturbed flow;and transverse hydrodynamic forces pushing fish radially away from the wake’s influ-ence zone,potentially mitigating the risk of collision with turbine blades.
基金supported by the Water Informatics Science and Engineering Centre for Doctoral Training(WISE CDT)under a grant from the Engineering and Physical Sciences Research Council(EPSRC)(Grant No.EP/L016214/1).
文摘With the global demand for more electricity,and for that electricity to be produced using low-carbon generation,a turbine was designed to extract energy from underutilised flows.The mechanism by which the turbine operates makes it highly demanding to represent using mesh-based numerical schemes,resulting in a need to investigate alternative methods.The Smoothed Particle Hydrodynamics(SPH)software,DualSPHysics,utilising the Chrono solid body solver,was used to represent the turbine as a free body in a 2-D environment allowing for evaluation of the free-spin velocity to be assessed.The aim of this being to ascertain the applicability of SPH to the modelling of vertical axis turbines with multiple moving parts,and also develop an understanding of the design itself.The model was found to compare favourably with lab results,showing that a vertical axis turbine may be represented in this fashion.The resilience of the device,a design driver and previously untested mode,was assessed by considering post-damage scenarios.From this,future flume study and parallel numerical modelling can guide this or other vertical axis turbines towards improved performance.
基金the support received from the National Key R&D Project from the Minister of Science and Technology(Nos.2021YFA1201601 and 2021YFA1201604)the Natural Science Foundation of Beijing Municipality(No.3222023)。
文摘The hydrokinetic energy of river current,as one of the essential and widespread renewable energies,is difficult to be harvested in low flow velocity and shallow water areas.In this work,a three-dimensional(3D)fully-enclosed triboelectric nanogenerator(FETENG)with bionic fish-like structure for harvesting hydrokinetic energy is reported,which is comprised of the triboelectric powergeneration unit,bionic fish-like structure and connection unit.Through the bionic structure,the FE-TENG realizes zero head power generation in shallow water with low flow velocity.What’s more,the effect of external excitations and bionic structures on the electrical performance are systematically studied in this work.The FE-TENG can generate peak power density of 7 and 0.36 W/m^(3)respectively under the simulated swing state with frequency of 1.25 Hz and simulated river current with flow velocity of 0.81 m/s.In practical applications,due to the 3D fully-enclosed design,the FE-TENG immersed in water for 35 days demonstrates excellent immersion durability with undiminished electrical performance.Therefore,the work proposes an efficient method realizing zero head power generation,and provides a good candidate for long-term service in the river current.
