Unmanned surface vehicles(USVs)play a crucial role in various fields,including ocean climate change monitoring,ma-rine resource exploitation,and ecological environment exploration.Out of the many types of USVs,unmanne...Unmanned surface vehicles(USVs)play a crucial role in various fields,including ocean climate change monitoring,ma-rine resource exploitation,and ecological environment exploration.Out of the many types of USVs,unmanned sailboats have gained considerable attention for their ability to conduct green,large-scale ocean observations.Building on this concept,this paper proposes an unmanned sailboat propelled by parallel dual-wing sails,which is designed to meet the demands of extensive and three-dimensional marine comprehensive observation and data collection.With a focus on the parallel dual-wing sails,this study particularly investi-gates the effects of variations in the airfoil’s angle of attack and the impact of the spacing ratio between the dual sails on propulsion performance.It further analyzes the influence of one sail’s angle of attack on the performance of the other sail,as well as the flow field between the two sails.For the air navigation and underwater states,the force characteristics of the dual sail under different inflow velocities were investigated.The research findings indicate that,under certain conditions,the thrust coefficient exhibits a trend of first increasing,then decreasing,and finally increasing again with alterations in the angle of attackα.Different single-sail angles of attack have varying impacts on the opposite sail and the flow field between the dual sails.Moreover,the generated forces are positively correlated with inflow velocity in the air navigation and underwater states.The findings reveal that it is possible to reduce drag,mitigate the adverse effects of sail interaction,and thereby enhance the propulsion performance and overall navigational stability of the sailboat by applying an optimal spacing ratio design and adjusting the angle of attack and inflow velocity.展开更多
On December 12,2020,I cast off with Argo,my trusty boat,for a solo voyage across the Atlantic.As we departed San Sebastian at dawn,the exhaustion from preparation already had me longing for sleep,which was a strange d...On December 12,2020,I cast off with Argo,my trusty boat,for a solo voyage across the Atlantic.As we departed San Sebastian at dawn,the exhaustion from preparation already had me longing for sleep,which was a strange desire on the very first day of what was to be a 70⁃day expedition.展开更多
Solar sailing is a promising propellant-free approach to propelling spacecraft in space.However, the propelling efficiency of conventional solar sail spacecraft is limited by their areato-mass ratios. This paper propo...Solar sailing is a promising propellant-free approach to propelling spacecraft in space.However, the propelling efficiency of conventional solar sail spacecraft is limited by their areato-mass ratios. This paper proposes a novel design of micro solar sails with area-to-mass ratios above 100 m^(2)/kg for next-generation chip-scale spacecraft. Bilayer thin films developed by Microelectromechanical Systems(MEMS) technologies were patterned into grid microstructures, and theoretical analysis of a sail prototype was conducted. The electro-thermal and thermo-mechanical models of the solar sail in geospace were established by taking effects of Joule heating, solar radiation, and thermal re-emission into consideration, enabling rapid prediction of its threedimensional(3-D) reconfiguration from the as-released two-dimensional(2-D) microstructure.Adjustment of the Chip Sail's acceleration arising from the sail's morphing was also analytically modeled. Fabrication and characterization of the sail prototype made of multiple Al/Ni_(50)Ti_(50) bilayer beams were accomplished. In-situ SEM imaging of the sail prototype in vacuum chamber witnessed an active and continuous 3-D reconfiguration under Joule heating, and over 90° deformation was detected by applying a DC voltage of 0.078 V. Theoretical and experimental work on the solar sail with at least 10 times higher area-to-mass ratios than conventional ones will lay a solid foundation for efficient solar sailing.展开更多
This paper studies the equilibrium state and trajectory dynamics of an axially symmetric Electric solar wind sail(E-sail)at arbitrary sail angles.The E-sail is assumed operating in a heliocentric-ecliptic orbit at app...This paper studies the equilibrium state and trajectory dynamics of an axially symmetric Electric solar wind sail(E-sail)at arbitrary sail angles.The E-sail is assumed operating in a heliocentric-ecliptic orbit at approximately one astronomic unit(au)from the Sun,and experiencing various dynamic disturbances like solar wind pressure,tether tension oscillations,and centrifugal forces.The study derives analytical expressions for the E-sail's equilibrium state and its maximal coning angle under small coning angle assumption.Subsequently,an improved propulsion model is developed for the E-sail in this equilibrium state.To assess the precision of these formulations,a high-fidelity E-sail dynamic model is constructed using the nodal position finite element method,where the tethers are modeled as two-noded tensile elements and the central spacecraft and remote units are simplified as lumped masses.Through thorough parametric analyses,this paper conclusively demonstrates that the operation of the E-sail at the equilibrium state can be achieved in accordance with the derived analytical prediction of the equilibrium state.Furthermore,the improved propulsion model is employed in trajectory analyses for a mission to reach the solar system's boundary.The study provides valuable insights and findings and foundation for the practical application and further advancement of the E-sail technology.展开更多
Sail is the core part of autonomous sailboat and wing sail is a new type of sail. Wing sail generates not only propulsion but also lateral force and heeling moment. The latter two will affect the navigation status and...Sail is the core part of autonomous sailboat and wing sail is a new type of sail. Wing sail generates not only propulsion but also lateral force and heeling moment. The latter two will affect the navigation status and bring resistance. Double sail can effectively reduce the center of wind pressure and heeling moment. In order to study the effect of distance between two sails, airfoil and attack angle on the total lift coefficient of double sail propulsion system, pressure coefficient distribution and lift coefficient calculation model have been established based on vortex panel method. By using the basic finite solution, the fluid dynamic forces on the two-dimensional sails are computed.The results show that, the distance in the range of 0 to 1 time chord length, when using the same airfoil in the fore and aft sail, the total lift coefficient of the double sail increases with the increase of distance, finally reaches a stable value in the range of one to three times chord length. Lift coefficients of thicker airfoils are more sensitive to the change of distance. The thicker the airfoil, the longer distance is required of the total lift coefficient toward stable.When different airfoils are adopted in fore and aft sail, the total lift coefficient increases with the increase of the thickness of aft sail. The smaller the thickness difference is, the more sensitive to the distance change the lift coefficient is. The thinner the fore sail is, the lower the influence will be on the lift coefficient of aft sail.展开更多
To analyze the influence of the chord length ratio and angle of attack on lift coefficients and explore the interaction mechanism between the two,we established a calculation model of the pressure distribution coeffic...To analyze the influence of the chord length ratio and angle of attack on lift coefficients and explore the interaction mechanism between the two,we established a calculation model of the pressure distribution coefficient on the airfoil surface and lift coefficient of a dual-wing sail on the basis of the vortex panel method.Computational fluid dynamics was used in auxiliary calculation and analysis.Results revealed a reciprocal interference between the front-wing and rear-wing sails.The total lift coefficient of the dual-sail increased with an increase in the front sail chord length.The lift coefficient of the rear sail decreased with an increase in the front sail chord length or angle of attack.The front sail wake affected the pressure distribution on the upper and lower surfaces of the rear sail leading edge.展开更多
Solar sail technology has been proposed and developed for space explorations with advantages of low launch cost,no-propellant consumption,and continuous thrust,which has great potentials in earth polar detection,inter...Solar sail technology has been proposed and developed for space explorations with advantages of low launch cost,no-propellant consumption,and continuous thrust,which has great potentials in earth polar detection,interstellar explorations and etc.The development of solar sail has made significant progress in structural design,manufacturing,materials,orbit transfer,and stability control in the past few decades,which makes meaningful contributions to astronomy,physics,and aerospace science.Technological breakthroughs of Solar Radiation Pressure(SRP)propulsion and interstellar transfer have been achieved in current solar sail missions.However,there are still many challenges and problems need to be solved.This paper attempts to summarize the research schemes and potential applications of solar sailing in space missions from the viewpoint of key technologies,so as to provide an overall perspective for researchers in this field.Analyses of the key technologies of solar sailing system design are provided.Finally,challenges and prospective development of solar sailing are discussed.展开更多
The wind-assisted propulsion system is becoming one of the most popular and efficient ways to reduce both fuel consumption and carbon dioxide emission from the ships.In this study,several analyses have been carried ou...The wind-assisted propulsion system is becoming one of the most popular and efficient ways to reduce both fuel consumption and carbon dioxide emission from the ships.In this study,several analyses have been carried out on a model of bulk carrier fitted with five rigid sails with a 180°rotating mechanism for maximum usage of wind power and a telescopic reefing mechanism for folding it during berthing.The stability of the ship has been verified through the calculations of initial stability,static stability,and dynamic stability through the fulfillment of the weather criterion using MAXSURF software.The structural analysis of the sail was carried out in ANSYS static structural module.Several flow simulations were carried out in ANSYS fluent module to predict the thrusts produced by the sails at different apparent wind angles,which would in turn reduce the thrust required from the propeller.In this way,the brake horse powers required for different sail arrangements were analyzed to find out a guideline for this wind propulsion system to generate better powering performances.To consider drift and yaw effect on propulsion system,an MMG mathematical model–based simulation was carried out for different drift angles of motion of the ship considering hard sail–based wind loads.Through these analyses,it has been found out that the hard sail–based wind-assisted propulsion system in some cases have produced a reduction of more than 30%brake power in straight ahead motion and around 20%reduction in case of drifting ships compared to the model having no sails.展开更多
Ships which have large structures above water surface,such as pure car carriers(PCCs) and container vessels,have large speed reduction by wind pressure.In the present study,the running speed of a large PCC with two or...Ships which have large structures above water surface,such as pure car carriers(PCCs) and container vessels,have large speed reduction by wind pressure.In the present study,the running speed of a large PCC with two or more sails for using wind power is simulated.The simulated results demonstrate that the ship can keep a constant service speed even in winds of 20m/s except head and bow winds.This sail system can shorten annual average navigation time by about 4 hours per voyage.展开更多
基金supported from the Shandong Provincial Natural Science Foundation(No.ZR2022ME147)the National Natural Science Foundation of China(No.52088102).
文摘Unmanned surface vehicles(USVs)play a crucial role in various fields,including ocean climate change monitoring,ma-rine resource exploitation,and ecological environment exploration.Out of the many types of USVs,unmanned sailboats have gained considerable attention for their ability to conduct green,large-scale ocean observations.Building on this concept,this paper proposes an unmanned sailboat propelled by parallel dual-wing sails,which is designed to meet the demands of extensive and three-dimensional marine comprehensive observation and data collection.With a focus on the parallel dual-wing sails,this study particularly investi-gates the effects of variations in the airfoil’s angle of attack and the impact of the spacing ratio between the dual sails on propulsion performance.It further analyzes the influence of one sail’s angle of attack on the performance of the other sail,as well as the flow field between the two sails.For the air navigation and underwater states,the force characteristics of the dual sail under different inflow velocities were investigated.The research findings indicate that,under certain conditions,the thrust coefficient exhibits a trend of first increasing,then decreasing,and finally increasing again with alterations in the angle of attackα.Different single-sail angles of attack have varying impacts on the opposite sail and the flow field between the dual sails.Moreover,the generated forces are positively correlated with inflow velocity in the air navigation and underwater states.The findings reveal that it is possible to reduce drag,mitigate the adverse effects of sail interaction,and thereby enhance the propulsion performance and overall navigational stability of the sailboat by applying an optimal spacing ratio design and adjusting the angle of attack and inflow velocity.
文摘On December 12,2020,I cast off with Argo,my trusty boat,for a solo voyage across the Atlantic.As we departed San Sebastian at dawn,the exhaustion from preparation already had me longing for sleep,which was a strange desire on the very first day of what was to be a 70⁃day expedition.
基金Supported by Excellent Youth Science Fund Project(Overseas)of Shandong Province,China(No.2023HWYQ-029)China Postdoctoral Science Foundation(No.2023MD744219)+3 种基金Zhejiang Province Selected Funding for Postdoctoral Research Projects,China(No.ZJ2023040)Youth Project of Natural Science Foundation of Shandong Province,China(No.ZR2023QE127)China National University Student Innovation and Entrepreneurship Development Program(No.202310422009)Major Basic Research Program of the Natural Science Foundation of Shandong Province,China(No.ZR2019ZD08).This research was in part carried out at the Center for Functional Nanomaterials(CFN),Brookhaven National Laboratory(BNL),which is supported by the U.S.Department of Energy,Office of Basic Energy Sciences,under Contract No.DE-SC0012704.
文摘Solar sailing is a promising propellant-free approach to propelling spacecraft in space.However, the propelling efficiency of conventional solar sail spacecraft is limited by their areato-mass ratios. This paper proposes a novel design of micro solar sails with area-to-mass ratios above 100 m^(2)/kg for next-generation chip-scale spacecraft. Bilayer thin films developed by Microelectromechanical Systems(MEMS) technologies were patterned into grid microstructures, and theoretical analysis of a sail prototype was conducted. The electro-thermal and thermo-mechanical models of the solar sail in geospace were established by taking effects of Joule heating, solar radiation, and thermal re-emission into consideration, enabling rapid prediction of its threedimensional(3-D) reconfiguration from the as-released two-dimensional(2-D) microstructure.Adjustment of the Chip Sail's acceleration arising from the sail's morphing was also analytically modeled. Fabrication and characterization of the sail prototype made of multiple Al/Ni_(50)Ti_(50) bilayer beams were accomplished. In-situ SEM imaging of the sail prototype in vacuum chamber witnessed an active and continuous 3-D reconfiguration under Joule heating, and over 90° deformation was detected by applying a DC voltage of 0.078 V. Theoretical and experimental work on the solar sail with at least 10 times higher area-to-mass ratios than conventional ones will lay a solid foundation for efficient solar sailing.
基金supported by the National Natural Science Foundation of China(No.12302052)the Fundamental Research Funds for the Central Universities,China(No.XJSJ23128)the Discovery Grant of Natural Sciences and Engineering Research Council of Canada(No.RGPIN2018-05991)。
文摘This paper studies the equilibrium state and trajectory dynamics of an axially symmetric Electric solar wind sail(E-sail)at arbitrary sail angles.The E-sail is assumed operating in a heliocentric-ecliptic orbit at approximately one astronomic unit(au)from the Sun,and experiencing various dynamic disturbances like solar wind pressure,tether tension oscillations,and centrifugal forces.The study derives analytical expressions for the E-sail's equilibrium state and its maximal coning angle under small coning angle assumption.Subsequently,an improved propulsion model is developed for the E-sail in this equilibrium state.To assess the precision of these formulations,a high-fidelity E-sail dynamic model is constructed using the nodal position finite element method,where the tethers are modeled as two-noded tensile elements and the central spacecraft and remote units are simplified as lumped masses.Through thorough parametric analyses,this paper conclusively demonstrates that the operation of the E-sail at the equilibrium state can be achieved in accordance with the derived analytical prediction of the equilibrium state.Furthermore,the improved propulsion model is employed in trajectory analyses for a mission to reach the solar system's boundary.The study provides valuable insights and findings and foundation for the practical application and further advancement of the E-sail technology.
基金financially supported by the JIANG Xinsong Innovation Fund(Grant No.Y8F7010701)
文摘Sail is the core part of autonomous sailboat and wing sail is a new type of sail. Wing sail generates not only propulsion but also lateral force and heeling moment. The latter two will affect the navigation status and bring resistance. Double sail can effectively reduce the center of wind pressure and heeling moment. In order to study the effect of distance between two sails, airfoil and attack angle on the total lift coefficient of double sail propulsion system, pressure coefficient distribution and lift coefficient calculation model have been established based on vortex panel method. By using the basic finite solution, the fluid dynamic forces on the two-dimensional sails are computed.The results show that, the distance in the range of 0 to 1 time chord length, when using the same airfoil in the fore and aft sail, the total lift coefficient of the double sail increases with the increase of distance, finally reaches a stable value in the range of one to three times chord length. Lift coefficients of thicker airfoils are more sensitive to the change of distance. The thicker the airfoil, the longer distance is required of the total lift coefficient toward stable.When different airfoils are adopted in fore and aft sail, the total lift coefficient increases with the increase of the thickness of aft sail. The smaller the thickness difference is, the more sensitive to the distance change the lift coefficient is. The thinner the fore sail is, the lower the influence will be on the lift coefficient of aft sail.
基金the Foundation of State Key Laboratory of Robotics(No.2020-Z14)the Jiang Xin-song Innovation Foundation(No.Y8F7010701)+1 种基金the National Natural Science Foundation of China(No.41906173)the China Postdoctoral Science Foundation(No.2019M662874)。
文摘To analyze the influence of the chord length ratio and angle of attack on lift coefficients and explore the interaction mechanism between the two,we established a calculation model of the pressure distribution coefficient on the airfoil surface and lift coefficient of a dual-wing sail on the basis of the vortex panel method.Computational fluid dynamics was used in auxiliary calculation and analysis.Results revealed a reciprocal interference between the front-wing and rear-wing sails.The total lift coefficient of the dual-sail increased with an increase in the front sail chord length.The lift coefficient of the rear sail decreased with an increase in the front sail chord length or angle of attack.The front sail wake affected the pressure distribution on the upper and lower surfaces of the rear sail leading edge.
基金co-supported by the Natural Science Foundation of China(No.51905527)China Scholarship Council(No.202104910450).
文摘Solar sail technology has been proposed and developed for space explorations with advantages of low launch cost,no-propellant consumption,and continuous thrust,which has great potentials in earth polar detection,interstellar explorations and etc.The development of solar sail has made significant progress in structural design,manufacturing,materials,orbit transfer,and stability control in the past few decades,which makes meaningful contributions to astronomy,physics,and aerospace science.Technological breakthroughs of Solar Radiation Pressure(SRP)propulsion and interstellar transfer have been achieved in current solar sail missions.However,there are still many challenges and problems need to be solved.This paper attempts to summarize the research schemes and potential applications of solar sailing in space missions from the viewpoint of key technologies,so as to provide an overall perspective for researchers in this field.Analyses of the key technologies of solar sailing system design are provided.Finally,challenges and prospective development of solar sailing are discussed.
文摘The wind-assisted propulsion system is becoming one of the most popular and efficient ways to reduce both fuel consumption and carbon dioxide emission from the ships.In this study,several analyses have been carried out on a model of bulk carrier fitted with five rigid sails with a 180°rotating mechanism for maximum usage of wind power and a telescopic reefing mechanism for folding it during berthing.The stability of the ship has been verified through the calculations of initial stability,static stability,and dynamic stability through the fulfillment of the weather criterion using MAXSURF software.The structural analysis of the sail was carried out in ANSYS static structural module.Several flow simulations were carried out in ANSYS fluent module to predict the thrusts produced by the sails at different apparent wind angles,which would in turn reduce the thrust required from the propeller.In this way,the brake horse powers required for different sail arrangements were analyzed to find out a guideline for this wind propulsion system to generate better powering performances.To consider drift and yaw effect on propulsion system,an MMG mathematical model–based simulation was carried out for different drift angles of motion of the ship considering hard sail–based wind loads.Through these analyses,it has been found out that the hard sail–based wind-assisted propulsion system in some cases have produced a reduction of more than 30%brake power in straight ahead motion and around 20%reduction in case of drifting ships compared to the model having no sails.
文摘Ships which have large structures above water surface,such as pure car carriers(PCCs) and container vessels,have large speed reduction by wind pressure.In the present study,the running speed of a large PCC with two or more sails for using wind power is simulated.The simulated results demonstrate that the ship can keep a constant service speed even in winds of 20m/s except head and bow winds.This sail system can shorten annual average navigation time by about 4 hours per voyage.
