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
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
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
深入分析翼型式船用风力辅助推进装置的空气动力性能,对近年来该领域的研究成果进行总结。通过查阅相关文献对该领域已有研究的主要内容和采用的方法进行分析,梳理研究进展情况,并提出未来研究需解决的问题。研究结果显示:目前船舶翼型...深入分析翼型式船用风力辅助推进装置的空气动力性能,对近年来该领域的研究成果进行总结。通过查阅相关文献对该领域已有研究的主要内容和采用的方法进行分析,梳理研究进展情况,并提出未来研究需解决的问题。研究结果显示:目前船舶翼型帆形式较多,包括NACA(National Advisory Committee for Aeronautics)截面翼型帆和吸力帆翼型帆,其中NACA截面翼型帆包括一元帆、二元帆和三元帆,其空气动力性能研究主要采用模型试验和数值计算等方法实现;与船舶转子帆相比,船舶翼型帆的数值计算研究更完善,其中NACA截面翼型帆的气弹性问题值得进一步研究。展开更多
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.
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.
文摘深入分析翼型式船用风力辅助推进装置的空气动力性能,对近年来该领域的研究成果进行总结。通过查阅相关文献对该领域已有研究的主要内容和采用的方法进行分析,梳理研究进展情况,并提出未来研究需解决的问题。研究结果显示:目前船舶翼型帆形式较多,包括NACA(National Advisory Committee for Aeronautics)截面翼型帆和吸力帆翼型帆,其中NACA截面翼型帆包括一元帆、二元帆和三元帆,其空气动力性能研究主要采用模型试验和数值计算等方法实现;与船舶转子帆相比,船舶翼型帆的数值计算研究更完善,其中NACA截面翼型帆的气弹性问题值得进一步研究。
