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
The article considers the issues on preliminary calculation of human-powered ornithopter general performances. The model of “simple ornithopter” is introduced. Giving an example of simple ornithopter interaction wit...The article considers the issues on preliminary calculation of human-powered ornithopter general performances. The model of “simple ornithopter” is introduced. Giving an example of simple ornithopter interaction with the environment, the formula of relation of ornithopter theoretically available propulsion to kinematic and physical parameters of its horizontal flight parameters is derived. The tasking is performed for the following stages of calculation and design of the human-powered ornithopter.展开更多
A comprehensive energy-saving sail (CES) has been proposed in order to promote energy saving and emission reduction from shipping. Wind energy is harvested for propulsion and electrical generator at the same time by a...A comprehensive energy-saving sail (CES) has been proposed in order to promote energy saving and emission reduction from shipping. Wind energy is harvested for propulsion and electrical generator at the same time by a unique structure of CES. A CFD (Computational Fluid Dynamics) code is verified by a case of arc wind sail, and it is used to simulate the pressure and velocity around the CES. The results show that the outlet velocity of air tunnel V<sub>o</sub> and wind velocity V<sub>i</sub> serve as an equation V<sub>o</sub> ≈ 1.31V<sub>i</sub>, which means the CES can effectively improve the conversion efficiency. In addition, it is found that V<sub>o</sub> increases with the tunnel diameter to some extend over which it will keep almost constant.展开更多
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The article considers the issues on preliminary calculation of human-powered ornithopter general performances. The model of “simple ornithopter” is introduced. Giving an example of simple ornithopter interaction with the environment, the formula of relation of ornithopter theoretically available propulsion to kinematic and physical parameters of its horizontal flight parameters is derived. The tasking is performed for the following stages of calculation and design of the human-powered ornithopter.
文摘A comprehensive energy-saving sail (CES) has been proposed in order to promote energy saving and emission reduction from shipping. Wind energy is harvested for propulsion and electrical generator at the same time by a unique structure of CES. A CFD (Computational Fluid Dynamics) code is verified by a case of arc wind sail, and it is used to simulate the pressure and velocity around the CES. The results show that the outlet velocity of air tunnel V<sub>o</sub> and wind velocity V<sub>i</sub> serve as an equation V<sub>o</sub> ≈ 1.31V<sub>i</sub>, which means the CES can effectively improve the conversion efficiency. In addition, it is found that V<sub>o</sub> increases with the tunnel diameter to some extend over which it will keep almost constant.
