The resistance between mud surface and ship-type paddy field machine hull accounts for a certain proportion of the total mechanical power consumption during the operation process.The special characteristic has been fo...The resistance between mud surface and ship-type paddy field machine hull accounts for a certain proportion of the total mechanical power consumption during the operation process.The special characteristic has been found via preliminary study,it showed that when starting or working at low velocity,the resistance is much greater than the machine working at the rated velocity.This characteristic affects the dynamic matching and structural design of the machine.The critical velocity of resistance distortion was around 0.025 m/s under the setting experimental conditions,and the mechanism of resistance distortion under multi-medium was analyzed.Based on water film drag reduction theory,a macroscopic structure of crocodile's abdominal armor biomimetic drag reduction method was proposed.Two kinds of bionic macroscopic structure ship board were fabricated.The macroscopic structure can introduce more water into the bottom surface of the hull;thicken the water film,which can reduce the travel resistance.Design and manufacture a ship-type paddy field experimental setup with velocity control,and compare the traditional smooth surface ship board with the two bionic macroscopic structure surfaces through orthogonal test.The experiment results demonstrated that the ship board with rectangle gully structure has better drag reduction effect than the hexagon one in the lower velocity.But when the travel velocity approach to the resistance distortion critical point,the hexagon gully structure become better than the other one.Through the orthogonal test,the best drag reduction combination is 2.5 kg load weight,0.025 m/s travel velocity with hexagon ship board,which decreases the drag by 6.3%.展开更多
Fang等基于Boussinesq型方程和GPU并行加速技术开发的海岸和近海波浪模拟系统(Coastal and Offshore Wave Simulator,COWS)具有稳定性强、计算效率高的特点。本研究对COWS模型进行扩展,通过在动量方程中添加移动压力源项来模拟船舶实际...Fang等基于Boussinesq型方程和GPU并行加速技术开发的海岸和近海波浪模拟系统(Coastal and Offshore Wave Simulator,COWS)具有稳定性强、计算效率高的特点。本研究对COWS模型进行扩展,通过在动量方程中添加移动压力源项来模拟船舶实际航行过程中船行波的生成过程。压力项的位置通过三次样条插值法确定,采用二阶中心差分格式近似。利用扩展后的COWS模型,计算了一维矩形横截面航道船行波、浅水区域船首孤立波、开阔水域以及弯曲航道船行波四种不同情形,并将计算结果与解析解、实验数据以及与其他模型计算结果进行了对比,讨论了计算结果的异同和模型的精度。展开更多
基金The authors gratefully acknowledge the financial support of Guangdong Provincial Special Fund for Modern Agriculture Industry Technology Innovation Teams under Grants No.2019KJ125the fund of Young Innovative Talents Project from Department of Education of Guangdong Province China(Grants No.2018KQNCX021).
文摘The resistance between mud surface and ship-type paddy field machine hull accounts for a certain proportion of the total mechanical power consumption during the operation process.The special characteristic has been found via preliminary study,it showed that when starting or working at low velocity,the resistance is much greater than the machine working at the rated velocity.This characteristic affects the dynamic matching and structural design of the machine.The critical velocity of resistance distortion was around 0.025 m/s under the setting experimental conditions,and the mechanism of resistance distortion under multi-medium was analyzed.Based on water film drag reduction theory,a macroscopic structure of crocodile's abdominal armor biomimetic drag reduction method was proposed.Two kinds of bionic macroscopic structure ship board were fabricated.The macroscopic structure can introduce more water into the bottom surface of the hull;thicken the water film,which can reduce the travel resistance.Design and manufacture a ship-type paddy field experimental setup with velocity control,and compare the traditional smooth surface ship board with the two bionic macroscopic structure surfaces through orthogonal test.The experiment results demonstrated that the ship board with rectangle gully structure has better drag reduction effect than the hexagon one in the lower velocity.But when the travel velocity approach to the resistance distortion critical point,the hexagon gully structure become better than the other one.Through the orthogonal test,the best drag reduction combination is 2.5 kg load weight,0.025 m/s travel velocity with hexagon ship board,which decreases the drag by 6.3%.
文摘Fang等基于Boussinesq型方程和GPU并行加速技术开发的海岸和近海波浪模拟系统(Coastal and Offshore Wave Simulator,COWS)具有稳定性强、计算效率高的特点。本研究对COWS模型进行扩展,通过在动量方程中添加移动压力源项来模拟船舶实际航行过程中船行波的生成过程。压力项的位置通过三次样条插值法确定,采用二阶中心差分格式近似。利用扩展后的COWS模型,计算了一维矩形横截面航道船行波、浅水区域船首孤立波、开阔水域以及弯曲航道船行波四种不同情形,并将计算结果与解析解、实验数据以及与其他模型计算结果进行了对比,讨论了计算结果的异同和模型的精度。
