【作者】 王鑫；

【导师】 袁利毫； 李磊；

【作者基本信息】 哈尔滨工程大学 ， 船舶与海洋工程（专业学位）， 2021， 硕士

【摘要】 镍、铁矿固体散货在海运前受湿雨天气等因素影响,在装运前具有一定的水分,这些细颗粒状固体散货在受到挤压、振动、自身惯性等作用而发生“振密”效应,内部发生水分迁移,在表层形成自由液面或稠密泥浆,即发生流态化。固体散货流态化后所呈现的复杂滑移特性有可能导致船舶稳性降低,存在倾覆的可能。水分迁移伴随整个固体散货流态化过程,而散货中的水主要以液桥形式存在,液桥的动态演变必然会对水分迁移过程产生影响。目前,从宏观试验角度无法准确捕捉固体散货流态化过程中的水分迁移现象,公开文献尚未揭示船运固体散货流态化的机理原因。本文从液桥角度出发,主要通过理论分析及数值手段,研究球形颗粒间液桥的拉伸、断裂及水分迁移行为,探究在颗粒相对运动过程中的颗粒间液桥复杂演变行为及颗粒受力特性,揭示水分迁移的细观机理。首先,基于对国内外研究现状的调研,确定从细观角度分析颗粒间液桥动力学演化行为的研究目标。采用理论方程,分析两球间液桥拉伸断裂特性,获得液桥力与颗粒间距、液桥体积和固-液接触角的关系式,确定液桥形成、断裂、消失的判定区域。然后,基于CFD方法研究静态和动态液桥力,得到拉伸速度、液桥体积、固-液接触角和颗粒粒径比对液桥拉伸、断裂行为的影响规律。最后,分析三球颗粒间钟摆状液桥的稳定性及在颗粒相对运动过程中液桥的演化过程,并从细观角度解释水分迁移行为,旨在为固体散货流态化机理研究提供一定的理论指导和技术支撑。更多还原

【Abstract】 The solid bulk cargo of nickel and iron ore is affected by wet rain and other factors before shipping,and has certain moisture before shipping.These fine granular solid bulk cargo has a "vibrating density" effect due to extrusion,vibration,self-inertia and other effects,and the internal moisture migration occurs,and the free liquid surface or dense mud is formed on the surface,which means fluidization.The complex slippage characteristics of solid bulk cargo after fluidization may lead to the decrease of ship stability and the possibility of overturning.Water transport is accompanied by the whole fluidization process of bulk cargo,and the water in bulk cargo mainly exists in the form of liquid bridge,which is bound to be affected by dynamic evolution.At present,the phenomenon of water transfer in the fluidization of solid bulk cargo can not be accurately captured from the perspective of macroscopic experiment.From the point of view of liquid bridge,this paper mainly studies the tensile,fracture and water transport behavior of liquid bridge between spherical particles by theoretical analysis and numerical methods.Firstly,based on the investigation of the present research situation at home and abroad,the research goal of analyzing the dynamic evolution of liquid bridge between particles is determined.The tensile fracture characteristics of liquid bridge between two spheres are analyzed by using theoretical equations.The relations between liquid bridge force and particle spacing,volume of liquid bridge and solid-liquid contact angle are obtained.The region of formation,fracture and disappearance of liquid bridge are determined.Then,static and dynamic liquid bridging forces were studied based on CFD method.The effects of stretching velocity,liquid bridging volume,solid-liquid contact angle and particle size ratio on the fracture behavior were obtained.Finally,the stability of the pendulum bridge between three particles and the evolution of the liquid bridge during the relative movement of the particles are analyzed,and the water migration behavior is explained from a microscopic perspective.更多还原