【摘要】 讨论了微重力效应及其分子物理学解释,万有引力的单极性决定了它的累积性和宏观性,重力对自由分子的影响是微乎其微的,然而在流体,特别是在液体内部的具体条件下,重力对流体内部分子集团产生明显影响,以宏观的静压强形式表现出来.而当重力变小,变微,流体内部的静压强也就趋于消失,由静压强产生的二级现象,如异相沉降或浮泛,同相的浮泛对流,液体自约束成球形,也就消失,这些就是微重力的一,二级物理效应.本文认为,Bossinesq近似对于流体而言实质上是线性热力学假设或近乎衡态假设,可以用初始平衡态的物性参量表征临界点时的无量纲数.提出一种重力消失诱发非平衡态向平衡态蜕变的猜想,从文中导出的瑞利数Ra的表达式可以看出,重力加速度的消失,可以使瑞利数的值从远离平衡态的湍流蜕变到稳定流动的瑞利-贝纳对流胞,甚至是没有宏观流动的平衡态.最后,将本文给出的理论解释模型应用到空间材料加工所需微重力水平的估算、空间材料加工工艺的微重力利用准则和空间装置中气体自然对流传热状态模拟的低真空和微重力的互换性方面.更多还原

【Abstract】 The effects and its explanation in the point of view of molecular physics are discussed in this paper Accumulative and macroscopic features of universal gravitation are determined by its’ monopole characteristics and it has almost no effects on free molecules. However, inside liquid, Especially in the liquor, obvious effects from gravity on molecular groups exist in the form of macroscopically static pressure, as gravity gets smaller and smaller, the static pressure inside liquid will disappear gradually and the secondary phenomena, such as sedimentation and floating in different phases and floating convection in same phases will also disappear.In this paper, it is pointed out that Bossinesq approximation is substantially a hypothesis of linear thermodynamics or quasi-equilibrium state, so it is possible to express the nondimensional numbers in the critical point with some physical property parameters in the initial equilibrium state. An idea is put forward that by eliminating gravity to induce a transform from non-equilibrium state to equilibrium state. The expression of Rayleigh number Ra derived in this paper shows that as gravity acceleration disappearing, the value of Ra will change from a turbulent state far from equilibrium to a ray Leigh-Benard convection cell in a stable flow, even to an equilibrium state without macroscopic flow. Finally, this theoretical explanation model is applied to estimate the microgravity level necessary for space materials processing and the interchangeability of low vacuum and microgravity in simulation of the heat conduction state in natural convections of gases in space devices.更多还原