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航天事业的发展,开拓了宇宙实验验室,为人类带来了珍贵的实验条件——微重力环境,它是指重力加速度低于10~(-6)g的航天器内环境,也可以说是一种“失重”环境。在微重力环境中,不仅重力微弱,而且还有超高真空、深冷、超净、无振动及充足的阳光等优异条件。作者对微重力环境流体的特性进行了定量分析。液体在微重力环境的静压梯度的绝对值是其在普通重力场中的1/10~6,可认为它趋于0,密度梯度也趋于0,由静压梯度引起的浮力也将趋于0,从而悬浮和沉定现象也消失;微重力环境中,在两水平层间发生对流的可能性减小到普通重力空间的1/10~6。在此环境中,液膜没有弯曲现象,拉制的薄片、薄膜和线材结构极为均匀,且厚度和直径非常理想。因无静压梯度、沉淀和悬浮,有利于冶炼优质金属及合金材料,生产均匀性达理想程度的晶体和玻璃材料。在无对流的条件下,材料的扩散控制容易实现,输运过程简化。在晶体或玻璃的生产过程中,可消除冷却结晶阶段因对流而引起的混合、扰动,还可实现材料生产的无容器过程。消除了因容器壁引进杂质和感应成核的问题,文章还探讨了微重力对流体力学基本方程组的影响。
The development of the aerospace industry has opened up the universe laboratory and brought precious experimental conditions to mankind - the micro-gravity environment, which refers to the spacecraft internal environment with the gravitational acceleration less than 10 ~ (-6) g, Is a “weightless” environment. In the micro-gravity environment, not only gravity is weak, but also ultra-high vacuum, cryogenic, clean, no vibration and sufficient sunlight and other excellent conditions. The authors quantitatively analyzed the properties of microfluidic fluids. The absolute value of the hydrostatic gradient of a liquid in a microgravity environment is 1/10 ~ 6 of its normal gravity field. It can be assumed that it tends to 0 and its density gradient also tends to zero. The buoyancy caused by the hydrostatic gradient will also tend to At 0, the phenomenon of suspension and sedimentation also disappears. In the microgravity environment, the possibility of convection between two horizontal levels is reduced to 1/10 ~ 6 of normal gravity space. In this environment, the liquid film is not bent, the drawn sheet, film and wire structure is extremely uniform, and the thickness and diameter are ideal. Because of no static pressure gradient, precipitation and suspension, is conducive to the smelting of high quality metal and alloy materials, the production uniformity of crystal and glass materials to an ideal level. Under the condition of no convection, the material diffusion control is easy to realize and the transport process is simplified. In the crystal or glass production process, can eliminate the cooling crystallization phase due to convection caused by mixing, disturbing, but also can realize the material-producing containerless process. The problem of introduction of impurities and induced nucleation in the vessel wall is eliminated. The article also discusses the effect of microgravity on the basic equations of fluid mechanics.