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水平向上表面蒸汽膜内气体的特点是:接触冷却介质的外层气体在上方,而接触高温表面的内层气体在下方。假如是孤立的蒸汽膜区,因上方被冷气体覆盖着,下方的热气体是无法向上流动的。所在表面只能通过传导和辐射向外散热。但是,这种平衡不稳定。当内外层气体的温差(△T)超过一定值后,通过随机扰动的触发,可开始气体的互动。再经过短时间的发展变化,会形成与其△T相适应的循环对流形式。△T的值越大,循环对流越剧烈,它的散热作用也越强。工件入液之初,靠下
The characteristics of the gas in the vapor film of the horizontal upward surface are that the outer gas contacting the cooling medium is above and the inner gas contacting the high temperature surface is below. If it is an isolated steam film area, because the top is covered by cold gas, the hot gas below can not flow upward. The surface can only be dissipated by conduction and radiation. However, this balance is not stable. When the temperature difference between inner and outer gas (ΔT) exceeds a certain value, the gas interaction can be started by triggering random disturbance. After a short period of development and change, it will form a circular convection with its △ T form. The greater the value of △ T, the more circulating convection, its cooling effect is also stronger. The beginning of the workpiece into the liquid, by the next