序言超低温流体经过导管输送时,必然伴随有热量的输入,一部分液体汽化,导管内产生如图1所示的各种流型的气液两相流。特别是液氢,其沸点比液氧和液氮更低,而且单位体积的蒸发潜热极小,因而可推想稍加热量就可转变为两相流。一般在设计输送流体的管路时,有必 Preamble Ultra-low temperature fluid through the catheter delivery, inevitably accompanied by heat input, part of the liquid vaporization, as shown in Figure 1 produces a variety of flow-type gas-liquid two-phase flow. In particular, liquid hydrogen has a lower boiling point than liquid and liquid nitrogen, and the latent heat of vaporization per unit volume is extremely small, so that it can be assumed that a slight amount of heat can be converted to a two-phase flow. It is always necessary when designing the piping for transporting fluids