液氮泡沫发生器内流动特性研究

低温液氮与泡沫混合液直接接触产生氮气泡沫是一种新型的掺混形式,利用液氮高汽化比的特点,搭建液氮泡沫可视化实验装置,进行氮气-水两相流及液氮泡沫流动特性的研究。结果表明,液氮相变产生大量氮气,其与泡沫液混合产生泡沫,温度有所回升,最终趋于泡沫混合液温度;管路沿程压降较小;液氮射流破碎及流动过程可分为6个区域:低温液氮区、向上循环翻滚区、滞留区、泡沫与泡沫混合液混合区、致密泡沫区、泡沫混合液区。流体向下游流动过程中持续发泡;为防止管路结冰,需合理控制泡沫混合液与液氮流量。

Characteristics of flow in a novel liquid nitrogen foam generator

The nitrogen gas foam produced by the cryogenic liquid nitrogen penetrated directly into the foam solution is a novel method of mixing. Based on the nature of high vaporization ratio of liquid nitrogen, a visualization experimental device of liquid nitrogen foam was built to study the flow characteristics of two-phase nitrogen-water flow and the liquid nitrogen foam. The results show that the liquid nitrogen phase transition produces a large amount of nitrogen gases, which are mixed with the foam solution to produce foam. The temperature rises and is finally close to the temperature of foam solution. The pressure drop along the pipe is smaller. The liquid nitrogen jet breaking and the flow process can be divided into six zones: the cryogenic liquid nitrogen zone, the upward circulation rolling zone, the retention zone, the foam and the solution mixed zone, the dense foam zone and the foam solution zone. The fluid is continuous foaming during flowing to the downstream. In order to prevent the pipeline from freezing, it is necessary to reasonably control the flow rates of the foam solution and liquid nitrogen.