The loop thermosyphons has advantages of high heat transmission efficiency and needing no additional power. It can quickly draw out the heat in the motorized spindle with no coolant getting into the shaft, and has a good application prospect in the field of motorized spindle cooling. However, the evaporation and condensation sections of a loop thermosyphon will be in the same pipe and at the same height under the heat conduction of the shaft. These structural changes will directly affect the flow characteristecs and heat transfer performance of the loop thermosyphon. This paper experimental studied the vapor-liquid two phase flow characteristics in a pentane loop thermosyphon. The effects of the heat input power and fill ratio on the flow characteristics were analyzed. Results show that the two-phase flow pattern transitions from stratified flow to wavy flow and finally to plug flow as fill ratio increases. The velocity of the liquid flow in the upper adiabatic section of the loop thermosyphon is on the order of 0.1 m·s-1, and it decreases with increasing heat input when the fill ratio is between 30 and 70 %.

环形热虹吸管具有传热效率高、无需额外动力的优点。可快速将电主轴内的热量排出，无需冷却液进入轴内，在电主轴冷却领域具有良好的应用前景。但是，在竖井的热传导作用下，回路热虹吸管的蒸发段和冷凝段将在同一管道中，处于同一高度。这些结构变化将直接影响回路热虹吸管的流动特性和传热性能。本文通过实验研究了戊烷回路热虹吸管中汽液两相流动特性。分析了热输入功率和填充比对流动特性的影响。结果表明，随着填充比的增加，两相流型从分层流转变为波状流，最后转变为塞流。环形热虹吸管上部绝热段的液流速度约为 0.1 m·s-1，当填充率在 30% 到 70% 之间时，它随着热输入的增加而减小。