Abstract Labyrinth seals are widely used to seal cryogenic fluids in rocket engine turbopumps and cryogenic cooling machine tools. Cavitation is inevitably induced by pressure drop inside the cryogenic labyrinth seal. However, the occurrence and development of the cavitation as well as the leakage characteristics of two-phase flow are unclear yet. This research focuses on revealing cryogenic cavitation behavior and predicting variables of two-phase flow in the labyrinth seal. The method to determine the cavitation position is presented. Theoretical labyrinth seal leakage models of two-phase flow are proposed for the first time, and a mathematical calculation method is formed. A higher accuracy has been proved using the numerical method. The results indicate the starting position of cavitation is related to the inlet pressure, subcooling degree and seal geometry. The steady tooth clearance pressure drop of two-phase flow is extremely small, resulting in a lower leakage compared to the liquid without phase change. Also, the leakage of two-phase flow is dependent on the vapor volume fraction. This work provides a theoretical basis for further studies on the labyrinth sealing performance of cryogenic fluids.

中文翻译：

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低温迷宫密封两相流泄漏特性的理论建模

摘要 迷宫密封广泛用于火箭发动机涡轮泵和低温冷却机床中低温流体的密封。低温迷宫式密封件内部的压降不可避免地会引起气穴现象。然而，空化的发生、发展以及两相流的泄漏特性尚不清楚。这项研究的重点是揭示迷宫密封中的低温空化行为和预测两相流的变量。给出了确定空化位置的方法。首次提出了两相流迷宫密封泄漏的理论模型，并形成了数学计算方法。使用数值方法证明了更高的精度。结果表明气穴的起始位置与入口压力有关，过冷度和密封几何形状。两相流的稳定齿间隙压降极小，与无相变的液体相比，泄漏量更低。此外，两相流的泄漏取决于蒸汽体积分数。该工作为进一步研究低温流体的迷宫密封性能提供了理论依据。