In the present study, the direct contact condensation (DCC) performance of the superheat GOX in subcooling LOX is explored by numerical simulations based on the VOF two-phase model. The flow condensation characteristics are analyzed in a practical condenser of a cryogenic liquid rocket. The coalescence phenomenon of the GOX streams is examined. The possible regimes of the coalescence are summarized and their effects on the condensation performance are explored. Besides, an improved GOX entrance layout is proposed to avoid the coalescence phenomenon and improve condensation performance. The main conclusions are concluded as follows: The gas condensation is the main heat transfer form in most of the pipe region. The bending section of the condenser pipe that connects the vertical section and horizontal section is the most active region for DCC. It is found that there can be two types of coalescences namely, transverse coalescence and longitudinal coalescence. Both coalescence regimes have strong negative effects on the heat transfer ability and condensation performance of the condenser pipe. The improved entrance layout can successfully avoid the coalescence of the GOX streams and reduce the flow distance of the GOX by about 93%. It is also concluded that an improvement of the condenser pipe should be effectively accomplished by controlling the coalescence of the GOX streams after injection.

在本研究中，通过基于 VOF 两相模型的数值模拟，探讨了过热 GOX 在过冷 LOX 中的直接接触冷凝 (DCC) 性能。在低温液体火箭的实际冷凝器中分析了流动冷凝特性。检查了 GOX 流的聚结现象。总结了可能的聚结机制，并探讨了它们对冷凝性能的影响。此外，还提出了改进的 GOX 入口布局，以避免聚结现象并提高冷凝性能。主要结论如下： 气体冷凝是大部分管道区域的主要传热形式。连接垂直段和水平段的冷凝器管道的弯曲段是DCC最活跃的区域。发现可以有两种类型的聚结，即横向聚结和纵向聚结。两种聚结方式对冷凝管的传热能力和冷凝性能都有很大的负面影响。改进的入口布局可以成功避免 GOX 流的合并，并将 GOX 的流动距离减少约 93%。还得出结论，冷凝管的改进应通过控制注入后 GOX 流的合并来有效实现。改进的入口布局可以成功避免 GOX 流的合并，并将 GOX 的流动距离减少约 93%。还得出结论，冷凝管的改进应通过控制注入后 GOX 流的合并来有效实现。改进的入口布局可以成功避免 GOX 流的合并，并将 GOX 的流动距离减少约 93%。还得出结论，冷凝管的改进应通过控制注入后 GOX 流的聚结来有效实现。