Abstract The uniform distribution of liquid oxygen is essential for design of feeding system in multi-engines of cryogenic rockets. Aiming at a cryogenic launch vehicle with four engines in parallel, a five-way spherical cavity structure was used to evenly distribute liquid oxygen in the multi-branch pipes. These cryogenic rocket engines need to be controlled by opening or closing states for multi-branch pipes to adapt different flight conditions. To study effect of working states on pressure drop in the four branch pipes with the five-way spherical cavity, a large-scale test system was constructed to carry out discharging flow of liquid oxygen. The feeding pipes of full-scale model were adopted, and forty-nine sensors were arranged in the pipes to measure pressure and temperature of liquid oxygen. The constant discharging flow was maintained by a feedback system of tank pressure. The opening or closing states of branch pipes were controlled by cut-off valves at the end of each branch pipe. The liquid oxygen tests were carried out under different actual flight conditions. The results shown that the opening or closing states for four branch pipes had a dramatic effect on the pressure drop in the multi-branch pipes. When the branch pipes all drained at the same time, there was a large pressure drop in two symmetrical branch pipes which enhanced linearly with the increase of Reynolds number. The pressure drop of two branch pipes on the symmetrical sides could exceed 0.1 MPa which was far greater than the normal flow resistance, when the Reynolds number was 5.0 × 106. It was found that there was a regular swirling flow formed in the five-way spherical cavity by using CFD method. When two branch pipes were turned off, whether symmetrical sides or adjacent sides, the large pressure drop still existed, and was positively correlated with the varying Reynolds number. The maximum pressure drop in the branch pipes was close to 0.09 MPa, when the Reynolds number was 3.3 × 106. When three branch pipes were closed, the large pressure drop disappeared, and the flow resistance related positively with the Reynolds number, which accorded with the normal flow resistance. Moreover, according to data of six hot test runs and two verification tests, it was found that the inlet pressure in the main pipe had greatly influence on the pressure drop, which raised sharply as the inlet pressure increased. These results could help to provide a design reference for feeding system of multi-engines in cryogenic rockets.

中文翻译：

---

不同工况下五通分配腔液氧进料管压降实验研究

摘要 液氧的均匀分布是低温火箭多发供料系统设计的关键。针对四发并列的低温运载火箭，采用五通球腔结构，将液氧均匀分布在多支管中。这些低温火箭发动机需要通过多支管的开启或关闭状态进行控制，以适应不同的飞行条件。为研究工作状态对四通球腔支管内压降的影响，搭建了大型试验系统进行液氧的放流。采用全尺寸模型的进料管，在管内布置49个传感器测量液氧的压力和温度。恒定的排放流量由罐压反馈系统维持。支管的启闭状态由各支管末端的截止阀控制。液氧试验是在不同的实际飞行条件下进行的。结果表明，四个支管的开启或关闭状态对多支管中的压降有显着影响。当支管全部同时排水时，对称的两条支管出现较大的压降，随着雷诺数的增加呈线性增加。当雷诺数为 5.0×106 时，对称侧的两条支管的压降可超过 0.1 MPa，远大于正常流阻。利用CFD方法发现五通球腔内形成了规则的涡流。当两条支管关闭时，无论是对称侧还是相邻侧，较大的压降仍然存在，并且与雷诺数的变化呈正相关。当雷诺数为 3.3×106 时，支管内最大压降接近 0.09 MPa。当三个支管关闭时，大压降消失，流阻与雷诺数正相关，符合正常流动阻力。此外，根据6次热试运行和2次验证试验的数据发现，主管道入口压力对压降影响很大，随着入口压力的增加，压降急剧上升。