液体火箭发动机热试车启动中导流锥对燃气管路流动特性影响研究

Effects of guide device on flow characteristics of gas pipeline during hot test start-up of liquid rocket engine

双推力室液体火箭发动机启动过程中,若出现两支管流量分配不均等现象,极易引起点火失败,造成重大损失。因此,燃气管路分叉处内部流动特性和在分叉处布置导流锥对改善流动特性影响的研究具有重要意义。本文针对某双推力室液体火箭发动机热试车启动过程中的燃气管路,以试验数据作为边界条件,开展了瞬态流动数值仿真研究。结果表明,火箭发动机热试车启动过程中,燃气管路流动呈现出4个典型阶段,分别为点火前的平稳期、点火后的一次上升期、下降期和二次上升期。在启动过程中,无导流锥时,导流罩进口存在预旋回流区、一侧出口存在滞止回流区,导流罩与燃气支管衔接处内侧存在转弯回流区,三者相互作用是造成两支管间压力分布不对称及出口质量流量分配不平衡的主要原因;有导流锥时,预旋回流区被导流锥约束而缩小,滞止回流区消失。有导流锥与无导流锥时相比,在启动过程中约0.2 s与0.6 s时刻,两支管对称测点压差均值分别降低约80.0%与80.0%,两支管出口质量流量差值分别降低约55.0%与80.8%。导流锥有效改善了流动特性,使得两支管压力分布的对称性提高,流量分配平衡性增强。导流锥对双推力室液体火箭发动机稳定性提高有重要作用。

During the start-up process of the double thrust chamber liquid rocket engine,if the flow distribution of the two pipes is uneven,it is easy to cause ignition failure and cause major losses.Therefore,it is of great significance to study the flow characteristics at the fork of the gas pipeline and the influence of the arrangement of the guide device at the bifurcation on improving the flow characteristics.A numerical simulation of transient flow was carried out for the gas pipeline during the hot test start-up of the double thrust chamber liquid rocket engine with the test data as the boundary condition.The results show that during the hot test start-up of the liquid rocket engine,the gas pipeline flow presents 4 typical stages,they are the stable period before ignition,the first rising period,the descending period and the secondary rising period after ignition.In the start-up process,when there is no guide device,there is a pre-swirl recirculation zone at the inlet of the shroud,a stagnant recirculation zone at one side of the outlet,and a turning recirculation zone at the inside of the junction between the shroud and the gas branch,the interaction of the three zones is the main reason for the asymmetrical pressure distribution between the two branches and the imbalance of the outlet mass flow distribution.When there is a guide device,the pre-swirl recirculation zone is constrained by the guide device and reduced,and the stagnant recirculation zone disappears.When there is a guide device compared to there is no guide device,during start-up about 0.2 s and 0.6 s moments,the average pressure difference of the symmetrical measurement point of the two pipes is reduced by about 80.0%and 80.0%,and the mass flow difference at the outlet of the two pipes is reduced by about 55.0%and 80.8%,respectively.Guide device effectively improves the flow characteristics,so that the symmetry of the pressure distribution of the two branches is improved,and the balance of flow distribution is enhanced.The guide device plays an important role in improving the stability of the double thrust liquid rocket engine.