Page 4 - 摩擦学学报2025年第8期

1102 摩擦学学报（中英文） 第 45 卷

results showed that: The numerical solution method of the homogeneous boiling model based on the finite element
method can be effectively used for the numerical analysis of the mechanical seal of the cryogenic oxygen medium with
the hydrodynamic-hydrostatic mechanical seal, and has the simulation capability of the gasification phase change region
of the liquid oxygen medium in a large range, and could be used for the calculation and evaluation of the mechanical seal
performance of gaseous oxygen and liquid oxygen medium. When the oxygen in the sealing cavity was liquid, with the
increase of temperature, the LOX phase change on the end face of the mechanical seal mainly occurred in the
downstream side of the equalizing tank. The phase transformation could enhance the static pressure effect of the fluid
film and can greatly reduce the mass leakage rate of dielectric oxygen. The spiral groove on the upstream side of the
pressure equalizing tank has the upstream pumping function, which provided a good hydrodynamic pressure effect while
pumping the liquid oxygen in the pressure equalizing tank to the upstream sealed chamber and plays the role of liquid
film bearing. With the increase of temperature, the hydrodynamic pressure effect is slightly weakened. Compared with
the classical liquid film lubrication model, the mass leakage rate of oxygen under the phase transition was 10% ~ 20% of
that under the liquid film lubrication model. the variation law of the performance of the combined mechanical seal based
on the homogeneous boiling model considering phase change is obviously different: Under the former model, the
opening force and upstream pumping rate decreased linearly with the increase of temperature, while under the
homogeneous boiling model, the opening force and upstream pumping rate showed a complex nonlinear change law,
which was mainly due to the nonlinear vaporization characteristics of liquid oxygen. When the sealing cavity was filled
with liquid oxygen, the phase change helped to improve the opening force of the fluid film. The opening force and
temperature of the end fluid film showed a nonlinear change law. In the study range, when the spiral groove depth was
12 microns, the dynamic and static combined mechanical seal had better fluid film opening force and upstream pumping
rate. Because of the isolation of the pressure equalizing groove, the spiral groove structure of the upstream side has no
direct effect on the phase transformation and leakage characteristics of the downstream side. In the design of sealing face
structure, the upstream spiral groove structure and the downstream sealing dam could be designed separately. The
research results could provide reference for the design of cryogenic medium end seal of turbopump.
Key words: turbopump; cryogenic medium; hydrodynamic-hydrostatic mechanical seal; phase change characteristics;
LOX

高可靠、长寿命和可重复使用的液体火箭发动机 基于均相流理论建立了稳态连续沸腾模型，研究了高
是航天强国的重点研究方向，也是我国航天事业发展 速机械密封流体膜相态的演变规律及其对密封性能

的重点. 涡轮泵是液体火箭发动机的核心部件，运行 的影响，提出了适用于螺旋槽端面密封的相态稳定
在高速和低温苛刻环境下，其安全性和可靠性由其密 判据. Migout等 假设流体膜是液体和气体的均匀混
[10]
[1]
封系统所决定 . 在深冷环境下，液氢液氧等深冷介质 合物，建立了密封薄膜的均相沸腾模型，研究指出在
的动力黏度低，极易汽化相变，导致涡轮泵用机械密 高于温度阈值时机械密封可能表现出不稳定的行为.
封端面变形、干磨和密封失稳等现象，严重影响涡轮 Tournerie等 建立了二维薄膜均相瞬态模型，计算结
[11]
泵甚至火箭的安全性和可靠性 [2-3] . 研究密封端面深冷 果与已有的两相机械密封模型的计算结果吻合较好.
[12]
介质的汽化相变特性及其对密封性能的影响，对高性 Brunetiere 在雷诺方程中引入了1个全相态质量分
能涡轮泵用机械密封的研制开发具有重要的理论意 数，将该经典润滑方程推广到液相、气相以及存在空
[13]
义和工程应用价值. 化的情况. Wang等 提出了1种基于质量守恒定律的
[4]
针对机械密封端面间液膜汽化特性，Lau等 和 均相相变模型，利用Comsol软件求解相变模型，研究
[5]
Lebeck等 假设液膜在沸腾界面完全转化为蒸汽，建 了三维端面结构对机械密封膜压和相变分布的影响.
[13]
立了机械密封液膜的二维轴对称间断沸腾模型，研究 基于Wang等 的均相相变模型，Gao等 和Yang等 [15]
[14]
发现当密封液体接近饱和态时沸腾发生的频率较高. 采用有限体积法求解数学模型，实现了空化和沸腾同
随后，Yasuna等 [6-7] 建立了连续沸腾模型，根据饱和状 时存在时机械密封间隙流场的数值分析.
态将润滑膜分为过热、饱和和过冷3个区域，并据此建 近年来，由于动静压型机械密封具有液膜承载能
立了机械密封的动态分析模型，但该模型在分析具有 力高和苛刻工况下端面接触磨损小等优点而受到学
三维面结构的两相机械密封时过于复杂. 彭旭东等 [8-9] 者们的关注，在火箭发动机涡轮泵的低黏度深冷介质