Abstract:

The turbopump isolation seal system plays a crucial role in the safe and reliable operation of liquid rocket engine turbopumps, and the design of the seal system must ensure that it has the ability of high speed resistance, long life, and strong resistance to external excitation. In order to solve the problem of seal failure caused by the change of seal leakage due to the change of rotational speed and pressure of the double bellows helium isolation seal under the operation condition, the simulation model of air film between sealing surfaces and the deformation model of dynamic and static rings were established to analyze the influence of the change of rotational speed and isolation medium pressure on the dynamic opening characteristics and the deformation of sealing surface under the operation condition, and the leakage volume of the seal under the different rotational speeds and isolation medium pressures was measured through the test. The leakage of the seal was measured under different speeds and pressures of the isolating medium. The results showed that the opening of the double bellows hydrostatic helium isolation seal did not depend on the rotational speed, the leakage almost did not change with the rotational speed, and it still had stable sealing performance when the rotational speed changes. With the increase of isolation medium pressure, the stiffness of the gas film showed an overall increasing trend, but there was a tendency to level off at 0.5—0.6MPa, which indicated that the isolation seal gas film stiffness will not increase indefinitely, and there was a stiffness limit. The seal was able to pass through the membrane pressure, and it can open under the different rotational speeds and isolation medium pressures. The seal can adaptively adjust the axial position of the static ring to establish a new balance through the mutual coordination of membrane pressure, membrane thickness and bellows. When the isolation medium pressure changed, the pressure in the stabilizing tank and the isolation medium pressure change trend was the same, and the seal can quickly respond to the pressure change.

Key words: turbopump, hydrostatic isolation seal, leakage, pressure variation, seal performance

摘要：

涡轮泵隔离密封系统对液体火箭发动机涡轮泵的安全可靠运行具有至关重要的作用，密封系统的设计必须确保其具备耐高速、长寿命以及强抗外部激振能力。针对双波纹管氦隔离密封在运转工况下，因转速、压力出现变化导致密封泄漏而引起的密封失效问题，建立了密封面间气膜仿真分析模型及动静环变形模型，分析了转速及隔离介质压力变化对动态开启特性的影响以及运转工况下密封端面的变形程度，并通过实验测量了密封在不同转速和隔离介质压力下的泄漏量。研究结果表明：双波纹管静压氦隔离密封的开启不依赖转速，泄漏量几乎不随转速发生变化，转速发生变化时仍具有稳定的密封性能；随着隔离介质压力的提高，气膜刚度整体上呈增大的趋势，但在0.5~0.6MPa时存在趋于平稳的趋势，表明隔离密封气膜刚度不会无限制地增大，存在刚度极限；密封能够通过膜压、膜厚与波纹管间的相互协调作用自适应调节静环轴向位置来建立新的平衡；在隔离介质压力变化时，稳压槽内压力与隔离介质压力变化趋势一致，密封能够迅速响应压力的变化。

关键词: 涡轮泵, 静压隔离密封, 泄漏量, 压力变化, 密封性能