Optimization Design of Sealing Performance for Gas Generators under Long-Term High Temperature Conditions
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摘要:针对低燃温燃气发生器在长时间工作周期中出现的密封失效问题，本文通过热-结构耦合仿真，揭示了原铜质垫圈在≥300 ℃高温下因蠕变、应力松弛及差异热膨胀导致的接触应力动态衰减与泄漏机制。据此，提出了3种密封改进方案：退火态1050-O铝垫圈、柔性石墨垫圈以及一种以“激光深熔焊接为主、铝垫圈预紧为辅”的复合密封结构。静压与点火联合试验表明：铝垫圈方案在5.5 MPa时出现微泄漏；石墨垫圈密封耐压可达8 MPa；而复合结构在-10～+65 ℃、10 MPa、1 400 s 条件下零泄漏，且焊缝熔深达1.15 mm、拉断力≥130 kN。研究表明，复合密封以冶金-机械双重屏障突破了传统垫圈的高温性能局限，为提升燃气发生器的长寿命与高可靠性提供了可工程化的解决方案。
Abstract:To address the sealing failure of low-temperature gas generators during long-duration pressurization missions, this paper combines fault-tree analysis with coupled thermo-mechanical simulation to demonstrate how copper gaskets lose elastic recovery above 300 ℃ owing to creep and stress relaxation, while differential thermal expansion further reduces contact stress and propagates dynamic gaps. Three remedies are proposed：annealed 1050-O aluminum gasket；flexible graphite gasket, and a hybrid scheme in which deep-penetration laser welding provides the primary seal and an aluminum gasket supplies secondary preload. Static-pressure and live-firing tests reveal that the aluminum gasket leaks slightly at 5.5 MPa, the graphite gasket remains leak-tight up to 8 MPa, and the hybrid seal achieves zero leakage at 10 MPa for 1 400 s over -10 ~ +65 ℃, with weld depths of 1.15 mm and tensile strengths exceeding 130 kN. The hybrid approach breaks the high-temperature performance ceiling of conventional gaskets through a metallurgical-mechanical dual barrier, offering an engineering-ready solution for long-life, highly reliable low-temperature gas generators.
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