Moon Outpost

SPACE | 低温流体SAFE-SHEAR™ 爆破片

作者:金斯敦-维克斯

低温液体管理是当前和未来空间项目的基础。这些推进液在发射时、在轨道仓库中以及在月球表面的可用性,对于未来人类探索火星的任务至关重要。低温液体存在于加压燃料箱和推进剂子系统中。保持这些燃料的安全运行压力是至关重要的,超压事件可能导致航天器的灾难性损失。关于低温燃料管理的另一个问题是一个叫做 "沸腾 "的过程。沸腾是指在长期的空间任务应用中,低温推进剂储存系统的产品损失。

在商品爆破片设计中,膜片在承受超过其极限的压力时就会破裂。这种 "易碎 "元件对这些类型的爆破片的能力有深刻的影响。冲击载荷、发射时的振动、中止程序、运行中的沸腾循环,以及长期服务的要求,使得依赖一个薄薄的单一膜片作为过压解决方案充其量是有点令人不安的。

Whether working on terrestrial,  in-atmosphere, or in-space applications, the impact of temperature must be factored into overpressure protection. Complications occur when specifying the specific rupture temperature for conventional frangible burst disc pressure.

Frangible disc rupture pressure is solely dependent on the physical strength of the thin diaphragm. These commodity discs risk high variance in specified burst pressure; lower temperature risks higher than rated burst pressure, higher temperature risks lower than rated burst pressure.

Obscuring this critical specification further, designers must make their best judgment as to the conditions that most likely risk an overpressure event.

This can be extremely difficult to predict in cases where runaway chemical reactions or unexpected component failures occur. (e.g. valves, pumps, switches, etc.)

Frangible discs limit system safety and limit the choice as to where the disc can be physically placed within the system.  Due to their thermal sensitivity, frangible designs must be placed very close to where the expected upset conditions occur.  Any locational offset can result in heat transfer and negatively impact frangible burst pressure.

There are reports that a 100° F difference in temperature yields a 20% offset in rupture pressure for conventional frangible designs.

In contrast, advanced SAFE-SHEAR™ burst disc designs are immune to many critical application parameters that destroy conventional/frangible rupture discs. These advanced burst discs can withstand millions of cycles of shock, vibration, thermal cycling, and sloshing up to 95% of rupture pressure. Our burst disc capabilities allow cryogenic fluid designers to optimize cylinder designs for high pressures, thereby ensuring adequate propellant and oxidizer are available to activate pressure-dependent systems. Our advanced burst disc accomplishes this while preventing product loss. Our leakage rates are less than 10-8 standard cubic centimeters per second of GHe. (sccs)

增强的安全功能和泄漏保护是通过其操作方法实现的。当来自液体或气体的内部压力达到预定的(和校准的)压差时,一个精确调整的贝勒维尔弹簧反转,迫使膜片进入锯齿状冲孔,从而释放出系统压力。这种运行机制使先进的爆破片能够提供显著的爆破精度。我们的SAFE-SHEAR™爆破片可以在1至10,000磅/平方英寸(0.007至690巴)的爆破压力下设置±1%,并在-457至1,000°F(-270至540°C)的温度范围内提供公差。

Animated Burst Disc

一旦冲头刺穿膜片,爆破片就会迅速释放所有压力。为了防止在有最低压力操作要求的应用中出现损失,或者在系统处于远程且无法重新充电的情况下,我们可以将泄压阀与爆破片集成在一起。我们的泄压阀可以防止所有产品压力的损失,因此允许依赖压力的部件继续运行。与其他冗余系统相比,我们的爆破片/泄压阀组件可节省多达80%的重量。

NASA认为我们这种先进的圆盘相当于两个泄压阀,让一个泄压阀满足NASA的两个容错要求(参考NASA有效载荷安全要求NHB 1700.7;NASA-JSC NSTS/ISS 18798;JCS Letter TA-88-074)。- "有效载荷的首选防爆盘设计是采用反转膜对抗切割边缘以确保破裂的设计。历史上的使用和经验表明,这种类型的防爆盘可以被认证为一种高度可靠的压力释放装置。"

爆破片的空间应用需要材料解决方案,以承受腐蚀性的火箭燃料、氧化剂和其他恶劣的液体。结构材料可以包括铝、不锈钢、超级合金和PTFE。

Aside from our Human Spaceflight applications, including the International Space Station, additional spacecraft, satellites and aircraft that utilize our SAFE-SHEAR™ technology include:

  • RRM3轨道补充燃料任务Astronaut Thumbs Up and Satellite with K-Port Seal
  • 卡西尼号飞船
  • 哈勃太空望远镜
  • 斯皮策望远镜
  • 广域红外测量探测器
  • 火星全球测量仪
  • 重力探测器-B
  • V-22鹗式飞机/KC-390