Challenge: Supply of vapor-free cryogenic liquid propellant in a rocket tank
The key to propellant transfer in microgravity is the propellant management device (PMD), which ensures that vapor-free propellant is supplied from a source tank (e.g. a fuel depot) to a receiver tank or engine. Failure to do so for engines will result in combustion inefficiencies and even engine failure. Most traditional surface-tension based PMDs face difficulties when handling cryogenic liquids, and thus primarily occupy low-to-mid technology readiness levels (TRLs). Bladders are an attractive alternative to surface-tension PMDs for handling cryogenic liquids.
The Technology: Origami bladder with varied wall geometry for storing cryogenic liquid propellant
Incorporation of origami structures (a compliant mechanism) into the bladder could substantially increase the reusability of the cryogenic PMD. WSU researchers have developed an expulsion bladder PMD from origami bellows and have demonstrated that the bladder can be cyclically filled with and expel liquid hydrogen (LH2). The device innovates with two varying wall geometries.
- Bellow structure to actuate between extended and collapsed positions by flexing hinges supplying liquid propellant from source tank to receiver tank in a rocket.
- Simplified expulsion process.
- Better performance of bellows with less stress on hinges and ensured deformation of bellows with increasing structure size.
- Use of plastic which is mostly at cryogenic temperatures ensures less likeliness to crack.
- Cryogenic origami bladders are an attractive low-TRL PMD.