Multi-Spherical Composite-Overwrapped Cryogenic Fuel Tanks for Hypersonic Aircrafts

In the field of cryogenic storage, the medium inside the pressure vessel is in a liquid state and therefore cannot be further compressed. As a result, the storage tank should be designed in such a way, that it makes the best possible use of the available space (under a minimum weight) where it will be placed (e.g. within a reusable flight vehicle). Unlike conventional cylindrical pressure vessels, conformable pressure vessels provide an effective solution for this application in terms of volumetric and gravimetric efficiency. More specifically, conformable structures in the form of intersecting spheres (multi-sphere)-manufactured from composite materials- would be a beneficial configuration, since they can lead to weight savings associated with equal membrane strains when subjected to uniform pressure. Furthermore, because spheres have the minimum surface area for a given volume, they result in the minimization of passive heat in the tank and fuel boil-off, thus reducing the weight penalty associated with required thermal insulation thickness in cryogenic environments. Therefore a vessel configuration that incorporates partially merged spheres overwrapped with uni-directional (UD) carbon fiber straps applied at the merging points to introduce a uniform strain field would lead to a high volumetric efficiency at a low weight penalty...