In-space cryogenic propellant transfer is a key enabling technology for future long duration space exploration missions. However, successfully refueling tankage with cryogenic propellants in space presents significant challenges related to the chilldown of the receiving tank. There is a limited supply of propellant in space depots and the cold propellant itself has to be used for chilldown purposes utilizing non-vented filling procedures while maintaining the pressure in the receiving tank below a prescribed threshold. Although filling protocols such as pulsed-injection and charge-vent-hold have been developed to optimally achieve high fill-levels during the refueling process, the success of attaining high fill refuel levels is largely dependent on the cooling efficiency of the tank walls and the ullage. It is envisioned that tank cooling will be facilitated by spray injection nozzles that remove thermal energy rapidly from the system minimizing boil-off, propellant loss and chilldown time. The innovation described in this proposal is a collaborative effort between CRAFT Tech and the University of Connecticut that involves detailed experimental visualization and diagnostic measurements involving the interaction of spray nozzles with tank environments and utilizing these observations for the development of specialized spray cooling models in a high-fidelity multiphysics simulation framework.
The technology will benefit NASA’s Reduced Gravity Cryogenic Transfer program by providing design support for critical components such as spray injection nozzles and predicting the amount propellant required for chilldown. Cryogenic propellant storage and transfer is critical to nearly all NASA’s future human exploration missions including the imminent Moon Gateway Mission and the more distant Mars Exploration Campaign. The success of these missions is reliant on reliable CFM including protocols for propellant storage and transfer.
The technology can be used to support launch activities related to SpaceX’s Falcon Heavy rocket as well as Blue Origin’s New Shepard rocket. Other applications include the design of cryogenic spray nozzles for advanced propulsion concepts. Non-Aerospace applications include the medical applications such as preservation of tissues (surgery) and organs (transplant), to life-support systems.