Improvement of cryogenic fluid storage and transfer technology for in-space propulsion systems is required for long-term human explorations beyond low earth orbit as identified in the NASA…

This federal contract award to Southwest Research Institute (SwRI), a nonprofit research and development organization based in San Antonio, Texas, is for the "Improvement of Cryogenic Fluid Storage and Transfer Technology for In-Space Propulsion Systems." The goal is to increase the technology readiness level of a tapered channel liquid acquisition device (LAD) design to TRL 5 by characterizing its performance in a relevant environment aboard a suborbital vehicle. The $185,410 grant from the National Aeronautics and Space Administration (NASA) aims to improve the delivery of cryogenic fluids for in-space propulsion systems, which is critical for long-term human exploration beyond low-Earth orbit. The contract does not have a set-aside designation. This research provides novel data that will directly benefit NASA's in-space propulsion technology development and enhance the fundamental understanding of gas/liquid behavior in microgravity, with potential cross-cutting applications in human health, life support, and thermal management systems.

Improvement of cryogenic fluid storage and transfer technology for in-space propulsion systems is required for long-term human explorations beyond low earth orbit as identified in the NASA technology roadmap technology area (TA) 02: in-space propulsion. Current technology relies on the capillary force within screened channels of a liquid acquisition device (LAD) to deliver vapor free cryogenic liquid during engine restart and critical transfer processes. However, due to the low temperatures associated with cryogenic fluids, external heating acting on the tank where this fluid is stored will cause vapor bubbles to form within the LAD that are difficult to remove in existing designs. A more efficient design is needed to reliably remove vapor bubbles without costly thrusting maneuvers or active separation systems. A small modification to a commonly used LAD is proposed: a tapered channel. This design passively removes or pumps-out cryogenic vapor bubbles that are internally generated, substantially improving transfer or delivery of cryogenic fluids. The goal of this project is to increase the technology readiness level (TRL) of this tapered channel LAD design to TRL 5 by characterizing its performance in a relevant environment aboard a suborbital vehicle that can provide multiple minutes of high quality microgravity. The test apparatus includes multiple tapered screen channels filled with liquid and a vapor bubble. A camera will record vapor bubble migration across each channel in all phases of flight. Image analysis will give bubble geometry, velocity, and travel distance, showing how internally generated vapor bubbles are passively removed in the tapered screen channel LAD. This experiment will provide novel data that will directly benefit NASA in-space propulsion technology by improving and validating tapered LAD designs as well as strengthening the knowledge of fundamental forces that affect gas/liquid behavior in microgravity. A reliable passive liquid delivery system would reduce costs associated with complex propellant tank designs to manage cryogenic fluids and propellant loss from thrusting in order to orient the ullage in the tank. Additionally, this test also provides cross-cutting data for better understanding the capillary forces inherent in separating gas from liquid in human health, life support, and habitation (TA06) and thermal management systems (TA14) applications.