NASA NTRS · 20230009044
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David Eddleman, Scott Kramer, Andrew Smith, Robert Walker. Low Leakage Cryogenic Valves. https://ntrs.nasa.gov/citations/20230009044
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This article describes the need and the strategy for CFD model development, validation, and verification for Cryogenic Fluid Management (CFM) of Propellant Tanks in Space. It describes the type of CFD models that must be developed to address the future needs of Space CFM. It also discusses the two classes of experiments currently used to validate the fidelity of the CFD models. These two experiment classes are: (a) the small-scale simulant fluid science experiments that are equipped with scientific diagnostics to elucidate the underlying two-phase fluid physics of the CFM processes; and (b) the large-scale cryogenic experiments that assess the engineering performance of the propellant tank for storage and transfer. The current status of the CFD model development and validation is briefly assessed by presenting examples of segregated two-phase flow problems that have been successfully modeled. The future model development directions for CFM situations involving more complex interpenetrating phases are also defined.
Liquid nitrogen is often used as a substitute for oxygen testing due to safety concerns, and the general similarity between their fluid properties. During the Cryogenic Fluid In-situ Liquefaction for Landers (CryoFILL) testing, an opportunity arose to compare liquid nitrogen and liquid oxygen behavior using the same test hardware in similar test conditions. Comparative testing would verify whether the system response to nitrogen and oxygen would behave in a similar manner. Tests that were investigated include system boil-off heat load determination, autogenous pressurization, cryocooler loop initiation, and cryocooler loop operations. Results from testing are shown and compared to verify that liquid nitrogen and liquid oxygen tests yield similar system responses, and that nitrogen can be used as a substitute for oxygen in developmental tests at cryogenic temperatures.
This paper presents a status update on the low leakage cryogenic test valves currently under development at NASA’s Marshall Space Flight Center. These valves consist of a 3-inch isolation valve, a 3-inch relief valve, and an 8-inch pre-valve. Each of these valves contain a self-aligning seat and poppet design to significantly reduce the quantity of propellant flowing past the seat when the valve is in its closed state (internal leakage). This self-aligning design utilizes a metallic poppet head with five degrees of freedom and is intended to allow a valve to be more tolerant of the imperfect contacts and misalignments that are commonly found between sealing surfaces. This paper covers the test articles, facilities, objectives, and preliminary results.