Liquid oxygen liquid acquisition device bubble point tests with high pressure lox at elevated temperatures

Abstract

When transferring propellant in space, it is most efficient to transfer single phase liquid from a propellant tank to an engine. In earth's gravity field or under acceleration, propellant transfer is fairly simple. However, in low gravity, withdrawing single-phase fluid becomes a challenge. A variety of propellant management devices (PMD) are used to ensure single-phase flow. One type of PMD, a liquid acquisition device (LAD) takes advantage of capillary flow and surface tension to acquire liquid. The present work reports on testing with liquid oxygen (LOX) at elevated pressures (and thus temperatures) (maximum pressure 1724 kPa and maximum temperature 122K) as part of NASA's continuing cryogenic LAD development program. These tests evaluate LAD performance for LOX stored in higher pressure vessels that may be used in propellant systems using pressure fed engines. Test data shows a significant drop in LAD bubble point values at higher liquid temperatures, consistent with lower liquid surface tension at those temperatures. Test data also indicates that there are no first order effects of helium solubility in LOX on LAD bubble point prediction. Test results here extend the range of data for LOX fluid conditions, and provide insight into factors affecting predicting LAD bubble point pressures.

Screen channel liquid acquisition device outflow tests in liquid hydrogen

“…The parameters that affect bubble point, including screen mesh type, liquid, liquid pressure and temperature (i.e. the amount of subcooling), pressurant gas type and pressurant gas temperature have been systematically investigated in four primary cryogenic liquids, including LH2 and liquid nitrogen (LN 2 ) [9, [14][15][16], LOX [17][18][19], and liquid methane (LCH 4 ) [20,21], as well as room temperature liquids [12,22,23]. Equations 1 and 3 can be used to predict the breakdown point of a screen channel LAD in any given gravitational and thermal environment.…”

International Space Exploration Coordination Group Assessment of Technology Gaps for LOx/Methane Propulsion Systems for the Global Exploration Roadmap

“…34 Liquid acquisition device bubble point and flow testing and characterization were accomplished. 35,36,37 The Radio Frequency Mass Gauge (RFMG) has been developed and demonstrated as a mass gauge in micro-gravity for various propellants, showing promising accuracy. 38 , 39 Vacuum chamber testing of cryogenic feed systems 40 with multiple RCS engines and single main engine have been conducted.…”

Noninvasive fluid bubble detection based on capacitive micromachined ultrasonic transducers

“…For instance, in clinical medicine, the existence of air bubbles in extracorporeal blood circulation (ECBC) and extracorporeal membrane oxygenation (ECMO) systems can lead to air embolisms (blocking blood from passing through) when bubbles infiltrate a vein or artery, resulting in serious injuries such as strokes and heart attacks or even death 4 , 5 . In aerospace applications, air bubbles in propellant can cause a rapid increase in air pressure in spacecraft tanks and thus an explosion 6 , 7 . To date, a variety of technologies have been developed for fluid bubble detection, including image analysis 2 , 8 , electroresistivity 9 , optics 10 , capacitance wire-mesh sensors 11 , X-rays 12 and ultrasound 13 , 14 .…”