Full-scale screen channel LADs

The purpose of this chapter is to present the experimental results for the full-scale LAD outflow tests in liquid hydrogen. Test conditions were taken over a wide range of liquid temperatures (20.3-24.2 K), tank pressures (100-350 kPa), and outflow rates (0.010-0.055 kg/s) thermally and operationally representative of an in-space propellant transfer from a depot storage tank or to a smaller scale in-space engine. Horizontal LAD tests were conducted to measure independently the frictional and dynamic losses down the channel. Flow-through-screen tests were performed to measure independently the dominate pressure loss in LEO, the FTS resistance. Meanwhile, 1-g inverted vertical LAD outflow tests were conducted to obtain performance data for two full-scale 325 x 2300 LAD channels. One of the channels had a perforated plate and a custom-built internal thermodynamic vent system to enhance performance. Model predictions from Chapter 3 are compared to each set of experimental data. 

In addition, the simplified ID steady state pressure drop model for screen channel liquid acquisition devices has been developed and compared to the FTS, horizontal LAD, and full-scale LAD outflow experimental data. Both experimental data and model confirm that, in 1-g outflow from a cryogenic propellant tank, the hydrostatic pressure drop is the leading order term, followed by the FTS pressure drop, and frictional and dynamic losses down the channel. The model qualitatively tracks the LH2 1-g inverted outflow test results the model predicts the breakdown point within 9% for the TVS cooled channel and 18% for the standard channel. Discrepancies between 1-g model and data are primarily attributed to a non-uniform FTS pressure distribution along the channel. Results show that both LAD channels behaved close to anticipated performance and that this simplified ID model can be used to qualitatively track LAD performance in a dynamic outflow environment. 

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