Thermal-fluid analysis of the fill and drain operations of a cryrogenic fuel tank

The Generic Research Cryogenic Tank was designed to establish techniques for testing and analyzing the behavior of reusable fuel tank structures subjected to cryogenic fuels and aerodynamic heating. The Generic Research Cryogenic Tank tests will consist of filling a pressure vessel to a prescribed fill level, waiting for steady-state conditions, then draining the liquid while heating the external surface to simulate the thermal environment associated with hypersonic flight. Initial tests of the Generic Research Cryogenic Tank will use liquid nitrogen with future tests requiring liquid hydrogen. Two-dimensional finite-difference thermal-fluid models were developed for analyzing the behavior of the Generic Research Cryogenic Tank during fill and drain operations. The development and results of the two-dimensional fill and drain models, using liquid nitrogen, are provided, along with results and discussion on extrapolating the model results to the operation of the full-size Generic Research Cryogenic Tank. These numerical models provided a means to predict the behavior of the Generic Research Cryogenic Tank during testing and to define the requirements for the Generic Research Cryogenic Tank support systems such as vent, drain, pressurization, and instrumentation systems. In addition, the fill model provided insight into the unexpected role of circumferential conduction in cooling the Generic Research Cryogenic Tank pressure vessel during fill operations

Low-level Carbon Monoxide Line Polarization in Two Protoplanetary Disks: HD 142527 and IM Lup

Magnetic fields are expected to play an important role in accretion processes for circumstellar disks. However, measuring the magnetic field morphology is difficult, especially when given that polarimetric (sub)millimeter continuum observations may not trace the fields in most disks. The Goldreich-Kylafis effect suggests that line polarization is perpendicular or parallel to the magnetic field direction. We attempt to observe CO(2-1), 13CO(2-1), and C18O(2-1) line polarization toward HD 142527 and IM Lup, which are large and bright protoplanetary disks. We use spatial averaging and spectral integration to search for signals in both disks, and we detect a potential CO(2-1) Stokes Q signal toward both disks. The total CO(2-1) polarization fractions are 1.57% ± 0.18% and 1.01% ± 0.10% for HD 142527 and IM Lup, respectively. Our Monte Carlo simulations indicate that these signals are marginal. We also stack Stokes parameters based on the Keplerian rotation, but no signal was found. Across the disk traced by dust of HD 142527, the 3σ upper limits for Pfrac at 0.″5 (∼80 au) resolution are typically less than 3% for CO(2-1) and 13CO(2-1) and 4% for C18O(2-1). For IM Lup the 3σ upper limits for these three lines are typically less than 3%, 4%, and 12%, respectively. Upper limits based on our stacking technique are up to a factor of ∼10 lower, although stacking areas can potentially average out small-scale polarization structure. We also compare our continuum polarization at 1.3 mm to observations at 870 μm from previous studies. The polarization in the northern dust trap of HD 142527 shows a significant change in morphology and an increase in Pfrac as compared to 870 μm. For IM Lup, the 1.3 mm polarization may be more azimuthal and has a higher Pfrac than at 870 μm.Fil: Stephens, Ian. Worcester State University; Estados UnidosFil: Fernandez Lopez, Manuel. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Li, Zhi-Yun. University of Virginia; Estados UnidosFil: Looney, Leslie W.. University of Illinois. Urbana - Champaign; Estados UnidosFil: Teague, Richard. Worcester State University; Estados Unido