Control of the thermodynamic state of space- stored cryogenic fluids by jet mixing
Jet mixing control of thermodynamic state of space stored cryogenic fluids, minimizing mass penalties resulting from equilibrium departures
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Jet mixing control of thermodynamic state of space stored cryogenic fluids, minimizing mass penalties resulting from equilibrium departures
The synthesis of a control system for a cryogenic fluid management facility was studied. The severe demand for reliability as well as instrumentation and control unique to the Space Station environment are prime considerations. Realizing that the effective control system depends heavily on quantitative description of the facility dynamics, a methodology for process identification and parameter estimation is postulated. A block diagram of the associated control system is also produced. Finally, an on-line adaptive control strategy is developed utilizing optimization of the velocity form control parameters (proportional gains, integration and derivative time constants) in appropriate difference equations for direct digital control. Of special concern are the communications, software and hardware supporting interaction between the ground and orbital systems. It is visualized that specialist in the OSI/ISO utilizing the Ada programming language will influence further development, testing and validation of the simplistic models presented here for adaptation to the actual flight environment.
This paper presents the development of a two-phase CFD model that is used to study sloshing of a cryogenic fluid (LN2) undergoing phase change generated by lateral acceleration and its effects on the ensuing heat and mass transfer and pressure drop in a small-scale tank. In this model the interface is captured using the volume-of-fluid (VOF) method [1]. Kinetic-theory based Schrage relation [2] is used for calculating phase change mass transfer at the liquid-vapor interface. Computational results are compared to the data provided by a non-isothermal sloshing experiment with phase change conducted by the University of Tokyo and JAXA in 2018 using liquid Nitrogen in a transparent tank. The effect of different thicknesses of a liquid temperature stratification layer created at the interface on the pressure drop during sloshing was studied experimentally. CFD results for interface movement and tank pressure are presented and compared in this paper to experimental data for the cases with the smallest and largest liquid temperature stratification thickness.
Reliability design concepts in cryogenic fluid systems in Saturn S-IV stage propulsion system, noting hydrogen and LOX tank pressurization systems
An overview is given of the Lewis Research Center's cryogenic fluid management program in the form of viewgraphs. Objectives, approach, program elements, cost analysis, modeling, and flight experiment development are outlined.
A history of technological development for subcritical cryogenic fluid management (CFM) through space experiments is given for the period 1960 to 1990. Space experiments with liquid hydrogen were conducted in the early 1960's. Efforts since then have consisted of studies and designs of potential space experiments. A chronology of CFM space experiments and design efforts is included.
Hot wire sensor combined with voltage-comparator circuit monitors liquid level in cryogenic-fluid storage tanks. Sensor circuit adaptable to different liquids and sensors. Constant-current source drives current through sensing probe and fixed resistor. Voltage comparator circuits interpret voltage drops to tell whether probe is immersed in liquid and is current in probe.
A summary of research into on-orbit cryogenic fluid transfer at the NASA Lewis Research Center (LRC) is presented. Variable test parameters and liquid injection configurations elucidated the conditions necessary for a successful transfer of liquid hydrogen by the no-vent fill method. The model is based on conservation of mass and a first-law energy balance for a control volume. The ullage, the bulk liquid, and the tank wall are each represented by a single node. The magnitude of the maximum receiver tank pressure was found to be dependent on the liquid inlet temperature, the inlet mass flow rate, and the initial temperature. A comparison of the test data and the analytical results for a no-vent fill test with a small receiver tank is presented.
Data are presented for the two phase choked flow of three cryogenic fluids - nitrogen, methane, and hydrogen - in four converging-diverging nozzles. The data cover a range of inlet stagnation conditions, all single phase, from well below to well above the thermodynamic critical conditions. In almost all cases the nozzle throat conditions were two phase. The results indicate that the choked flow rates were not very sensitive to nozzle geometry. However, the axial pressure profiles, especially the throat pressure and the point of vaporization, were very sensitive to both nozzle geometry and operating conditions. A modified Henry-Fauske model correlated all the choked flow rate data to within + or - 10 percent. Neither the equilibrium model nor the Henry-Fauske model predicted throat pressures well over the whole range of data. Above the thermodynamic critical temperature the homogeneous equilibrium model was preferred for both flow rate and pressure ratio. The data of the three fluids could be normalized by the principle of corresponding states.
Conceptual designs were developed for the determination of rotordynamic coefficients of cryogenic fluid film bearings. The designs encompassed the use of magnetic and conventional excitation sources as well as the use of magnetic bearings as support bearings. Test article configurations reviewed included overhung, floating housing, and fixed housing. Uncertainty and forced response analyses were performed to assess quality of data and suitability of each for testing a variety of fluid film bearing designs. Development cost and schedule estimates were developed for each design. Facility requirements were reviewed and compared with existing MSFC capability. The recommended configuration consisted of a fixed test article housing centrally located between two magnetic bearings. The magnetic bearings would also serve as the excitation source.
Development for an in-space demonstration of a CubeS at as a Cryogenic Fluid Management (CFM) test bed is currently underway. The favorable economics of CubeSats make them appealing for technology development activity. While their size limits testing to smaller scales, many of the regimes relevant to CFM can still be achieved. The first demo flight of this concept, CryoCube®-1, will focus on oxygen liquefaction and low-gravity level sensing using Reduced Gravity CryoTracker®. An extensive thermal modeling effort has been underway to both demonstrate concept feasibility and drive the prototype design. The satellite will utilize both a sun- and earth-shield to passively cool its experimental tank below 115 K. An on-board gas generator will create high pressure gaseous oxygen, which will be throttled into a bottle in the experimental node and condensed. The resulting liquid will be used to perform various experiments related to level sensing. Modeling efforts have focused on the spacecraft thermal performance and its effects on condensation in the experimental node. Parametric analyses for both optimal and suboptimal conditions have been considered and are presented herein.
Duct coupling with nickel steel diaphragm of low thermal expansivity is leakproof when used with cryogenic fluids. The diaphragm, located between the two flanges of the coupling, reduces axial shrinkage at the coupling flanges to a minimum.
The conceptual design of a space station Technology Development Mission (TDM) experiment to demonstrate and evaluate cryogenic fluid storage and transfer technologies is presented. The experiment will be deployed on the initial operational capability (IOC) space station for a four-year duration. It is modular in design, consisting of three phases to test the following technologies: passive thermal technologies (phase 1), fluid transfer (phase 2), and active refrigeration (phase 3). Use of existing hardware was a primary consideration throughout the design effort. A conceptual design of the experiment was completed, including configuration sketches, system schematics, equipment specifications, and space station resources and interface requirements. These requirements were entered into the NASA Space Station Mission Data Base. A program plan was developed defining a twelve-year development and flight plan. Program cost estimates are given.
An in-house study was performed to design a cryogenic Space Transfer Vehicle (STV) for the late 1990s that can evolve with the demanding mission requirements of the manned exploration initiatives. An assessment of cryogenic fluid management technology issues associated with the STV was performed to identify technology gaps and propose advanced development activities.
The Fluid Dynamics Branch has positioned itself to support a wide range of customers in need of Cryogenic Fluid Management (CFM) analysis. A computational fluid dynamics (CFD) tool used for all manner of internal and external propulsion applications has been extended and refined to better model cryogenic propellant storage and tanking operations. Through the CFM Portfolio project, several validation activities were initiated. Validation of propellant tank self-pressurization, autogenous pressurization, slosh-induced ullage collapse, and jet-induced mixing all aid in defining model accuracy. The on-going validation effort has enabled confident application of the tool to in-line design and evaluation of CFM hardware and operations. Recent project support included design of no-vent fill operations using various techniques for the Human Landing System (HLS). Propellant transfer dynamics were predicted to ensure complete propellant delivery. Many more activities in support of HLS and other projects and programs were supported. The branch has engaged the CFM community to share recent findings and capabilities through conferences. To reach the wider community, a consolidation of fundamental findings from work on in-space pulsed settling maneuvers was distilled in an AIAA paper. Development and demonstration of CFM modeling capabilities continues in order to meet the needs of the agency and its industry partners in the endeavor to sustainably reach the Moon and beyond.
Recent technology development work conducted at NASA in the area of Cryogenic Fluid Management (CFM) storage is highlighted, including summary results, key impacts, and ongoing efforts. Thermodynamic vent system (TVS) ground test results are shown for hydrogen, methane, and oxygen. Joule-Thomson (J-T) device tests related to clogging in hydrogen are summarized, along with the absence of clogging in oxygen and methane tests. Confirmation of analytical relations and bonding techniques for broad area cooling (BAC) concepts based on tube-to-tank tests are presented. Results of two-phase lumped-parameter computational fluid dynamic (CFD) models are highlighted, including validation of the model with hydrogen self pressurization test data. These models were used to simulate Altair representative methane and oxygen tanks subjected to 210 days of lunar surface storage. Engineering analysis tools being developed to support system level trades and vehicle propulsion system designs are also cited. Finally, prioritized technology development risks identified for Constellation cryogenic propulsion systems are presented, and future efforts to address those risks are discussed.
This paper describes the results of the "Experimentation for the Maturation of Deep Space Cryogenic Refueling Technology" study. The purposes of this study were to identify cryogenic fluids management technologies requiring low gravity flight experiments to bring to technology readiness level (TRL) 5-6; to study many possible flight experiment options; and to develop near-term low-cost flight experiment concepts to mature core technologies of refueling. A total of twenty-five white papers were prepared in the course of this study. Each white paper is briefly summarized and relevant references cited. A total of 90 references are cited.
A subcritical liquid hydrogen orbital storage and transfer experiment was designed for flight in the Shuttle cargo bay. The Cryogenic Fluid Management Experiment (CFME) includes a liquid hydrogen tank supported in a vacuum jacket by two fiberglass epoxy trunnion mounts. This composite material was selected for the trunnions since it provides desirable strength, weight and thermal characteristics for supporting cryogenic tankage. An experimental program was conducted to provide material property and fatigue data for S-glass epoxy composite materials at ambient and liquid hydrogen temperatures and to verify structural integrity of the CFME trunnion supports.