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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Aerogel-Based Insulation Materials for Cryogenic Applications

Many different aerogel-based materials are now being used in thermal insulation systems for cryogenic applications. These materials include flexible composite blankets, bulk-fill particles, and polymer composites in both evacuated and non-evacuated environments. In ambient environments, aerogels provide superior thermal performance compared to conventional polymeric foam and cellular glass insulations while offering unique advantages in solving problems with weathering, moisture, and mechanical damage. Aerogels are also used as spacer materials in multilayer insulation systems. These layered systems provide combined structural-thermal capability for cryogenic systems in either vacuum-jacketed or externally-applied insulation designs. Test data (effective thermal conductivity) include a wide range of both commercial and experimental aerogel materials. Testing was performed using laboratory cryostats and standard methods including full range vacuum (from ambient pressure to high vacuum) and boundary temperatures 293 K and 78 K. Examples of aerogel-based insulation systems are given for both evacuated and non-evacuated applications.

aerogel layered composites↗
NASA NTRS2016

Physics Based Model for Cryogenic Chilldown and Loading. Part III: Correlations

In this report we discuss the details of the correlations used to recognize flow patterns and predict frictional losses, heat and mass transfer in the cryogenic two phase flow. The emphasis are put on the formulation of the correlation problem in terms of concise parametric and functional spaces allowing for efficient online search of the model parameters and accurate prediction of the phenomena observed during cryogenic loading. A special attention is paid to the discussion of the correlation dependence on the gravity. In this context the physics of stability, friction, and boiling in the two-phase flow that underlies the required correlations is discussed.

two-phase flow↗
NASA NTRSDate not supplied

On the Use of Liquid Nitrogen Droplets as Flow Tracers in Cryogenic Flow Facilities at NASA Langley Research Center

The injection of liquid nitrogen droplets to cool the gas temperature in cryogenic wind tunnels is discussed as a method of natural seeding for velocimetry-focused, particle-based, laser diagnostics. Historical observations and issues with seeding are presented for both ground-test facilities of interest in this work at NASA Langley: the 0.3-m Transonic Cryogenic Wind Tunnel (TCT) and the National Transonic Facility (NTF). Recent observations of natural seeding with a Rayleigh scattering instrument are presented in the two facilities, which motivated the purposeful use of a pulse-burst laser system to observe the particles directly with a sequentially operated laser sheet for the first time. Time-resolved image sequences of unevaporated liquid nitrogen droplets were readily acquired for tunnel total temperatures of 200 K and below. The preliminary results promote a discussion on the fitness of these natural particles as flow tracers for either a particle image velocimetry or a particle tracking velocimetry instrument in these high-Reynolds-number facilities.

cryogenic wind tunnels↗
NASA NTRSDate not supplied

CFD Modeling of Cryogenic Chilldown in a Complex Channel under Normal and Low Gravity Conditions

Future NASA architectures have baselined cryogenic propulsion systems as well as cryogenic fluid management to support lunar missions and ultimately to support future missions to Mars. These missions will require chilling hardware down prior to engine restart as well as chilling lines and tanks prior to transferring and refueling these propulsion elements in orbit. In lieu of expensive tests conducted on-orbit, accurate predictive computational models of these chilldown processes can be used to reduce system and propellant mass as well as mission risk.

CFD↗
NASA NTRS2021

Assessment of Governing Heat and Mass Transfer Coefficients for Cryogenic No-Vent Top-Off Modeling

No-vent fill / no-vent top-off (NVF/NVTO) is a method to enable the trans-fer of cryogenic propellants without the need to vent. Transferring propellants inmicrogravity environments is necessary to support the long-duration space missionsplanned for the coming decades. A key developmental milestone to developing thiscapability fully is the simulation and experimentation of NVF/NVTO in 1-g settings.This work seeks to advance the former by assessing the effectiveness of different heattransfer correlations used in a 1-g non-equilibrium model. Heat transfer correlationsfor natural convection and two-phase boiling heat transfer are compared against ex-perimental results for 34 different tests. Two distinct experiments, comprised of 21tests, are presented in detail here. These tests cover a variety of different injectionmethods, receiver tank geometries, receiver tank materials, cryogenic propellants, andinitial tank states. Overall for the cases tested in this work, the model was able topredict the pressure response within the receiver tank to a mean absolute percentageerror of 25.9%. The temperature response error rate was 29.5% and 24.9% for wall-gasand two-phase nodes, respectively. Compared to the worst case correlation set tested,the pressure prediction error rate represents a 31% improvement. For the cases pre-sented in this work, the mean pressure prediction error rate was 15.5%. Future workcould evaluate the effectiveness of this model against experiments conducted withdifferent propellants or different initial conditions. In its current form, however, themodel can still be used to help reduce design and testing time for 1-g experiments,enabling the quicker iteration that is necessary to meet the technological demands offuture space missions.

No-Vent Top Off↗
NASA NTRSDate not supplied

Liquefaction of Cryogenic Fluids for Production and Storage of Commodities on Extra-Terrestrial Surfaces

The Cryogenic Fluid In-situ Liquefaction for Landers (CryoFILL) activity has been investigating concepts for the liquefaction of cryogenic fluids produced on the surface of the Moon and Mars. CryoFILL consists of four activities: liquid nitrogen liquefaction testing that was completed in 2019, liquid oxygen liquefaction testing planned to begin in early 2022, fiber-optic sensor temperature measurement system development, and lightweight vacuum jacketed systems designed for the atmosphere of Mars. Additional activities include the development and validation of numerical modeling systems at three stages: thermodynamic models of the liquefaction process for basic energy/mass estimates, nodal models to predict liquefaction tank system level performance, and computational fluid dynamics to assess fluid phenomena occurring within the tank, specifically condensation and stratification within the ullage. These developments form a combined liquefaction and storage solution to support Lunar and Martian exploration. Key testing results from liquid nitrogen testing as well as plans for liquid oxygen testing will be discussed including key sensitivities from analytical evaluation of completed test results. Progress on the development and improvements on fiber optic sensor testing and developments will also be provided. Finally, work on the progress of the lightweight vacuum jacketed systems being co-developed by NASA and industry will be summarized.

Liquefaction↗
NASA NTRSDate not supplied

NASA Meeting on Cryogenic Fuel Systems for Aircraft: Overview of Previous Workshops and Studies

NASA is holding a meeting on Cryogenic Fuel Systems for Aircraft. To help guide meeting focus, a brief review of previous studies and workshops is included delineated among airframe, propulsion, and fuel system topics. Information is limited to cryogenic fuel-related information, such as liquid methane (LNG) or liquid hydrogen. Older studies (from 1950s) as well as present efforts are briefly highlighted. A more comprehensive listing of recent efforts that may be pertinent are included in the bibliography.

Cryogenic fuel systems↗
NASA NTRSDate not supplied

Operational Techniques in Microgravity for Cryogenic Fluid Management

Management of cryogens in microgravity is a critical challenge for exploration missions to the Moon and Mars. Operational strategies to aid in cryogenic fluid management (CFM) are proposed and demonstrated using computational fluid dynamics simulations. Application of axial settling thrust is an essential – but potentially expensive – tool for CFM. Demonstrations show that its utilization and timing are important during certain unsettling events, such as engine cutoff. At other times, substantial savings can be realized by reducing the average acceleration (through pulsing thrusters, for example). If the metric for reaching a settled condition is a particular number of slosh periods, then fewer settling resources are needed with a lower acceleration. Alternatively, if a target wave amplitude is the settling objective, then a lower average acceleration will also allow for a higher allowable amplitude for the same heat transfer. Savings can also be obtained by rolling the vehicle, which can mitigate lateral slosh. Advantages and disadvantages of anti-slosh baffles are also discussed along with practical examples of their impact on CFM and ullage collapse. Ullage collapse examples are presented along with recommendations for slewing a vehicle with angular and translational acceleration to mitigate mixing between liquid and ullage.

Cryogenic Fluid Management↗
NASA NTRS2023

Improvement of Pressure Sensitive Paint in A Cryogenic Oxygen-Poor Environment

This report details specific improvements to the use of Pressure Sensitive Paint (PSP) in an oxygen-poor environment, with an emphasis on cryogenic PSP in the National Transonic Facility (NTF). For this work, several improvements to the application of PSP and data acquisition have been investigated in the 0.3-m Transonic Cryogenic Tunnel (generally considered a pilot facility for the NTF) and these results will be presented. In addition, several improvements to the existing PSP system at NTF are presented as well as a brief section on further improvements that can be investigated.

Cryogenic ground testing↗
NASA NTRS2022

Recent Concept Study for Cryogenic Fluid Management to Support Opposition Class Crewed Missions to Mars

NASA recently completed a mission concept study to evaluate the feasibility and propulsion technology development requirements for reduced travel duration crewed missions to Mars. A high-level goal of the study was to minimize the health impact on the crew caused by the space environment. This was implemented in the study by limiting the crew to a total of approximately-two years of in-space operations and travel time. For the initial mission, the crew would stay about 30 days on the Martian surface. The propulsive demands of such a mission are immense, and the study identified two advanced propulsion options with the potential to meet the mission requirements—both options rely on nuclear fission to provide efficient propulsive energy. One propulsion option was a nuclear electric propulsion (NEP)/Chem Hybrid, with a reactor and energy conversion system powering xenon propellant ion thrusters to provide an efficient, but lower-thrust, push for most of the mission duration. This concept also relied on a liquid oxygen/liquid methane (LO2/LCH4) chemical propulsion stage to provide high thrust for maneuvers while near the Earth and Mars. The second propulsion option was nuclear thermal propulsion (NTP), in which the reactor heats liquid hydrogen (LH2) propellant to expand through a nozzle for thrust at about twice the efficiency of the best chemical propulsion systems. Both vehicle concepts rely on storing large amounts of cryogenic propellant (either LO2/LCH4 or LH2) for multiple years in space without loss, far exceeding state-of-the-art capability. To enable this new capability, the team assumed the use of several advanced cryogenic fluid management (CFM) technologies and analyzed the integrated system performance. This included considering the vehicle-level effects of the size, mass, and power requirements of these CFM elements. Further, the team evaluated the development required to enable such a mission in the mid-2030 s and determined that it was feasible. The paper elaborates on the assumed CFM technologies, provides key analysis results, and illustrates the feasibility of technology development for the proposed solutions to the CFM challenges for each propulsion concept.

cryogenic propellant↗
NASA NTRSDate not supplied

Recent Advancements in Electrical Capacitance Mass Gauging for Cryogenic PropellantTanks

The current lack of unsettled mass gauging is a key roadblock for many space activities, such as orbital refueling, missions to the Moon and Mars, and nuclear thermal and nuclear electric propulsion technologies. Liquid can form any one of an infinite number of configurations in microgravity, such as floating in globs or accumulating on tank surfaces in discontiguous volumes, or both. Capacitive sensing requires no moving parts and dissipates close to zero heat, making it an ideal candidate for cryogenic fluid mass gauging in settled and unsettled configurations. Capacitive sensing has a history of proven use in space propellant tanks, including tanks on the space shuttle, Saturn V, and the Apollo Lunar Excursion Module. Modern capacitive sensor technology allows using the entire tank as the capacitor volume by placing electrodes on the tank walls and propellant management surfaces. Capacitance is directly related to density, and therefore to mass for fixed volumes. In this presentation, we discuss the concepts behind whole-tank capacitance mass gauging and associated engineering challenges. We describe recent efforts to develop a micro-g unsettled cryogenic mass gauge using whole-tank capacitance sensing, including the development of test beds, electronics, and algorithms. We describe several mathematical processing techniques, including empirical-based averaging, electrical capacitance volume tomography, and spatial regularization. A modeling study, performed using settled configurations in gravity and no gravity, and with a set of 100 random fluid configurations, has indicated that spatial regularization, in which capacitance measurements are weighted to account for non-uniform electric fields, yields a mass fraction accuracy of 8% for any fluid configuration. Such a sensor is expected to operate in real time with a sampling frequency of at least 1 kHz.

cryogenic↗
NASA NTRSDate not supplied

CFD Modeling of a Cryogenic Methane Drain Test with and without Induced Sloshing

Current planned NASA missions to the Moon and Mars involve the transfer of cryogenic propellants in orbit. These activities require large amounts of cryogenic propellant and the ability to transfer these fluids from one tank to another in an efficient manner. Predicting the pressurant required for the supply tank pressurization during the initial pressurization and expulsion process will be important to understand priori to reduce propellant margin.

Low Gravity Fluid Modeling↗
NASA NTRS2023

Thermal Desktop Modeling of the RRM3 On-Orbit Cryogenic Methane Storage and Active Cooling Experiment

The storing of cryogenic propellants is an enabling technology for NASA as it moves to expand future missions into low Earth orbit (LEO) and beyond. The Robotic Refueling Mission–3 (RRM3) experiment launched in 2018 and was designed to demonstrate tank self-pressurization during storage and active cooling of liquid methane in microgravity. Creating accurate models using existing datasets from flight experiments such as RRM3 is a vital step toward developing appropriate modeling tools to form pre-test predictions for future flight systems. The goal of this work was to create a working model in Thermal Desktop of the RRM3 source Dewar during the microgravity self-pressurization experiment. The pressure rise, temperature distribution of the fluid inside the tank, and the wall temperatures were all tracked and compared with test data. Initial results show good agreement between each of these metrics and the experimental results. This work is ongoing and will yield further insights into the thermal behavior of cryogens in microgravity.

Tank self-pressurization↗
NASA NTRSDate not supplied

NASA Cryogenic Fluid Management Flight Demonstration Summary: SpaceX 2020 Tipping Point

NASA Science and Technology Mission Directorate is investing in advancement of on-orbit cryogenic fluid management technologies by partnering with industry through Tipping Point contracts with the primary objective of reducing development costs and schedules for infusion into long duration missions utilizing cryogenic propellant. SpaceX was selected as a partner in 2020 to conduct a demonstration of CFM technologies on a Starship Mission. This presentation provides a summary of the top-level goals and objectives of this contract and how NASA has structured this partnership.

cryogenic fluid management↗
NASA NTRSDate not supplied

Nodal Modeling of Submerged Helium Injection Pressurization of a Cryogenic Propellant Tank

Subcooling of cryogenic propellant by helium injection is one of the most effective methods for suppressing bulk boiling and keeping subcooled propellant conditions for pre-launch, launch, and post-launch pressurization applications. For tank pressurization, submerged helium injection can substantially reduce helium consumption by infusing gaseous propellant into the tank ullage. This paper describes a thermodynamic model of the helium bubbling process in liquid oxygen to estimate the amount of oxygen vapor absorbed by the rising helium bubbles and the amount of subcooling of liquid oxygen due to evaporative heat and mass transfer. The physics of helium dissolution during the pressurization process is also modeled, primarily for liquid hydrogen propellant where the dissolution is more significant. The analyses were performed in a simulation model of tank pressurization built with Generalized Fluid System Simulation Program (GFSSP), a general-purpose flow network code developed at NASA/Marshall Space Flight Center. The numerical predictions of subcooling have been compared with the experimental data of Cho et al. which investigated the propellant subcooling effect as a function of system pressure, helium injection temperature, and flowrate for a non-drained submerged injection system. The numerical predictions of helium consumption have been compared with the test data from a NASA Centaur test vehicle which included both direct and submerged injection with draining of propellants. Hydrogen propellant testing of the Cryogenic Propellant Storage and Transfer Engineering Developmental Unit (CPST EDU) conducted at NASA/Glenn Research Facility was also analyzed. The data used for the model validation were taken in 1-g, but the model was developed to be applicable in both multi-g and micro-g environments.

tank pressurization↗
NASA NTRSDate not supplied

Electrified Aircraft Propulsion Integration Concepts: Primary Fuel Cells and Cryogenic Hydrogen Storage

This presentation leverages lessons learned from the multiple activities funded by the National Aeronautics and Space Agency (NASA) to convey development paths for implementing an Electrified Aircraft Propulsion (EAP) system powered by primary fuel cells systems and fueled by cryogenically stored hydrogen. To reduce greenhouse gas emissions associated with all aspects of hydrogen-fueled aviation, this work minimizes required energy and time per payload distance at take-off so as to reduce emissions associated with ground operations and the production, liquefaction, transfer, and storage of hydrogen. The approach targets efficient system integration, maximizing hydrogen utilization efficiency, maximizing power system efficiency, and viable operational concepts for delivered payload distances. The discussion outlines the performance and compliance challenges revealed by analyses of current fuel cell and cryogenic management technologies. The conclusion offers potential mitigation strategies to the identified the performance and compliance challenges.

Fuel Cell↗
NASA NTRSDate not supplied

Simulations of Cryogenic Line Chilldown with Advanced Sub-Grid Wall Boiling Models

A meso-scale model developed at MIT [2][11] for boiling processes in water was adapted for cryogens and demonstrated for chilldown of propellant transfer lines in both liquid nitrogen and hydrogen. The sub-grid boiling model accurately captures the contributions to heat transfer from the generation of bubble nuclei, growth, and interaction of the bubbles in the microlayer as well as quenching of the boiling surface following bubble departure. It was adapted for cryogenic fluids using thermodynamic scaling concepts taking into account non-dimensional pressures and temperatures that are scaled by the corresponding critical values for the fluid. The boiling model was demonstrated for line chilldown in liquid nitrogen (Darr et al. [6]). The predicted wall temperature at which quenching occurs was close to the test data while the slope of the temperature curve after quenching is initiated, showing a steeper variation than the test data. Simulations were also performed for liquid hydrogen by simulating experiments of Hartwig et al. [7]. Chilldown times in liquid hydrogen are much more rapid due to higher heat transfer in the film boiling regime and accounting for the higher turbulence levels were found to be important. Furthermore, at the much lower fluid temperatures in liquid hydrogen flows, accounting for the variable thermal properties of the solid material is critical and has a dramatic impact on the quench times. The need for additional studies to better understand the evolution of the quench front in liquid hydrogen was noted.

Computational Fluid Dynamics↗