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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 343 records · Page 19

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NASA NTRS1976

Power calculations for isentropic compressions of cryogenic nitrogen

A theoretical analysis has been made of the power required for isentropic compressions of cryogenic nitrogen in order to determine the extent that the drive power for cryogenic tunnels might be affected by real gas effects. The analysis covers temperatures from 80 to 310K, pressures from 1.0 to 8.8 atm and fan pressure ratios from 1.025 to 1.200. The power required to compress cryogenic nitrogen was found to be lower than that required for an ideal diatomic gas by as much as 9.5 percent. Simple corrections to the ideal gas values were found to give accurate estimates of the real gas power values.

Real gas↗

NASA NTRS1977

Power calculations for isentropic compressions of cryogenic nitrogen

A theoretical analysis was made of the power required for isentropic compressions of cryogenic nitrogen in order to determine the extent to which the drive power for cryogenic tunnels might be affected by real-gas effects. The analysis covers temperatures from 80 to 310 K, pressures from 1.0 to 8.8 atm, and fan pressure ratios from 1.025 to 1.200. The power required to compress cryogenic nitrogen was found to be as much as 9.5 percent lower than that required to compress an ideal diatomic gas. Simple corrections to the ideal-gas values were found to give accurate estimates of the real-gas power values.

Real gas↗

NASA NTRS2003

Material Damping Experiments at Cryogenic Temperatures

A unique experimental facility has been designed to measure damping of materials at cryogenic temperatures. The test facility pays special attention to removing other sources of damping in the measurement by avoiding frictional interfaces, decoupling the test specimen from the support system, and by using a non-contacting measurement device; Damping data is obtained for materials (AI, GrEp, Be, Fused Quartz), strain amplitudes (less than 10-6 ppm), frequencies (20Hz-330Hz) and temperatures (20K-293K) relevant to future precision optical space missions. The test data shows a significant decrease in viscous damping at cryogenic temperatures and can be as low as 10-4%, but the amount of the damping decrease is a function of frequency and material. Contrary to the other materials whose damping monotonically decreased with temperature, damping of Fused Quartz increased substantially at cryo, after reaching a minimum at around l50 K. The damping is also shown to be insensitive to strain for low strain levels. At room temperatures, the test data correlates well to the analytical predictions of the Zener damping model. Discrepancies at cryogenic temperatures between the model predictions and the test data are observed.

cryogenic↗

NASA NTRS2012

Cryogenic Amplifier Based Receivers at Submillimeter Wavelengths

The operating frequency of InP high electron mobility transistor (HEMT) based amplifiers has moved well in the submillimeter-wave frequencies over the last couple of years. Working amplifiers with usable gain in waveguide packages has been reported beyond 700 GHz. When cooled cryogenically, they have shown substantial improvement in their noise temperature. This has opened up the real possibility of cryogenic amplifier based heterodyne receivers at submillimeter wavelengths for ground-based, air-borne, and space-based instruments for astrophysics, planetary, and Earth science applications. This paper provides an overview of the science applications at submillimeter wavelengths that will benefit from this technology. It also describes the current state of the InP HEMT based cryogenic amplifier receivers at submillimeter wavelengths.

cryogenically cooled superconductorinsulator- supe↗

NASA NTRS2013

Temperature Stratification in a Cryogenic Fuel Tank

A reduced dynamical model describing temperature stratification effects driven by natural convection in a liquid hydrogen cryogenic fuel tank has been developed. It accounts for cryogenic propellant loading, storage, and unloading in the conditions of normal, increased, and micro- gravity. The model involves multiple horizontal control volumes in both liquid and ullage spaces. Temperature and velocity boundary layers at the tank walls are taken into account by using correlation relations. Heat exchange involving the tank wall is considered by means of the lumped-parameter method. By employing basic conservation laws, the model takes into consideration the major multi-phase mass and energy exchange processes involved, such as condensation-evaporation of the hydrogen, as well as flows of hydrogen liquid and vapor in the presence of pressurizing helium gas. The model involves a liquid hydrogen feed line and a tank ullage vent valve for pressure control. The temperature stratification effects are investigated, including in the presence of vent valve oscillations. A simulation of temperature stratification effects in a generic cryogenic tank has been implemented in Matlab and results are presented for various tank conditions.

stratification↗

NASA NTRS2014

Physics Based Model for Cryogenic Chilldown and Loading. Part IV: Code Structure

This is the fourth report in a series of technical reports that describe separated two-phase flow model application to the cryogenic loading operation. In this report we present the structure of the code. The code consists of five major modules: (1) geometry module; (2) solver; (3) material properties; (4) correlations; and finally (5) stability control module. The two key modules - solver and correlations - are further divided into a number of submodules. Most of the physics and knowledge databases related to the properties of cryogenic two-phase flow are included into the cryogenic correlations module. The functional form of those correlations is not well established and is a subject of extensive research. Multiple parametric forms for various correlations are currently available. Some of them are included into correlations module as will be described in details in a separate technical report. Here we describe the overall structure of the code and focus on the details of the solver and stability control modules.

cryogenic fluid management↗

NASA NTRS2015

Some General Principles in Cryogenic Design, Implementation, and Testing

Brief Course Description: In 2 hours only the most basic principles of cryogenics can be presented. I will concentrate on the differences between a room temperature thermal analysis and cryogenic thermal analysis, namely temperature dependent properties. I will talk about practical materials for thermal contact and isolation. I will finish by describing the verification process and instrumentation used that is unique to cryogenic (in general less than 100K) systems.

heat transfer↗

NASA NTRS2016

Performance of the Primary Mirror Center-of-curvature Optical Metrology System During Cryogenic Testing of the JWST Pathfinder Telescope

The James Webb Space Telescope (JWST) primary mirror (PM) is 6.6 m in diameter and consists of 18 hexagonal segments, each 1.5 m point-to-point. Each segment has a six degree-of-freedom hexapod actuation system and a radius-of-curvature (RoC) actuation system. The full telescope will be tested at its cryogenic operating temperature at Johnson Space Center. This testing will include center-of-curvature measurements of the PM, using the Center-of-Curvature Optical Assembly (COCOA) and the Absolute Distance Meter Assembly (ADMA). The COCOA includes an interferometer, a reflective null, an interferometer-null calibration system, coarse & fine alignment systems, and two displacement measuring interferometer systems. A multiple-wavelength interferometer (MWIF) is used for alignment & phasing of the PM segments. The ADMA is used to measure, and set, the spacing between the PM and the focus of the COCOA null (i.e. the PM center-of-curvature) for determination of the ROC. The performance of these metrology systems was assessed during two cryogenic tests at JSC. This testing was performed using the JWST Pathfinder telescope, consisting mostly of engineering development & spare hardware. The Pathfinder PM consists of two spare segments. These tests provided the opportunity to assess how well the center-of-curvature optical metrology hardware, along with the software & procedures, performed using real JWST telescope hardware. This paper will describe the test setup, the testing performed, and the resulting metrology system performance. The knowledge gained and the lessons learned during this testing will be of great benefit to the accurate & efficient cryogenic testing of the JWST flight telescope.

optical testing↗

NASA NTRS2016

Successful Completion of the JWST OGSE2 Cryogenic Test at JSC Chamber-A While Managing Numerous Challenges

The James Webb Space Telescope (JWST) Optical Telescope Element (OTE) assembly is the largest optically stable infrared-optimized telescope currently being manufactured and assembled, and scheduled for launch in 2018. The JWST OTE, including the primary mirrors, secondary mirror, and the Aft Optics Subsystems (AOS) are designed to be passively cooled and operate at near 45 degrees Kelvin. Due to the size of its large sunshield in relation to existing test facilities, JWST cannot be optically or thermally tested as a complete observatory-level system at flight temperatures. As a result, the telescope portion along with its instrument complement will be tested as a single unit very late in the program, and on the program schedule critical path. To mitigate schedule risks, a set of 'pathfinder' cryogenic tests will be performed to reduce program risks by demonstrating the optical testing capabilities of the facility, characterizing telescope thermal performance, and allowing project personnel to learn valuable testing lessons off-line. This paper describes the 'pathfinder' cryogenic test program, focusing on the recently completed second test in the series called the Optical Ground Support Equipment 2 (OGSE2) test. The JWST OGSE2 was successfully completed within the allocated project schedule while faced with numerous conflicting thermal requirements during cool-down to the final cryogenic operational temperatures, and during warm-up after the cryo-stable optical tests. The challenges include developing a pre-test cool-down and warm-up profiles without a reliable method to predict the thermal behaviors in a rarified helium environment, and managing the test article hardware safety driven by the project Limits and Constraints (L&C's). Furthermore, OGSE2 test included the time critical Aft Optics Subsystem (AOS), a part of the flight Optical Telescope Element that would need to be placed back in the overall telescope assembly integrations. The OGSE2 test requirements included the strict adherence of the project contamination controls due to the presence of the contamination sensitive flight optical elements. The test operations required close coordination of numerous personnel while they being exposed and trained for the 'final' combined OTE and instrument cryo-test in 2017. This paper will also encompass the OGSE2 thermal data look-back review.

JWST OGSE2 Cryogenic Test↗

NASA NTRS2017

Cryogenic Testing of the Thermal Vacuum Chamber and Ground Support Equipment for the James Webb Space Telescope in Chamber A at Johnson Space Center

The James Webb Space Telescope (JWST) is the largest cryogenic instrument telescope to be developed for space flight. The telescope will be passively cooled to 50 K and the instrument package will be at 40 K with the mid-infrared instrument at 6 K. The final cryogenic test of the Optical Telescope Element (OTE) and Integrated Science Instrument Module (ISIM) as an assembly (OTE + ISIM OTIS) will be performed in the largest 15 K chamber in the world, Chamber A at Johnson Space Center. The planned duration of this test will be 100 days in the middle of 2017. Needless to say, this ultimate test of OTIS, the cryogenic portion of JWST will be crucial in verifying the end-to-end performance of JWST. A repeat of this test would not only be expensive, but would delay the launch schedule (currently October 2018). Therefore a series of checkouts and verifications of the chamber and ground support equipment were planned and carried out between 2012 and 2016. This paper will provide a top-level summary of those tests, trades in coming up with the test plan, as well as some details of individual issues that were encountered and resolved in the course of testing.

thermal vacuum chamber↗

NASA NTRS2017

Research and Development History of Glass Bubbles Bulk-Fill Thermal Insulation Systems for Large-Scale Cryogenic Liquid Hydrogen Storage Tanks

Based on the published literature record, this document provides an overview of the research and development of glass bubbles bulk-fill thermal insulation systems for cryogenic equipment in general and, in particular, for large-scale cryogenic liquid hydrogen (LH2) storage spheres. Glass bubbles (also known as hollow glass microspheres) are used in place of perlite powder which began use in double-wall cryogenic tanks in the 1930s. Included in this overview is a historical summary, a development timeline, a selected publications list, and the key technical points from those publications.

Cryogenic storage tanks↗

NASA NTRS2016

Cryogenic Selective Surfaces

There are many challenges involved in deep-space exploration, but several of these can be mitigated, or even solved, by the development of a coating that can reject most of the Sun's energy and yet still provide some far-infrared heat emission. Such a coating would allow non-heat-generating objects in space to reach cryogenic temperatures without using an active cooling system. This would be a benefit to deep-space sensors that require low temperatures, such as the James Webb Telescope focal plane array. It would also allow the use of superconductors in deep space, which could lead to magnetic energy storage rings, lossless power delivery, or perhaps a large-volume magnetic shield against galactic cosmic radiation. But perhaps the most significant enablement achieved from such a coating would be the long-term storage in deep space of cryogenic liquids, such as liquid oxygen (LOX).In this report, we review the state of the art in low-temperature coatings and calculate the lowest temperatures each of these can achieve, demonstrating that cryogenic temperatures cannot be reached in deep space in this fashion. We then propose a new coating that does allow coated objects in deep space to achieve the very low temperatures required to store liquid oxygen or nitrogen. These new coatings consist of a moderately thick scattering layer (typically 5 mm) composed of a material transparent to most of the solar spectrum. This layer acts as a scatterer to the Sun's light, performing the same process as titanium dioxide in white paint in the visible. Under that layer, we place a metallic reflector, e.g. silver, to reflect long-wave radiation that is not well scattered. The result is a coating we call "Solar White," in that it scatters most of the solar spectrum just as white paint does for the visible. Our modeling of these coatings has shown that temperatures as low as 50 K can be reached for a coated object fully exposed to sunlight at 1 AU from the Sun and far from the Earth.In the second half of the report we explore a mission application of this coating in order to show that it allows LOX to be carried on a mission to Mars. Heat can reach a LOX tank in five ways: direct radiation from the Sun, scattered or reflected radiation from the Sun off of spacecraft components, radiation from nearby planets or the Moon, radiation from the infrared emission of other parts of the spacecraft, and conduction along support struts and flow lines. We discuss these and sum their total contribution when using a Solar White coating to demonstrate an architecture that allows the transportation of LOX to Mars. After this, other applications of Solar White are listed.

Cryogenic Materials↗

NASA NTRS2014

Influential Factors for Liquid Acquisition Device Screen Selection for Cryogenic Propulsion Systems

This paper presents the influential factors which govern screen selection for liquid acquisition devices (LADs) operating in microgravity conditions for future in-space cryogenic propulsion engines and cryogenic propellant depots. Space flight requirements, which include mass flow rate, acceleration level and direction, and thermal environment, dictate screen selection for a particular mission. The five influential factors include bubble point pressure, flow-through-screen pressure drop, wicking rate, screen compliance, and material compatibility. Governing equations and analytical models for these parameters are developed from first principles. A comprehensive survey of the historical data on coarser LAD meshes over four decades of work is conducted, and liquid hydrogen data for finer Dutch Twill meshes (325 x 2300, 450 x 2750, 510 x 3600) from recently concluded experiments is also presented to validate analytical models. Each of these parameters is measurable from ground based tests, making it facile to predict flight system performance. Therefore analytical models in this paper will be valuable for future LAD designs for both cryogenic and storable propulsion systems. Additionally, analysis will be given on the impact of the factors on liquid hydrogen systems.

Fuel Depot↗

NASA NTRS2016

Cryogenic Low Noise MMIC Amplifiers for U-Band (40-60 GHz)

In this work, we describe monolithic millimeter-wave integrated circuit (MMIC) Low Noise Amplifier (LNA) and mixer designs for U-Band, also known as the WR19 waveguide band (40-60 GHz). The LNAs were fabricated in NGC’s 35 nm InP HEMT MMIC process. The MMICs were packaged in WR19 waveguide housings and tested for noise, both at room temperature and cryogenically. We present the results, including a comparison to the state-of-the-art, and discuss applications for amplifiers in this frequency range. To date, these are the first cryogenic 35 nm InP MMIC results covering the 40-60 GHz range. We achieved a noise temperature less than 30 K over the 40-60 GHz range, when the amplifiers were cryogenically cooled. These results are comparable with other results in the literature, and we believe are the lowest reported for MMICs in the 50-60 GHz range.

MMIC↗

NASA NTRSDate not supplied

A Cryogenically-Cooled MW Inverter for Electric Aircraft Propulsion

Power electronic converter will be a key enabler for future electrified aircraft propulsion system. In aircraft applications, superconducting technologies such as superconducting motors and generators along with supporting power systems will grow in importance. Utilizing cryogenic cooling for power converter potentially can significantly improve the inverter system efficiency and specific power. This paper presents the cooling, hardware,and testing of a cryogenically-cooled MW inverter developed for electrified aircraft propulsion system. The 1 MVA full load testing with cryogenic cooling is demonstrated. The developed inverter system achieves 18 kVA/kg specific power and 99% efficiency, which provides a promising solution to achieve high power density and efficiency for future electrified aircraft propulsion system.

cryogenically-cooled inverter↗

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. To gain confidence in these computational models, appropriate anchoring and validation to experimental data in a relevant environment needs to be performed. Recent ground and sub-orbital flight experiments conducted by the Japan Aerospace Exploration Agency (JAXA) investigated chilldown of a complex channel resembling a turbopump bearing cavity at low flow rates. This work presents Computational Fluid Dynamics (CFD) model development of the chilldown experiment employing two-phase flow boiling models available in commercial CFD software STAR-CCM+ using Volume of Fluid (VOF) and the traditional Euler-Euler multiphase flow solvers. Comparisons of the numerical and experimental results under normal and low-gravity conditions are presented. An assessment of solid wall temperatures and phase distribution yielded important insights into multiphase solver choice, dependence on gravity environment, and challenges associated with cryogenic flow boiling prediction and validation.

CFD↗

NASA NTRSDate not supplied

Autogenous Pressurization of a Cryogenic Tank Using Computational Fluid Dynamics

Well-validated simulation tools can be used to predict long-term storage and transfer of cryogenic propellants, which are essential to NASA’s mission plan to return to the Moon and continue to Mars. Autogenous pressurization of propellant tanks is used to supply rocket engine turbopumps with pressurized liquid fuel and oxidizer, preventing cavitation. Additionally, autogenous pressurization can be used to pressurize propellant tanks to support on-orbit propellant transfer. In lieu of expensive tests conducted on-orbit, accurate predictive computational models of these processes can be used to reduce system and propellant mass as well as mission risk. Using simulation tools also reduces the cost of analyzing and developing this technology. This study presents a multiphase computational fluid dynamics model capable of simulating autogenous pressurization of a large cryogenic tank using the commercial code STAR-CCM+. Experimental data from a full-scale tank pressurization test under terrestrial gravity is compared to simulation results using transient error metrics. Comparisons show good agreement and give confidence in using these and other validated simulation tools to develop cryogenic pressurization systems.

Cryogenics↗

NASA NTRSDate not supplied

Autogenous Pressurization of a Cryogenic Tank using Computational Fluid Dynamics

cryogenics↗