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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 145 records · Page 8
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NASA NTRS2021

From Starspots to Stellar Coronal Mass Ejections Revisiting Empirical Stellar Relations

Upcoming missions, including the James Webb Space Telescope, will soon characterize the atmospheres of terrestrial-type exoplanets in habitable zones around cool K- and M-type stars searching for atmospheric biosignatures. Recent observations suggest that the ionizing radiation and particle environment from active cool planet hosts may be detrimental for exoplanetary habitability. Since no direct information on the radiation field is available, empirical relations between signatures of stellar activity, including the sizes and magnetic fields of starspots, are often used. Here, we revisit the empirical relation between the starspot size and the effective stellar temperature and evaluate its impact on estimates of stellar flare energies, coronal mass ejections, and fluxes of the associated stellar energetic particle events.

Konstantin Herbst↗
NASA NTRS1993

Moving-Temperature-Gradient Heat-Pipe Furnace Element

In improved apparatus, ampoule of material directionally solidified mounted in central hole of annular heat pipe, at suitable axial position between heated and cooled ends. Heated end held in fixed position in single-element furnace; other end left in ambient air or else actively cooled. Gradient of temperature made to move along heat pipe by changing pressure of noncondensable gas. In comparison with prior crystal-growing apparatuses, this one simpler, smaller, and more efficient.

Gillies, Donald C.↗
NASA NTRS1995

High-Aspect-Ratio Cooling Channel Concept Tested in Lewis' Rocket Engine Test Facility

Rocket combustion chamber walls are exposed to the high-temperature environment caused by the combustion of propellants. Even with the walls actively cooled by the fuel, the hot gases can deteriorate the walls severely and limit any possibility for reusing the combustion chamber. For many years, the NASA Lewis Research Center has performed subscale investigations of potential improved cooling concepts to extend the life and reliability of the combustion chamber. Results from previous subscale tests have shown that, by increasing the coolant channel height-to-width aspect ratio, the rocket combustion chamber hot gas side wall temperature can be reduced by as much as 28 percent, without an increase in the coolant pressure drop. Recently, a series of experiments were completed in Lewis' Rocket Engine Test Facility (RETF) to validate the benefits of high aspect ratio cooling channels with a high-pressure, contoured rocket combustion chamber.

Source record↗
NASA NTRS1997

Operational Characteristics of Four Commercially Available Personal Cooling Vests

Personal thermoregulatory systems which provide chest cooling are used in the industrial and aerospace environments to alleviate thermal stress. However, little information is available regarding the physiologic and circulatory changes produced by routine operation of these systems. The objectives of this study were to compare the effectiveness of two passive and two active cooling vests, and to measure the body temperature and circulatory changes produced by each cooling vest configuration. The MicroClimate Systems and the Life Enhancement Tech(LET) lightweight liquid cooling vests, the Steele Vest and LET's Zipper Front Garment were used to cool the chest region of 11 male and 10 female subjects (25 to 55 yr.) in this study. Calf, forearm and finger blood flows were measured using a tetrapolar impedance rheograph. The subjects, seated in an upright position at normal room temperature (approx.21 C), were tested for 60 min. with the cooling system operated at its maximum cooling capacity. Blood flows were recorded continuously using a computer data acquisition system with a sampling frequency of 250 Hz. Oral, right and left ear temperatures and cooling system parameters were logged manually every 5 min. Arm, leg, chest and rectal temperatures; heart rate; respiration; and an activity index were recorded continuously on a URI Inc. Biolog ambulatory monitor. In general, the male and female subjects' rectal and ear temperature responses to cooling were similar for all vest configurations tested. Oral temperatures during the recovery period were significantly (P<0.05) lower than during the control period, approx.0.2 - 0.5 C, for both men and women wearing any of the four different garments. The corresponding car temperatures were significantly (P<0.05) decreased approx.0.2 - 0.3 C by the end of the recovery period. Compared to the control period, no significant differences were found in rectal temperatures during cooling and recovery periods. These results show that all vest configurations elicit a similar thermal response in both male and female subject groups. However, subject population variance was rather large and may have masked differences between the vests. One vest may prove more effective than another for a given individual, and experience is the only means of determining this.

Ku, Yu-Tsuan E.↗
NASA NTRS2015

Reduced Boil-Off System Sizing

NASA is currently developing cryogenic propellant storage and transfer systems for future space exploration and scientific discovery missions by addressing the need to raise the technology readiness level of cryogenic fluid management technologies. Cryogenic propellants are baselined in many propulsion systems due to their inherently high specific impulse; however, their low boiling points can cause substantial boil-off losses over time. Recent efforts such as the Reduced Boil-off Testing and the Active Thermal Control Scaling Study provide important information on the benefit of an active cooling system applied to LH2 propellant storage. Findings show that zero-boil off technologies can reduce overall mass in LH2 storage systems when low Earth orbit loiter periods extend beyond two months. A significant part of this mass reduction is realized by integrating two stages of cooling: a 20 K stage to intercept heat at the tank surface, and a 90 K stage to reduce the heat entering the less efficient 20 K stage. A missing element in previous studies, which is addressed in this paper, is the development of a direct method for sizing the 90 K cooling stage. Such a method requires calculation of the heat entering both the 90 K and 20 K stages as compared to the overall system masses, and is reliant upon the temperature distribution, performance, and unique design characteristics of the system in question. By utilizing the known conductance of a system without active thermal control, the heat being intercepted by a 90 K stage can be calculated to find the resultant lift and mass of each active thermal control stage. Integral to this is the thermal conductance of the cooling straps and the broad area cooling shield, key parts of the 90 K stage. Additionally, a trade study is performed to show the ability of the 90 K cooling stage to reduce the lift on the 20 K cryocooler stage, which is considerably less developed and efficient than 90 K cryocoolers.

Cryogenic fluid management↗
NASA NTRS2015

Cryogenic Selective Surface - How Cold Can We Go?

Selective surfaces have wavelength dependent emissivitya bsorption. These surfaces can be designed to reflect solar radiation, while maximizing infrared emittance, yielding a cooling effect even in sunlight. On earth cooling to -50 C below ambient has been achieved, but in space, outside of the atmosphere, theory using ideal materials has predicted a maximum cooling to 40 K! If this result holds up for real world materials and conditions, then superconducting systems and cryogenic storage can be achieved in space without active cooling. Such a result would enable long term cryogenic storage in deep space and the use of large scale superconducting systems for such applications as galactic cosmic radiation (GCR) shielding and large scale energy storage.

Emmissivity↗
NASA NTRSDate not supplied

Thermal-Fluid Analysis of a Liquid-Cooled Battery Module for Electrified Aircraft

The development of safe, energy-dense batteries is critical to advancing hybrid electric and fully electrified aircraft propulsion. Achieving this capability requires a thermal management system that can maintain battery performance and safety under demanding operational conditions. The objective of this project is to support the maturation of next-generation lithium-ion batteries for electrified aircraft by conducting performance testing on integrated battery modules, specifically a 2-cell series configuration module housed within an aluminum enclosure. Designed to operate at a nominal 7.2 V with discharge rates up to 2.5C, the module will eventually be used to power an electric motor and DC-DC converter, generating substantial thermal loads that must be effectively managed to increase the usable energy and power density of electrified aircraft. To address these thermal challenges, this study presents the development and thermal-fluid analysis of a liquid-cooled thermal management system. While the full aircraft architecture utilizes an eight-string configuration, the present work evaluates a representative single-string water coolant loop to characterize baseline performance. The active cooling loop circulates water through a reservoir, pump, the battery module, and a variable area flow meter. Key performance metrics including component-level temperatures, mass flow rates, and pressure drops are quantified across the loop. Across discharge rates ranging from 0.5C to 2.5C, the active thermal loop consistently and effectively removed heat from the module, validating the design approach and confirming readiness for further development. The validated thermal performance indicates a path toward scalable battery modules that could enable energy and power dense systems for hybrid electric aircraft.

Electrified Aircraft↗
NASA NTRS2019

Multiple Boundary Layer Instability Modes with Nonequilibrium and Wall Temperature Effects Using LASTRAC

Prediction and control of boundary layer transition from laminar to turbulent is important to many flow regimes and vehicle designs, including vehicles operating at hypersonic conditions where nonequilibrium effects may be encountered. Wall cooling is known to affect the instability characteristics of the boundary layer and subsequently the transition location. Design considerations, including material failure and fuel chemistry, require the use of actively cooled walls in hypersonic vehicles, further motivating the study of wall temperature effects on top of the considerations of reducing heat flux, drag, and uncertainty. In this work, we analyze the stability of a boundary layer with chemical and thermal nonequilibrium on a Mach 20, 6 wedge. We investigate the effects of wall temperature on multiple unstable modes individually and on the integrated growth of disturbances along the surface. We use the LAngley Stability and TRansition Analysis Code (LASTRAC) to evaluate boundary layer stability, using capabilities implemented by the authors. Included are results that address chemical nonequilibrium with both thermal equilibrium and nonequilibrium.

Kline, H. L.↗
NASA NTRS2009

The James Webb Space Telescope: Mission Overview and Status

The James Webb Space Telescope (JWST) is the infrared successor to the Hubble Space Telescope. It is a cryogenic infrared space observatory with a 25 sq. m aperture (6 m telescope yielding diffraction limited angular resolution at a wavelength of 2 micron. The science instrument payload includes three passively cooled near-infrared instruments providing broad- and narrow-band imagery, coronagraphy, as well as multi object and integral-field spectroscopy over the 0.6 < 0 < 5.0 micron spectrum. An actively cooled mid-infrared instrument provides broad-band imagery, coronagraphy, and integral-field spectroscopy over the 5.0 < 0 < 29 micron spectrum. The JWST is being developed by NASA, in partnership with the European and Canadian Space Agencies, as a general user facility with science observations to be proposed by the international astronomical community in a manner similar to the Hubble Space Telescope. Technology development and mission design are complete, and construction is underway in all areas of the program. The JWST is on schedule to reach launch readiness during 2014.

Greenhouse, Matthew A.↗
NASA NTRS2011

The James Webb Space Telescope: Mission Overview and Status

The James Webb Space Telescope (JWST) is the Infrared successor to the Hubble Space Telescope. It is a cryogenic infrared space observatory with a 25 sq m aperture (6 m class) telescope yielding diffraction limited angular resolution at a wave1ength of 2 micron. The science instrument payload includes three passively cooled near-infrared instruments providing broad- and narrow-band imagery, coronagraphy, as well as multi-object and integral-field spectroscopy over the 0.6 <lambda < 5.0 micron spectrum. An actively cooled mid-infrared instrument provides broad-band imagery, coronagraphy, and integral-field spectroscopy over the 5.0 < lambda < 29 micron spectrum. The JWST is being developed by NASA, in partnership with the European and Canadian Space Agencies, as a general user facility with science observations to be proposed by the international astronomical community in a manner similar to the Hubble Space Telescope. Technology development and mission design are complete, and construction is underway in all areas of the program.

Greenhouse, Matthew A.↗
NASA NTRS2014

The JWST Science Instrument Payload: Mission Context and Status

The James Webb Space Telescope (JWST) is the scientific successor to the Hubble Space Telescope. It is a cryogenic infrared space observatory with a 25 sq m aperture (6 m class) telescope that will achieve diffraction limited angular resolution at a wavelength of 2 microns. The science instrument payload includes four passively cooled near-infrared instruments providing broad- and narrow-band imagery, coronography, as well as multi-object and integral-field spectroscopy over the 0.6 < lambda < 5.0 microns spectrum. An actively cooled mid-infrared instrument provides broad-band imagery, coronography, and integral-field spectroscopy over the 5.0 < lambda < 29 microns spectrum. The JWST is being developed by NASA, in partnership with the European and Canadian Space Agencies, as a general user facility with science observations to be proposed by the international astronomical community in a manner similar to the Hubble Space Telescope. Technology development and mission design are complete. Construction, integration and verification testing is underway in all areas of the program. The JWST is on schedule for launch during 2018.

cryogenic infrared space observatory↗
NASA NTRS2019

The James Webb Space Telescope: Mission Overview and Status

The James Webb Space Telescope (JWST) is the scientific successor to the Hubble Space Telescope. It is a cryogenic infrared space observatory with a 25 m2 aperture (6 m class) telescope that will achieve diffraction limited angular resolution at a wavelength of 2 um. The science instrument payload includes four passively cooled near-infrared instruments providing broad- and narrow-band imagery, coronography, as well as multi-object and integral-field spectroscopy over the 0.6 < λ < 5.0 µm spectrum. An actively cooled mid-infrared instrument provides broad-band imagery, coronography, and integral-field spectroscopy over the 5.0 < λ < 29 µm spectrum. The JWST is being developed by NASA, in partnership with the European and Canadian Space Agencies, as a general user facility with science observations proposed by the international astronomical community in a manner similar to the Hubble Space Telescope. Technology development and mission design are complete. Construction, integration and verification testing is underway in all areas of the program. The JWST is on schedule for launch during 2021.

Greenhouse, Matthew↗
NASA NTRS2022

Extreme Energetic Particle Events By Superflare-Associated CMES From Solar-Like Stars

Discovery of frequent superflares on active cool stars opened a new avenue in understanding the properties of eruptive events and their impact on exoplanetary environments. Solar data suggest that coronal mass ejections (CMEs) should be associated with superflares on active solar-like planet hosts and produce solar/stellar energetic particle (SEP/StEP) events. Here, we apply the 2D Particle Acceleration and Transport in the Heliosphere model to simulate the SEPs accelerated via CME-driven shocks from the Sun and young solar-like stars. We derive the scaling of SEP fluence and hardness of energy spectra with CME speed and associated flare energy. These results have crucial implications for the prebiotic chemistry and expected atmospheric biosignatures from young rocky exoplanets as well as the chemistry and isotopic composition of circumstellar disks around infant solar-like stars.

Junxiang Hu↗
NASA NTRS1990

Thermal/structural analyses of several hydrogen-cooled leading-edge concepts for hypersonic flight vehicles

The aerodynamic heating at high flight Mach numbers, when shock interference heating is included, can be extremely high and can exceed the capability of most conventional metallic and potential ceramic materials available. Numerical analyses of the heat transfer and thermal stresses are performed on three actively cooled leading-edge geometries (models) made of three different materials to address the issue of survivability in a hostile environment. These analyses show a mixture of results from one configuration to the next. Results for each configuration are presented and discussed. Combinations of enhanced internal film coefficients and high material thermal conductivity of copper and tungsten are predicted to maintain the maximum wall temperature for each concept within acceptable operating limits. The exception is the TD nickel material which is predicted to melt for most cases. The wide range of internal impingement film coefficients (based on correlations) for these conditions can lead to a significant uncertainty in expected leading-edge wall temperatures. The equivalent plastic strain, inherent in each configuration which results from the high thermal gradients, indicates a need for further cyclic analysis to determine component life.

Gladden, Herbert J.↗
NASA NTRS1990

Thermal/structural analyses of several hydrogen-cooled leading-edge concepts for hypersonic flight vehicles

The aerodynamic heating at high flight Mach numbers, when shock interference heating is included, can be extremely high and can exceed the capability of most conventional metallic and potential ceramic materials available. Numerical analyses of the heat transfer and thermal stresses are performed on three actively cooled leading-edge geometries (models) made of three different materials to address the issue of survivability in a hostile environment. These analyses show a mixture of results from one configuration to the next. Results for each configuration are presented and discussed. Combinations of enhanced internal film coefficients and high material thermal conductivity of copper and tungsten are predicted to maintain the maximum wall temperature for each concept within acceptable operating limits. The exception is the TD nickel material which is predicted to melt for most cases. The wide range of internal impingement film coefficients (based on correlations) for these conditions can lead to a significant uncertainty in expected leading-edge wall temperatures. The equivalent plastic strain, inherent in each configuration which results from the high thermal gradients, indicates a need for further cyclic analysis to determine component life.

Gladden, Herbert J.↗
NASA NTRS1999

A High Spatial Resolution Study of Far IR Emission of Galaxies

This grant funded observations and data reduction on the Kuiper Airborne Observatory. The research project was successfully completed. New insights into the distribution of far infrared emission across star-forming galaxies was obtained, and student training was achieved. The efforts contributed towards new observing strategies that will impact future NASA missions. The results of the effort have been presented in several papers in the refereed literature, including: "Morphology of Far Infrared Emission in Galaxies". "Far Infrared Thermal Emission from the Inner Cooling Flow Region of NGC1275". "Distribution of Light in the'Dusty-Hand'Galaxy NGC2146". Presentations of the results of this program have also been given at the following meetings and symposia: "High Spatial Resolution Study of the Active Cooling Flow Galaxy NGC 1275" "The Extent of Far IR Emission in Luminous Galaxies".

Lester, Dan↗
NASA NTRS2015

The JWST Science Instrument Payload: Mission Context and Status

The James Webb Space Telescope (JWST) is the scientific successor to the Hubble Space Telescope. It is a cryogenic infrared space observatory with a 25 sq m aperture (6 m class) telescope that will achieve diffraction limited angular resolution at a wavelength of 2 micrometers. The science instrument payload includes four passively cooled near-infrared instruments providing broad- and narrow-band imagery, coronography, as well as multi-object and integral-field spectroscopy over the 0.6 is less than lambda is less than 5.0 micrometers spectrum. An actively cooled mid-infrared instrument provides broad-band imagery, coronography, and integral-field spectroscopy over the 5.0 is less than lambda is less than 29 micrometers spectrum. The JWST is being developed by NASA, in partnership with the European and Canadian Space Agencies, as a general user facility with science observations proposed by the international astronomical community in a manner similar to the Hubble Space Telescope. Technology development and mission design are complete. The science instrument payload is in the final stage of testing ahead of delivery for integration with the telescope during early 2016. The JWST is on schedule for launch during 2018.

narrow-band imagery↗
NASA NTRS2014

Design Concepts for Cooled Ceramic Matrix Composite Turbine Vanes

This project demonstrated that higher temperature capabilities of ceramic matrix composites (CMCs) can be used to reduce emissions and improve fuel consumption in gas turbine engines. The work involved closely coupling aerothermal and structural analyses for the first-stage vane of a high-pressure turbine (HPT). These vanes are actively cooled, typically using film cooling. Ceramic materials have structural and thermal properties different from conventional metals used for the first-stage HPT vane. This project identified vane configurations that satisfy CMC structural strength and life constraints while maintaining vane aerodynamic efficiency and reducing vane cooling to improve engine performance and reduce emissions. The project examined modifications to vane internal configurations to achieve the desired objectives. Thermal and pressure stresses are equally important, and both were analyzed using an ANSYS® structural analysis. Three-dimensional fluid and heat transfer analyses were used to determine vane aerodynamic performance and heat load distributions.

Boyle, Robert↗