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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

System-size dependence of charged-particle suppression in ultrarelativistic nucleus-nucleus collisions

High-energy partons lose energy while propagating through the hot, strongly interacting medium produced in ultrarelativistic nucleus-nucleus collisions, leading to a suppression of particle production at high transverse momentum (p T ). The dependence of this energy loss on the size of the colliding nuclear system has yet to be firmly established experimentally. This Letter presents a systematic study of charged-particle suppression across four different nucleus-nucleus collision systems using nuclear modification factors (R AA ) measured by the CMS Collaboration at the CERN LHC. Previous CMS measurements of R AA in oxygen-oxygen, xenon-xenon, and lead-lead collisions are recast with identical p T intervals and are complemented by the first measurement of the charged-particle R AA in neon-neon collisions at $\sqrt{S_{NN}}$ = 5.36 Te V . The neon-neon data correspond to an integrated luminosity of 0.76 nb −1 . The R AA in all collision systems examined show similar qualitative trends as a function of p T , but have a magnitude which is ordered with the nucleon number A. The R AA feature a downward slope at low p T , a local minimum at around 5–7 Ge V , and an upward slope with increasing p T . The R AA are also compared in terms of A 1/3 , which is proportional to the nuclear radius. Models including only initial-state nuclear effects fail to reproduce the observed trends, whereas energy loss models reproduce the trends in the region p T > 9.6 Ge V .

CMS↗
NASA NTRS2011

Dual Heat Pulse, Dual Layer Thermal Protection System Sizing Analysis and Trade Studies for Human Mars Entry Descent and Landing

NASA has been recently updating design reference missions for the human exploration of Mars and evaluating the technology investments required to do so. The first of these started in January 2007 and developed the Mars Design Reference Architecture 5.0 (DRA5). As part of DRA5, Thermal Protection System (TPS) sizing analysis was performed on a mid L/D rigid aeroshell undergoing a dual heat pulse (aerocapture and atmospheric entry) trajectory. The DRA5 TPS subteam determined that using traditional monolithic ablator systems would be mass expensive. They proposed a new dual-layer TPS concept utilizing an ablator atop a low thermal conductivity insulative substrate to address the issue. Using existing thermal response models for an ablator and insulative tile, preliminary hand analysis of the dual layer concept at a few key heating points indicated that the concept showed potential to reduce TPS masses and warranted further study. In FY09, the followon Entry, Descent and Landing Systems Analysis (EDL-SA) project continued by focusing on Exploration-class cargo or crewed missions requiring 10 to 50 metric tons of landed payload. The TPS subteam advanced the preliminary dual-layer TPS analysis by developing a new process and updated TPS sizing code to rapidly evaluate mass-optimized, full body sizing for a dual layer TPS that is capable of dual heat pulse performance. This paper describes the process and presents the results of the EDL-SA FY09 dual-layer TPS analyses on the rigid mid L/D aeroshell. Additionally, several trade studies were conducted with the sizing code to evaluate the impact of various design factors, assumptions and margins.

McGuire, Mary Kathleen↗
NASA NTRS1980

Smaller SPS system sizing tradeoffs

The solar power satellite and associated microwave system was reoptimized with larger antennas (at 2.45 GHz), reduced output powers, and smaller rectennas. Four constraints were considered: (1) the 23 mw/sq cm ionospheric limit; (2) a higher (54 mW/sq cm) ionospheric limit; (3) the 23 KW/sq cm thermal limit in the antenna; and (4) an improved thermal design allowing 33% additional waste heat. The differential costs in electricity for seven antenna/rectenna configurations operating at 2.45 GHz and five satellite systems operating at 5.8 GHz were calculated. It is concluded that a larger antenna/smaller rectenna configurations are economically feasible under certain conditions; a transmit antenna diameters should be limited to 1 to 1.5 Km for 2.45 GHz operation and .75 to 1.0 Km for 5.8 GHz; the present ionospheric limit of 23 mw/sq cm is probably too low and should be raised after ionospheric heating tests and studies are completed; the 5.8 GHz configurations are constrainted by antenna thermal limitations, rather than ionospheric limits; and multiple (two to four) antennas on a single solar satellite are recommended regardless of the particular antenna/rectenna configuration chosen.

Arndt, G. D.↗
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 NTRS1990

Comparison of drop size distributions from two droplet sizing systems

A comparison between the Phase Doppler Particle Analyzer and the combined measurements from Particle Measuring Systems' Forward Scattering Spectrometer Probe and the Optical Array Probe was conducted in an icing wind tunnel using NASA Icing Research Tunnel spray nozzles to produce the supercooled water droplet cloud. Clouds having a range of volume median diameters from 10 to greater than 50 microns were used for the instrument comparisons. A volume median diameter was calculated from combining the droplet distributions of the Optical Array Probe and the Forward Scattering Spectrometer Probe. A comparison of the combined volume median diameters and the Phase Doppler Particle Analyzer volume median diameters showed agreement from 10 microns up to 30 microns. Typical drop size distributions from the Phase Doppler Particle Analyzer, the Forward Scattering Spectrometer Probe, and Optical Array Probe are presented for several median volume diameters. A comparison of the distributions illustrates regions of the distributions where there is good agreement and other regions where there are discrepancies between the Phase Doppler Particle Analyzer and the Particle Measuring Systems' droplet size instruments.

Oldenburg, John R.↗
NASA NTRS1981

Solar power satellite system sizing tradeoffs

Technical and economic tradeoffs of smaller solar power satellite systems configured with larger antennas, reduced output power, and smaller rectennas, are considered. The differential costs in electricity for seven antenna/rectenna configurations operating at 2.45 GHz and five satellite systems operating at 5.8 GHz are calculated. Two 2.45 GHz configurations dependent upon the ionospheric power density limit are chosen as examples. If the ionospheric limit could be increased to 54 mW sq/cm from the present 23 mW sq/cm level, a 1.53 km antenna satellite operating at 2.45 GHz would provide 5.05 GW of output power from a 6.8 km diameter rectenna. This system gives a 54 percent reduction in rectenna area relative to the reference solar power satellite system at a modest 17 percent increase in electricity costs. At 5.8 GHz, an 0.75 km antenna providing 2.72 GW of power from a 5.8 km diameter rectenna is selected for analysis. This configuration would have a 67 percent reduction in rectenna area at a 36 percent increase in electricity costs. Ionospheric, atmospheric, and thermal limitations are discussed. Antenna patterns for three configurations to show the relative main beam and sidelobe characteristics are included.

Arndt, G. D.↗
NASA NTRSDate not supplied

Thermal Management System Sizing and Mission Analysis for the SUSAN Electrofan Aircraft

This paper will detail the design, sizing, and mission analysis for the thermal management system (TMS) for the Subsonic Single Aft eNgine (SUSAN) aircraft. Previous work has defined key performance parameters (KPPs) for the electrical power system on SUSAN. These KPPs, efficiency and specific power, were assigned values for each power system component at minimum, nominal, and maximum levels of technology development. The values were based on NASA’s research in Electrified Aircraft Propulsion (EAP) technology. A similar approach was taken in this work, defining and assigning values for KPPs for each component of the TMS. These KPPs are used as inputs to the TMS analysis and sizing and establish targets for future technology development. The minimum level is based on the current state of the art, using available data on commercial off-the-shelf products from suppliers, datasheets, or testing. The nominal level is based on recent published research and on-going NASA-funded work. The maximum level represents a projection of technology performance into the future.

Electrified Aircraft↗
NASA NTRS1974

Influence of propulsion system size, shape, and location on supersonic aircraft design

The effects of various propulsion system parameters on the characteristics of a supersonic transport were investigated. The effects of arbitrarily scaling engine size on wave drag, friction drag, drag-due-to-lift, wing sizing, airplane balance, and airplane weight were studied. These evaluations were made for two families of nacelle shapes, resulting from typical turbojet and turbofan installations. Also examined were effects of nacelle location, and the wing camber plane deformations required to cancel the nacelle interference pressure field at cruise Mach number (2.7 M) were determined. The most drag-sensitive parameter is found to be nacelle shape. Similarly, wing deformation requirements are found to be primarily affected by nacelle shape. Effects of engine size variations are noted primarily in airplane gross weight.

Bonner, E.↗
DOE OSTI2025

System size and energy dependence of the mean transverse momentum fluctuations at the LHC

Event-by-event fluctuations of the event-wise mean transverse momentum, $\langle$p T $\rangle$, of charged particles produced in proton–proton (pp) collisions at $\sqrt{s}$ = 5.02 TeV, Xe–Xe collisions at $\sqrt{s_{NN}}$ = 5.44 TeV, and Pb–Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV are studied using the ALICE detector based on the integral correlator $\langle$$\langle$Δp T Δp T $\rangle$$\rangle$. The correlator strength is found to decrease monotonically with increasing produced charged-particle multiplicity measured at midrapidity in all three systems. In Xe–Xe and Pb–Pb collisions, the multiplicity dependence of the correlator deviates significantly from a simple power-law scaling as well as from the predictions of the HIJING and AMPT models. The observed deviation from power-law scaling is expected from transverse radial flow in semicentral to central Xe–Xe and Pb–Pb collisions. In pp collisions, the correlation strength is also studied by classifying the events based on the transverse spherocity, S 0 , of the particle production at midrapidity, used as a proxy for the presence of a pronounced back-to-back jet topology. Low-spherocity (jetty) events feature a larger correlation strength than those with high spherocity (isotropic). The strength and multiplicity dependence of jetty and isotropic events are well reproduced by calculations with the PYTHIA 8 and EPOS LHC models.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS2006

The Effect of Forebody Geometry on Turbulent Heating and Thermal Protection System Sizing for Future Mars Mission Concepts

Past Mars entry missions have made extensive use of 70° sphere-cone forebody heatshields. This shape was chosen for its aerodynamic stability during direct entry, either ballistic or low L/D trajectories. Historic missions, including Viking in 1976, Pathfinder in1997, and Mars Rover in 2004, have provided a large aerodynamic and aerothermodynamic database for the70° sphere-cone shape that perpetuates continued use for future Mars missions. Using 3D Real-Gas Navier-Stokes simulations, we show that once turbulent heating occupies a significant portion of the mission trajectory, undesirable aerothermodynamic properties arise associated with the 70° sphere-cone heatshield geometry. As an additional consideration, the pitch angle to achieve high L/D of a Mars aerocapture trajectory mitigates the stability justification for the 70° sphere-cone. This suggests that alternative forebody geometries should be considered for future Mars missions.

Aeroheating↗
NASA NTRS1984

Discovery of solar system-size halos around young stars

Near-infrared speckle interferometric observations of five pre-main-sequence stars reveal a core-halo structure around two of these stars: HL Tau and R Mon. The halo light distribution is shown to arise from scattered light from small circumstellar particles. Halo sizes of 320 x 200 AU (alpha x delta FWHM) and 1300 x 1300 AU are deduced for HL Tau and R Mon, respectively, and the halo light is substantially bluer than the stellar light. The minimum mass of small particles in the scattering regions is comparable to the earth's mass in HL Tau and ten times greater in R Mon. Mass loss from the stars is almost certainly insufficient to produce the halo matter. The halos probably consist of relatively slowly moving matter bound gravitationally to the stars. From the size and mass of the circumstellar matter, it appears likely that these halos are in the early stage in the formation of planet-forming disks around the young stars.

Beckwith, S.↗
NASA NTRS1988

Comparison of UNL laser imaging and sizing system and a phase/Doppler system for analyzing sprays from a NASA nozzle

Aerosol spray characterization was done using a P/DPA and a laser imaging/video processing system on a NASA MOD-1 air-assist nozzle being evaluated for use in aircraft icing research. Benchmark tests were performed on monodispersed particles and on the NASA MOD-1 nozzle under identical laboratory operating conditions. The laser imaging/video processing system and the P/DPA showed agreement on calibration tests in monodispersed aerosol sprays of + or - 2.6 microns with a standard deviation of + or - 2.6 microns. Tests were performed on the NASA MOD-1 nozzle on the centerline and radially at one-half inch increments to the outer edge of the spray plume at a distance two feet (0.61 m) downstream from the exit of the nozzle. Comparative results at two operating conditions of the nozzle are presented for the two instruments. For the first case, the deviation in arithmetic mean diameters determined by the two instruments was in a range of 0.1 to 2.8 microns, and the deviation in Sauter mean diameters varied from 0 to 2.2 microns. Operating conditions in the second case were more severe which resulted in the arithmetic mean diameter deviating from 1.4 to 7.1 microns and the deviation in the Sauter mean diameters ranging from 0.4 to 6.7 microns.

Alexander, Dennis R.↗
NASA NTRS1990

Comparison of two droplet sizing systems in an icing wind tunnel

A comparison between the Phase Doppler Analyzer and the combined measurements from the Particle Measuring Systems Forward Scattering Spectrometer Probe and the Optical Array Probe was conducted in an icing wind tunnel using NASA Icing Research Tunnel spray nozzles to produce the icing cloud. Clouds with a range of volume median diameters from 10 to greater than 50 microns were used for the instrument comparisons. A comparison of the volume median diameter from the Phase Doppler Particle Analyzer and only the Forward Scattering Spectrometer Probe indicated agreement up to 18 microns. A combined volume median diameter was calculated from the droplet distribution of the Optical Array Probe and the Forward Scattering Spectrometer Probe. A comparison of the combined volume median diameters and the Phase Doppler Particle Analyzer volume median diameters showed agreement up to 30 microns with the agreement deteriorating rapidly above 30 microns. Droplet distributions from the Phase Doppler Particle Analyzer, the Forward Scattering Spectrometer Probe, and Optical Array Probe are presented.

Oldenburg, J. R.↗
NASA NTRS1990

Comparison of two droplet sizing systems in an icing wind tunnel

A comparison between the Phase Doppler Analyzer and the combined measurements from the Particle Measuring Systems Forward Scattering Spectrometer Probe and the Optical Array Probe was conducted in an icing wind tunnel using NASA Icing Research Tunnel spray nozzles to produce the icing cloud. Clouds with a range of volume median diameterss from 10 to greater than 50 microns were used for the instrument comparisons. A comparison of the volume median diameter from the Phase Doppler Particle Analyzer and only the Forward Scattering Spectrometer Probe indicated agreement up to 18 microns. A combined volume median diameter was calculated from the droplet distribution of the Optical Array Probe and the Forward Scattering Spectrometer Probe. A comparison of the combined volume median diameters and the Phase Doppler Particle Analyzer volume median diameters showed agreement up to 30 microns with the agreement deteriorating rapidly above 30 microns. Droplet distributions from the Phase Doppler Particle Analyzer, the Forward Scattering Spectrometer Probe, and Optical Array Probe are presented.

Oldenburg, John R.↗
NASA NTRS1990

Comparison of UNL laser imaging and sizing system and a phase Doppler system for analyzing sprays from a NASA nozzle

Research was conducted on characteristics of aerosol sprays using a P/DPA and a laser imaging/video processing system on a NASA MOD-1 air assist nozzle being evaluated for use in aircraft icing research. Benchmark tests were performed on monodispersed particles and on the NASA MOD-1 nozzle under identical lab operating conditions. The laser imaging/video processing system and the P/DPA showed agreement on a calibration tests in monodispersed aerosol sprays of + or - 2.6 micron with a standard deviation of + or - 2.6 micron. Benchmark tests were performed on the NASA MOD-1 nozzle on the centerline and radially at 0.5 inch increments to the outer edge of the spray plume at a distance 2 ft downstream from the exit nozzle. Comparative results at two operation conditions of the nozzle are presented for the two instruments. For the 1st case studied, the deviation in arithmetic mean diameters determined by the two instruments was in a range of 0.1 to 2.8 micron, and the deviation in Sauter mean diameters varied from 0 to 2.2 micron. Severe operating conditions in the 2nd case resulted in the arithmetic mean diameter deviating from 1.4 to 7.1 micron and the deviation in the Sauter mean diameters ranging from 0.4 to 6.7 micron.

Alexander, Dennis R.↗
NASA NTRS2000

Near-Infrared Interferometric Images of the Solar System Sized Disk Surrounding the Herbig Ae/Be Star MWC 349A

We present images of the Herbig Ae/Be star MWC 349A at 1.65 and 2.27, and 3.08 micrometers, reconstructed from complex visibility data obtained with an aperture masking interferometric technique on the Keck I telescope. These images have an approximately elliptical shape, and are consistent with the expected shape of a nearly edge-on Keplerian disk. Visibility data were fitted with uniform ellipses with major axes 36 +/- 2, 47 +/- 2, and 62 +/- 1 mas, respectively. The axial ratio of the ellipses is approximately 0.5 +/- 0.1, and the major axis is at a position angle of 100 +/- 3 degrees, consistent with the position angle of the dark lane observed previously in the Very Large Array (VLA) radio continuum maps at 8 and 22 GHz, perpendicular to the symmetry axis of the bipolar lobes of H66(alpha) recombination line emission, and consistent with positions of the recombination line maser spots at 1.3 mm. At an assumed distance of 1.2 kpc, the linear sizes of the disk are 44 and 57 AU at 1.65 and 2.2 micrometers, respectively. The disk is the presumed source of ionized material in the bipolar outflow and ultracompact HII region around the star.

Danchi, W.C.↗