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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

An improved computer model for prediction of axial gas turbine performance losses

The calculation model performs a rapid preliminary pitchline optimization of axial gas turbine annular flowpath geometry, as well as an initial estimate of blade profile shapes, given only a minimum of thermodynamic cycle requirements. No geometric parameters need be specified. The following preliminary design data are determined: (1) the optimum flowpath geometry, within mechanical stress limits; (2) initial estimates of cascade blade shapes; and (3) predictions of expected turbine performance. The model uses an inverse calculation technique whereby blade profiles are generated by designing channels to yield a specified velocity distribution on the two walls. Velocity distributions are then used to calculate the cascade loss parameters. Calculated blade shapes are used primarily to determine whether the assumed velocity loadings are physically realistic. Model verification is accomplished by comparison of predicted turbine geometry and performance with an array of seven NASA single-stage axial gas turbine configurations.

Jenkins, R. M.↗
NASA NTRS1985

A two-photon laser-induced fluorescence field instrument for ground-based and airborne measurements of atmospheric NO

This paper reports on a new two-photon laser-induced fluorescence (TP-LIF) sensor capable of making routine measurements at the few parts per trillion volume level. This direct spectroscopic detection method has been demonstrated to be a reliable instrument while performing both on the ground and in the air. As currently designed it is unique in being 'signal' rather than 'signal-to-noise' limited. The latter characteristic enables the TP-LIF sensor to make atmospheric measurements of NO under environmental conditions that might normally be considered unsuitable for a laser technique. These include clouds, rain, and, in general, high-atmospheric-aerosol loading conditions. Of special interest is the insensitivity of the TP-LIF NO instrument to changes in pressure while operating in the troposphere. This characteristic has enabled this sensor to be used to record real-time altitude profiles of NO. Future improvements should make possible two measurement opportunities: (1) NO flux measurements via the airborne eddy-correlation method and (2) nitrogen isotopic distribution measurements (e.g., (N-15)(0-16) versus (N-14)(0-16) as a means of identifying specific NO(x) sources.

Bradshaw, J. D.↗
NASA NTRS2022

Dermatitis during Spaceflight Associated with HSV-1 Reactivation

Human alpha herpesviruses herpes simplex virus (HSV-1) and varicella zoster virus (VZV) establish latency in various cranial nerve ganglia and often reactivate in response to stress-associated immune system dysregulation. Reactivation of Epstein Barr virus (EBV), VZV, HSV-1, and cytomegalovirus (CMV) is typically asymptomatic during spaceflight, though live/infectious virus has been recovered and the shedding rate increases with mission duration. The risk of clinical disease, therefore, may increase for astronauts assigned to extended missions (>180 days). Here, we report, for the first time, a case of HSV-1 skin rash (dermatitis) occurring during long-duration spaceflight. The astronaut reported persistent dermatitis during flight, which was treated onboard with oral antihistamines and topical/oral steroids. No HSV-1 DNA was detected in 6-month pre-mission saliva samples, but on flight day 82, a saliva and rash swab both yielded 4.8 copies/ng DNA and 5.3 × 104 copies/ng DNA, respectively. Post-mission saliva samples continued to have a high infectious HSV-1 load (1.67 × 107 copies/ng DNA). HSV-1 from both rash and saliva samples had 99.9% genotype homology. Additional physiological monitoring, including stress biomarkers (cortisol, dehydroepiandrosterone (DHEA), and salivary amylase), immune markers (adaptive regulatory and inflammatory plasma cytokines), and biochemical profile markers, including vitamin/mineral status and bone metabolism, are also presented for this case. These data highlight an atypical presentation of HSV-1 during spaceflight and underscore the importance of viral screening during clinical evaluations of in-flight dermatitis to determine viral etiology and guide treatment.

Satish K. Mehta↗
NASA NTRSDate not supplied

Dermatitis During Spaceflight Associated With HSV-1 Reactivation- A Case Study

Human alpha herpesviruses herpes simplex virus (HSV-1 or -2) and varicella zoster virus (VZV) establish latency in various cranial nerve ganglia, and often reactivate in response to stress-associated immune system dysregulation. Reactivation of Epstein Barr Virus (EBV), VZV, HSV-1 and Cytomegalovirus (CMV) is typically asymptomatic during spaceflight, though live/infectious virus has been recovered and the shedding rate increases with mission duration. The risk of clinical disease, therefore, may increase for astronauts assigned to extended missions (>180 days). Here, we report for the first time, a case of HSV-1 skin rash (dermatitis) occurring during a long duration spaceflight. The astronaut reported persistent dermatitis during flight, which was treated onboard with oral antihistamines and topical/oral steroids. No HSV-1 DNA was detected in 6-month pre-mission saliva samples, but on flight day 82, a saliva and rash swab both yielded 4.8 copies/ng DNA and 5.3×104 copies/ng DNA, respectively. Post-mission saliva samples continued to have high infectious HSV-1 load (1.67×107 copies/ng DNA). HSV-1 from both rash and saliva samples had 99.4% genotype homology. Additional physiological monitoring, including stress biomarkers (cortisol, dehydroepiandrosterone (DHEA), and salivary amylase), immune markers (adaptive regulatory and inflammatory plasma cytokines) and biochemical profile markers including vitamin/mineral status and bone metabolism are also presented for this case. These data highlight an atypical presentation of HSV-1 during spaceflight and underscore the importance of viral screening during clinical evaluations of in-flight dermatitis, to determine viral etiology and guide treatment.

Herpes, Viral Reactivation, Spaceflight, Dermatiti↗
NASA NTRS1990

A real time neural net estimator of fatigue life

A neural net architecture is proposed to estimate, in real-time, the fatigue life of mechanical components, as part of the Intelligent Control System for Reusable Rocket Engines. Arbitrary component loading values were used as input to train a two hidden-layer feedforward neural net to estimate component fatigue damage. The ability of the net to learn, based on a local strain approach, the mapping between load sequence and fatigue damage has been demonstrated for a uniaxial specimen. Because of its demonstrated performance, the neural computation may be extended to complex cases where the loads are biaxial or triaxial, and the geometry of the component is complex (e.g., turbopump blades). The generality of the approach is such that load/damage mappings can be directly extracted from experimental data without requiring any knowledge of the stress/strain profile of the component. In addition, the parallel network architecture allows real-time life calculations even for high frequency vibrations. Owing to its distributed nature, the neural implementation will be robust and reliable, enabling its use in hostile environments such as rocket engines. This neural net estimator of fatigue life is seen as the enabling technology to achieve component life prognosis, and therefore would be an important part of life extending control for reusable rocket engines.

Troudet, T.↗
NASA NTRS1990

A real time neural net estimator of fatigue life

A neural network architecture is proposed to estimate, in real-time, the fatigue life of mechanical components, as part of the intelligent Control System for Reusable Rocket Engines. Arbitrary component loading values were used as input to train a two hidden-layer feedforward neural net to estimate component fatigue damage. The ability of the net to learn, based on a local strain approach, the mapping between load sequence and fatigue damage has been demonstrated for a uniaxial specimen. Because of its demonstrated performance, the neural computation may be extended to complex cases where the loads are biaxial or triaxial, and the geometry of the component is complex (e.g., turbopumps blades). The generality of the approach is such that load/damage mappings can be directly extracted from experimental data without requiring any knowledge of the stress/strain profile of the component. In addition, the parallel network architecture allows real-time life calculations even for high-frequency vibrations. Owing to its distributed nature, the neural implementation will be robust and reliable, enabling its use in hostile environments such as rocket engines.

Troudet, T.↗
NASA NTRS1997

Nonlinear Transient Thermal Analysis by the Force-Derivative Method

High-speed vehicles such as the Space Shuttle Orbiter must withstand severe aerodynamic heating during reentry through the atmosphere. The Shuttle skin and substructure are constructed primarily of aluminum, which must be protected during reentry with a thermal protection system (TPS) from being overheated beyond the allowable temperature limit, so that the structural integrity is maintained for subsequent flights. High-temperature reusable surface insulation (HRSI), a popular choice of passive insulation system, typically absorbs the incoming radiative or convective heat at its surface and then re-radiates most of it to the atmosphere while conducting the smallest amount possible to the structure by virtue of its low diffusivity. In order to ensure a successful thermal performance of the Shuttle under a prescribed reentry flight profile, a preflight reentry heating thermal analysis of the Shuttle must be done. The surface temperature profile, the transient response of the HRSI interior, and the structural temperatures are all required to evaluate the functioning of the HRSI. Transient temperature distributions which identify the regions of high temperature gradients, are also required to compute the thermal loads for a structural thermal stress analysis. Furthermore, a nonlinear analysis is necessary to account for the temperature-dependent thermal properties of the HRSI as well as to model radiation losses.

Balakrishnan, Narayani V.↗
NASA NTRS1984

The boundary layer on compressor cascade blades

The characteristics of the flow field about highly loaded turbocompressor blades in a cascade wind tunnel were investigated. Experimental tests were conducted at chord Reynolds number (R sub c) near 500,000. A laser Doppler anemometer was employed in flow velocity measurement. Suction surface mean velocity and turbulence intensity profiles at a single incidence angle are presented. These data contribute to further understanding of two-dimensional boundary layer profiles, points of separation, and transition zones for turbomachine blades, and concomitantly, to compressor cascade predictive models.

Deutsch, S.↗
NASA NTRS1999

Autolanding Trajectory Design for the X-34

An Autolanding I-load Program (ALIP) is developed to design unpowered autolanding trajectories for the X-34 Mach 8 vehicle. The trajectory is comprised of geometric flight segments that are based on the shuttle approach and landing design (steep glideslope, circular flare, exponential flare to shallow glideslope). Enforcing physical constraints such as loads, vertical descent rate, continuity and smoothness reduces the design problem to a two point boundary value problem with conditions on the initial and final dynamic pressure. Finding a solution required the development of trajectory simulation techniques that constrained the flight profile to a prescribed geometry. The design methodology can be extended beyond the autolanding flight regime by repeating the series of geometric segments and solving multiple two-point boundary values problems (one for each series). The techniques described in this paper facilitate rapid design of reference trajectories.

Barton, Gregg H.↗
NASA NTRS2016

Elevated Aerosol Layers and Their Radiative Impact over Kanpur During Monsoon Onset Period

Accurate information about aerosol vertical distribution is needed to reduce uncertainties in aerosol radiative forcing and its effect on atmospheric dynamics. The present study deals with synergistic analyses of aerosol vertical distribution and aerosol optical depth (AOD) with meteorological variables using multisatellite and ground-based remote sensors over Kanpur in central Indo-Gangetic Plain (IGP). Micro-Pulse Lidar Network-derived aerosol vertical extinction (sigma) profiles are analyzed to quantify the interannual and daytime variations during monsoon onset period (May-June) for 2009-2011. The mean aerosol profile is broadly categorized into two layers viz., a surface layer (SL) extending up to 1.5 km (where sigma decreased exponentially with height) and an elevated aerosol layer (EAL) extending between 1.5 and 5.5 km. The increase in total columnar aerosol loading is associated with relatively higher increase in contribution from EAL loading than that from SL. The mean contributions of EALs are about 60%, 51%, and 50% to total columnar AOD during 2009, 2010, and 2011, respectively. We observe distinct parabolic EALs during early morning and late evening but uniformly mixed EALs during midday. The interannual and daytime variations of EALs are mainly influenced by long-range transport and convective capacity of the local emissions, respectively. Radiative flux analysis shows that clear-sky incoming solar radiation at surface is reduced with increase in AOD, which indicates significant cooling at surface. Collocated analysis of atmospheric temperature and aerosol loading reveals that increase in AOD not only resulted in surface dimming but also reduced the temperature (approximately 2-3 C) of lower troposphere (below 3 km altitude). Radiative transfer simulations indicate that the reduction of incoming solar radiation at surface is mainly due to increased absorption by EALs (with increase in total AOD). The observed cooling in lower troposphere in high aerosol loading scenario could be understood as a dynamical feedback of EAL-induced stratification of lower troposphere. Further, the observed radiative effect of EALs increases the stability of the lower troposphere, which could modulate the large-scale atmospheric dynamics during monsoon onset period. These findings encourage follow-up studies on the implication of EALs to the Indian summer monsoon dynamics using numerical models.

aerosol vertical distribution↗
NASA NTRS1979

Evaluation of high-contact-ratio spur gears with profile modification

Scoring tests, surface fatigue tests, and single-tooth bending fatigue tests were conducted with four sets of spur gears of standard design and three sets of spur gears of new-tooth-form design. The new-tooth-form and standard gears scored at approximately the same gear bulk temperature of 409 K (277 F). The scoring load for the new-tooth-form gears was 22 percent less than that for the standard gears. The pitting fatigue lives of the standard and new-tooth-form gears were statistically equal for equal Hertz stress, while the surface fatigue life of the nw-tooth-form gears was approximately five times that of the standard gears at the same load. The standard gears failed at a 17 percent higher bending stress than the new-tooth-form gears when stress was calculated by the AGMA method. However, the difference is not statistically significant. The standard gears failed at a tooth load 1.9 times that for the new-tooth-form gears.

Towsend, D. P.↗
NASA NTRS1959

Experimental Investigation of a 0.35 Hub-Tip Radius Ratio Transonic Axial Flow Rotor Designed for 40 Pounds per Second per Square Foot with a Design Tip Diffusion Factor of 0.20

In order to determine the effect of a low design diffusion factor on the performance of a transonic axial-flow compressor rotor, a high-specific-flow rotor with a 0.35 hub-tip radius ratio was designed, fabricated and tested. This rotor used a design tip diffusion factor of 0.20 with a design corrected specific weight flow of 40 pounds per second per square foot of frontal area, a total-pressure ratio of 1.27, and an adiabatic efficiency of 0.96. The design, rotor performance, and blade element performance are presented with a discussion on rotor shock losses and a comparison with a similarly designed rotor with a tip diffusion factor of 0.35. At the design corrected tip speed of 1100 feet per second, a peak rotor adiabatic efficiency of 0.88 was attained at a corrected specific weight flow of 39 pounds per second per square foot of frontal area with a mass-averaged total-pressure ratio of 1.27. The blade element tip diffusion factor was 0.281, which is 0.08 higher than the design value of 0.20. Peak efficiencies of 0.95, 0.91, 0.89, and 0.85 were obtained at 70, 80, 90, and 110 percent of design speed, respectively. Comparison of the performance of the rotor reported herein and a similarly designed rotor with increased blade loading indicates that higher blade loading results in a more desirable rotor because of a higher pressure ratio and equivalent efficiency. Computed values of shock losses at the rotor tip section indicate that the losses at peak efficiency are primarily a function of shock losses since the profile losses are only a small percentage of the total loss.

Yasaki, Paul T.↗
NASA NTRS2000

Parametric Weight Comparison of Advanced Metallic, Ceramic Tile, and Ceramic Blanket Thermal Protection Systems

A parametric weight assessment of advanced metallic panel, ceramic blanket, and ceramic tile thermal protection systems (TPS) was conducted using an implicit, one-dimensional (I-D) finite element sizing code. This sizing code contained models to account for coatings fasteners, adhesives, and strain isolation pads. Atmospheric entry heating profiles for two vehicles, the Access to Space (ATS) vehicle and a proposed Reusable Launch Vehicle (RLV), were used to ensure that the trends were not unique to a certain trajectory. Ten TPS concepts were compared for a range of applied heat loads and substructural heat capacities to identify general trends. This study found the blanket TPS concepts have the lightest weights over the majority of their applicable ranges, and current technology ceramic tiles and metallic TPS concepts have similar weights. A proposed, state-of-the-art metallic system which uses a higher temperature alloy and efficient multilayer insulation was predicted to be significantly lighter than the ceramic tile stems and approaches blanket TPS weights for higher integrated heat loads.

Myers, David E.↗
NASA NTRSDate not supplied

Tailored Arrival Manager Plan for ecoD 2020

TAM is an automated approach to ensuring safe separation while maximizing throughput and efficiency; as currently conceived, it would serve as an ATC tool. TAM relies on NASA’s Autoresolver technology to compute trajectory-based arrival solutions that provide separation assurance while maximizing airspace and airport capacity utilization. In addition, TAM enables optimized profile descents that minimize altitude level offs and speed interruptions. Importantly, TAM trajectory clearances are intended for delivery to the flight deck through datacomm rather than voice-based communications. Once received on the flight deck, TAM solutions can be auto-loaded into a Flight Management System (FMS) for precision guidance and control along the intended arrival trajectory.

Richard A Coppenbarger↗
NASA NTRSDate not supplied

Impact of the ISS Environment on CNS in Drosophila Melanogaster

Altered gravity and elevated carbon dioxide (CO 2 ) levels as experienced on the ISS can adversely affect human health across various organ systems, especially the Central Nervous System (CNS). Investigating these changes is essential for understanding the long-term effects of spaceflight on human physiology to ensure crew health. Ground-based analogs provide an efficient method to evaluate alterations induced by chronic spaceflight on a larger scale. This study focuses on CNS changes in response to hypergravity (HG) and elevated CO 2 levels via a ground-based analog using the well-established model organism, Drosophila melanogaster. We hypothesize behavior and physiological changes immediately post exposure to HG+CO 2 , along with chronic effects up to 25 days post-exposure. Adult male and female flies were exposed to varying gravity loads (1g, 1.2g, and 3g) and elevated CO 2 levels (~4000 ppm, mimicking CO 2 levels on the ISS) for 15 days and were assessed immediately and at 5-, 10-, and 25-days post-exposure, mirroring astronauts’ post-return profiling. The flies were assessed for neurobehavioral changes, including longevity and negative geotaxis; brain morphological changes, such as dopaminergic neuron count, apoptosis, and glial cell density; and bioenergetic changes in the brain, including mitochondrial abundance and membrane potential. Longevity remained unchanged under hypergravity, even with the addition of elevated CO 2 as a stressor. However, despite the stable lifespan, quality of life appeared to be affected, as shown by negative geotaxis and neuroanatomical changes. Negative geotaxis testing revealed a reduction in motor ability at R0 across all conditions, which correlated with a decrease in dopaminergic (DA) neuron count. Additional observations suggested further systemic alterations, including a decrease in glial cell count, an increase in apoptosis, and notable bioenergetic changes. Collectively, these findings contribute to our understanding of the long-term effects of spaceflight on the CNS.

spaceflight↗
NASA NTRS1994

Hydro-isostatic deflection and tectonic tilting in the central Andes: Initial results of a GPS survey of Lake Minchin shorelines

Sufficiently large lake loads provide a means of probing rheological stratification of the crust and upper mantle. Lake Minchin was the largest of the late Pleistocene pluvial lakes in the central Andes. Prominent shorelines, which formed during temporary still-stands in the climatically driven lake level history, preserve records of lateral variations in subsequent net vertical motions. At its maximum extent the lake was 140 m deep and spanned 400 km N-S and 200 km E-R. The load of surficial water contained in Lake Minchin was sufficient to depress the crust and underlying mantle by 20-40 m, depending on the subjacent rheology. Any other differential vertical motions will also be recorded as departures from horizontality of the shorelines. We recently conducted a survey of shoreline elevations of Lake Minchin with the express intent of monitoring the hydro-isostatic deflection and tectonic tilting. Using real-time differential Global Positioning System (GPS), we measured topographic profiles across suites of shorelines at 15 widely separated locations throughout the basin. Horizontal and vertical accuracies attained are roughly 30 and 70 cm, respectively. Geomorphic evidence suggests that the highest shoreline was occupied only briefly (probably less than 200 years) and radiocarbon dates on gastropod shells found in association with the shore deposits constrain the age to roughly 17 kyr. The basin-side pattern of elevations of the highest shoreline is composed of two distinct signals: (27 +/- 1) m of hydro-isostatic deflection due to the lake load, and a planar tilt with east and north components of (6.8 +/- 0.4) 10(exp -5) and 9-5.3 +/- 0.3) 10(exp -5). This rate of tilting is too high to be plausibly attributed to steady tectonism, and presumably reflects some unresolved combination of tectonism plus the effects of oceanic and lacustrine loads on a laterally heterogeneous substrate. The history of lake level fluctuations is still inadequately known to allow detailed inferences of crust and mantle rheology. However, it is already clear that the effective elastic plate thickness is closer to 40 km than the 60-70 km crustal thickness in the central Andes and the effective viscosity is less than 5 10(exp 20) Pa s.

Bills, Bruce G.↗
NASA NTRS2018

Adaptive Load Control of Flexible Aircraft Wings Using Fiber Optic Sensing

Over the past century aircraft wing design has transformed from the morphing wing used on the Wright Flyer to rigid wings with little to no shape-tailoring abilities. Modern day wings are designed to fly at a single trim condition and optimized to have a maximum aerodynamic efficiency at only this condition. Shape morphing wings on the other hand have the potential to undergo geometric changes allowing them to adapt to their mission profiles. Several flight demonstrations have been conducted over the decades using morphing-wing technologies. Active wing-twist control was demonstrated on the X-53 Active Aeroelastic Wing (AAW) research project by utilizing multiple leading- and trailing-edge control surfaces. Passive morphing technology has been demonstrated on the Rockwell RPRV-870 Highly Maneuverable Aircraft Technology (HiMAT) aircraft. In the current study, the wings of a small unmanned aerial system (sUAS) were modified to have segmented control surfaces (SCS). The modifications include segmenting the original wing control surfaces (one flap and one aileron per wing) into 44 individual sections, each section having its own independent servo control motor. The wings were also instrumented with a network of over 1800 fiber-optic strain sensors (on four sensing fibers distributed over the top and bottom surfaces of the wing) monitoring the strain response of the wing to aerodynamic loading. The SCS positions were manipulated in real time to modify the spanwise lift distribution of the wings on the sUAS. The change in the structural response of the wings caused by load redistribution was quantified by measuring the bending strains on the upper and lower wing surfaces using an on-board compact fiber-optic strain sensing (cFOSS) system. A feedback controller was developed to control the SCS positions using strain-based shape estimations from the Displacement Transfer Function (DTF). Post-processing of the strain data allowed for the transverse displacement distributions and load distributions to be compared for the conventional and segmented control surface cases using displacements and loads algorithms developed by Richards and Ko at AFRC (refs. 5-10). While the current study focused on the shifting of the spanwise aerodynamic loads as quantified by displacements, future applications for loads or displacement control might include active gust alleviation and flutter suppression.

Pena, Francisco↗
NASA NTRS1983

Effect of oxygen concentration in ZDP containing oils on surface composition and wear

A pin-on-disk wear study was performed with the lubricants dibutyl sebacate (DBS) and mineral oil (MO) with and without 1 weight percent zinc-dialkyl-dithiophospatee (ZDP) as an additive. The pin was annealed pure iron and the disk was M-2 tool steel. The selected load and speed guaranteed boundary lubrication. The ambient atmospheric oxygen concentration in an oxygen-nitrogen mixture was varied from 0 percent to 20 percent in order to examine its relationship to ZDP effectiveness. Auger electron spectroscopy combined with argon ion bombardment (depth profiling) was used to determine surface elemental composition on the pin when tested in DBS with and without ZDP. The ambient atmosphere was found to cause large variations in wear rate and surface composition. With MO, ZDP reduced wear under all conditions, but had little advantage over oxides formed at 20 percent oxygen atmosphere. With DBS, ZDP reduced wear at 0 percent oxygen, but gave varied results at other oxygen concentrations. Depth profiling revealed sulfuide formation at 0 percent oxygen and probably sulfates at 20 percent oxygen. The results are significant because varied oxygen concentrations can occur under actual lubricating conditions in practical machinery.

Brainard, W. A.↗