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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 1,693 records · Page 94
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Comparison of temperature data from a four-vane static cascade and a research gas turbine engine for a chordwise-finned, impingement- and film-cooled vane

Experimental heat-transfer data obtained for a chordwise-finned, impingement- and film-cooled turbine vane tested in a four-vane static cascade to a gas temperature and a gas pressure of 2250 F and 80 psia, respectively, are presented. Average and local vane temperatures are correlated and compared with correlations of temperature data obtained from tests of the same vane in a modified J-75 turbojet engine. The measured vane temperatures obtained from these tests in the two test stands are also compared with analytically determined temperatures.

Gladden, H. J.↗
NASA NTRS1985

Constitutive modeling for isotropic materials (HOST)

This report presents the results of the second year of work on a problem which is part of the NASA HOST Program. Its goals are: (1) to develop and validate unified constitutive models for isotropic materials, and (2) to demonstrate their usefulness for structural analyses of hot section components of gas turbine engines. The unified models selected for development and evaluation are that of Bodner-Partom and Walker. For model evaluation purposes, a large constitutive data base is generated for a B1900 + Hf alloy by performing uniaxial tensile, creep, cyclic, stress relation, and thermomechanical fatigue (TMF) tests as well as biaxial (tension/torsion) tests under proportional and nonproportional loading over a wide range of strain rates and temperatures. Systematic approaches for evaluating material constants from a small subset of the data base are developed. Correlations of the uniaxial and biaxial tests data with the theories of Bodner-Partom and Walker are performed to establish the accuracy, range of applicability, and integability of the models. Both models are implemented in the MARC finite element computer code and used for TMF analyses. Benchmark notch round experiments are conducted and the results compared with finite-element analyses using the MARC code and the Walker model.

Lindholm, U. S.↗
DOE OSTI2017

Portable nitrous oxide sensor for understanding agricultural and soil emissions

Nitrous oxide (N2O) is the third most important greenhouse gas (GHG,) with an atmospheric lifetime of ~114 years and a global warming impact ~300 times greater than that of carbon dioxide. The main cause of nitrous oxide’s atmospheric increase is anthropogenic emissions, and over 80% of the current global anthropogenic flux is related to agriculture, including associated land-use change. An accurate assessment of N2O emissions from agriculture is vital not only for understanding the global N2O balance and its impact on climate but also for designing crop systems with lower GHG emissions. Such assessments are currently hampered by the lack of instrumentation and methodologies to measure ecosystem-level fluxes at appropriate spatial and temporal scales. Southwest Sciences and Princeton University are developing and testing new open-path eddy covariance instrumentation for continuous and fast (10 Hz) measurement of nitrous oxide emissions. An important advance, now being implemented, is the use of new mid-infrared laser sources that enable the development of exceptionally low power (<10 W) compact instrumentation that can be used even in remote sites lacking in power. The instrumentation will transform the ability to measure and understand ecosystem-level nitrous oxide fluxes. The Phase II results included successful extended field testing of prototype flux instruments, based on quantum cascade lasers, in collaboration with Michigan State University. Results of these tests demonstrated a flux detection limit of 5 µg m-2 s-1 and showed excellent agreement and correlation with measurements using chamber techniques. Initial tests of an instrument using an interband cascade laser (ICL) were performed, verifying that an order of magnitude reduction in instrument power requirements can be realized. These results point toward future improvements and testing leading to introduction of a commercial open path instrument for N2O flux measurements that is truly portable and cost-effective. The technology developed on this project is especially groundbreaking as it could be widely applied across FLUXNET and AmeriFlux sites (>1200 worldwide) for direct measurements of N2O exchange. The technology can be more broadly applied to gas monitoring requirements in industry, environmental monitoring, health and safety, etc.

47 OTHER INSTRUMENTATION↗
DOE OSTI2019

Development of a Corrosion Monitoring System for Advanced Molten Salt Reactors

Molten salt reactors (MSRs) have been identified as one of several possible next-generation advanced reactor designs that could replace the aging fleet. There are many inherent advantages to MSRs, including higher power density, lower pressure, low stored energy, and prompt negative temperature reactivity coefficient Ezell et al. [2018]. However, there are challenges related to the operating temperatures, as well as, the corrosive salts attacking the structural materials. During the Molten Salt Reactor Experiment (MSRE), which was operated at Oak Ridge National Laboratory (ORNL) (Ignatiev et al. [2014], Forsberg et al. [2007], Forsberg et al. [2008], Delpech et al. [2009], Serp et al. [2014], Ignatiev and Surenkov [2017]) corrosion was monitored by sampling the salt for chromium. However, this type of monitoring does not identify the location of corrosion. In FY18, ORNL developed a novel in-situ corrosion sensor that could be placed on the outside of the structure to monitor changes in magnetic susceptibility of salt-wetted alloys as corrosion occurs Holcomb et al. [2019]. Initial testing with this novel sensor demonstrated a correlation between the change in signal output from the sensor to the various levels of pre-corroded test specimens. However, all initial testing was performed at room temperatures, which is not realistic for the harsh MSR environment. Based on this research, FY19 funding allowed for development of a high-temperature version of the sensor to be installed at various locations on the reactor infrastructure. The high-temperature sensor can operate at up to 750°C and can monitor development of corrosion inside the pipe. This sensor measures the increase in magnetic susceptibility that occurs as chromium dissolves from the inner surface of the pipe, when paramagnetic structural alloys become ferromagnetic with the loss of chromium. This report will discuss the development of corrosion monitoring sensor and the testing with results of corroded specimens at increasing temperatures.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
NASA NTRS1979

PRSA hydrogen tank thermal acoustic oscillation study

The power reactant storage assembly (PRSA) hydrogen tank test data were reviewed. Two hundred and nineteen data points illustrating the effect of flow rate, temperature ratio and configuration were identified. The test data were reduced to produce the thermal acoustic oscillation parameters. Frequency and amplitude were determined for model correlation. A comparison of PRSA hydrogen tank test data with the analytical models indicated satisfactory agreement for the supply and poor agreement for the full line.

Riemer, D. H.↗
NASA NTRS2010

Roles of Engineering Correlations in Hypersonic Entry Boundary Layer Transition Prediction

Efforts to design and operate hypersonic entry vehicles are constrained by many considerations that involve all aspects of an entry vehicle system. One of the more significant physical phenomenon that affect entry trajectory and thermal protection system design is the occurrence of boundary layer transition from a laminar to turbulent state. During the Space Shuttle Return To Flight activity following the loss of Columbia and her crew of seven, NASA's entry aerothermodynamics community implemented an engineering correlation based framework for the prediction of boundary layer transition on the Orbiter. The methodology for this implementation relies upon the framework of correlation techniques that have been in use for several decades. What makes the Orbiter boundary layer transition correlation implementation unique is that a statistically significant data set was acquired in multiple ground test facilities, flight data exists to assist in establishing a better correlation and the framework was founded upon state of the art chemical nonequilibrium Navier Stokes flow field simulations. The basic tenets that guided the formulation and implementation of the Orbiter Return To Flight boundary layer transition prediction capability will be reviewed as a recommended format for future empirical correlation efforts. The validity of this approach has since been demonstrated by very favorable comparison of recent entry flight testing performed with the Orbiter Discovery, which will be graphically summarized. These flight data can provide a means to validate discrete protuberance engineering correlation approaches as well as high fidelity prediction methods to higher confidence. The results of these Orbiter engineering and flight test activities only serve to reinforce the essential role that engineering correlations currently exercise in the design and operation of entry vehicles. The framework of information-related to the Orbiter empirical boundary layer transition prediction capability will be utilized to establish a fresh perspective on this role, to illustrate how quantitative statistical evaluations of empirical correlations can and should be used to assess accuracy and to discuss what the authors' perceive as a recent heightened interest in the application of high fidelity numerical modeling of boundary layer transition. Concrete results will also be developed related to empirical boundary layer transition onset correlations. This will include assessment of the discrete protuberance boundary layer transition onset data assembled for the Orbiter configuration during post-Columbia Return To Flight. Assessment of these data will conclude that momentum thickness Reynolds number based correlations have superior coefficients and uncertainty in comparison to roughness height based Reynolds numbers, aka Re(sub k) or Re(sub kk). In addition, linear regression results from roughness height Reynolds number based correlations will be evaluated, leading to a hypothesis that non-continuum effects play a role in the processes associated with incipient boundary layer transition on discrete protuberances.

Campbell, Charles H.↗
NASA NTRS1990

Structural properties of laminated Douglas fir/epoxy composite material

This publication contains a compilation of static and fatigue strength data for laminated-wood material made from Douglas fir and epoxy. Results of tests conducted by several organizations are correlated to provide insight into the effects of variables such as moisture, size, lamina-to-lamina joint design, wood veneer grade, and the ratio of cyclic stress to steady stress during fatigue testing. These test data were originally obtained during development of wood rotor blades for large-scale wind turbines of the horizontal-axis (propeller) configuration. Most of the strength property data in this compilation are not found in the published literature. Test sections ranged from round cylinders 2.25 in. in diameter to rectangular slabs 6 by 24 in. in cross section and approximately 30 ft. long. All specimens were made from Douglas fir veneers 0.10 in. thick, bonded together with the WEST epoxy system developed for fabrication and repair of wood boats. Loading was usually parallel to the grain. Size effects (reduction in strength with increase in test volume) are observed in some of the test data, and a simple mathematical model is presented that includes the probability of failure. General characteristics of the wood/epoxy laminate are discussed, including features that make it useful for a wide variety of applications.

Spera, David A.↗
NASA NTRS1994

On the affinities of lambda 5778 and other broad diffuse interstellar bands

The authors examined the broad band 5778 A because of the quantity and quality of data that exists in literature. To investigate the affinity of that band with the bands of Family 1, the ratio W(sub lambda)(4430)/W(sub lambda)(5797) was formed. If the two band belong to the same family then the ratio should be a constant from star to star and it should not be possible to find an independent variable with which the ratio is correlated. If, however, a variable is found which does produce a statistically significant correlation with the ratio of equivalent widths then the bands cannot be in the same family. To test the affinity of the band at 5778 A with the other families the procedure was repeated using the bands at 5780 and 5787 A as being representative of Families 2 and 3 respectively. The measurement results of this test are shown using 21 stars taken from Herbig. Statistically significant correlations resulted when the band at 5778 A was tested against the bands of Families 1 and 2 but there was no correlation with Family 3. It is concluded that lambda 5778 is unlikely a member of Family 1 and so all the broad bands do not have their origin in a single carrier. Also, lambda 5778 does not appear to be a member of Family 2 either, but may be a member of Family 3. It appears that either a single carrier can be the origin of both broad and narrow bands or that the bands are produced by different carriers which exist in similar interstellar habitats. This latter possibility would require the introduction of a fourth family of bands.

Mcintosh, Alan↗
NASA NTRS1971

Design and preliminary testing of a Brayton space radiator concept

A low-temperature radiator has been designed to reject 17.62 kW of thermal power from an isotope Brayton power system. This power system has an electrical output of 7.1 kW. The total radiator consists of two radiators connected in series. Both radiators have a redundant coolant loop, shared fins, and are close to flight configuration. A silicone oil is used as the working fluid. Low flow rates and moderate pressure drop in the radiator required a small hydraulic diameter with large heat transfer area and large flow area. To obtain these characteristics and meet schedule limitations, an expanded tube configuration (with an approximately trapezoidal cross section) was selected. Because of the low flow rates and unconventional tube shape, small scale tests were performed to evaluate the validity of existing heat transfer and pressure drop correlations to this case. The results of these tests were in good agreement with predictions.

Miller, T. J.↗
NASA NTRS1996

Study of Critical Heat Flux and Two-Phase Pressure Drop Under Reduced Gravity

The design of the two-phase flow systems which are anticipated to be utilized in future spacecraft thermal management systems requires a knowledge of two-phase flow and heat transfer phenomena in reduced gravities. This program was funded by NASA headquarters in response to NRA-91-OSSA-17 and was managed by Lewis Research Center. The main objective of this program was to design and construct a two-phase test loop, and perform a series of normal gravity and aircraft trajectory experiments to study the effect of gravity on the Critical Heat Flux (CHF) and onset of instability. The test loop was packaged on two aircraft racks and was also instrumented to generate data for two-phase pressure drop. The normal gravity tests were performed with vertical up and downflow configurations to bound the effect of gravity on the test parameters. One set of aircraft trajectory tests was performed aboard the NASA DC-9 aircraft. These tests were mainly intended to evaluate the test loop and its operational performance under actual reduced gravity conditions, and to produce preliminary data for the test parameters. The test results were used to demonstrate the applicability of the normal gravity models for prediction of the two-phase friction pressure drop. It was shown that the two-phase friction multipliers for vertical upflow and reduced gravity conditions can be successfully predicted by the appropriate normal gravity models. Limited critical heat flux data showed that the measured CHF under reduced gravities are of the same order of magnitude as the test results with vertical upflow configuration. A simplified correlation was only successful in predicting the measured CHF for low flow rates. Instability tests with vertical upflow showed that flow becomes unstable and critical heat flux occurs at smaller powers when a parallel flow path exists. However, downflow tests and a single reduced gravity instability experiment indicated that the system actually became more stable with a parallel single-phase flow path. Several design modifications have been identified which will improve the system performance for generating reduced gravity data. The modified test loop can provide two-phase flow data for a range of operating conditions and can serve as a test bed for component evaluation.

Abdollahian, Davood↗
NASA NTRS2009

Modeling and Simulation of the Second-Generation Orion Crew Module Air Bag Landing System

Air bags were evaluated as the landing attenuation system for earth landing of the Orion Crew Module (CM). An important element of the air bag system design process is proper modeling of the proposed configuration to determine if the resulting performance meets requirements. Analysis conducted to date shows that airbags are capable of providing a graceful landing of the CM in nominal and off-nominal conditions such as parachute failure, high horizontal winds, and unfavorable vehicle/ground angle combinations. The efforts presented here surround a second generation of the airbag design developed by ILC Dover, and is based on previous design, analysis, and testing efforts. In order to fully evaluate the second generation air bag design and correlate the dynamic simulations, a series of drop tests were carried out at NASA Langley's Landing and Impact Research (LandIR) facility. The tests consisted of a full-scale set of air bags attached to a full-scale test article representing the Orion Crew Module. The techniques used to collect experimental data, construct the simulations, and make comparisons to experimental data are discussed.

Timmers, Richard B.↗
NASA NTRS2009

Modeling and Simulation of the Second-Generation Orion Crew Module Air Bag Landing System

Air bags were evaluated as the landing attenuation system for earth landing of the Orion Crew Module (CM). Analysis conducted to date shows that airbags are capable of providing a graceful landing of the CM in nominal and off-nominal conditions such as parachute failure, high horizontal winds, and unfavorable vehicle/ground angle combinations, while meeting crew and vehicle safety requirements. The analyses and associated testing presented here surround a second generation of the airbag design developed by ILC Dover, building off of relevant first-generation design, analysis, and testing efforts. In order to fully evaluate the second generation air bag design and correlate the dynamic simulations, a series of drop tests were carried out at NASA Langley s Landing and Impact Research (LandIR) facility in Hampton, Virginia. The tests consisted of a full-scale set of air bags attached to a full-scale test article representing the Orion Crew Module. The techniques used to collect experimental data, develop the simulations, and make comparisons to experimental data are discussed.

Timmers, Richard B.↗
DOE OSTI2019

Module Level Exposure and Evaluation Test (MLEET) for Real- world and Laboratory-based PV Modules: Common Data and Analytics for Quantitative Cross-correlation and Validation

Our objective is to develop a set of lifetime performance prediction models for PV modules. Models were developed based on common I-V, P mp datastreams from modules under outdoor (real-world) exposure and indoor (laboratory-based) accelerated exposures and temporal analytics. These common datastreams that span both indoor and outdoor exposures were supplemented with additional information such as meteorology data, climate and PV module make/model and module specifications. The predictive models were developed using a stressor/mechanism/response framework in which all data are categorized as stressor, mechanism or performance variables and are represented as time-series datastreams. We develop and validate these accelerated indoor exposures and evaluation tests and models and cross-correlate the temporal signatures of PV module degradation mechanisms in the I-V, P mp time-series between outdoor and accelerated indoor tests. The predictive test and model specify indoor and outdoor exposure and data acquisition criteria, variable selection, and temporal duration and variance.

14 SOLAR ENERGY↗
NASA NTRS1986

Rotor/wing aerodynamic interactions in hover

An experimental and theoretical investigation of rotor/wing aerodynamic interactions in hover is described. The experimental investigation consisted of both a large-scale and small-scale test. A 0.658-scale, V-22 rotor and wing was used in the large-scale test. Wind download, wing surface pressure, rotor performance, and rotor downwash data from the large-scale test are presented. A small-scale experiment was conducted to determine how changes in the rotor/wing geometry affected the aerodynamic interactions. These geometry variations included the distance between the rotor and wing, wing incidence angle, and configurations both with the rotor axis at the tip of the wing (tilt rotor configuration) and with the rotor axis at the center of the wing (compound helicopter configuration). A wing with boundary-layer control was also tested to evaluate the effect of leading and trailing edge upper surface blowing on the wing download. A computationally efficient, semi-empirical theory was developed to predict the download on the wing. Finally, correlations between the theoretical predictions and test data are presented.

Felker, F. F.↗
NASA NTRS1986

Rotor/wing aerodynamic interactions in hover

An experimental and theoretical investigation of rotor/wing aerodynamic interactions in hover is described. The experimental investigation consisted of both a large-scale and small-scale test. A 0.658-scale, V-22 rotor and wing was used in the large-scale test. Wind download, wing surface pressure, rotor performance, and rotor downwash data from the large-scale test are presented. A small-scale experiment was conducted to determine how changes in the rotor/wing geometry affected the aerodynamic interactions. These geometry variations included the distance between the rotor and wing, wing incidence angle, and configurations both with the rotor axis at the tip of the wing (tilt rotor configuration) and with the rotor axis at the center of the wing (compound helicopter oonfiguration). A wing with boundary-layer control was also tested to evaluate the effect of leading and trailing edge upper surface blowing on the wing download. A computationally efficient, semi-empirical theory was developed to predict the download on the wing. Finally, correlations between the theoretical predictions and test data are presented.

Felker, F. F.↗
NASA NTRS2004

Enzyme-Cascade Analysis of the Rio Tinto Subsurface Environment: A Biosensor Experiment

The Portable Test System (PTS), designed & developed by Charles Rivers Laboratories, Inc. (Charleston, SC) is a portable instrument that was designed to perform analysis of enzymatic assays related to rapid assessment of microbial contamination (Wainwright, 2003). The enzymatic cascade of Limulus Amebocyte Lysate (LAL) is known to be one of the most sensitive techniques available for microbial detection, enabling the PTS to be evaluated as a potential life detection instrument for in situ Astrobiology missions. In the summer of 2003 the system was tested as a part of the Mars Astrobiology Research and Technology Experiment (MARTE) ground truth science campaign in the Rio Tinto Analogue environment near Nerva, Spain. The preliminary results show that the PTS analysis correlates well with the contamination control tests and the more traditional lab-based biological assays performed during the MARTE field mission. Further work will be conducted on this research during a second field campaign in 2004 and a technology demonstration of a prototype instrument that includes autonomous sample preparation will occur in 2005.

McKay, David S.↗
DOE OSTI2020

Minimal Experimental Bias on the Hydrogen Bond Greatly Improves Ab Initio Molecular Dynamics Simulations of Water

Experiment Directed Simulations (EDS) is a method within a class of techniques seeking to improve molecular simulations by minimally biasing the system Hamiltonian to reproduce certain experimental observables. In a previous application of EDS to ab initio molecular dynamics (AIMD) simulation based on electronic density functional theory (DFT), the AIMD simulations of water were biased to reproduce its experimentally derived solvation structure. In particular, by solely biasing the O-O pair correlation functions, other structural and dynamical properties that were not biased were improved. In this work, the hypothesis is tested that directly biasing the OH pair correlation (and hence the H-O∙∙∙H hydrogen bonding), will provide an even better improvement of DFT-based water properties in AIMD simulations. The logic behind this hypothesis is that for most electronic DFT descriptions of water the hydrogen bonding is known to be deficient due to anomalous charge transfer and over polarization in the DFT. Using recent advances to the EDS learning algorithm, we thus train a minimal bias on AIMD water that reproduces the O-H radial distribution function derived from the highly accurate MB-pol model of water. Finally, it is then confirmed that biasing the O-H pair correlation alone can lead to improved AIMD water properties, with structural and dynamical properties in even closer to experiment than the previous EDS-AIMD model.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1988

Late Eocene impact events recorded in deep-sea sediments

Raup and Sepkoski proposed that mass extinctions have occurred every 26 Myr during the last 250 Myr. In order to explain this 26 Myr periodicity, it was proposed that the mass extinctions were caused by periodic increases in cometary impacts. One method to test this hypothesis is to determine if there were periodic increases in impact events (based on crater ages) that correlate with mass extinctions. A way to test the hypothesis that mass extinctions were caused by periodic increases in impact cratering is to look for evidence of impact events in deep-sea deposits. This method allows direct observation of the temporal relationship between impact events and extinctions as recorded in the sedimentary record. There is evidence in the deep-sea record for two (possibly three) impact events in the late Eocene. The younger event, represented by the North American microtektite layer, is not associated with an Ir anomaly. The older event, defined by the cpx spherule layer, is associated with an Ir anomaly. However, neither of the two impact events recorded in late Eocene deposits appears to be associated with an unusual number of extinctions. Thus there is little evidence in the deep-sea record for an impact-related mass extinction in the late Eocene.

Glass, B. P.↗