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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 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Model Specification for Rework of Aircraft Engine, Power Transmission, and Accessory/Auxiliary Ball and Roller Bearings

This document provides a model specification for the rework and/or repair of bearings used in aircraft engines, helicopter main power train transmissions, and auxiliary bearings determined to be critical by virtue of performance, function, or availability. The rolling-element bearings to be processed under the provisions of this model specification may be used bearings removed after service, unused bearings returned from the field, or certain rejected bearings returned for reinspection and salvage. In commercial and military aircraft application, it has been a practice that rolling-element bearings removed at maintenance or overhaul be reworked and returned to service. Depending on the extent of rework and based upon theoretical analysis, representative life factors (LF) for bearings subject to rework ranged from 0.87 to 0.99 the lives of new bearings. Based on bearing endurance data, 92 percent of the bearing sets that would be subject to rework would result in L(sub 10) lives equaling and/or exceeding that predicted for new bearings. The remaining 8 percent of the bearings have the potential to achieve the analytically predicted life of new bearings when one of the rings is replaced at rework. The potential savings from bearing rework varies from 53 to 82 percent of that of new bearings depending on the cost, size, and complexity of the bearing

Zaretsky, Erwin V.↗
NASA NTRS2008

Population Analysis: Communicating in Context

Providing accommodation to a widely varying user population presents a challenge to engineers and designers. It is often even difficult to quantify who is accommodated and who is not accommodated by designs, especially for equipment with multiple critical anthropometric dimensions. An approach to communicating levels of accommodation referred to as population analysis applies existing human factors techniques in novel ways. This paper discusses the definition of population analysis as well as major applications and case studies. The major applications of population analysis consist of providing accommodation information for multivariate problems and enhancing the value of feedback from human-in-the-loop testing. The results of these analyses range from the provision of specific accommodation percentages of the user population to recommendations of design specifications based on quantitative data. Such feedback is invaluable to designers and results in the design of products that accommodate the intended user population.

Rajulu, Sudhakar↗
NASA NTRS2010

Cryogenic Vacuum Insulation for Vessels and Piping

Cryogenic vacuum insulation systems, with proper materials selection and execution, can offer the highest levels of thermal performance. Three areas of consideration are vital to achieve the optimum result: materials, representative test conditions, and engineering approach for the particular application. Deficiency in one of these three areas can prevent optimum performance and lead to severe inefficiency. Materials of interest include micro-fiberglass, multilayer insulation, and composite arrangements. Cylindrical liquid nitrogen boil-off calorimetry methods were used. The need for standard thermal conductivity data is addressed through baseline testing. Engineering analysis and design factors such as layer thickness, density, and practicality are also considered.

Kogan, A.↗
NASA NTRS2012

Scaling of Lift Degradation Due to Anti-Icing Fluids Based Upon the Aerodynamic Acceptance Test

In recent years, the FAA has worked with Transport Canada, National Research Council Canada (NRC) and APS Aviation, Inc. to develop allowance times for aircraft operations in ice-pellet precipitation. These allowance times are critical to ensure safety and efficient operation of commercial and cargo flights. Wind-tunnel testing with uncontaminated anti-icing fluids and fluids contaminated with simulated ice pellets had been carried out at the NRC Propulsion and Icing Wind Tunnel (PIWT) to better understand the flowoff characteristics and resulting aerodynamic effects. The percent lift loss on the thin, high-performance wing model tested in the PIWT was determined at 8 angle of attack and used as one of the evaluation criteria in determining the allowance times. Because it was unclear as to how performance degradations measured on this model were relevant to an actual airplane configuration, some means of interpreting the wing model lift loss was deemed necessary. This paper describes how the lift loss was related to the loss in maximum lift of a Boeing 737-200ADV airplane through the Aerodynamic Acceptance Test (AAT) performed for fluids qualification. A loss in maximum lift coefficient of 5.24 percent on the B737-200ADV airplane (which was adopted as the threshold in the AAT) corresponds to a lift loss of 7.3 percent on the PIWT model at 8 angle of attack. There is significant scatter in the data used to develop the correlation related to varying effects of the anti-icing fluids that were tested and other factors. A statistical analysis indicated the upper limit of lift loss on the PIWT model was 9.2 percent. Therefore, for cases resulting in PIWT model lift loss from 7.3 to 9.2 percent, extra scrutiny of the visual observations is required in evaluating fluid performance with contamination.

Broeren, Andy P.↗
NASA NTRS2012

Review of the Aerodynamic Acceptance Test and Application to Anti-Icing Fluids Testing in the NRC Propulsion and Icing Wind Tunnel

In recent years, the FAA has worked with Transport Canada, National Research Council of Canada (NRC) and APS Aviation, Inc. to develop allowance times for aircraft operations in ice-pellet precipitation. These allowance times are critical to ensure safety and efficient operation of commercial and cargo flights. Wind-tunnel testing with uncontaminated anti-icing fluids and fluids contaminated with simulated ice-pellets had been carried out at the NRC Propulsion and Icing Wind Tunnel (PIWT) to better understand the flowoff characteristics and resulting aerodynamic effects. The percent lift loss on the thin, high-performance wing model tested in the PIWT was determined at 8 angle of attack and used as one of the evaluation criteria in determining the allowance times. Because it was unclear as to how performance degradations measured on this model were relevant to an actual airplane configuration, some means of interpreting the wing model lift loss was deemed necessary. In this report, the lift loss was related to the loss in maximum lift of a Boeing 737-200ADV airplane through the Aerodynamic Acceptance Test (AAT) performed for fluids qualification. This report provides a review of the research basis of the AAT in order to understand how this correlation was applied. A loss in maximum lift coefficient of 5.24 percent on the B737-200ADV airplane (which was adopted as the threshold in the AAT) corresponds to a lift loss of 7.3 percent on the PIWT model at 8 degrees angle of attack. There is significant scatter in the data used to develop the correlation related to varying effects of the various antiicing fluids that were tested and other factors. A statistical analysis indicated the upper limit of lift loss on the PIWT model was 9.2 percent. Therefore, for cases resulting in PIWT model lift loss from 7.3 to 9.2 percent, extra scrutiny of the visual observations is required in evaluating fluid performance with contamination. Additional research may result in future changes to this correlation.

Broeren, Andy P.↗
NASA NTRS2012

Scaling of Lift Degradation Due to Anti-Icing Fluids Based Upon the Aerodynamic Acceptance Test

In recent years, the FAA has worked with Transport Canada, National Research Council Canada (NRC) and APS Aviation, Inc. to develop allowance times for aircraft operations in ice-pellet precipitation. These allowance times are critical to ensure safety and efficient operation of commercial and cargo flights. Wind-tunnel testing with uncontaminated anti-icing fluids and fluids contaminated with simulated ice pellets had been carried out at the NRC Propulsion and Icing Wind Tunnel (PIWT) to better understand the flow-off characteristics and resulting aerodynamic effects. The percent lift loss on the thin, high-performance wing model tested in the PIWT was determined at 8 deg. angle of attack and used as one of the evaluation criteria in determining the allowance times. Because it was unclear as to how performance degradations measured on this model were relevant to an actual airplane configuration, some means of interpreting the wing model lift loss was deemed necessary. This paper describes how the lift loss was related to the loss in maximum lift of a Boeing 737-200ADV airplane through the Aerodynamic Acceptance Test (AAT) performed for fluids qualification. A loss in maximum lift coefficient of 5.24% on the B737-200ADV airplane (which was adopted as the threshold in the AAT) corresponds to a lift loss of 7.3% on the PIWT model at 8 deg. angle of attack. There is significant scatter in the data used to develop the correlation related to varying effects of the anti-icing fluids that were tested and other factors. A statistical analysis indicated the upper limit of lift loss on the PIWT model was 9.2%. Therefore, for cases resulting in PIWT model lift loss from 7.3% to 9.2%, extra scrutiny of the visual observations is required in evaluating fluid performance with contamination.

Broeren, Andy↗
NASA NTRS2018

Orion Optical Navigation Progress Toward Exploration Mission 1

Optical navigation of human spacecraft was proposed on Gemini and implemented successfully on Apollo as a means of autonomously operating the vehicle in the event of lost communication with controllers on Earth. The Orion emergency return system utilizing optical navigation has matured in design over the last several years, and is currently undergoing the final implementation and test phase in preparation for Exploration Mission 1 (EM-1) in 2019. The software development is past its Critical Design Review, and is progressing through test and certification for human rating. The filter architecture uses a square-root-free UDU covariance factorization. Linear Covariance Analysis (LinCov) was used to analyze the measurement models and the measurement error models on a representative EM-1 trajectory. The Orion EM-1 flight camera was calibrated at the Johnson Space Center (JSC) electro-optics lab. To permanently stake the focal length of the camera a 500 mm focal length refractive collimator was used. Two Engineering Design Unit (EDU) cameras and an EDU star tracker were used for a live-sky test in Denver. In-space imagery with high-fidelity truth metadata is rare so these live-sky tests provide one of the closest real-world analogs to operational use. A hardware-in-the-loop test rig was developed in the Johnson Space Center Electro-Optics Lab to exercise the OpNav system prior to integrated testing on the Orion vehicle. The software is verified with synthetic images. Several hundred off-nominal images are also used to analyze robustness and fault detection in the software. These include effects such as stray light, excess radiation damage, and specular reflections, and are used to help verify the tuning parameters chosen for the algorithms such as earth atmosphere bias, minimum pixel intensity, and star detection thresholds.

Holt, Greg N.↗
NASA NTRS2017

Comparison of Oxygen Liquefaction Methods for Use on the Martian Surface

In order to use oxygen that is produced on the surface of Mars from In-Situ production processes in a chemical propulsion system, the oxygen must first be converted from vapor phase to liquid phase and then stored within the propellant tanks of the propulsions system. There are multiple ways that this can be accomplished, from simply attaching a liquefaction system onto the propellant tanks to carrying separate tanks for liquefaction and storage of the propellant and loading just prior to launch (the way that traditional rocket launches occur on earth). A study was done into these various methods by which the oxygen (and methane) could be liquefied and stored on the Martian surface. Five different architectures or cycles were considered: Tube-on-Tank (also known as Broad Area Cooling or Distributed Refrigeration), Tube-in-Tank (also known as Integrated Refrigeration and Storage), a modified Linde open liquefaction/refrigeration cycle, the direct mounting of a pulse tube cryocooler onto the tank, and an in-line liquefier at ambient pressure. Models of each architecture were developed to give insight into the performance and losses of each of the options. The results were then compared across eight categories: Mass, Power (both input and heat rejection), Operability, Cost, Manufacturability, Reliability, Volumility, and Scalability. The result was that, given the current state of technology maturity, Tube-on-Tank architectures were the most attractive solution, closely followed by Tube-in-Tank. As a result of this technical analysis and other factors, NASA has determined to focus its Martian surface liquefaction activities and technology development on Tube-on-Tank liquefaction cycles.

Cryogenic propellants↗
NASA NTRS2004

SIM spectral characteristics and accuracy analysis

The Space Interferometry Mission (SIM) will perform global astrometry (full sky), local wide-angle (15 degree) and narrow-angle (1 degree) observations to search extra-solar planets, and can calibrate stellar and galactic evolution theories. The astrometric accuracy of the SIM mission depends on spectral characteristics of the optics, detectors and targets. This paper will discuss the photometric throughput of the SIM instrument, and analyze effects of wavefront errors, optical mismatches and control biases as a function of wavelength. The color dependence models of the instrument optics including mirrors, lenses, field-stop and beam-splitter are presented. The performances of different detectors with a variety of coatings are compared. A model of the SIM fringe spectrometer is created. For early and late types of stars, brightness dependency errors are analyzed for different combinations of optics and detectors. Visibility loss due to imperfect optics is investigated in detail. Based on the models of instrument and estimated visibilities, the astrometric accuracies for various kinds of stars are evaluated. It is important to emphasize that not only light sources, mirrors, lenses, field stop and detectors are all wavelength dependent, but also fringe visibility loss, wavefront error, optics control error, etc. are all a function of wavelengths. For the first time the estimate of SIM performance is based on spectral analysis of all factors above, rather than monochromatic approximations of detected fringes, or simply adopted constants. This paper summarizes the astrometric accuracies for a wide range of stars and various combinations of optical design and detector configurations. It has been verified that SIM has astrometric accuracy of about 4 μas for targets with different spectra.

Shao, Michael↗
NASA NTRSDate not supplied

A Study on Effect of Tuning Capacitor in Dynamic Radioisotope Power Systems

This study presents the effect of the tuning capacitor on the stability and electrical power output of a gas spring-based free-piston Stirling convertor (FPSC) when the FPSC runs on a forced-oscillation type controller. It has been widely accepted that the tuning capacitor is an important circuit component of the FPSC to stabilize piston amplitude and maximize electrical power output by correcting the power factor. Recent modeling analysis, however, suggests that while the effect on the stability is significant, the effect on the electrical power output is almost negligible as long as the operating frequency the FPSC is fixed by a forced-oscillation controller and operating conditions, such as the hot-end/cold-end temperatures, piston amplitude, and pressure, are unchanged. To verify the modeling analysis results, Advanced Stirling Convertor (ASC) is controlled by an AC power supply and the piston amplitude, hot-end temperature, cold-end temperature, and pressure are actively controlled to 4.3mm, 760˚C, 40˚C and 485psig, respectively, while the tuning capacitor value is changed from 840μF to 1040μF and 1240μF. Furthermore, the vibration test results of the ASC with the three tuning capacitor values are also presented to show the effect of the tuning capacitor on stability. The test results suggest that when the FPSC operates at a fixed frequency, the effect of tuning capacitor on electrical power output is negligible while the effect on stability is rather significant. Therefore, the tuning capacitor value should be selected toward the highest stability.

Free-Piston Stirling Convertor Controller↗
DOE OSTI2020

REopt Lite Overview & Training Exercise

This training exercise provides users with an introduction to and hands-on, interactive exploration of REopt Lite's capabilities. REopt Lite is a free, publicly available techno-economic optimization web tool for distributed energy systems, developed at the National Renewable Energy Laboratory (NREL). REopt Lite helps organizations evaluate the economic viability of grid-connected solar photovoltaics (PV), wind turbines, and battery storage; identify system sizes and battery dispatch strategies to minimize energy costs; and estimate how long a system can sustain critical load during a grid outage. The model is formulated as a mixed-integer linear program based in an underlying application programming interface (API) that is also free and publicly available. This training activity is structured as a group exercise. Participants split into eight groups and each group is assigned a different hypothetical site to model and assess the opportunity for solar PV + battery storage. Groups work together to develop results for their site and then re-convene to compare and discuss results, inputs/drivers of the analysis, and other factors impacting the decision-making process for behind-the-meter solar PV and battery storage.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2016

On the Modeling of Wall Heat Flux Partitioning in Subcooled Flow Boiling

Accurate prediction of void distribution in reactor coolant channels at subcooled boiling conditions is an important factor in the analysis of the operating conditions of both pressurized water reactors (PWRs) and boiling water reactors (BWRs). Its importance arises from purely thermal-hydraulic considerations (thermal limits, CRUD formation, etc.) and the impact of void reactivity feedback on core neutronics. A mechanistic multidimensional model of subcooled boiling was originally developed by Kurul and Podowski. Whereas this model has been implemented in several commercial CFD codes and successfully used in computer simulations of flow and phase distributions in the coolant channels of light water reactor, additional new modeling aspects of forced-convection subcooled boiling heat transfer have been investigated in recent studies. The purpose of this paper is to formulate a modified model of wall heat flux partitioning, which allows for capturing and quantifying the effect of simultaneous evaporation and condensation at the heated wall on the net evaporation rate and wall temperature. The new model has been implemented in the NPHASE-CMFD code, numerically tested and validated against experimental data. A mechanistic wall heat flux partitioning model for subcooled flow boiling has been presented. This model has been combined with extensively tested models of interfacial mass, momentum and energy transfer terms. It turns out that the model predictions of the wall temperature and void fraction are in good agreement with the experimental data of reference. Future work will focus on the continuation of model validation against experimental data, and on extending its scope to include the phenomena governing departure from nucleate boiling. (authors)

42 ENGINEERING↗
DOE OSTI2017

Influence of Axial Power Distributions on Rod-to-wall Gap

In a scaled-down (3 x 3, 4 x 4, 5 x 5 or 6 x 6) rod bundle thermal hydraulic experiment, channel walls were often applied to surround the experimental rod bundle and provide a hydraulic flow boundary for the experiments. However, in the actual PWR (Pressurized Water Reactor), there are no walls surrounding the rod bundle fuel assembly. These non-representative walls can lead to non-prototypical conditions in the rod bundle experiments. There are several researches about the wall effects in rod bundle experiments. Based on hydraulic consideration, Zang developed a wall effect factor by subchannel analysis method to investigate the wall effects of different scale rod bundles. He did not pay attention to the wall effects in thermal aspects. Li studied the wall effects of different scale rod bundles of tight arrangement spiral-fin fuel assembly by CFD. The existing researches mostly focus on the wall effects of different scale rod bundles. There are very few, if any at all, studies focus on how to avoid or minimize wall effects through proper experimental design by adjusting the rod-to-wall gap (the gap between the channel wall and outer rod wall) for rod bundles of various scales. In addition, the axial power distribution is different in different periods of the life cycle in the PWR core. For example, it usually is outlet peak power distribution in the axial direction at the beginning of life span. However, it may turn to the inlet peak power distribution when the control rods are pulled out from the high burn up of fuel in the reactor core. Both flow dynamics and heat transfer mechanism change depending on various axial power distributions. Subsequently, it is important to study the impacts of the wall effects on flow and heat transfer with different axial power distributions in rod bundle experiments. That is, in the evaluation of rod-to-wall gap in rod bundle experiments, the influence of axial power distributions should be examined. In this paper, the rod-to-wall gap was calculated in axially uniform and non-uniform power, including inlet peak, cosine, and exit peak heat flux distributions. The rod-to-wall gap calculation results were then compared with respect to two different criterion: the average fluid temperature and the maximum wall temperature criterion, to study the influence of axial heat flux profile on radial thermal distribution.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
NASA NTRS2000

Cirrus Parameter Retrieval by Combined Analysis of Spectral Thermal Infrared and Lidar Sensing from Aircraft and Space

The distribution, radiative and microphysical parameters of cirrus clouds are an important factor for cloud effects on the global radiation balance and climate. Multispectral thermal infrared observation are the most significant method used to remote sense cirrus parameter from current and planned passive satellite observations. Passive sensing alone has the limitation that both the cloud radiative temperature, or height, and the spectral emissivity must be derived in the analysis. Factors such as multiple cloud laying, which is very common, are known to introduce ambiguities in results. The addition of lidar cloud height structure measurements significantly improves retrievals. Such active/passive observations have been applied from the NASA ER-2 high altitude remote sensing aircraft since 1983. Applications include the study of the effective effective particle size of cirrus and application toward remote sensing of the ice/water content of cirrus clouds in addition to radiative parameters. Limitations, accuracy and examples of retrievals are presented. In 1997 a space shuttle hitch hiker experiment was flown which included a new technology Infrared Spectral Imaging Radiometer and a laser altimeter for direct cloud height measurements. A 30 orbit data set to test global application of combined spectral infrared and laser height measurements were obtained. Initial results for cirrus analysis from the shuttle experiment will also be presented.

Spinhirne, James D.↗
DOE OSTI2019

Importance of proton-coupled electron transfer in cathodic regeneration of organic hydrides

Electrochemical regeneration of organic hydrides is often hindered by the rapid dimerization of organic radicals produced as the first intermediates of these electrochemical transformations. Here, we utilize proton-coupled electron transfer to outcompete the undesired dimerization and achieve successful hydride regenerations of two groups of organic hydrides – acridines and benzimidazoles. An analysis of the critical factors that control the regeneration pathways of organic hydrides is demonstrated in this report.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1978

Man-machine interface analysis of the flight design system

The objective of the current effort was to perform a broad analysis of the human factors issues involved in the design of the Flight Design System (FDS). The analysis was intended to include characteristics of the system itself, such as: (1) basic structure and functional capabilities of FDS; (2) user backgrounds, capabilities, and possible modes of use; (3) FDS interactive dialogue, problem solving aids; (4) system data management capabilities; and to include, as well, such system related matters as: (1) flight design team structure; (2) roles of technicians; (3) user training; and (4) methods of evaluating system performance. Wherever possible, specific recommendations are made. In other cases, the issues which seem most important are identified. In some cases, additional analyses or experiments which might provide resolution are suggested.

Ramsey, H. R.↗
DOE OSTI2019

The $B\to D^\ast\ell\nu$ Semileptonic Decay at Nonzero Recoil and Its Implications for $\ |V_{cb}\ |$ and $R(D^\ast)$

We present nearly final results from our analysis of the form factors for $B\to D^\ast\ell\nu$ decay at nonzero recoil. Our analysis includes 15 MILC asqtad ensembles with $N_f=2+1$ flavors of sea quarks and lattice spacings ranging from $a\approx0.15$ fm down to $0.045$ fm. The valence light quarks employ the asqtad action, whereas the $b$ and $c$ quarks are treated using the Fermilab action. We discuss the impact that our results will have on $\ |V_{cb}\ |$ and $R(D^\ast)$.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗