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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS2014

A Systems Engineering Approach to Quality Assurance for Aerospace Testing

On the surface, it appears that AS9100 has little to say about how to apply a Quality Management System (QMS) to major aerospace test programs (or even smaller ones). It also appears that there is little in the quality engineering Body of Knowledge (BOK) that applies to testing, unless it is nondestructive examination (NDE), or some type of lab or bench testing associated with the manufacturing process. However, if one examines: a) how the systems engineering (SE) processes are implemented throughout a test program; and b) how these SE processes can be mapped to the requirements of AS9100, a number of areas for involvement of the quality professional are revealed. What often happens is that quality assurance during a test program is limited to inspections of the test article; what could be considered a manufacturing al fresco approach. This limits the quality professional and is a disservice to the programs and projects, since there are a number of ways that quality can enhance critical processes, and support efforts to improve risk reduction, efficiency and effectiveness. The Systems Engineering (SE) discipline is widely used in aerospace to ensure the progress from Stakeholder Expectations (the President, Congress, the taxpayers) to a successful, delivered product or service. Although this is well known, what is not well known is that these same SE processes are implemented in varying complexity, to prepare for and implement test projects that support research, development, verification and validation, qualification, and acceptance test projects. Although the test organization's terminology may vary from the SE terminology, and from one test service provider to another, the basic process is followed by successful, reliable testing organizations. For this analysis, NASA Procedural Requirements (NPR) 7123.1, NASA Systems Engineering Processes and Requirements is used to illustrate the SE processes that are used for major aerospace testing. Many of these processes are also implemented for smaller test projects, and this set of processes will also look familiar to those who have participated in launch site activation and flight demonstrations.

Shepherd, Christena C.↗
NASA NTRS2015

The Evolution of On-Board Emergency Training for the International Space Station Crew

The crew of the International Space Station (ISS) receives extensive ground‐training in order to safely and effectively respond to any potential emergency event while on‐orbit, but few people realize that their training is not concluded when they launch into space. The evolution of the emergency On‐ Board Training events (OBTs) has recently moved from paper "scripts" to an intranet‐based software simulation that allows for the crew, as well as the flight control teams in Mission Control Centers across the world, to share in an improved and more realistic training event. This emergency OBT simulator ensures that the participants experience the training event as it unfolds, completely unaware of the type, location, or severity of the simulated emergency until the scenario begins. The crew interfaces with the simulation software via iPads that they keep with them as they translate through the ISS modules, receiving prompts and information as they proceed through the response. Personnel in the control centers bring up the simulation via an intranet browser at their console workstations, and can view additional telemetry signatures in simulated ground displays in order to assist the crew and communicate vital information to them as applicable. The Chief Training Officers and emergency instructors set the simulation in motion, choosing the type of emergency (rapid depressurization, fire, or toxic atmosphere) and specific initial conditions to emphasize the desired training objectives. Project development, testing, and implementation was a collaborative effort between ISS emergency instructors, Chief Training Officers, Flight Directors, and the Crew Office using commercial off the shelf (COTS) hardware along with simulation software created in‐house. Due to the success of the Emergency OBT simulator, the already‐developed software has been leveraged and repurposed to develop a new emulator used during fire response ground‐training to deliver data that the crew receives from the handheld Compound Specific Analyzer for Combustion Products (CSA‐CP). This CSA‐CP emulator makes use of a portion of codebase from the Emergency OBT simulator dealing with atmospheric contamination during fire scenarios, and feeds various data signatures to crew via an iPod Touch with a flight‐like CSA‐CP display. These innovative simulations, which make use of COTS hardware with custom in‐house software, have yielded drastic improvements to emergency training effectiveness and risk reduction for ISS crew and flight control teams during on‐orbit and ground training events.

LaBuff, Skyler↗
NASA NTRS2015

A Systems Engineering Approach to Quality Assurance for Aerospace Testing

On the surface, it appears that AS91001 has little to say about how to apply a Quality Management System (QMS) to major aerospace test programs (or even smaller ones). It also appears that there is little in the quality engineering Body of Knowledge (BOK)2 that applies to testing, unless it is nondestructive examination (NDE), or some type of lab or bench testing associated with the manufacturing process. However, if one examines: a) how the systems engineering (SE) processes are implemented throughout a test program; and b) how these SE processes can be mapped to the requirements of AS9100, a number of areas for involvement of the quality professional are revealed. What often happens is that quality assurance during a test program is limited to inspections of the test article; what could be considered a manufacturing al fresco approach. This limits the quality professional and is a disservice to the programs and projects, since there are a number of ways that quality can enhance critical processes, and support efforts to improve risk reduction, efficiency and effectiveness.

Shepherd, Christena C.↗
NASA NTRS2017

Core/Combustor Noise - Research Overview

Contributions from the combustor to the overall propulsion noise of civilian transport aircraft are starting to become important due to turbofan design trends and advances in mitigation of other noise sources. Future propulsion systems for ultra-efficient commercial air vehicles are projected to be of increasingly higher bypass ratio from larger fans combined with much smaller cores, with ultra-clean burning fuel-flexible combustors. Unless effective noise-reduction strategies are developed, combustor noise is likely to become a prominent contributor to overall airport community noise in the future. This presentation gives a brief overview of the NASA outlook on pertinent issues and far-term research needs as well as current and planned research in the core/combustor-noise area. The research described herein is aligned with the NASA Ultra-Efficient Commercial Transport strategic thrust and is supported by the NASA Advanced Air Vehicle Program, Advanced Air Transport Technology Project, under the Aircraft Noise Reduction Subproject. The overarching goal of the Advanced Air Transport Technology (AATT) Project is to explore and develop technologies and concepts to revolutionize the energy efficiency and environmental compatibility of fixed wing transport aircrafts. These technological solutions are critical in reducing the impact of aviation on the environment even as this industry and the corresponding global transportation system continue to grow.

Turbomachinery Noise↗
NASA NTRS2017

DART Core/Combustor-Noise Initial Test Results

Contributions from the combustor to the overall propulsion noise of civilian transport aircraft are starting to become important due to turbofan design trends and advances in mitigation of other noise sources. Future propulsion systems for ultra-efficient commercial air vehicles are projected to be of increasingly higher bypass ratio from larger fans combined with much smaller cores, with ultra-clean burning fuel-flexible combustors. Unless effective noise-reduction strategies are developed, combustor noise is likely to become a prominent contributor to overall airport community noise in the future. The new NASA DGEN Aero0propulsion Research Turbofan (DART) is a cost-efficient testbed for the study of core-noise physics and mitigation. This presentation gives a brief description of the recently completed DART core combustor-noise baseline test in the NASA GRC Aero-Acoustic Propulsion Laboratory (AAPL). Acoustic data was simultaneously acquired using the AAPL overhead microphone array in the engine aft quadrant far field, a single midfield microphone, and two semi-infinite-tube unsteady pressure sensors at the core-nozzle exit. An initial assessment shows that the data is of high quality and compares well with results from a quick 2014 feasibility test. Combustor noise components of measured total-noise signatures were educed using a two-signal source-separation method an dare found to occur in the expected frequency range. The research described herein is aligned with the NASA Ultra-Efficient Commercial Transport strategic thrust and is supported by the NASA Advanced Air Vehicle Program, Advanced Air Transport Technology Project, under the Aircraft Noise Reduction Subproject.

Aeroacoustics↗
NASA NTRS2018

Core/Combustor-Noise Baseline Measurements for the DGEN Aeropropulsion Research Turbofan

Contributions from the combustor to the overall propulsion noise of civilian transport aircraft are starting to become important due to turbofan design trends and advances in mitigation of other noise sources. Future propulsion systems for ultra-efficient commercial air vehicles are projected to be of increasingly higher bypass ratio from larger fans combined with much smaller cores, with ultra-clean burning fuel-flexible combustors. Unless effective noise-reduction strategies are developed, combustor noise is likely to become a prominent contributor to overall airport community noise in the future. The new NASA DGEN Aeropropulsion Research Turbofan (DART) is a cost-efficient testbed for the study of core-noise physics and mitigation. This paper describes the recently completed DART core/combustor-noise baseline test in the NASA GRC Aero-Acoustic Propulsion Laboratory (AAPL). Acoustic data were simultaneously acquired using the AAPL overhead microphone array in the engine aft quadrant farfield, a single midfield microphone, and two semi-infinite-tube unsteady pressure sensors at the core-nozzle exit. Combustor-noise components of measured total-noise signatures were educed using a two-signal source-separation method and are found to occur in the expected frequency range. The acoustic data compare well with results from a limited 2014 feasibility test and will serve as a high-quality baseline for future research using the DART. The research described herein is aligned with the NASA Ultra-Efficient Commercial Transport strategic thrust and is supported by the NASA Advanced Air Vehicle Program, Advanced Air Transport Technology Project, under the Aircraft Noise Reduction Subproject.

Turbomachinery Noise↗
NASA NTRS2018

Core/Combustor-Noise Update

Future propulsion systems for ultra-efficient commercial air vehicles are projected to be of increasingly higher bypass ratios resulting from larger fans combined with much smaller cores, with ultra-clean burning fuel-flexible combustors. Unless effective noise-reduction strategies are developed, combustor noise is likely to become a prominent contributor to overall airport community noise in the future. This presentation gives a brief overview of the NASA outlook on pertinent issues and far-term research needs as well as current and planned research in the core/combustor-noise area. The research described herein is aligned with the NASA Ultra-Efficient Commercial Transport strategic thrust and is supported by the NASA Advanced Air Vehicle Program, Advanced Air Transport Technology Project, under the Aircraft Noise Reduction Subproject. The overarching goal of the Advanced Air Transport Technology (AATT) Project is to explore and develop technologies and concepts to revolutionize the energy efficiency and environmental compatibility of fixed wing transport aircrafts. These technological solutions are critical in reducing the impact of aviation on the environment even as this industry and the corresponding global transportation system continue to grow.

Hultgren, Lennart S.↗
NASA NTRSDate not supplied

Modeling Pore Closure in the Hot Isostatic Pressing of Additively Manufactured Inconel 718 Samples

Additive manufacturing provides opportunity for a new world of possibilities for metallic component design and fabrication; however, as-built part quality is notoriously variable, anisotropic, and degraded by porous defects. To improve quality, parts are commonly post processed using a variety of techniques including hot isostatic pressing (HIP). During HIP, high temperature and pressure is employed to improve microstructure and reduce pore volume by inducing visco-plastic deformation in the metallic substrate. Validated computational capabilities can provide predictions to guide the selection of processing condition, expected pore reduction, and the effects of varying entrapped gas in the pores. This discussion describes a micro-scale finite element structural model developed to predict pore closure due to HIP in as-built additively manufactured Inconel 718 samples produced by the laser powder bed fusion process. The model accounts for plastic deformation, creep, and internal pressure for a single pore. Pores are characterized in physical samples before and after HIP, and model predictions are compared to this measured data.

defect model prediction↗
NASA NTRS1994

An Approximate Kalman Filter for Ocean Data Assimilation; An Example with an Idealized Gulf Stream Model

A practical method of data assimilation for use with large, nonlinear, ocean general circulation models is explored. A Kalman filter based on approximations of the state error covariance matrix is presented, employing a reduction of the effective model dimension, the error's asymptotic steady-state limit, and a time-invariant linearization of the dynamic model for the error integration. The approximations lead to dramatic computational savings in applying estimation theory to large complex systems. We examine the utility of the approximate filter in assimilating different measurement types using a twin experiment of an idealized Gulf Stream. A nonlinear primitive equation model of an unstable east-west jet is studied with a state dimension exceeding 170,000 elements. Assimilation of various pseudo measurements is examined, including velocity, density, and volume transport at localized arrays, and realistic distributions of satellite altimetry and acoustic tomography observations. Results are compared in terms of their effects on the accuracies of the estimation. The approximate filter is shown to outperform a previous study that used an empirical nudging scheme. The examples demonstrate that useful approximate estimation errors can be computed in a practical manner for general circulation models.

['Kalman↗
NASA NTRS2022

Satellite Data Applications for Sustainable Energy Transitions

Transitioning to a sustainable energy system poses a massive challenge to communities, nations, and the global economy in the next decade and beyond. A growing portfolio of satellite data products is available to support this transition. Satellite data complement other information sources to provide a more complete picture of the global energy system, often with continuous spatial coverage over targeted areas or even the entire Earth. We find that satellite data are already being applied to a wide range of energy issues with varying information needs, from planning and operation of renewable energy projects, to tracking changing patterns in energy access and use, to monitoring environmental impacts and verifying the effectiveness of emissions reduction efforts. While satellite data could play a larger role throughout the policy and planning lifecycle, there are technical, social, and structural barriers to their increased use. We conclude with a discussion of opportunities for satellite data applications to energy and recommendations for research to maximize the value of satellite data for sustainable energy transitions.

energy↗
NASA NTRS2022

CLASSY. II. A Technical Overview of the COS Legacy Archive Spectroscopic Survey

The COS Legacy Archive Spectroscopic SurveY (CLASSY) is designed to provide the community with a spectral atlas of 45 nearby star-forming galaxies that were chosen to cover similar properties to those seen at high z (z > 6). The prime high-level science product of CLASSY is accurately coadded UV spectra, ranging from ∼1000 to 2000 Å, derived from a combination of archival and new data obtained with HST's Cosmic Origins Spectrograph (COS). This paper details the multistage technical processes of creating this prime data product and the methodologies involved in extracting, reducing, aligning, and coadding far-ultraviolet and near-ultraviolet (NUV) spectra. We provide guidelines on how to successfully utilize COS observations of extended sources, despite COS being optimized for point sources, and best-practice recommendations for the coaddition of UV spectra in general. Moreover, we discuss the effects of our reduction and coaddition techniques in the scientific application of the CLASSY data. In particular, we find that accurately accounting for flux calibration offsets can affect the derived properties of the stellar populations, while customized extractions of NUV spectra for extended sources are essential for correctly diagnosing the metallicity of galaxies via C iii] nebular emission. Despite changes in spectral resolution of up to ∼25% between individual data sets (due to changes in the COS line-spread function), no adverse affects were observed on the difference in velocity width and outflow velocities of isolated absorption lines when measured in the final combined data products, owing in part to our signal-to-noise regime of S/N < 20.

Bethan L. James↗
NASA NTRS1991

Mechanisms of ilmenite reduction and their impact on the design of effective reactor systems

One of the first activities at a lunar base could be oxygen recovery from ilmenite (FeTiO3). Oxygen produced from lunar soils could be used to fuel transportation vehicles operating in near-earth space. The first step in developing a suitable reactor system for lunar operation is to determine the mechanisms and rates of oxygen removal from ilmenite. In-situ gravimetric measurements and microscopic examinations were used to determine the hydrogen reduction mechanisms of synthetic ilmenite discs between 823 to 1353 K. A shrinking core reaction model, modified to account for the growth of an iron film on the surface of discs, was capable of predicting experimentally observed conversion-time relationships. The observed reduction mechanism, kinetic rates, and associated activation energy established a base line from which comparisons could be made to improve oxygen yield and removal rates. One proposed technique to improve the rate and extent of oxygen removal was to preoxidize ilmenite. Preoxidation is commonly used during the reduction of ilmenite ores in the iron industry and has been employed for many years to lower operating temperatures and increase reduction rates. This technology could prove beneficial for oxygen production facilities on the Moon as less massive reactor vessels and/or less energy could be associated with a process including preoxidation. X ray diffraction and energy dispersive spectroscopy were utilized to follow the progression of ilmenite oxidation at 1123 and 1140 K and the reduction of pseudobrookite (Fe2TiO5) at 873 and 973 K. Structures formed during the progress of oxidation were related to the system's phase diagrams. Results indicated that after initially producing ilmenite-hematite solutions and rutile (TiO2), pseudobrookite was the end product of oxidation at all temperatures examined (1049 to 1273 K). Initial results from the reduction of pseudobrookite indicate a series of phases are produced including ferropseudobrookite (FeTi2O5), ulvospinel (Fe2TiO4), and ilmenite. Rates of pseudobrookite reduction were typically 50 to 200 times that of ilmenite.

Briggs, R. A.↗
NASA NTRS1995

Effects of Nesting on Compression-Loaded 2-D Woven Textile Composites

Layer nesting was investigated in five harness satin weave textile composite laminates under static compression loading. Two carbon/epoxy material systems, AS4/3501-6 and IM7/8551-7A were considered. Laminates were fabricated with three idealized nesting cases: stacked, split-span and diagonal. Similar compression strength reductions due to the effects of idealized nesting were identified for each material. The diagonal nesting geometry produced the largest reduction in static strength when compared to the compression strength of a conventional textile composite. All three nesting cases produced reductions in strength and ultimate strain due to the effects of idealized nesting. Finite element results showed consistent strength reduction trends for the idealized nesting cases, however the magnitudes of compressive strengths were overpredicted.

Adams, Daniel OHare↗
NASA NTRS1992

The simulated features of heliospheric cosmic-ray modulation with a time-dependent drift model. IV - The role of heliospheric neutral sheet deformation

Previous calculations with a time-dependent drift model revealed the model to be less successful in describing time-dependent modulation during periods of moderate to large solar activity. In this paper, it is argued that a major reason for this is that the previously used wavy heliospheric neutral sheet (HNS) description was based on an idealized HNS not subject to any spatial evolution while propagating radially outward. It is suggested that the deformation and compression of HNS wave peaks will lead to significant increases in the crossfield diffusion across these peaks (short-circuiting). The cosmic rays will effectively experience reduced tilt angles and therefore a reduction in the integrated HNS modulation effect between an observer and the heliospheric boundary. During periods of moderate to large solar activity these HNS deformation processes are progressively more frequent and should lead to a significant reduction in time-dependent modulation as predicted by drift models. Calculations done with radially propagating tilt angles that effectively decrease with radial distance give the expected reduction which improves the general description of modulation from 1987-1988.

Le Roux, J. A.↗
NASA NTRS2014

Aeromechanical Evaluation of Smart-Twisting Active Rotor

An investigation of Smart-Twisting Active Rotor (STAR) was made to assess potential benefits of the current active twist rotor concept for performance improvement, vibration reduction, and noise alleviation. The STAR rotor is a 40% Mach-scaled, Bo105 rotor with an articulated flap-lag hinge at 3.5%R and no pre-cone. The 0-5 per rev active twist harmonic inputs were applied for various flight conditions including hover, descent, moderate to high speed level flights, and slowed rotor high advance ratio. For the analysis, the STAR partners used multiple codes including CAMRAD II, S4, HOST, rFlow3D, elsA, and their associated software. At the high thrust level in hover, the 0 per rev active twist with 80% amplitude increased figure of merit (FM) by 0.01-0.02 relative to the baseline. In descent, the largest BVI noise reduction was on the order of 2 to 5 dB at the 3 per rev active twist. In the high speed case (mu = 0.35), the 2 per rev actuation was found to be the most effective in achieving a power reduction as well as a vibration reduction. At the 2 per rev active twist, total power was reduced by 0.65% at the 60 deg active twist phase, and vibration was reduced by 47.6% at the 45 deg active twist phase. The use of the 2 per rev active twist appears effective for vibration reduction. In the high advance ratio case (mu = 0.70), the 0 per rev actuation appeared to have negligible impact on performance improvement. In summary, computational simulations successfully demonstrated that the current active twist concept provided a significant reduction of the maximum BVI noise in descent, a significant reduction of the vibration in the high speed case, a small improvement on rotor performance in hover, and a negligible impact on rotor performance in forward flight.

Lim, Joon W.↗
NASA NTRS2010

Fifty Years of Fluidic Injection for Jet Noise Reduction

The paper reviews 50 years of research investigating jet noise reduction through fluidic injection. Both aqueous and gaseous injection concepts for supersonic and subsonic jet exhausts are discussed. Aqueous injection reduces jet noise by reducing main jet temperature through evaporation and main jet velocity through momentum transfer between water droplets and the main jet. In the launch vehicle environment where large quantities of fluid do not have to be carried with the vehicle, water injection is very effective at reducing excess overpressures. For in-flight use, aqueous injection is problematic as most studies show that either large quantities of water or high injection pressures are required to achieve noise reduction. The most effective noise reduction injection systems require water pressures above 2000 kPa (290 psi) and water-to-mainjet mass flow rates above 10% to achieve overall sound pressure level reductions of roughly 6 dB in the peak jet noise direction. Injection at lower pressure (roughly 1034 kPa or 150 psi) has resulted in a 1.6 EPNdb reduction in effective perceived noise level. Gaseous injection reduces noise through jet plume modifications resulting from the introduction of streamwise vorticity in the main jet. In subsonic single-stream jets, air injection usually produces the largest overall sound pressure level reductions (roughly 2 dB) in the peak jet noise direction. In dual-stream jets, properly designed injection systems can reduce overall sound pressure levels and effective perceived noise levels but care must be taken to choose injector designs that limit sound pressure level increases at high frequencies. A reduction of 1.0 EPNdB has been achieved with injection into the fan and core streams. However, air injection into dual-stream subsonic jets has received little attention and the potential for noise reduction is uncertain at this time. For dual-stream supersonic jets, additional research needs to be conducted to determine if reductions can be achieved with injection pressures available from current aircraft engines. 1.

Henderson, Brenda↗
NASA NTRS2007

Effective Jet Properties for the Prediction of Turbulent Mixing Noise Reduction by Water Injection

A one-dimensional control volume formulation is developed for the determination of jet mixing noise reduction due to water injection. The analysis starts from the conservation of mass, momentum and energy for the control volume, and introduces the concept of effective jet parameters (jet temperature, jet velocity and jet Mach number). It is shown that the water to jet mass flow rate ratio is an important parameter characterizing the jet noise reduction on account of gas-to-droplet momentum and heat transfer. Two independent dimensionless invariant groups are postulated, and provide the necessary relations for the droplet size and droplet Reynolds number. Results are presented illustrating the effect of mass flow rate ratio on the jet mixing noise reduction for a range of jet Mach number and jet Reynolds number. Predictions from the model show satisfactory comparison with available test data on supersonic jets. The results suggest that significant noise reductions can be achieved at increased flow rate ratios.

Kandula, Max↗