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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 1,261 records · Page 70
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Comparison under a simulated sun of two black-nickel-coated flat-plate solar collectors with a nonselective black-paint-coated collector

A performance evaluation was made of two, black nickel coated, flat plate solar collectors. Collector performance was determined under a simulated sun for a wide range of inlet temperatures, including the temperature required for solar powered absorption air conditioning. For a basis of comparison a performance test was made on a traditional, two glass, nonselective, black paint coated, flat plate collector. Performance curves and performance parameters are presented to point out the importance of the design variables which determine an efficient collector. A black nickel coated collector was found to be a good performer at the conditions expected for solar powered absorption air conditioning. This collector attained a thermal efficiency of 50 percent at an inlet temperature of 366 K (200 F) and an incident flux of 946 watts/sq m (300 Btu/hr-sq ft).

Simon, F. F.↗
NASA NTRS1981

In-flight direct-strike lightning research

Tests designed to investigate the lightning-generated electromagnetic environment affecting aircraft are discussed. An F-106B aircraft specially instrumented for lightning electromagnetic measurements was used. The instrumentation system is reviewed and typical results recorded by the instrumentation during simulated-lightning ground tests performed for a safety survey are presented. Several examples of data obtained during summer flight testing are presented and future plans are discussed.

Pitts, F. L.↗
NASA NTRS1991

ECLSS regenerative systems comparative testing and subsystem selection

In support of Space Station Freedom Phase C/D Environmental Control and Life Support Systems (ECLSS) regenerative systems development, comparative testing was performed on predevelopment hardware of competing technologies for each regenerative function. The purpose of the test program was to collect data on latest generation hardware in order to make final technology selections for each subassembly in the oxygen recovery and water reclamation strings. This paper discusses the testing performed, test results, and evaluation of these results relative to subsystem selections for CO2 reduction, O2 generation, potable water processing, hygiene water processing, and urine processing.

Carasquillo, Robyn L.↗
NASA NTRS2000

Stress Counter-Response Training Via Physiological Self-Regulation During Flight Simulation

This study provided the first evaluation of a new training concept and technology aimed at training pilots to maintain physiological equilibrium during circumstances in an airplane cockpit. Thirty healthy subjects (16 males and 14 females) between the ages of 18 and 35 were randomized into two study groups, A and B. Subjects participated individually in a sequence of four study sessions. In the first visit, subjects were taught to operate a desktop fighter jet flight simulation program. In the three sessions that followed, subjects in group A were trained to minimize their autonomic deviation from baseline values while operating the desktop flight simulation. This was done by making their skin conductance and hand temperature deviations from baseline impair the functionality of the aircraft controls. Subjects also received auditory and visual cues about their autonomic deviation, and were instructed to keep these within pre-set limits to retain full control of the aircraft. Subjects in group B were subjected to periods of impaired aircraft functionality independent of their physiologic activity, and thus served as a control group. No statistically significant group differences were found in the flight performance scores from the three training sessions, and post-training flight performance scores of the two groups were not different. We conclude that this study did not provide clear support for this training methodology in optimizing pilot performance. However, a number of shortcomings in the current status of this training methodology may account for the lack of demonstrable training benefit to the experimental group. Suggested future modifications for research on this training methodology include: Limiting the amount of instrument impairment resulting from physiological deviations; conducting a greater number of physiological training sessions per subject; using pre-post training performance tests which invoke a greater amount of stress in subjects; and developing a more detailed performance scoring system.

Palsson, Olafur S.↗
NASA NTRS2000

Production Strategies for Production-Quality Parts for Aerospace Applications

A combination of rapid prototyping processes (3D Systems' stereolithography and Sanders Prototyping's ModelMaker) are combined with gelcasting to produce high quality silicon nitride components that were performance tested under simulated use conditions. Two types of aerospace components were produced, a low-force rocket thruster and a simulated airfoil section. The rocket was tested in a test stand using varying mixtures of H2 and O2, whereas the simulated airfoil was tested by subjecting it to a 0.3 Mach jet-fuel burner flame. Both parts performed successfully, demonstrating the usefulness of the rapid prototyping in efforts to effect materials substitution. In addition, the simulated airfoil was used to explore the possibility of applying thermal/environmental barrier coatings and providing for internal cooling of ceramic parts. It is concluded that this strategy for processing offers the ceramic engineer all the flexibility normally associated with investment casting of superalloys.

Cawley, J. D.↗
NASA NTRS2003

Threshold Assessment of Gear Diagnostic Tools on Flight and Test Rig Data

A method for defining thresholds for vibration-based algorithms that provides the minimum number of false alarms while maintaining sensitivity to gear damage was developed. This analysis focused on two vibration based gear damage detection algorithms, FM4 and MSA. This method was developed using vibration data collected during surface fatigue tests performed in a spur gearbox rig. The thresholds were defined based on damage progression during tests with damage. The thresholds false alarm rates were then evaluated on spur gear tests without damage. Next, the same thresholds were applied to flight data from an OH-58 helicopter transmission. Results showed that thresholds defined in test rigs can be used to define thresholds in flight to correctly classify the transmission operation as normal.

Dempsey, Paula J.↗
NASA NTRS2006

JWST NIRSpec Cryogenic Light Shield Mechanism

The focal plane detectors for the Near-Infrared Spectrometer (NIRSpec) instrument on the James Webb Space Telescope (JWST) require a light tight cover for calibration along with an open field-of-view during g round performance testing within a cryogenic dewar. In order to meet the light attenuation requirements and provide open and closed fields of view without breaking vacuum, a light shield mechanism was designe d. This paper describes the details of the light shield mechanism design and test results. Included is information on the labyrinth light p ath design, motor capability and performance, dry film lubrication, m echanism control, and mechanism cryogenic performance results.

Hale, Kathleen↗
NASA NTRS2016

Improved ASTM G72 Test Method for Ensuring Adequate Fuel-to-Oxidizer Ratios

The ASTM G72/G72M-15 Standard Test Method for Autogenous Ignition Temperature of Liquids and Solids in a High-Pressure Oxygen-Enriched Environment is currently used to evaluate materials for the ignition susceptibility driven by exposure to external heat in an enriched oxygen environment. Testing performed on highly volatile liquids such as cleaning solvents has proven problematic due to inconsistent test results (non-ignitions). Non-ignition results can be misinterpreted as favorable oxygen compatibility, although they are more likely associated with inadequate fuel-to-oxidizer ratios. Forced evaporation during purging and inadequate sample size were identified as two potential causes for inadequate available sample material during testing. In an effort to maintain adequate fuel-to-oxidizer ratios within the reaction vessel during test, several parameters were considered, including sample size, pretest sample chilling, pretest purging, and test pressure. Tests on a variety of solvents exhibiting a range of volatilities are presented in this paper. A proposed improvement to the standard test protocol as a result of this evaluation is also presented. Execution of the final proposed improved test protocol outlines an incremental step method of determining optimal conditions using increased sample sizes while considering test system safety limits. The proposed improved test method increases confidence in results obtained by utilizing the ASTM G72 autogenous ignition temperature test method and can aid in the oxygen compatibility assessment of highly volatile liquids and other conditions that may lead to false non-ignition results.

Juarez, Alfredo↗
NASA NTRS2016

Improved ASTM G72 Test Method for Ensuring Adequate Fuel-to-Oxidizer Ratios

The ASTM G72/G72M-15 Standard Test Method for Autogenous Ignition Temperature of Liquids and Solids in a High-Pressure Oxygen-Enriched Environment is currently used to evaluate materials for the ignition susceptibility driven by exposure to external heat in an enriched oxygen environment. Testing performed on highly volatile liquids such as cleaning solvents has proven problematic due to inconsistent test results (non-ignitions). Non-ignition results can be misinterpreted as favorable oxygen compatibility, although they are more likely associated with inadequate fuel-to-oxidizer ratios. Forced evaporation during purging and inadequate sample size were identified as two potential causes for inadequate available sample material during testing. In an effort to maintain adequate fuel-to-oxidizer ratios within the reaction vessel during test, several parameters were considered, including sample size, pretest sample chilling, pretest purging, and test pressure. Tests on a variety of solvents exhibiting a range of volatilities are presented in this paper. A proposed improvement to the standard test protocol as a result of this evaluation is also presented. Execution of the final proposed improved test protocol outlines an incremental step method of determining optimal conditions using increased sample sizes while considering test system safety limits. The proposed improved test method increases confidence in results obtained by utilizing the ASTM G72 autogenous ignition temperature test method and can aid in the oxygen compatibility assessment of highly volatile liquids and other conditions that may lead to false non-ignition results.

Juarez, Alfredo↗
NASA NTRS2019

Electric Sail Tether Deployment System for CubeSats

An Electric Sail (E-Sail) propulsion system consists of long, thin tethers - positively-charged wires extending radially and symmetrically outward from a spacecraft. Tethers must be biased using a high-voltage power supply to ensure that the solar wind produces thrust. While the E-Sail concept shows great promise for flying heliopause missions with higher characteristic acceleration than solar sails, there are significant technical challenges related to deploying and controlling multiple tethers. A typical full-scale design involves a hub and spoke arrangement of 10 to 100 tethers, each 20 km long. In the last 20 years, there have been multiple space mission failures due to tether deployment and control issues, and most configurations involved a single tether. This paper describes an effort to develop and test a simple yet robust single-tether deployment system for a two-6U CubeSat configuration. The project included the following: a) Tether dynamic modeling/simulation b) E-Sail single-tether prototype development and testing c) Space environmental effects testing to identify best materials for further development. These three areas of investigation were needed to provide technical rationale for an E-Sail flight demonstration mission that is expected to be proposed for the 2022 time frame. The project team used an “agile” engineering approach in which E-Sail single-tether prototype designs were iteratively developed and tested to solve problems and identify design improvements. The agile approach was ideal for this low Technology Readiness Level (TRL) project because tether deployer development involved many unknowns in prototype development that could only be discovered through iterative cycles of construction and testing. Extensive modeling and simulation were accomplished for three types of tether deployment: a) Stage 1: propulsive separation with one 6U fixed b) Stage 2: propulsive spin-up with one 6U fixed c) Stage 3: propulsive spin-up with both 6Us free Simulation results were valuable for understanding the propulsive and braking forces needed for controlled tether deployment. This paper describes the evolution, insights, and test/ performance data related to the resultant single-tether two-6U E-Sail test article which has been demonstrated in a test laboratory. The development effort suggests near-term work needed to achieve a useful flight demonstration, and provides ideas for how multiple-tether deployment systems might evolve going forward. A planned next-generation E-Sail prototype will include autonomous propulsive tether deployment while monitoring tether tension, location on the floor, distance between tether ends, acceleration, velocity, and propellant used.

Tinker, Michael↗
NASA NTRS2017

NASA Handbook 7010: Direct Field Acoustic Testing

Instruments, spacecraft, antennas, reflectors, and other mechanical hardware have been undergoing acoustic qualification testing over the last decade using loudspeakers. This speaker-generated Direct Field Acoustic Test (DFAT) method offers cost, mobility, and schedule advantages over the conventional Reverberant Acoustic Field Test (RAFT) method. To develop most appropriate acoustic test program using the DFAT method for a flight project, flight project managers and their technical staffs will need overall guidance and technical rational for using DFAT to qualify flight hardware for acoustic environments. The NASA Chief Engineer Office had tasked JPL to prepare a NASA Handbook for DFAT Dynamics Testing. The handbook was completed and was released by NASA headquarters in 2015. The handbook provides advantages and disadvantages of such method of testing, key references and a series of recommended practices for test preparation and test performance. This paper will summarize key and important steps related to this method of acoustic testing.

Kolaini, Ali R↗
NASA NTRSDate not supplied

Remotely Administered Psychoacoustic Test for sUAS Noise to Gauge Feasibility of Remote UAM Noise Study

The National Aeronautics and Space Administration (NASA) remotely administered a psychoacoustic test in fall of 2022 as the first of two phases of a cooperative Urban Air Mobility (UAM) vehicle noise human response study. The first phase, the Feasibility Test, described in this paper, determined the feasibility of the remote test method, in contrast to a previous in-person psychoacoustic test that found an annoyance response difference between small unmanned aerial system (sUAS) noise and ground vehicle noise. This paper discusses the Feasibility Test online layout, sound calibration method, remote test software development, stimuli selection, test subject recruitment, and test administration. Test performance is measured through comparison of annoyance response data with the previous in-person test results. The paper also investigates if providing a contextual cue to test subjects influenced their annoyance response. Response differences between test subjects in geographically distinct areas are analyzed. Administrative challenges that were encountered during the test are discussed. The second phase of this study, the implementation phase, will use a remote (web-based) test method and leverage the cooperation of multiple government agencies, academia, and industry to gain human response insights from a wide range of UAM vehicle sounds that would be challenging for a single organization to acquire. Improvements to administering a remote test for the implementation phase of the UAM vehicle noise human response study are recommended.

Remote Psychoacoustic Test↗
NASA NTRSDate not supplied

Remotely Administered Psychoacoustic Test for sUAS Noise to Gauge Feasibility of Remote UAM Noise Study

The National Aeronautics and Space Administration (NASA) remotely administered a psychoacoustic test in fall of 2022 as the first of two phases of a cooperative Urban Air Mobility (UAM) vehicle noise human response study. The first phase, the Feasibility Test, described in this paper, determined the feasibility of the remote test method, in contrast to a previous in-person psychoacoustic test that found an annoyance response difference between small unmanned aerial system (sUAS) noise and ground vehicle noise. This paper discusses the Feasibility Test online layout, sound calibration method, remote test software development, stimuli selection, test subject recruitment, and test administration. Test performance is measured through comparison of annoyance response data with the previous in-person test results. The paper also investigates if providing a contextual cue to test subjects influenced their annoyance response. Response differences between test subjects in geographically distinct areas are analyzed. Administrative challenges that were encountered during the test are discussed. The second phase of this study, the implementation phase, will use a remote (web-based) test method and leverage the cooperation of multiple government agencies, academia, and industry to gain human response insights from a wide range of UAM vehicle sounds that would be challenging for a single organization to acquire. Improvements to administering a remote test for the implementation phase of the UAM vehicle noise human response study are recommended.

Remote Psychoacoustic Test↗
NASA NTRS1971

Redundancy management of electrohydraulic servoactuators by mathematical model referencing

A description of a mathematical model reference system is presented which provides redundancy management for an electrohydraulic servoactuator. The mathematical model includes a compensation network that calculates reference parameter perturbations induced by external disturbance forces. This is accomplished by using the measured pressure differential data taken from the physical system. This technique was experimentally verified by tests performed using the H-1 engine thrust vector control system for Saturn IB. The results of these tests are included in this report. It was concluded that this technique improves the tracking accuracy of the model reference system to the extent that redundancy management of electrohydraulic servosystems may be performed using this method.

Campbell, R. A.↗
NASA NTRS1972

Effects of stress upon psychophysiological responses and performance following sleep deprivation

The usefulness of psychological and physiological variables in predicting performance under stress of 48 hours of sleep deprivation was investigated. Performance tests, with subjects of different ego strength personalities, in concept acquisition, reading comprehension, word association, word memory, and anagrams were conducted, and physiological measurements of (1) the phasic and tonic electrodermal, (2) galvanic skin response, (3) thermal skin resistance, (4) heart rate, (5) respiration, and (6) plethysmographic finger pulse volumn were recorded. It was found that the changes in the pattern of performance were the result of testing subjects at times when they would normally be sleeping, and that sleep deprivation longer than 48 hours must be maintained to produce changes in simple or well learned tasks.

Roessler, R.↗
DOE OSTI2024

Mercury Testing with Sludge Batch 10 Tank 40 Simulant

Savannah River Mission Completion (SRMC) requested that researchers at Savannah River National Laboratory (SRNL) perform testing designed to examine why the Defense Waste Processing Facility (DWPF) is not collecting elemental mercury in the Mercury Water Wash Tank (MWWT). In order for DWPF to recover mercury, mercuric oxide must first be reduced to elemental mercury. The elemental mercury must then be steam stripped, condense, and coalesce in the Mercury Water Wash Tank (MWWT) during chemical processing in the Sludge Receipt and Adjustment Tank (SRAT). The efficiency of these steps was investigated in a series of laboratory scale SRAT experiments under the nitric-glycolic and nitric-formic flowsheets utilizing Momentive Y-17112 and Antifoam 747. Mercury speciation in the Slurry Mix Evaporator Condensate Tank (SMECT) and condensate streams was also examined. The key conclusions from these experiments are as follows: Mercury II Oxide may not be fully reduced to elemental mercury during acid addition at 93°C. Higher temperatures, i.e., boiling may be necessary to fully reduce Mercury II Oxide. The highest percent mercury recovery (71 %) in the MWWT was observed in the MS-NGA-17112 experiment (nitric-glycolic acid flowsheet with Momentive Y-17112), which is how DWPF is currently operating the SRAT.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1979

Indoor test for thermal performance evaluation of seven Elcam fin-tube solar collector configurations

The test procedure used and the results obtained from an evaluation test program conducted to obtain thermal performance data on seven Elcam fin-tube solar collector configurations under simulated conditions are described. These tests were made using the Marshall Space Flight Center solar facilities. The Elcam fin-tube (liquid) solar collectors each consist of an absorber plate 5.9 inches wide by 83 inches long and a type M copper tube of 0.569 inch nominal inside diameter. No cover plate was used with any of the specimens. The uniqueness of each of the seven configurations is described, and tests were performed on each separate configuration.

Source record↗