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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 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Aeromechanical stability of a full-scale hingeless rotor in hover

The aeroelastic stability in hover of a 9.8-m-diam, hingeless helicopter rotor system is evaluated. Rotor inplane damping data were obtained for rotor operation between 350 and 425 rpm for thrust coefficients between 0.0 and 0.12. At constant rotor rotational speed, a minimum inplane damping level was obtained at a thrust coefficient of approximately 0.02. At constant rotor thrust, a minimum in rotor inplane damping was measured at 400 rpm. Correlation with a comprehensive aeroelastic stability program is found to be good. The influence of different aerodynamic inflow models on predicted damping levels is shown. Best correlation with experimental data is obtained using a dynamic inflow model rather than static or quasi-static inflow models. Comparison with other full-scale, hingeless rotor stability data in hover is presented. Also, direct comparisons are made with data from a full-scale bearingless main rotor test performed on the same general-purpose test apparatus. Although the bearingless rotor is more highly damped at design tip speed and 1-g thrust operation, greater sensitivity to operating conditions is shown.

Peterson, R. L.↗
NASA NTRS1986

Design and development of a large diameter high pressure fast acting propulsion valve and valve actuator

The design and development of a large diameter high pressure quick acting propulsion valve and valve actuator is described. The valve is the heart of a major test facility dedicated to conducting full scale performance tests of aircraft landing systems. The valve opens in less than 300 milliseconds releasing a 46-centimeter- (18-in.-) diameter water jet and closes in 300 milliseconds. The four main components of the valve, i.e., valve body, safety shutter, high speed shutter, and pneumatic-hydraulic actuator, are discussed. This valve is unique and may have other aerospace and industrial applications.

Srinivasan, K. V.↗
NASA NTRS1988

A differential approach to microcomputer test battery development and implementation

The present microcomputer-based performance test battery emphasizes psychometric theory and utility for repeated-measures applications during extended exposure to various environmental stressors. In the menu that has been defined at the current state of this system's development, there are more than 30 'qualified' mental tests which stabilize in less than 10 min and possess test-retest reliabilities greater than 0.7 for a three-minute test/work period. The battery encompasses tests of cognition, information processing, psychomotor skill, memory, mood, etc. Several of the tests have demonstrated sensitivity to chemoradiotherapy, sleep loss, hypoxia, amphetamines, thermal stress, sensory deprivation, altitude, fatigue, and alcohol use. Recommendations are presented for 6-, 12-, and 22-min batteries.

Kennedy, R. S.↗
NASA NTRS1988

Composite panel development at JPL

Parametric computer studies can be use in a cost effective manner to determine optimized composite mirror panel designs. An InterDisciplinary computer Model (IDM) was created to aid in the development of high precision reflector panels for LDR. The materials properties, thermal responses, structural geometries, and radio/optical precision are synergistically analyzed for specific panel designs. Promising panels designs are fabricated and tested so that comparison with panel test results can be used to verify performance prediction models and accommodate design refinement. The iterative approach of computer design and model refinement with performance testing and materials optimization has shown good results for LDR panels.

Mcelroy, Paul↗
NASA NTRS1986

Design and Development of a Large Diameter, High Pressure, Fast Acting Propulsion Valve and Valve Actuator

This paper describes the design and development of a large diameter high pressure quick acting propulsion valve and valve actuator. The valve is the heart of a major test facility dedicated to conducting full scale performance tests of aircraft landing gear systems. The valve opens in less than 300 milliseconds releasing a 46 cm (18 in) diameter water jet and closes in 300 milliseconds. The four main components of the valve, i.e., valve body, safety shutter, high speed shutter, and pneumatic-hydraulic actuator, are discussed. This valve is unique and may have other aerospace and industrial applications.

Srinivasan, K. V.↗
NASA NTRS2003

Enhanced Mixing in a Rectangular Duct

An experimental investigation of the mixing of non-reacting opposed rows of jets injected normal to a confined rectangular crossflow has been conducted. Planar Mie-scattering was used to measure the time-average concentration distribution of the jet fluid in planes perpendicular to the duct axis. Particular emphasis was placed on the study of closely spaced orifice configurations applicable to the mixing zone of an RQL combustor. Baseline studies were performed of mixing under "ideal" conditions, i.e., plenum fed jets injecting into a crossflow uniform in velocity and turbulence intensity. In addition, more practical ("non-ideal") issues encountered during hardware design were also studied. As in other studies, mixing effectiveness, determined using a spatial unmixedness parameter based on the variance of mean jet concentration distributions, was found to be optimum when the spacing-to-duct-height ratio was inversely proportional to the square root of the jet-to-mainstream momentum-flux ratio. This relationship is suitable for design under ideal flow conditions. Inlet flow boundary conditions of the jet and approach flow (mainstream) were found to strongly influence mixing performance, but no attempt was made to determine optimum performance under non-ideal conditions. The tests performed do offer some guidance as to expected mixing behavior for several common variables likely to be imposed by hardware constraints. Additionally, in this study it was found that for rows of orifices with opposite centerlines inline, mixing was similar for blockages up to 89 percent (previous crossflow mixing studies concerned with dilution zone configurations, blockages were typically less than 50 percent). Lower levels of unmixedness were obtained as a function of downstream location when axial injection length was minimized. Mixing may be enhanced if orifice centerlines of opposed rows are staggered, but blockage must be =50 percent in this configuration. Round hole and "square" orifice shapes had similar performance. Other variations in orifice shape did not substantially augment overall mixing performance. Furthermore an isothermal mixing data set was generated and used by CFDRC as input to a NO(x) inference code.

Liscinsky, D. S.↗
NASA NTRS2005

Static Aerodynamic Performance Investigation of a Fluid Shield Nozzle

In pursuit of an acoustically acceptable, high performance exhaust system capable of meeting Federal Aviation Regulation 36 Stage 3 noise goals for the High Speed Civil Transport application, General Electric Aircraft Engines conducted a design study to incorporate a fluid shield into a 36-chute suppressor exhaust-nozzle system. After a full scale preliminary mechanical design of the resulting fluid shield exhaust system, scale model aerodynamic performance tests and acoustic tests were conducted to establish both aerodynamic performance and acoustic characteristics. Data are presented as thrust coefficients, discharge coefficients, chute-base pressure drags, and plug static pressure distributions.

Balan, C.↗
NASA NTRS2006

A Preliminary Study of Peer-to-Peer Human-Robot Interaction

The Peer-to-Peer Human-Robot Interaction (P2P-HRI) project is developing techniques to improve task coordination and collaboration between human and robot partners. Our work is motivated by the need to develop effective human-robot teams for space mission operations. A central element of our approach is creating dialogue and interaction tools that enable humans and robots to flexibly support one another. In order to understand how this approach can influence task performance, we recently conducted a series of tests simulating a lunar construction task with a human-robot team. In this paper, we describe the tests performed, discuss our initial results, and analyze the effect of intervention on task performance.

Fong, Terrence↗
NASA NTRS2007

Measurement of Creep Properties of Ultra-High-Temperature Materials by a Novel Non-Contact Technique

A non-contact technique for measuring the creep properties of materials has been developed and validated as part of a collaboration among the University of Massachusetts, NASA Marshall Space Flight Center Electrostatic Levitation Facility (ESL), and the University of Tennessee. This novel method has several advantages over conventional creep testing. The sample is deformed by the centripetal acceleration from the rapid rotation, and the deformed shapes are analyzed to determine the strain. Since there is no contact with grips, there is no theoretical maximum temperature and no concern about chemical compatibility. Materials may be tested at the service temperature even for extreme environments such as rocket nozzles, or above the service temperature for accelerated testing of materials for applications such as jet engines or turbopumps for liquid-fueled engines. The creep measurements have been demonstrated to 2400 C with niobium, while the test facility, the NASA MSFC ESL, has processed materials up to 3400 C. Furthermore, the ESL creep method employs a distribution of stress to determine the stress exponent from a single test, versus the many tests required by conventional methods. Determination of the stress exponent from the ESL creep tests requires very precise measurement of the surface shape of the deformed sample for comparison to deformations predicted by finite element models for different stress exponents. An error analysis shows that the stress exponent can be determined to about 1% accuracy with the current methods and apparatus. The creep properties of single-crystal niobium at 1985 C showed excellent agreement with conventional tests performed according to ASTM Standard E-139. Tests on other metals, ceramics, and composites relevant to rocket propulsion and turbine engines are underway.

Hyers, Robert W.↗
NASA NTRS2001

Space Shuttle Orbital Drag Parachute Design

The drag parachute system was added to the Space Shuttle Orbiter's landing deceleration subsystem beginning with flight STS-49 in May 1992. The addition of this subsystem to an existing space vehicle required a detailed set of ground tests and analyses. The aerodynamic design and performance testing of the system consisted of wind tunnel tests, numerical simulations, pilot-in-the-loop simulations, and full-scale testing. This analysis and design resulted in a fully qualified system that is deployed on every flight of the Space Shuttle.

Meyerson, Robert E.↗
NASA NTRS2010

Impact Testing for Materials Science at NASA - MSFC

The Impact Testing Facility (ITF) at NASA - Marshall Space Flight Center is host to different types of guns used to study the effects of high velocity impacts. The testing facility has been and continues to be utilized for all NASA missions where impact testing is essential. The Facility has also performed tests for the Department of Defense, other corporations, as well as universities across the nation. Current capabilities provided by Marshall include ballistic guns, light gas guns, exploding wire gun, and the Hydrometeor Impact Gun. A new plasma gun has also been developed which would be able to propel particles at velocities of 20km/s. This report includes some of the guns used for impact testing at NASA Marshall and their capabilities.

Sikapizye, Mitch↗
NASA NTRS2011

Testing of Large Diameter Fresnel Optics for Space Based Observations of Extensive Air Showers

The JEM-EUSO mission will detect extensive air showers produced by extreme energy cosmic rays. It operates from the ISS looking down on Earth's night time atmosphere to detect the nitrogen fluorescence and Cherenkov produce by the charged particles in the EAS. The JEM-EUSO science objectives require a large field of view, sensitivity to energies below 50 EeV, and must fit within available ISS resources. The JEM-EUSO optic module uses three large diameter, thin plastic lenses with Fresnel surfaces to meet the instrument requirements. A bread-board model of the optic has been manufactured and has undergone preliminary tests. We report the results of optical performance tests and evaluate the present capability to manufacture these optical elements.

Adams, James H.↗
NASA NTRS2012

STS-133/ET-137 Tanking Test Photogrammetry Assessment

Following the launch scrub of Space Shuttle mission STS-133 on November 5, 2010, an anomalous condition of cracked and raised thermal protection system (TPS) foam was observed on the External Tank (ET). Subsequent dissection of the affected TPS region revealed cracks in the feet of two Intertank (IT) metallic stringers. An extensive investigation into the cause(s) and corrective action(s) for the cracked stringers was initiated, involving a wide array of material and structural tests and nondestructive evaluations, with the intent to culminate into the development of flight rational. One such structural test was the instrumented tanking test performed on December 17, 2010. The tanking test incorporated two three-dimensional optical displacement measurement systems to measure full-field outer surface displacements of the TPS surrounding the affected region that contained the stringer cracks. The results showed that the radial displacement and rotation of the liquid oxygen (LO2) tank flange changed significantly as the fluid level of the LO2 approached and passed the LO2 tank flange.

Oliver, Stanley T.↗
NASA NTRS2012

TriG: Next Generation Scalable Spaceborne GNSS Receiver

TriG is the next generation NASA scalable space GNSS Science Receiver. It will track all GNSS and additional signals (i.e. GPS, GLONASS, Galileo, Compass and Doris). Scalable 3U architecture and fully software and firmware recofigurable, enabling optimization to meet specific mission requirements. TriG GNSS EM is currently undergoing testing and is expected to complete full performance testing later this year.

Global Navigation Satellite Systems (GNSS)↗
NASA NTRS2013

EMC Test Report: StangSat - CubeSat Program

This report documents the Electromagnetic Interference E M I testing performed on the StangSat; the unit under test (UUT). Testing was per the requirements of MIL STD-461F. The UUT was characterized and passed the radiated emissions (RE102 limit for Spacecraft) testing.

High School↗
NASA NTRS1996

Mechanical Pumped Cooling Loop for Spacecraft Thermal Control

The Mars Pathfinder (MPF) spacecraft, scheduled for a December '96 launch to Mars, uses a mechanically pumped loop to transfer dissipated heat from the insulated lander electronics to an external radiator. This paper discusses the tradeoffs performed before choosing a mechanically pumped loop as the thermal control system for MPF. It describes the analysis, design, and predicted performance of this system. The various development tests performed are discussed along with the current status of this cooling system. Finally, some thoughts on the development of mechanically pumped loops for future spacecraft are presented.

Mars↗
NASA NTRSDate not supplied

Introduction to Aircraft Icing and NASA's Approach to Understanding It

This presentation provides an introduction to aircraft icing and describes NASA’s approach to understanding it. The presentation covers various topics on icing. A general overview of different types of icing is provided, which includes airframe icing, jet engine icing, and rotorcraft icing. The presentation discusses NASA’s approach to studying the various forms of aircraft icing, which includes conducting flight tests, performing ground-based icing wind tunnel tests, and developing computational tools that simulate the icing physics. An overview on the future of aviation and icing is provided. The presentation is largely high level, but also provides some technical icing physics discussion.

Aircraft Icing↗
NASA NTRS2024

The Effect of Impingement Angle on Bipropellant Thruster Plume Degradation of Spacecraft Materials

Unburned and partially combusted liquid propellant present in bipropellant thruster plumes can contaminate and damage external spacecraft materials. Microscopic impact features due to high-speed droplet impacts have been observed on space shuttle flight experiments and International Space Station (ISS) returned flight hardware. Analytical results have shown that particle impingement angle greatly affects surface damage, with normal impacts being the most severe and highly oblique impacts being more benign. The effect of thruster plume impingement angle on material degradation has now been further studied following a bipropellant thruster plume test performed at the high-vacuum plume test facility for chemical thrusters at DLR Göttingen, STG-CT. Several spacecraft material samples were exposed to the freely expanding pulsed thruster plume at a range of impingement angles (from 0 to 75 deg). Results of post-test evaluations and potential spaceflight applications are summarized.

Gateway↗