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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Laser-free GHz stroboscopic transmission electron microscope: Components, system integration, and practical considerations for pump–probe measurements

In this work a 300 keV transmission electron microscope was modified to produce broadband pulsed beams that can be, in principle, between 40 MHz and 12 GHz, corresponding to temporal resolution in the nanosecond to picosecond range without an excitation laser. The key enabling technology is a pair of phase-matched modulating and de-modulating traveling wave metallic comb striplines (pulsers). An initial temporal resolution of 30 ps was achieved with a strobe frequency of 6.0 GHz. The placement of the pulsers, mounted immediately below the gun, allows for preservation of all optical configurations, otherwise available to the unmodified instrument, and therefore makes such a post-modified instrument for dual-use, i.e., both pulsed-beam mode (i.e., stroboscopic time-resolved) and conventional continuous waveform mode. In this article, we describe the elements inserted into the beam path, challenges encountered during integration with an in-service microscope, and early results from an electric-field-driven pump–probe experiment. We conclude with ideas for making this class of instruments broadly applicable for examining cyclical and repeatable phenomena.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1973

An ironless armature brushless torque motor

A high torque motor with improved servo mechanism is reported. Armature windings are cast into an epoxy cylinder and armature conductors are integrally cast with an aluminum mounting ring which provides thermal conductance directly into the structure. This configuration eliminates magnetic hysteresis because there is no relative motion between the rotating magnetic field and any stationary iron. The absence of destabilization forces provides a fast electrical response compared with a typical torquer of conventional construction.

Studer, P. A.↗
NASA NTRS1976

Results of investigations conducted in the LaRC 8-foot transonic pressure tunnel using the 0.010-scale 72-OTS model of the space shuttle integrated vehicle (IA93)

Test procedures, history, and data from the wind tunnel test are presented. Aero-loads were investigated on the updated configuration-5 space shuttle launch vehicle at Mach numbers from 0.600 to 1.205. Six-component vehicle forces and moments, base and sting-cavity pressures, elevon hinge moments, wing-root bending and torsion moments, and normal shear force data were obtained. Full simulation of updated vehicle protuberances and attach hardware was employed. Various elevon deflection angles were tested with two different forward orbiter-to-external-tank attach-strut configurations. The entire model was supported by means of a balance mounted in the orbiter through its base and suspended from a sting.

Nichols, M. E.↗
NASA NTRS1977

Experimental subsonic drag properties of the space shuttle orbiter TPS tiles

The drag characteristics of the space shuttle orbiter thermal protection system (TPS) tiles were studied experimentally in subsonic flow. Full-scale tiles were mounted to a 3.05 x 3.5 m test board in four configurations plus a completely smooth case. Pressure gradients were produced by tilting the board relative to the freestream. The drags due to steps, slots, and gaps between the tiles were evaluated at various orientations, pressure gradients, and Reynolds numbers. Results showed that the contribution of gaps and slots were minor compared to those of typical steps. The results for skin friction did not correlate as a fully rough surface. Thus, the surface area of the TPS tiles was sufficient to allow smooth-wall Reynolds number effects even though the steps between tiles could double the skin friction.

Norton, D. J.↗
NASA NTRS1978

Non-tracking solar energy collector system

A solar energy collector system characterized by an improved concentrator for directing incident rays of solar energy on parallel vacuum-jacketed receivers or absorbers is described. Numerous individually mounted reflector modules of a common asymmetrical triangular cross-sectional configuration are supported for independent reorientation. Asymmetric vee-trough concentrators are defined.

Selcuk, M. K.↗
NASA NTRS1978

Non-tracking solar energy collector system

A solar energy collector system is described characterized by an improved concentrator for directing incident rays of solar energy on parallel strip-like segments of a flatplate receiver. Individually mounted reflector modules of a common asymmetrical triangular cross-sectional configuration supported for independent orientation are asymmetric included with vee-trough concentrators for deflecting incident solar energy toward the receiver.

Selcuk, M. K.↗
NASA NTRS1980

Flight and tunnel test results of the MDC mechanical jet noise suppressor nozzle

The flight and wind tunnel tests to determine the acoustic and performance effects of a mechanical jet noise suppressor nozzle mounted on a Viper engine of an HS-125 airplane are discussed. Flyover noise measurements were made with microphones mounted on top of a 137.5 m bridge tower. Seven nozzle configurations including two references nozzles, two suppressors, and three ejector inlets were tested. The suppressor nozzle of interest for an advanced supersonic transport, the suppressor/treated ejector, achieved a measured noise reduction of 14 EPNdB relative to a conventional conical reference nozzle at the highest pressure ratio tested (approximately 2.5). The unique engine nacelle, flight hardware, and nacelles from the HS-125 flight test program, combined with a simulated HS-125 fuselage were windtunnel tested. Both propulsion and acoustic data were recorded. Preliminary thrust data results from the wind tunnel tests are summarized and compared to other mechanical suppressor test results. The test results indicate that a noise reduction of at least 16 EPNdB would be possible for the suppressor/ejector nozzle scaled to typical AST engine size with a 5% thrust loss at a typical takeoff climb speed.

Fitzsimmons, R. D.↗
NASA NTRS1983

Studies with the Pinhole/Occulter Facility

The scientific justifications for high-resolution hard X-ray astronomy are reviewed, and a scheme for making such observations from the Space Shuttle payload bay is presented. High-resolution X-ray observations at photon energies above 10 keV are important for the understanding of the physics of solar flares, coronal disturbances related to flares, and corona fine structure, as well as nonsolar X-ray sources. In order to study these phenomena, concepts have been developed for the Shuttle Pinhole/Occulter Facility (P/OF), an instrument based on the principles of the pinhole camera which will have an angular resolution of 0.2 arc sec. The proposed P/OF configuration consists of four separate telescopes or position-sensitive counters mounted on a detector plane and looking toward the target through separate portions of an aperture mask (occulter plane). The two planes are separated by a self-deployable 50-m boom, which is to be made essentially rigid by direct control of its lowest normal modes.

Tandberg-Hanssen, E.↗
NASA NTRS1982

Space station preliminary design report

The results of a 3 month preliminary design and analysis effort is presented. The configuration that emerged consists of a very stiff deployable truss structure with an overall triangular cross section having universal modules attached at the apexes. Sufficient analysis was performed to show feasibility of the configuration. An evaluation of the structure shows that desirable attributes of the configuration are: (1) the solar cells, radiators, and antennas will be mounted to stiff structure to minimize control problems during orbit maintenance and correction, docking, and attitude control; (2) large flat areas are available for mounting and servicing of equipment; (3) Large mass items can be mounted near the center of gravity of the system to minimize gravity gradient torques; (4) the trusses are lightweight structures and can be transported into orbit in one Shuttle flight; (5) the trusses are expandable and will require a minimum of EVA; and (6) the modules are anticipated to be structurally identical except for internal equipment to minimize cost.

Source record↗
NASA NTRS1988

Future MAUS payload and the TWIN-MAUS configuration

The German MAUS project (materials science autonomous experiments in weightlessness) was initiated in 1979 for optimum utilization of NASA's Get Away Special (GAS) program. The standard MAUS system was developed to meet GAS requirements and can accommodate a wide variety of GAS-type experiments. The system offers a range of services to experimenters within the framework of standardized interfaces. Four MAUS payloads being prepared for future space shuttle flight opportunities are described. The experiments include critical Marangoni convection, oscillatory Marangoni convection, pool boiling, and gas bubbles in glass melts. Scientific objectives as well as equipment hardware are presented together with recent improvements to the MAUS standard system, e.g., a new experiment control and data management unit and a semiconductor memory. A promising means of increasing resources in the field of GAS experiments is the interconnection of GAS containers. This important feature has been studied to meet the challenge of future advanced payloads. In the TWIN-MAUS configuration, electrical power and data will be transferred between two containers mounted adjacent to each other.

Staniek, S.↗
NASA NTRS1990

Exploratory wind tunnel investigation of the stability and control characteristics of a three-surface, forward-swept wing advanced turboprop model

The purpose of the present investigation was to parametrically study the stability and control characteristics of a forward-swept wing three-surface turboprop model through an extended angle of attack range, including the deep-stall region. As part of a joint research program between North Carolina State University and NASA Langley Research Center, a low-speed wind tunnel investigation was conducted with a three-surface, forward-swept wing, aft-mounted, twin-pusher propeller, model, representative of an advanced turboprop configuration. The tests were conducted in the NASA Langley 12-Foot Low-Speed Wind Tunnel. The model parameters varied in the test were horizontal tail location, canard size, sweep and location, and wing position. The model was equipped with air turbines, housed within the nacelles and driven by compressed air, to model turboprop power effects. A three-surface, forward-swept wing configuration that provided satisfactory static longitudinal and lateral/directional stability was identified. The three-surface configuration was found to have greater longitudinal control and increased center of gravity range relative to a conventional (two-surface) design. The test showed that power had a large favorable effect on stability and control about all three axis in the post-stall regime.

Coe, Paul L., Jr.↗
NASA NTRS1995

Flight-Test Fixture For Aerodynamic Research

Second-generation flight-test fixture (FTF-II) developed to be used as generic test bed for research in aerodynamics and fluid mechanics. Highly instrumented finlike structure mounted on lower fuselage surface of F-15B airplane. Modular configuration makes possible to modify FTF-II to satisfy variety of flight-test requirements. Fixture used at airspeeds up to mach 2.0.

Richwine, David M.↗
NASA NTRS1995

A Unique Facility For Metabolic and Thermoregulatory Studies

A unique exercise facility has been developed and used to perform tipper body ergometry tests for space applications. Originally designed to simulate the muscular, cardiovascular and thermoregulatory responses to working in zero gravity, this facility may be used to conduct basic thermoregulatory investigations applicable to multiple sclerosis patients. An environmental chamber houses the tipper body ergometer and permits control of temperature, air now and humidify. The chamber is a closed system and recirculate-s air after conditioning if. A Cybex Lipper body ergometer has been mounted horizontally on the wall of the environmental chamber. In this configuration, the subject lies underneath the arm crank on a supine seat in order to turn the crank. The supine seat can be removed in order to introduce other equipment into the chamber such as a stool to allow upright arm cranking, or a treadmill to allow walk-run experiments. Physiological and environmental signals are fed into a Strawberry Tree data acquisition system while being monitored and logged using the Workbench software program. Physiological monitoring capabilities include 3-lead EKG using an H-P patient monitor, 5 site skin temperature and core temperature using YSI thermistors, and O2 consumption and CO2 production using AMFTFK Applied Electrochemistry analyzers and sensors. This comprehensive data acquisition set tip allows for calculation of various thermoregulatory indices including heat storage, evaporative heat loss, latent heat loss, and metabolic rate. The current system is capable of adding more data acquisition channels if needed. Some potential studies that could be carried out using the facility include: 1) An investigation into the efficiency of cooling various segments of the body to lower Tc 1-2 F. 2) A series of heat and mass balance studies comparing various LCG configurations.

Williamson, Rebecca C.↗
NASA NTRS2004

Force, Surface Pressure, and Flowfield Measurements on a Slender Missile Configuration with Square Cross-Section at Supersonic Speeds

A wind-tunnel investigation of a square cross-section missile configuration has been conducted to obtain force and moment measurements, surface pressure measurements, and vapor screen flow visualization photographs for comparison with computational fluid dynamics studies conducted under the auspices of The Technical Cooperation Program (TTCP). Tests were conducted on three configurations which included: (1) body alone, (2) body plus tail fins mounted on the missile corners, and (3) body plus tail fins mounted on the missile side. This test was conducted in test section #2 of the NASA Langley Unitary Plan Wind Tunnel at Mach numbers of 2.50 and 4.50 and at a Reynolds number of 4 million per ft. The data were obtained over an angle of attack range from -4 deg. to 24 deg. and roll angles from 0 deg. to 45 deg., i.e., from a diamond shape (as viewed from the rear) at a roll angle of 0 deg. to a square shape at 45 deg.

Wilcox, Floyd J., Jr.↗
NASA NTRS1953

A Transonic Wind-Tunnel Investigation of the Trim and Dynamic Response Characteristics of the Horizontal Tail of a 1/7-Scale Model of the Complete Tail of the Grumman XF10F-1 Airplane

An investigation was made of the trim and dynamic response characteristics of the free-floating horizontal tail of a 1/7-scale model of the complete tail of the Grumman XF10F-1 airplane in the Langley 8-foot transonic tunnel at Mach numbers up to 1.13. The complete tail was mounted in the tunnel on a 3deg conical support body. Various configurations were investigated. A loss in damping of the horizontal tail at transonic speeds was shown by both tunnel and flight tests. The loss in damping extended over a greater Mach number range and the maximum loss occurred at a higher Mach number in the tunnel tests. Large-amplitude oscillations of the horizontal tail of the basic configuration which occurred at low supersonic Mach numbers appeared to be primarily due to the vertical tail of the basic configuration and the interference effects associated with this tail. Secondary factors contributing to the development of the large-amplitude oscillations of the horizontal tail of the basic configuration were probably the loss in damping of the horizontal tail at transonic speeds and the turbulence of the airstream itself.

Luoma, Arvo A.↗
NASA NTRS2006

Measurement of Model Noise in a Hard-Wall Wind Tunnel

Identification, analysis, and control of fluid-mechanically-generated sound from models of aircraft and automobiles in special low-noise, semi-anechoic wind tunnels are an important research endeavor. Such studies can also be done in aerodynamic wind tunnels that have hard walls if phased microphone arrays are used to focus on the noise-source regions and reject unwanted reflections or background noise. Although it may be difficult to simulate the total flyover or drive-by noise in a closed wind tunnel, individual noise sources can be isolated and analyzed. An acoustic and aerodynamic study was made of a 7-percent-scale aircraft model in a NASA Ames 7-by-10-ft (about 2-by-3-m) wind tunnel for the purpose of identifying and attenuating airframe noise sources. Simulated landing, takeoff, and approach configurations were evaluated at Mach 0.26. Using a phased microphone array mounted in the ceiling over the inverted model, various noise sources in the high-lift system, landing gear, fins, and miscellaneous other components were located and compared for sound level and frequency at one flyover location. Numerous noise-alleviation devices and modifications of the model were evaluated. Simultaneously with acoustic measurements, aerodynamic forces were recorded to document aircraft conditions and any performance changes caused by geometric modifications. Most modern microphone-array systems function in the frequency domain in the sense that spectra of the microphone outputs are computed, then operations are performed on the matrices of microphone-signal cross-spectra. The entire acoustic field at one station in such a system is acquired quickly and interrogated during postprocessing. Beam-forming algorithms are employed to scan a plane near the model surface and locate noise sources while rejecting most background noise and spurious reflections. In the case of the system used in this study, previous studies in the wind tunnel have identified noise sources up to 19 dB below the normal background noise of the wind tunnel. Theoretical predictions of array performance are used to minimize the width and the side lobes of the beam pattern of the microphone array for a given test arrangement. To capture flyover noise of the inverted model, a 104-element microphone array in a 622-mm-diameter cluster was installed in a 19-mm-thick poly(methyl methacrylate) plate in the ceiling of the test section of the wind tunnel above the aircraft model (see Figure 1). The microphones were of the condenser type, and their diaphragms were mounted flush in the array plate, which was recessed 12.7 mm into the ceiling and covered by a porous aromatic polyamide cloth (not shown in the figure) to minimize boundary-layer noise. This design caused the level of flow noise to be much less than that of flush-mount designs. The drawback of this design was that the cloth attenuated sound somewhat and created acoustic resonances that could grow to several dB at a frequency of 10 kHz.

Soderman, Paul T.↗
NASA NTRS2013

Recent Enhancements to the NASA Langley Structural Acoustics Loads and Transmission (SALT) Facility

The Structural Acoustics Loads and Transmission (SALT) facility at the NASA Langley Research Center is comprised of an anechoic room and a reverberant room, and may act as a transmission loss suite when test articles are mounted in a window connecting the two rooms. In the latter configuration, the reverberant room acts as the noise source side and the anechoic room as the receiver side. The noise generation system used for qualification testing in the reverberant room was previously shown to achieve a maximum overall sound pressure level of 141 dB. This is considered to be marginally adequate for generating sound pressure levels typically required for launch vehicle payload qualification testing. Recent enhancements to the noise generation system increased the maximum overall sound pressure level to 154 dB, through the use of two airstream modulators coupled to 35 Hz and 160 Hz horns. This paper documents the acoustic performance of the enhanced noise generation system for a variety of relevant test spectra. Additionally, it demonstrates the capability of the SALT facility to conduct transmission loss and absorption testing in accordance with ASTM and ISO standards, respectively. A few examples of test capabilities are shown and include transmission loss testing of simple unstiffened and built up structures and measurement of the diffuse field absorption coefficient of a fibrous acoustic blanket.

Rizzi, Stephen A.↗
NASA NTRS2017

Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) Instrument Improvements

The Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR) combines airborne sun tracking and sky scanning with grating spectroscopy to improve knowledge of atmospheric constituents and their links to air-pollution and climate. Hyper-spectral measurements of direct-beam solar irradiance provide retrievals of gas constituents, aerosol optical depth, and aerosol and thin cloud optical properties. Sky radiance measurements in the principal and almucantar planes enhance retrievals of aerosol absorption, aerosol type, and size mode distribution. Zenith radiance measurements are used to retrieve cloud properties and phase, which in turn are used to quantify the radiative transfer below cloud layers. These airborne measurements tighten the closure between satellite and ground-based measurements. In contrast to the Ames Airborne Tracking Sunphotometer (AATS-14) predecessor instrument, new technologies for each subsystem have been incorporated into 4STAR. In particular, 4STAR utilizes a modular sun-trackingsky-scanning optical head with fiber optic signal transmission to rack mounted spectrometers, permitting miniaturization of the external optical head, and spectrometerdetector configurations that may be tailored for specific scientific objectives. This paper discusses technical challenges relating to compact optical collector design, radiometric dynamic range and stability, and broad spectral coverage at high resolution. Test results benchmarking the performance of the instrument against the AATS-14 standard and emerging science requirements are presented.

Atmopheric Research (4STAR)↗