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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 919 records · Page 51

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NASA NTRS1981

High intensity surge and seasonal effects in the dark current of the Nimbus-4 BUV experiment

Seasonal global maps of the dark current produced by corpuscular radiation contributing to the background level of the Nimbus-4 Backscattered Ultraviolet (BUV) instrument were developed, using BUV monochrometer nighttime data in the pulse counting mode during solar and magnetically quiet periods. The existence of high intensity surges has been discovered which occur on a sporadic basis and which cause sufficient enhancements of dark current within the subauroral regions to produce background levels similar to those within the South Atlantic anomaly. Examples are provided of the nominal quiet dark current intensity maps, and the variability and implications of the surge data are discussed.

Stassinopoulos, E. G.↗

NASA NTRS1983

Atmospheric simulator and calibration system for remote sensing radiometers

A system for calibrating the MAPS (measurement of air pollution from satellites) instruments was developed. The design of the system provides a capability for simulating a broad range of radiant energy source temperatures and a broad range of atmospheric pressures, temperatures, and pollutant concentrations for a single slab atmosphere. The system design and the system operation are described.

Holland, J. A.↗

NASA NTRS1983

An evaluation of Space Shuttle Orbiter forward fuselage surface pressures - Comparison with wind tunnel and theoretical predictions

In order for ground-based pressure distribution techniques to be verified by the actual performance of the Space Shuttle Orbiter in flight, a comparative study of flight pressure data and both wind tunnel and computational data is presented. The flight pressure data, obtained from measurements on the Orbiter's surface during atmospheric reentry, are part of the overall Orbiter flight data system designated Development Flight Instrumentation. Also given is an analysis of the Orbiter pressure data system, including its transducers, their behavior, and their calibration. The two analyses are the bases of an error assessment calculation for the flight data, as well as an explanation of any discrepancies between flight and ground-based data.

Bradley, P. F.↗

NASA NTRS1982

Faint-object spectrograph optical bench

The Faint-Object Spectrograph (FOS) is one of five scientific instruments under development for use with the Optical Telescope Assembly (OTA) of NASA's Space Telescope. It is a dual-channel spectrograph operating with two independent 512-channel pulse-counting Digicons. The FOS will be employed in connection with the study of scientific questions associated with quasars, active galaxies, normal distant and local group galaxies, a wide class of objects within the Milky Way Galaxy and neighboring galaxies, and objects within the solar system. The FOS contains an optical bench which supports all optical elements. Dimensional stability was the primary design requirement for the optical bench. This led to the selection of a graphite/epoxy structure using laminates with very low coefficients of thermal expansion and high stiffness. The technical requirements are considered and details of fabrication are discussed.

Toth, J. M., Jr.↗

NASA NTRS1983

Shuttle Entry Air Data System concepts applied to Space Shuttle Orbiter flight pressure data to determine air data - STS 1-4

The Shuttle Entry Air Data System (SEADS) is the implementation of a new concept in air data systems, with application to entry vehicles. This concept incorporates an array of flush orifices in the nose and forward fuselage of the vehicle and a new flowfield modeling concept for the analysis of flight data and the determination of the required air data parameters. Although the SEADS has not been fully demonstrated, a developmental analysis capability has been assembled and demonstrated. This analytical capability has been used to analyze selected Development Flight Instrumentation (DFI) pressure data from STS-1 through STS-4 and determine angle of attack and freestream dynamic pressure. The results of this study verify the potential of the SEADS as a highly fault tolerant operational air data system. In addition, the transition of SEADS from its present status as an experimental system to an operational system is shown to be readily achievable.

Siemers, P. M., III↗

NASA NTRS1983

Acoustic ground impedance meter

A compact, portable instrument was developed to measure the acoustic impedance of the ground, or other surfaces, by direct pressure-volume velocity measurement. A Helmholtz resonator, constructed of heavy-walled stainless steel but open at the bottom, is positioned over the surface having the unknown impedance. The sound source, a cam-driven piston of known stroke and thus known volume velocity, is located in the neck of the resonator. The cam speed is a variable up to a maximum 3600 rpm. The sound pressure at the test surface is measured by means of a microphone flush-mounted in the wall of the chamber. An optical monitor of the piston displacement permits measurement of the phase angle between the volume velocity and the sound pressure, from which the real and imaginary parts of the impedance can be evaluated. Measurements using a 5-lobed cam can be made up to 300 Hz. Detailed design criteria and results on a soil sample are presented. Previously announced in STAR as N82-17476

Zuckerwar, A. J.↗

NASA NTRS1983

New approaches to planetary exploration - Spacecraft and information systems design

Approaches are recommended for use by the NASA Solar System Exploration Committee (SSEC) in lowering the costs of planetary missions. The inclusion of off-the-shelf hardware, i.e., configurations currently in use for earth orbits and constructed on a nearly assembly-line basis, is suggested. Alterations would be necessary for the thermal control, power supply, telecommunications equipment, and attitude sensing in order to be serviceable as a planetary observer spacecraft. New technology can be developed only when cost reduction for the entire mission would be realized. The employment of lower-cost boost motors, or even integrated boost motors, for the transfer out of earth orbit is indicated, as is the development of instruments that do not redundantly gather the same data as previous planetary missions. Missions under consideration include a Mars geoscience climatology Orbiter, a lunar geoscience Orbiter, a near-earth asteroid rendezvous, a Mars aeronomy Orbiter, and a Venus atmospheric probe.

Diaz, A. V.↗

NASA NTRS1985

Measuring Tracking Accuracy of CCD Imagers

Tracking accuracy and resolution of charge-coupled device (CCD) imaging arrays measured by instrument originally developed for measuring performance of star-tracking telescope. Operates by projecting one or more artifical star images on surface of CCD array, moving stars in controlled patterns, and comparing star locations computed from CCD outputs with those calculated from step coordinates of micropositioner.

Stanton, R. H.↗

NASA NTRS1983

SAR calibration: A technology review

Various potential applications of amplitude-calibrated SAR systems are briefly described, along with an estimate of calibration performance requirements. A review of the basic SAR calibration problem is given. For background purposes and to establish consistent definition of terms, various conventional SAR performance parameters are reviewed along with three additional parameters which are directly related to calibrated SAR systems. Techniques for calibrating a SAR are described. Included in the results presented are: calibration philosophy and procedures; review of the calibration signal generator technology development with results describing both the development of instrumentation and internal calibration measurements for two SAR systems; summary of analysis and measurements required to determine optimum retroreflector design and configuration for use as a reference for the absolute calibration of a SAR system; and summary of techniques for in-flight measurements of SAR antenna response.

Larson, R. W.↗

NASA NTRS1984

A technique combining the visibility of a Doppler signal with the peak intensity of the pedestal to measure the size and velocity of droplets in a spray

A technique combining the visibility of a Doppler signal and the intensity of the scattered light to measure the size and velocity of particles is presented. It is shown that using only the visibility technique can lead to large errors under many conditions such as dense sprays. It is also shown that this error is considerably reduced and very high resolution is obtained by combining the visibility with the intensity of the scattered light. An instrument was developed using this new concept and measurements were performed in sprays of known characteristics. The results of monodispersed, bimodal and trimodal sprays are reported.

Hess, C. F.↗

NASA NTRS1984

Air-sampling inlet contamination by aircraft emissions on the NASA CV-990 aircraft

Results of an experimental investigation of the contamination of air sampling inlets by aircraft emissions from the NASA CV-990 research aircraft are presented. This four-engine jet aircraft is a NASA facility used for many different atmospheric and meteorological experiments, as well as for developing spacecraft instrumentation for remote measurements. Our investigations were performed to provide information on which to base the selection of sampling locations for a series of multi-instrument missions for measuring tropospheric trace gases. The major source of contamination is the exhaust from the jet engines, which generate many of the same gases that are of interest in atmospheric chemistry, as well as other gases that may interfere with sampling measurements. The engine exhaust contains these gases in mixing ratios many orders of magnitude greater than those that occur in the clean atmosphere which the missions seek to quantify. Pressurized samples of air were collected simultaneously from a scoop located forward of the engines to represent clean air and from other multiport scoops at various aft positions on the aircraft. The air samples were analyzed in the laboratory by gas chromatography for carbon monoxide, an abundant combustion by-product. Data are presented for various scoop locations under various flight conditions.

Condon, E. P.↗

NASA NTRS1984

Comparison of the information content of data from the Landsat-4 Thematic Mapper and the Multispectral Scanner

There has been a steady increase with respect to the available capability to monitor the earth's surface from satellite platforms. Developments regarding instrumentation should now be considered in the context of the possible commercialization of space systems. The satellite data user is to select his data with many variables in mind, including cost. The present investigation provides a statistical comparison of simultaneously acquired data from the Landsat-4 Thematic Mapper (TM) and the Multispectral Scanner (MSS) for five scenes acquired over agricultural areas. Simple examination of photographic products and manipulation and display of image data suggests that the utility of the TM data will be far greater than that of the MSS. However, factors of cost and frequency of observations can also be important. The approach employed in the investigation should facilitate evaluation of future remote sensing systems.

Price, J. C.↗

NASA NTRS1984

The use of an optical data acquisition system for bladed disk vibration analysis

A new concept in instrumentation was developed by engineers at NASA Lewis Research Center to collect vibration data from multi-bladed rotors. This new concept, known as the optical data acquisition system, uses optical transducers to measure bladed tip delections by reflection light beams off the tips of the blades as they pass in front of the optical transducer. By using an array of transducers around the perimeter of the rotor, detailed vibration signals can be obtained. In this study, resonant frequencies and mode shapes were determined for a 56 bladed rotor using the optical system. Frequency data from the optical system was also compared to data obtained from strain gauge measurements and finite element analysis and was found to be in good agreement.

Lawrence, C.↗

NASA NTRS1985

Results of aeroheating DFI and ET design-data test on a 0.0175-scale model 60-OTS conducted in the Von Karman Gas Dynamics Facility (VKF) 40" supersonic and the 50" hypersonic wind tunnels A and C

The 0.0175-scale thin-skin thermocouple Model 60-OTS was tested in the von Karman Gas Facility 40-inch continuous flow supersonic tunnel A and the VKF Tunnel C. Testing was conducted at Mach numbers 2.25 to 4.0, and Reynolds numbers from 0.4 x 10 to the 6th power/ft to 6.6 x 10 to the 6th power/ft. Angle of attack range was from -5.0 to +5.0 degrees, and angle of sideslip range was from -6 to +6 degrees. The primary objective of this test was to provide a valid base for the external tank (ET) and solid rocket booster (SRB) heating prediction methodology for ascent flight by taking heating data at Development Flight Instrumentation (DFI) locations for flight conditions simulating STS-1 through -4. A second objective was to obtain additional aeroheating data to support potential reduction of the thermal protection system (TPS) on the ET. The third phase of the test was funded and conducted by NASA/MSFC for the purpose of establishing confidence in the data base from the lower temperature tunnel A.

Marroquin, J.↗

NASA NTRS1985

Remote sensing of directional wave spectra using the surface contour radar

A unique radio-oceanographic remote sensing instrument was developed. The 36 GHz airborne Surface Contour Radar (SCR) remotely produces a real-time topographical map of the sea surface beneath the aircraft. It can routinely produce ocean directional wave spectra with off-line data processing. The transmitter is a coherent dual-frequency device that uses pulse compression to compensate for the limited available power at Ka band. The radar has selectable pulse widths of 1, 2, 4, and 10 nanoseconds. The transmitting antenna is a 58 lambda horn fed dielectric lens whose axis is parallel to the longitudinal axis of the aircraft. It illuminates an elliptical mirror which is oriented 45 deg to the lens' longitudinal axis to deflect the beam towards the region beneath the aircraft. The mirror is oscillated in a sinusoidal fashion through mechanical linkages driven to a variable speed motor to scan the transmitter beam (1.2 deg X 1.2 deg) with + or - 16 deg of the perpendicular to the aircraft wings in the plane perpendicular to the aircraft flight direction.

Walsh, E. J.↗

NASA NTRS1985

Solar infrared photometer

A sun photometer which operates at five wavelengths in the near infrared between 1.0 and 4.0 microns has been developed. The instrument is a manually operated, filter wheel design and has principal applications for atmospheric aerosol studies. The wavelength filters were selected at bands with minimal gaseous absorption. A modified Langley analysis which accounts for residual gaseous absorption is employed for the instrument calibration. Calibration and stability results for the instrument are presented.

Spinhirne, J. D.↗

NASA NTRS1986

Formation and characterization of simulated small droplet icing clouds

Two pneumatic two-fluid atomizers operating at high liquid and gas pressures produced water sprays that simulated small droplet clouds for use in studying icing effects on aircraft performance. To measure median volume diameter, MVD or D sub v.5, of small droplet water sprays, a scattered-light scanning instrument was developed. Drop size data agreed fairly well with calculated values at water and nitrogen pressures of 60 and 20 psig, respectively, and at water and nitrogen pressures of 250 and 100 psig, respectively, but not very well at intermediate values of water and nitrogen pressure. MVD data were correlated with D sub 0, W sub N, and W sub w, i.e., orifice diameter, nitrogen, and water flowrate, respectively, to give the expression for MVD in microns.

Ingebo, R. D.↗

NASA NTRS1985

Methods for heat transfer and temperature field analysis of the insulated diesel phase 2 progress report

This report describes work done during Phase 2 of a 3 year program aimed at developing a comprehensive heat transfer and thermal analysis methodology for design analysis of insulated diesel engines. The overall program addresses all the key heat transfer issues: (1) spatially and time-resolved convective and radiative in-cylinder heat transfer, (2) steady-state conduction in the overall structure, and (3) cyclical and load/speed temperature transients in the engine structure. During Phase 2, radiation heat transfer model was developed, which accounts for soot formation and burn up. A methodology was developed for carrying out the multi-dimensional finite-element heat conduction calculations within the framework of thermodynamic cycle codes. Studies were carried out using the integrated methodology to address key issues in low heat rejection engines. A wide ranging design analysis matrix was covered, including a variety of insulation strategies, recovery devices and base engine configurations. A single cylinder Cummins engine was installed at Purdue University, and it was brought to a full operational status. The development of instrumentation was continued, concentrating on radiation heat flux detector, total heat flux probe, and accurate pressure-crank angle data acquisition.

Morel, T.↗