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  • Other Sources  (1,114)
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  • 1
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    Hot wire/film behavior in low-temperature gases (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Commercially available hot wires/films were used to measure the velocities of evaporated hydrogen or helium gas during cryogenic mixing experiments. Hot wires were found to be too delicate to use in this harsh environment. Hot films were rugged enough to use at cryogenic temperatures even though they failed after a number of thermal cycles. Since the hot films have small aspect ratios, 13.4 and 20, they are quite sensitive to the thermal loading, Tw/Tg, even with a correction for the conduction end loss. In general, although the increase of the Nusselt number with Reynolds number at low temperatures was similar to that at room temperature, there was also a pronounced variation with Tw/Tg over the large range of 1.2 to 12 investigated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: ASME, Transactions, Journal of Heat Transfer (ISSN 0022-1481); 114; 4; p. 859-865.
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  • 2
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    Longitudinal vortex control - Techniques and applications (The 32nd Lanchester Lecture) (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: A summary is presented of vortex control applications and current techniques for the control of longitudinal vortices produced by bodies, leading edges, tips and intersections. Vortex control has up till now been performed by many approaches in an empirical fashion, assisted by the essentially inviscid nature of much of longitudinal vortex behavior. Attention is given to Reynolds number sensitivities, vortex breakdown and interactions, vortex control on highly swept wings, and vortex control in juncture flows.
    Keywords: AERODYNAMICS
    Type: Aeronautical Journal (ISSN 0001-9240); 96; 958; p. 293-312.
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  • 3
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    Unsteady two- and three-dimensional Navier-Stokes simulations of multistage turbomachinery flows (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The flow-field within an axial flow turbomachine, such as a turbine or compressor, is extremely complex because of three-dimensional features such as hub-corner stall, tip-leakage flows, and airfoil wakes. These flow features interact with each other and with rotor and stator airfoils inducing time-varying forces on the airfoils. These complicated rotor-stator interactions must be understood in order to design turbomachines that are light and compact as well as reliable and efficient. Two codes, STAGE-2 and STAGE-3, have been developed to compute these unsteady rotor-stator interaction flows in multistage turbomachines. An implicit, thin-layer Euler/Navier-Stokes zonal algorithm is used to compute the unsteady flow-field within both turbine and compressor configurations. Results include surface pressures and wake profiles for two-dimensional turbine and compressor configurations and surface pressures for a three-dimensional single-stage turbine configuration. The results compare well with experimental data and other unsteady computations.
    Keywords: AERODYNAMICS
    Type: Computing Systems in Engineering (ISSN 0956-0521); 3; 1-4; p. 231-240.
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  • 4
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    Numerical simulation of jet noise (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Jet noise and jet-induced structural loads have become key issues in the design of commercial and military aircraft. Computational Fluid Dynamics (CFD) can be of use in predicting the underlying jet shear-layer instabilities and, in conjunction with classical acoustic theory, jet noise. The computational issues involved in the resolution of high Reynolds number unsteady jet flows are addressed in this paper. Once these jet flows can be accurately resolved, it should be possible to use acoustic theory to extract, for example, the far-field jet noise. An assessment of future work and computational resources required for directly computing far-field jet noise is also presented.
    Keywords: AERODYNAMICS
    Type: Computing Systems in Engineering (ISSN 0956-0521); 3; 1-4; p. 169-179.
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  • 5
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    Temporal averaging in a turbulent environment - Compensation for phase drifts in phase shifting interferometry (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: In an effort to improve the signal to noise in an interference experiment, we have developed a method to remove systematic phase drift between data sets acquired over long time intervals. Using this technique, it is possible to average repeatedly acquired phase measurements and improve the phase estimate without sacrificing spatial resolution. Results from tests using real-time phase stepping holographic interferometry applied to cantilever bending of a piezoelectric bimorph indicate that white noise has been reduced from 3 to less than 1 deg (lambda/360) by averaging 36 phase compensated data sets before object bending and 36 data sets after bending.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Laser interferometry IV: Computer-aided interferometry; Proceedings of the Meeting, San Diego, CA, July 22-24, 1991 (A93-44185 18-35); p. 221-230.
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  • 6
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    Supersonic laminar flow control (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: A development status evaluation is presented for the theoretical understanding and design conceptualization of boundary layer control (BLC) systems applicable to supersonic transports, such as the currently envisioned NASA High Speed Civil Transport. By reducing fuel burned, supersonic BLC techniques could expand ranges to Pacific-crossing scales, while lowering sonic boom effects and upper-atmosphere pollution and even reducing skin friction temperature. The critical consideration for supersonic BLC is the presence of wave effects.
    Keywords: AERODYNAMICS
    Type: In: Natural laminar flow and laminar flow control (A93-41776 17-02); p. 233-245.
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  • 7
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    Wave interaction theory and LFC (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Attention is drawn to the influence of preexisting finite-amplitude instabilities on the growth of other disturbances; current design tools for LFC take no notice of this kind of interaction. When a rational accounting is accomplished for the evolution of incoming disturbances in finite-amplitude solutions of the equations of motion, future transition-prediction methods will need to take these wave interactions into account. Attention is given here to interactions in the presence of crossflow vortices and interactions involving Goertler vortices.
    Keywords: AERODYNAMICS
    Type: In: Natural laminar flow and laminar flow control (A93-41776 17-02); p. 223-232.
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  • 8
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    Laminar flow control - Introduction and overview (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: A development history and a development-trends evaluation are presented for laminar flow controlled airfoil technologies and design concepts, including the search for 'natural' laminar flow and actively controlled flow via suction through small pores on the airfoil surface. While most NASA activities in this field have been concerned with subsonic aircraft, it has been projected that the control of boundary layer turbulence may be even more critical to the aerodynamic efficiency of supersonic aircraft. Developmental programs for these techniques have been conducted with several modified conventional aircraft.
    Keywords: AERODYNAMICS
    Type: In: Natural laminar flow and laminar flow control (A93-41776 17-02); p. 1-21.
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  • 9
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    Subsonic natural-laminar-flow airfoils (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: An account is given of the development history of natural laminar-flow (NLF) airfoil profiles under guidance of an experimentally well-verified theoretical method for the design of airfoils suited to virtually all subcritical applications. This method, the Eppler Airfoil Design and Analysis Program, contains a conformal-mapping method for airfoils having prescribed velocity-distribution characteristics, as well as a panel method for the analysis of potential flow about given airfoils and a boundary-layer method. Several of the NLF airfoils thus obtained are discussed.
    Keywords: AERODYNAMICS
    Type: In: Natural laminar flow and laminar flow control (A93-41776 17-02); p. 143-176.
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  • 10
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    The Objective Double Crystal Spectrometer (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The solar corona, supernova remnants, the hot diffuse interstellar gas in the Galaxy, galactic halos, and the hot intracluster gas in rich clusters of galaxies, are examples of extended astrophysical plasmas which emit line-rich spectra in the X-ray spectral range from 1.5 to 25 A. These phenomena represent a significant fraction of the baryonic matter in the universe. The study of the composition, structure and dynamics of these astrophysical plasmas requires observations with both high spectral and spatial resolution simultaneously. The Objective Double Crystal Spectrometer, coupled with a grazing incidence X-ray telescope, represents a stigmatic instrument which is highly efficient for the study of such sources. We describe the configuration and performance (spatial resolution, spectral resolution and efficiency) of the Objective Double Crystal spectrometer.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Multilayer and grazing incidence X-ray(EUV optics; Proceedings of the Meeting, San Diego, CA, July 22-24, 1991 (A93-39658 15-74); p. 461-470.
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  • 11
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    Hydrogen Lyman-alpha coronagraph/polarimeter (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The present treatment of vector magnetic field measurement in coronas by means of the Hanle effect of the Lyman-alpha line uses data from all-reflecting imaging coronagraph/polarimeters. The polarization sensitivity, bandpass, and spatial resolution of these instruments are defined through a modeling of the Hanle-effect signature in Lyman-alpha emission from coronal magnetic loops; the line-of-sight integration through an inhomogeneous coronal medium is taken into account. The use of the Hanle effect to measure solar corona vector magnetic fields is verified.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Multilayer and grazing incidence X-ray(EUV optics; Proceedings of the Meeting, San Diego, CA, July 22-24, 1991 (A93-39658 15-74); p. 402-413.
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  • 12
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    Cosmic X-ray spectroscopy with multilayer optics (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Multilayer optics operated at normal incidence offer a powerful new technology for the study of the solar spectrum in the XUV. The spectra of most cosmic X-ray sources are strongly extinguished at wavelengths above 40 A due to absorption and scattering by interstellar grains. We describe a number of configurations which allow multilayer optics to be used at nonnormal angles of incidence in conjunction with grazing incidence optics to analyze the spectra of cosmic X-ray sources in the wavelength interval between 1.5 and 40 A. These optical configurations utilize both multilayer mirrors and gratings, and permit the efficient observation of extended sources using stigmatic spectrographs. The response of the instruments described to typical cosmic X-ray sources is also discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Multilayer and grazing incidence X-ray(EUV optics; Proceedings of the Meeting, San Diego, CA, July 22-24, 1991 (A93-39658 15-74); p. 333-344.
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  • 13
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    Photographic films for the Multi-Spectral Solar Telescope Array (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The rocketborne Multi-Spectral Solar Telescope Array (MSSTA) uses an array of Ritchey-Chretien, Cassegrain, and Herschelian telescopes to produce ultrahigh-resolution full-disk images of the sun within the soft X-ray, EUV, and FUV ranges. Such imaging of the solar disk and corona out to several solar radii placed great demands on the MSSTA's data storage capabilities; in addition, its photographic films required very low outgassing rates. Results are presented from calibration tests conducted on the MSSTA's emulsions, based on measurements at NIST's synchrotron facility.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Multilayer and grazing incidence X-ray(EUV optics; Proceedings of the Meeting, San Diego, CA, July 22-24, 1991 (A93-39658 15-74); p. 188-204.
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  • 14
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    Design and analysis of soft X-ray imaging microscopes (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The spherical Schwarzschild microscope for soft X-ray applications in microscopy and projection lithography consists of two concentric spherical mirrors configured such that the third-order spherical aberration and coma are zero. Since multilayers are used on the mirror substrates for X-ray applications, it is desirable to have only two reflecting surfaces in a microscope. To reduce microscope aberrations and increase the field of view, generalized mirror surface profiles are here considered. Based on incoherent and sine wave modulation transfer function calculations, the object plane resolution of a microscope has been analyzed as a function of the object height and numerical aperture (NA) of the primary for several spherical Schwarzschild, conic, and aspherical Head reflecting two-mirror microscope configurations. The Head microscope with a NA of 0.4 achieves diffraction limited performance for objects with a diameter of 40 microns. Thus, it seems possible to record images with a feature size less than 100 A with a 40x microscope when using 40 A radiation.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Multilayer and grazing incidence X-ray(EUV optics; Proceedings of the Meeting, San Diego, CA, July 22-24, 1991 (A93-39658 15-74); p. 117-124.
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  • 15
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    A cryogenic multichannel electronically scanned pressure module (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Consideration is given to a cryogenic multichannel electronically scanned pressure (ESP) module developed and tested over an extended temperature span from -184 to +50 C and a pressure range of 0 to 5 psig. The ESP module consists of 32 pressure sensor dice, four analog 8 differential-input multiplexers, and an amplifier circuit, all of which are packaged in a physical volume of 2 x 1 x 5/8 in with 32 pressure and two reference ports. Maximum nonrepeatability is measured at 0.21 percent of full-scale output. The ESP modules have performed consistently well over 15 times over the above temperature range and continue to work without any sign of degradation. These sensors are also immune to repeated thermal shock tests over a temperature change of 220 C/sec.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: International Instrumentation Symposium, 38th, Las Vegas, NV, Apr. 26-30, 1992, Proceedings (A93-37851 15-35); p. 773-791.
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  • 16
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    Digital resolver for helicopter model blade motion analysis (1992)
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    Publication Date: 2011-08-24
    Description: The paper reports the development and initial testing of a digital resolver to replace existing analog signal processing instrumentation. Radiometers, mounted directly on one of the fully articulated blades, are electrically connected through a slip ring to analog signal processing circuitry. The measured signals are periodic with azimuth angle and are resolved into harmonic components, with 0 deg over the tail. The periodic nature of the helicopter blade motion restricts the frequency content of each flapping and yaw signal to the fundamental and harmonics of the rotor rotational frequency. A minicomputer is employed to collect these data and then plot them graphically in real time. With this and other information generated by the instrumentation, a helicopter test pilot can then adjust the helicopter model's controls to achieve the desired aerodynamic test conditions.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: International Instrumentation Symposium, 38th, Las Vegas, NV, Apr. 26-30, 1992, Proceedings (A93-37851 15-35); p. 619-628.
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  • 17
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    Radii effect on the translation spring constant of force transducer beams (1992)
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    Publication Date: 2011-08-24
    Description: Multi-component strain-gage force transducer design requires the designer to determine the spring constant of the numerous beams or flexures incorporated in the transducer. The classical beam deflection formulae that are used in calculating these spring constants typically assume that the beam has a uniform moment of inertia along the entire beam length. In practice all beams have a radius at the end where the beam interfaces with the shoulder of the transducer, and on short beams in particular this increases the beam spring constant considerably. A Basic computer program utilizing numerical integration is presented to determine this effect.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: International Instrumentation Symposium, 38th, Las Vegas, NV, Apr. 26-30, 1992, Proceedings (A93-37851 15-35); p. 417-432.
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  • 18
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    Miniature high temperature plug-type heat flux gauges (1992)
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    Publication Date: 2011-08-24
    Description: The objective is to describe continuing efforts to develop methods for measuring surface heat flux, gauge active surface temperature, and heat transfer coefficient quantities. The methodology involves inventing a procedure for fabricating improved plug-type heat flux gauges and also for formulating inverse heat conduction models and calculation procedures. These models and procedures are required for making indirect measurements of these quantities from direct temperature measurements at gauge interior locations. Measurements of these quantities were made in a turbine blade thermal cycling tester (TBT) located at MSFC. The TBT partially simulates the turbopump turbine environment in the Space Shuttle Main Engine. After the TBT test, experiments were performed in an arc lamp to analyze gauge quality.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: International Instrumentation Symposium, 38th, Las Vegas, NV, Apr. 26-30, 1992, Proceedings (A93-37851 15-35); p. 263-271.
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  • 19
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    The rapidly moving telescope - A progress report (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: A ground-based optical telescope system has been constructed with the capability to locate fast optical transients that may be associated with gamma-ray bursts (GRBs). The instrument has been integrated and operated during a shakedown period at GSFC, Maryland. Results of 35 hours of 'state mode' data are presented. The telescope has the proven capability to slew to any point on the night sky within 1.0 sec, track that position with better than one arcsecond stability, and image a 9 x 12 arcmin field of view with 1 arcsec angular resolution with 1.5 sec time resolution. The telescope-CCD camera system has a sensitivity of 13th magnitude for transients and 14th mag for field stars. In the 35 hr of operation many single frame transients of instrumental and optical origin have been observed; no two-sequential frame astrophysical transients have been identified. The combined rate of instrumental transients (predominantly sea-level muons) is 7.2/hr and of optical transients (satellite glints, airplane strobe lights, and meteors) is 5.1/hr. The RMT will operate in conjunction with the MIT Explosive Transient Camera survey instrument at Kitt Peak National Observatory, Tucson. The RMT is now being installed at Kitt Peak. Full operation will begin this summer.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Robotic telescopes in the 1990s; Proceedings of the Symposium, 103rd Annual Meeting of the Astronomical Society of the Pacific, Univ. of Wyoming, Laramie, June 22-24, 1991, 1991 (A93-36457 14-89); p. 137-150.
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  • 20
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    An airborne system for collecting polarization imagery (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: This paper describes a recently completed electrooptical camera flying onboard the NASA ER-2 high altitude aircraft. The device includes a six-position filter wheel which can be fitted with a combination of polarizing and/or spectral filters. An alternate configuration will include a polarizing filter which can be rotated to any angle under computer control. The camera mount in the nose of the ER-2 can tilt forward or aft up to 40 degrees, both for bidirectional reflectance studies and for image motion compensation (the aircraft moves 34 meters between frame acquisitions). The ground resolution is nominally 5 meters from and altitude of 20 km. Spectral responsivity is that of the silicon imaging array (Kodak KAF-1400). Initial data sets were acquired in support of the International Satellite Cloud Climatology Program Regional Experiment of November, 1991, and will be used to study cirrus cloud properties.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Polarization and remote sensing; Proceedings of the Meeting, San Diego, CA, July 22, 23, 1992 (A93-30026 11-35); p. 200-204.
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  • 21
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    The microstrip proportional counter (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Microstrip detectors in which the usual discrete anode and cathode wires are replaced by conducting strips on an insulating or partially insulating substrate are fabricated using integrated circuit-type photolithographic techniques and hence offer very high spatial accuracy and uniformity, together with the capability of producing extremely fine electrode structures. Microstrip proportional counters have now been variously reported having an energy resolution of better than 11 percent FWHM at 5.9 keV. They have been fabricated with anode bars down to 2 microns and on a variety of substrate materials including thin films which can be molded to different shapes. This review will examine the development of the microstrip detector with emphasis on the qualities which make this detector particularly interesting for use in astronomy.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: EUV, X-ray, and gamma-ray instrumentation for astronomy III; Proceedings of the Meeting, San Diego, CA, July 22-24, 1992 (A93-29476 10-35); p. 96-103.
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  • 22
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    Automated anomaly detection for Orbiter High Temperature Reusable Surface Insulation (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The description, analysis, and experimental results of a method for identifying possible defects on High Temperature Reusable Surface Insulation (HRSI) of the Orbiter Thermal Protection System (TPS) is presented. Currently, a visual postflight inspection of Orbiter TPS is conducted to detect and classify defects as part of the Orbiter maintenance flow. The objective of the method is to automate the detection of defects by identifying anomalies between preflight and postflight images of TPS components. The initial version is intended to detect and label gross (greater than 0.1 inches in the smallest dimension) anomalies on HRSI components for subsequent classification by a human inspector. The approach is a modified Golden Template technique where the preflight image of a tile serves as the template against which the postflight image of the tile is compared. Candidate anomalies are selected as a result of the comparison and processed to identify true anomalies. The processing methods are developed and discussed, and the results of testing on actual and simulated tile images are presented. Solutions to the problems of brightness and spatial normalization, timely execution, and minimization of false positives are also discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Cooperative intelligent robotics in space III; Proceedings of the Meeting, Boston, MA, Nov. 16-18, 1992 (A93-29101 10-54); p. 330-340.
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  • 23
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    On Capaciflector sensor data interpretation using the constrained deconvolution algorithm (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The Capaciflector, a capacitive proximity sensor, is being developed by NASA for collision avoidance. Capaciflector provides a single output value as measure of altered base frequency. This value is a characteristic of an external object in the sensor's field of view. An attempt is made to use the Capaciflector for imaging with operating range from 1 to 2 inches. By positional arangement of sensors in a grid pattern and electronic activation of sensors over the grid one at a time an object characteristic image is obtained. The article describes the Capaciflector experimental imaging system and preliminary results obtained by the system.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Cooperative intelligent robotics in space III; Proceedings of the Meeting, Boston, MA, Nov. 16-18, 1992 (A93-29101 10-54); p. 13-24.
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  • 24
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    Utilization of biosensors and chemical sensors for space applications (1992)
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    Publication Date: 2011-08-24
    Description: There will be a need for a wide array of chemical sensors for biomedical experimentation and for the monitoring of water and air recycling processes on Space Station Freedom. The infrequent logistics flights of the Space Shuttle will necessitate onboard analysis. The advantages of biosensors and chemical sensors over conventional analysis onboard spacecraft are manifold. They require less crew time, space, and power. Sample treatment is not needed. Real time or near-real time monitoring is possible, in some cases on a continuous basis. Sensor signals in digitized form can be transmitted to the ground. Types and requirements for chemical sensors to be used in biomedical experimentation and monitoring of water recycling during long-term space missions are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Biosensors and Bioelectronics (ISSN 0956-5663); 7; 8; p. 535-548.
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  • 25
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    Selection of LCTV operating curves for input and filter (1992)
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    Publication Date: 2011-08-24
    Description: A liquid crystal television (LCTV) SLM's phase, amplitude, and polarization all influence our selection of operating curves for input and filter. With its continuum of drive voltage, the LCTV permits grey-level control in both locations. Selection of an optimum curve depends on expected variations in signal amplitude, presence of input scene structured noise, and other factors. Using modulators obtained from a commercially available projection LCTV, and with no specifically added input noise present, we have obtained laboratory results in which the ratio of peak intensity to correlator system noise exceeded 100:1. Unfortunately, it was massively inefficient to implement the algorithm which had been developed as the abstract for this paper was submitted. Fortunately, we have quite recently developed two insights that will speed it by several orders of magnitude, and we shall report that result in the future. We will also extend the work to include clutter objects and additive input scene noise.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Optical pattern recognition III; Proceedings of the Meeting, Orlando, FL, Apr. 21, 22, 1992 (A93-28672 10-63); p. 78-82.
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  • 26
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    Space micro-guidance and control - Applications and architectures (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The features and the components of a new microscale guidance, navigation, and control (GN&C) system for future space systems are discussed. An approach is described for the utilization of new microengineering technologies for achieving major reductions in the GN&C system's mass, size, power, and costs. The micro-GN&C system and the component concepts include microactuated adaptive optics, micromachined inertial sensors, fiberoptic data nets with light-power transmission, and VLSI microcomputers. The GN&C system will be applied in microspacecraft, microlanders, microrovers, remote sensing platforms, interferometers, and deployable reflectors.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Sensors and sensor systems for guidance and navigation II; Proceedings of the Meeting, Orlando, FL, Apr. 22, 23, 1992 (A93-28151 10-35); p. 144-158.
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    Commercial applications multispectral sensor system (1992)
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    Publication Date: 2011-08-24
    Description: NASA's Office of Commercial Programs is funding a multispectral sensor system to be used in the development of remote sensing applications. The Airborne Terrestrial Applications Sensor (ATLAS) is designed to provide versatility in acquiring spectral and spatial information and will be a test bed for the development of specifications for airborne and spaceborne remote sensing instrumentation for dedicated applications. This objective requires spectral coverage from the visible through thermal IR wavelengths, variable spatial resolution form 2-25 meters; high geometric and geolocation accuracy; on-board radiometric calibration; digital recording; and optimized performance for minimized cost, size, and weight.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Small satellite technologies and applications II; Proceedings of the Meeting, Orlando, FL, Apr. 21, 22, 1992 (A93-28076 10-12); p. 63-74.
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    The NASA Electronic Still Camera system (1992)
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    Publication Date: 2011-08-24
    Description: The Electronic Still Camera (ESC) project has been implemented in its first form for space shuttle operations. The system is composed of three components: (1) a hand-held battery-operated fully digital and programmable high-resolution camera; (2) a laptop-computer-based playback/downlink unit for onboard image processing; and (3) a ground station capable of receiving shuttle data, processing images, producing hardcopies, and distributing the data and hardcopies to end users. The advantages of the ESC system over film and satellites are discussed, and system specifications are summarized.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: IGARSS '92; Proceedings of the 12th Annual International Geoscience and Remote Sensing Symposium, Houston, TX, May 26-29, 1992. Vol. 1 (A93-47551 20-43); p. 149-151.
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    Dielectric measurement using an open ended coaxial line with an extended center conductor (1992)
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    Publication Date: 2011-08-24
    Description: Permittivity may be determined by measuring the complex reflection coefficient of an open-ended coaxial line placed in contact with a test sample. This method works best for liquid samples. For the measurement of non-liquid materials problems can arise. A perfect preparation is needed to provide a good contact between the tip and the dielectric medium. At times, the dimension of the sensor cannot be freely chosen, as is the case for the measurement of the dielectric constant of the xylem layer of a living tree. The influence of the installation of the sensor on a tree's water status must be minimized by using a small sensor. In such cases the capacitance cannot be optimized. By extending the center conductor of the open-ended coaxial line, some of these problems can be avoided. This provides an additional tool to tune the capacitance of the sensor by adjusting the length of the extension. Therefore the measurement accuracy can be optimized. The sensor also becomes sensitive to a larger volume. A comparative study of a flush and extended tipped probes shows that the ability to measure the dielectric constant of trees has been notably increased due to the extension of the center conductor.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: IGARSS '92; Proceedings of the 12th Annual International Geoscience and Remote Sensing Symposium, Houston, TX, May 26-29, 1992. Vol. 1 (A93-47551 20-43); p. 443-445.
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    Correction-free radiometry on specular spheres for containerless processing in microgravity (1992)
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    Publication Date: 2011-08-24
    Description: An analysis is presented that establishes how correction-free radiance measurements or pyrometry can be performed on targets in furnaces where there may be significant additional radiance from heated furnace walls or from reflecting surfaces close to the target. These configurations are common in microgravity and containerless processing applications where a specular target is radiantly heated in a hot-wall furnace, or inductively heated from the fields arising from nearby closely spaced electromagnetic coils. Proper design requires that the pyrometer does not view any images of the background features in the specular target so that stray radiation will not be reflected into the viewing optics of the pyrometer. To analyze the problem, conventional paraxial optics analysis is shown to be significantly in error. Instead a method of nonparaxial ray tracing, based on the derivatives of the ray paths, shows how the images must be located. This leads to analytical results that can be used to design such systems. The findings are applied to the furnace geometries that are presently being considered for flight in LEO.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments (ISSN 0034-6748); 63; 11; p. 5394-5402.
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    Energetics of gas-surface interactions in transitional flows at entry velocities (1992)
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 29; 6; p. 786-793.
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    Shock interference prediction using direct simulation Monte Carlo (1992)
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 29; 6; p. 780-785.
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    The simulation of multispectral composite satellite imagery on 8-bit color workstations (1992)
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    Publication Date: 2011-08-24
    Description: A technique is described which combines up to three channels of imagery into a single 8-bit composite color image. Each image controls a specific color or colors (red, green, or blue) in the resultant color composite image, allowing for improved interpretation of scene characteristics. The technique is a useful tool for the forecaster and satellite image analyst. In addition to providing the capability of displaying multichannel images on an 8-bit desktop color workstation, the technique allows sophisticated image manipulation to be performed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Conference on Satellite Meteorology and Oceanography, 6th, Atlanta, GA, Jan. 5-10, 1992, Preprints (A93-36051 14-47); p. J92-J95.
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    Hover performance analysis of advanced rotor blades (1992)
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    Publication Date: 2011-08-24
    Description: This is an effort aimed at validating recent hover prediction methods. The experimental basis for this validation work is an extensive set of loads, wake and performance data, which were obtained from a pressure instrumented model UH-60 rotor tested at the Sikorsky hover test facility and at Duits-Nederlandse Windtunnel (DNW). This model was equipped with replaceable tips - including a tapered and a BERP-type tip - which permitted studies of the effects of rotor geometry. The central prediction method studied is a free-wake, vortex embedded, full-potential CFD method - called HELIX-I. It is found that the HELIX-I code produces very good comparisons with the data including wake, surface pressure and performance. Comparisons with the measured radial load distributions have permitted an improved understanding of the wake resolution modelling requirements of CFD methods. Since HELIX-I is a combined Eulerian/Lagrangian method, limited comparisons are also made with a Lagrangian boundary element code (called EHPIC) and an Eulerian Navier-Stokes code (called TURNS). In most cases all methods produce good comparisons with the data. It is found that the HELIX-I code provides a good compromise between the speed of boundary integral methods and the comprehensive nature of Navier-Stokes methods.
    Keywords: AERODYNAMICS
    Type: In: AHS, Annual Forum, 48th, Washington, June 3-5, 1992, Proceedings. Vol. 2 (A93-35901 14-01); p. 1367-1384.
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    Shadowgraph flow visualization of isolated tiltrotor and rotor/wing wakes (1992)
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    Publication Date: 2011-08-24
    Description: Shadowgraph flow visualization images were acquired from a 0.184-scale tiltrotor and wing in hover. Measurements and details of the vortex core structure were examined as a function of thrust condition and wake age. Experimental data for the isolated rotor wake geometry and rotor wake interactions with a semi-span wing and image plane were acquired. Quantitative measurements and comparisons of wake geometry and distortion were made for three configurations: the isolated rotor, rotor/wing, and rotor/wing/image plane. Comparisons between tiltrotor and helicopter rotor wake geometry measurements were made. Experimental wake geometry data were also compared with two wake models. Suggestions for improvements to existing prescribed-wake and free-wake models are proposed.
    Keywords: AERODYNAMICS
    Type: In: AHS, Annual Forum, 48th, Washington, June 3-5, 1992, Proceedings. Vol. 2 (A93-35901 14-01); p. 1323-1344.
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    A study of the rotor wake of a small-scale rotor model in forward flight using laser light sheet flow visualization with comparisons to analytical models (1992)
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    Publication Date: 2011-08-24
    Description: An experimental investigation was conducted in the 14 by 22 ft subsonic tunnel at NASA Langley Research Center to quantify the rotor wake behind a scale model helicopter rotor in forward flight (mu = 0.15 and 0.23) at one thrust level (C sub T = 0.0064). The rotor system used in the present test consisted of a four-bladed, fully articulated hub and utilized blades of rectangular planform with a NACA-0012 airfoil section. A laser light sheet, seeded with propylene glycol smoke, was used to visualize the flow in planes parallel and perpendicular to the freestream flow. Quantitative measurements of vortex location, vertical skew angle, and vortex particle void radius were obtained for vortices in the flow; convective velocities were obtained for blade tip vortices. Comparisons were made between the experimental results and the wake geometry generated by computational predictions. The results of these comparisons show that the interaction between wake vortex structures is an important consideration for correctly predicting the wake geometry.
    Keywords: AERODYNAMICS
    Type: In: AHS, Annual Forum, 48th, Washington, June 3-5, 1992, Proceedings. Vol. 1 (A93-35901 14-01); p. 697-719.
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    Numerical simulation of a hovering rotor using embedded grids (1992)
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    Publication Date: 2011-08-24
    Description: The flow field for a rotor blade in hover was computed by numerically solving the compressible thin-layer Navier-Stokes equations on embedded grids. In this work, three embedded grids were used to discretize the flow field - one for the rotor blade and two to convect the rotor wake. The computations were performed at two hovering test conditions, for a two-bladed rectangular rotor of aspect ratio six. The results compare fairly with experiment and illustrates the use of embedded grids in solving helicopter type flow fields.
    Keywords: AERODYNAMICS
    Type: In: AHS, Annual Forum, 48th, Washington, June 3-5, 1992, Proceedings. Vol. 1 (A93-35901 14-01); p. 429-445.
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    A finite-volume Euler solver for computing rotary-wing aerodynamics on unstructured meshes (1992)
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    Publication Date: 2011-08-24
    Description: An unstructured-grid solver for the unsteady Euler equations has been developed for predicting the aerodynamics of helicopter rotor blades. This flow solver is a finite-volume scheme that computes flow quantities at the vertices of the mesh. Special treatments are used for the flux differencing and boundary conditions in order to compute rotary-wing flowfields, and these are detailed in the paper. The unstructured-grid solver permits adaptive grid refinement in order to improve the resolution of flow features such as shocks, rotor wakes and acoustic waves. These capabilities are demonstrated in the paper. Example calculations are presented for two hovering rotors. In both cases, adaptive-grid refinement is used to resolve high gradients near the rotor surface and also to capture the vortical regions in the rotor wake. The computed results show good agreement with experimental results for surface airloads and wake geometry.
    Keywords: AERODYNAMICS
    Type: In: AHS, Annual Forum, 48th, Washington, June 3-5, 1992, Proceedings. Vol. 1 (A93-35901 14-01); p. 419-428.
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    Results from a Si(Li) gamma ray detector stack for future Mars missions (1992)
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    Publication Date: 2011-08-24
    Description: We present Monte Carlo analysis and experimental data from a novel lithium-drifted silicon detector stack for gamma ray spectroscopy instrumentation in future Mars surface landers and other planetary missions. The Monte Carlo analysis shows full energy photopeaks even in the range of about 100 keV to 2 MeV where, in Si, Compton scattering dominates the absorption processes. Laboratory data is shown for an experimental detector stack of four planar Si(Li) devices, each 5 mm thick with an active area 2 cm in diameter. All the experimental data were collected with maximum temperature of the stack at 175 K. Background reduction is achieved by using the detector of the stack closest to the source in anticoincidence. We present a comparison of experimental data from the stack with the Monte Carlo model for Cs-137 (662 keV). Agreement is shown to be good, with a full energy photopeak clearly seen (FWHM about 10 keV). Experimental stack data is also shown for multiple peaks at 511 keV (Na-22) and 662 keV (Cs-137). The peaks are clearly resolved (FWHM 10 keV), and are compared with the results obtained using a 8 percent resolution, 3 in. x 3 in. NaI(TI) device (FWHM about 50 keV).
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Transactions on Nuclear Science (ISSN 0018-9499); 39; 4; p. 981-986.
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    An Automated Thermocouple Calibration System (1992)
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    Publication Date: 2011-08-24
    Description: An Automated Thermocouple Calibration System (ATCS) was developed for the unattended calibration of type K thermocouples. This system operates from room temperature to 650 C and has been used for calibration of thermocouples in an eight-zone furnace system which may employ as many as 60 thermocouples simultaneously. It is highly efficient, allowing for the calibration of large numbers of thermocouples in significantly less time than required for manual calibrations. The system consists of a personal computer, a data acquisition/control unit, and a laboratory calibration furnace. The calibration furnace is a microprocessor-controlled multipurpose temperature calibrator with an accuracy of +/- 0.7 C. The accuracy of the calibration furnace is traceable to the National Institute of Standards and Technology (NIST). The computer software is menu-based to give the user flexibility and ease of use. The user needs no programming experience to operate the systems. This system was specifically developed for use in the Microgravity Materials Science Laboratory (MMSL) at the NASA LeRC.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Transactions on Instrumentation and Measurement (ISSN 0018-9456); 41; 5; p. 702-706.
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    Distributed optical proximity sensor system - HexEYE (1992)
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    Publication Date: 2011-08-24
    Description: A novel optical proximity sensor system, capable of measuring the distance to the orientation and the discontinuity at a local area of an object surface, was designed and evaluated for robotic applications. The sensor system gets its name, Hexagonal Eye, (HexEYE) from its shape where seven identical hexagonal sensing units were configured hexagonally into a compact geometric structure. The seven sensing units were grouped into multiple combinations of three sensing units to measure the surface orientation as well as surface discontinuity. The distinctive features of HexEYE are an order of magnitude increased in distance sensitivity by optimizing the curvature of a conical mirror, the enhanced measurement accuracy based on multiple levels of sensor fusion, and the compactness in size due to a sensing mechanism based on the Gaussian lens law. A prototype of single sensing unit has been built and was evaluated experimentally.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: 1992 IEEE International Conference on Robotics and Automation, 8th, Nice, France, May 12-14, 1992, Proceedings. Vol. 2 (A93-35501 13-63); p. 1567-1572.
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    The Airborne Ocean Color Imager - System description and image processing (1992)
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    Publication Date: 2011-08-24
    Description: The Airborne Ocean Color Imager was developed as an aircraft instrument to simulate the spectral and radiometric characteristics of the next generation of satellite ocean color instrumentation. Data processing programs have been developed as extensions of the Coastal Zone Color Scanner algorithms for atmospheric correction and bio-optical output products. The latter include several bio-optical algorithms for estimating phytoplankton pigment concentration, as well as one for the diffuse attenuation coefficient of the water. Additional programs have been developed to geolocate these products and remap them into a georeferenced data base, using data from the aircraft's inertial navigation system. Examples illustrate the sequential data products generated by the processing system, using data from flightlines near the mouth of the Mississippi River: from raw data to atmospherically corrected data, to bio-optical data, to geolocated data, and, finally, to georeferenced data.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Imaging Science and Technology (ISSN 8750-9237); 36; 5; p. 423-430.
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    Two-mode elliptical-core weighted fiber sensors for vibration analysis (1992)
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    Publication Date: 2011-08-24
    Description: Two-mode, elliptical-core optical fibers are demonstrated in weighted, distributed and selective vibration-mode-filtering applications. We show how appropriate placement of optical fibers on a vibrating structure can lead to vibration mode filtering. Selective vibration-mode suppression on the order of 10 dB has been obtained using tapered two-mode, circular-core fibers with tapering functions that match the second derivatives of the modes of vibration to be enhanced. We also demonstrate the use of chirped, two-mode gratings in fibers as spatial modal sensors that are equivalents of shaped piezoelectric sensors.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Distributed and multiplexed fiber optic sensors; Proceedings of the Meeting, Boston, MA, Sept. 4, 5, 1991 (A93-49426 21-35); p. 53-66.
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    A miniature high-resolution accelerometer utilizing electron tunneling (1992)
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    Publication Date: 2011-08-24
    Description: New methods have been developed to implement high-resolution position sensors based on electron tunneling. These methods allow miniaturization while utilizing the position sensitivity of electron tunneling to give high resolution. A single-element tunneling accelerometer giving a displacement resolution of 0.002 A/sq rt Hz at 10 Hz, corresponding to an acceleration resolution of 5 x 10 exp -8 g/sq rt Hz, is described. A new dual-element tunneling structure which overcomes the narrow bandwidth limitations of a single-element structure is described. A sensor with an operating range of 5 Hz to 10 kHz, which can have applications as an acoustic sensor, is discussed. Noise is analyzed for fundamental thermal vibration of the suspended masses and is compared to electronic noise. It is shown that miniature tunnel accelerometers can achieve resolution such that thermal noise in the suspended masses is the dominant cause of the resolution limit. With a proof mass of order 100 mg, noise analysis predicts limiting resolutions approaching 10 exp -9 g/sq rt Hz in a 300 Hz band and 10 exp -8 g/sq rt Hz at 1 kHz.
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    Type: ; : International Conf
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    Theory and application of scanning electron acoustic microscopy (1992)
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    Publication Date: 2011-08-24
    Description: A three-dimensional theoretical model based on the application of the thermal conduction and Navier equations to a chopped electron beam incident on a disk specimen is used to obtain the particle displacement field in the specimen. The results lead to a consideration of the signal generation, spatial resolution, and contrast mechanisms in scanning electron acoustic microscopy (SEAM). The model suggests that the time-variant heat source produced by the beam chopping generates driving source, thermal wave, and acoustic wave displacements simultaneously in the specimen. Evidence of the correctness of the prediction is obtained from the mathematically similar problem of pulsed laser light injection into a tank of water. High speed Schlieren photographs taken following laser injection show the simultaneous evolution of thermal and acoustic waveforms. Examples of contrast reversal, stress-induced contrast, and acoustic zone contrast and resolution with SEAM are presented and explained in terms of the model features.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: ; : Conference on the
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    Airborne wavemeter validation and calibration (1992)
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    Publication Date: 2011-08-24
    Description: This manuscript outlines a continuing effort to validate and verify the performance of an airborne autonomous wavemeter for tuning solid state lasers to a desired wavelength. The application is measuring the vertical profiles of atmospheric water vapor using a differential absorption lidar (DIAL) technique. Improved wavemeter performance data for varying ambient temperatures are presented. This resulted when the electronic grounding and shielding were improved. The results with short pulse duration lasers are also included. These lasers show that similar performance could be obtained with lasers operating in the continuous and the pulsed domains.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Laser interferometry IV: Computer-aided interferometry; Proceedings of the Meeting, San Diego, CA, July 22-24, 1991 (A93-44185 18-35); p. 110-116.
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    Response of a piezoelectric pressure transducer to IR laser beam impingement (1992)
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    Publication Date: 2011-08-24
    Description: The non-pressure response of a PCB Model 113A transducer to a far infrared radiation impulse from a carbon dioxide laser was investigated. Incident radiation was applied both to the bare transducer diaphragm and to coated diaphragms. Coatings included two common ablative materials and a reflective gold coating. High-flux radiation impulses induced an immediate brief negative output followed by a longer-duration positive output. Both timing and amplitude of the responses will be discussed, and the effects of coatings will be compared. Bursts of blackbody radiation from a 1500 K source produced qualitatively similar responses.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: International Instrumentation Symposium, 38th, Las Vegas, NV, Apr. 26-30, 1992, Proceedings (A93-37851 15-35); p. 793-807.
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    Development of an optical flameout detection system for High Temperature Wind Tunnels (1992)
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    Publication Date: 2011-08-24
    Description: This paper outlines the design and development of a flameout detection system for future use in the 8-Foot High Temperature Wind Tunnel (8' HTT) at the NASA Langley Research Center. The proposed system is required to function reliably in an oxidizing environment with pressures up to 28 MPa (4,000 psi), survive temperatures reaching 1700 C (3100 F), and respond with a shut-down signal upon flameout in less than 100 milliseconds. The 7-Inch High Temperature Pilot Tunnel (7" HTT), a one-twelfth scale version of the 8' HTT, was used to develop a prototype system and to obtain data on the spectral content of the flame during combustion. The design and development of the spectral data acquisition system for the 7" HTT is presented here.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: International Instrumentation Symposium, 38th, Las Vegas, NV, Apr. 26-30, 1992, Proceedings (A93-37851 15-35); p. 629-638.
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    Using silicon diodes for detecting the liquid-vapor interface in hydrogen (1992)
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    Publication Date: 2011-08-24
    Description: Tests were performed using commercially available silicon diode temperature sensors to detect the location of the liquid-vapor interface in hydrogen during ground test programs. Results show that by increasing the current into the sensor, silicon diodes can be used as liquid level point sensors. After cycling the sensors from liquid to vapor several times, it was found that with a 30 mA (milliamps) input current, the sensors respond within 2 seconds by measuring a large voltage difference when transitioning from liquid to vapor across the interface. Nearly instantaneous response resulted during a transition from vapor to liquid. Detailed here are test procedures, experimental results, and guidelines for applying this information to other test facilities.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: International Instrumentation Symposium, 38th, Las Vegas, NV, Apr. 26-30, 1992, Proceedings (A93-37851 15-35); p. 287-299.
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    Stepwise shockwave velocity determinator (1992)
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    Publication Date: 2011-08-24
    Description: To provide an uncomplicated and inexpensive method for measuring the far-field velocity of a surface shockwave produced by an explosion, a stepwise shockwave velocity determinator (SSVD) was developed. The velocity determinator is constructed of readily available materials and works on the principle of breaking discrete sensors composed of aluminum foil contacts. The discrete sensors have an average breaking threshold of approximately 7 kPa. An incremental output step of 250 mV is created with each foil contact breakage and is logged by analog-to-digital instrumentation. Velocity data obtained from the SSVD is within approximately 11 percent of the calculated surface shockwave velocity of a muzzle blast from a 30.06 rifle.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: International Instrumentation Symposium, 38th, Las Vegas, NV, Apr. 26-30, 1992, Proceedings (A93-37851 15-35); p. 157-163.
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    Cryogenic blackbody radiation calibration source (1992)
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    Publication Date: 2011-08-24
    Description: A cryogenic blackbody radiation source for providing target temperatures between room temperature and -100 C was designed, fabricated, and tested. This blackbody radiation source is intended for calibration of radiometric infrared imaging systems down to -100 C. The construction and operating principles of this apparatus are described. The long term and short term stability of the radiant source have been investigated. The emittance of the source and the source radiant uniformity have been addressed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: International Instrumentation Symposium, 38th, Las Vegas, NV, Apr. 26-30, 1992, Proceedings (A93-37851 15-35); p. 273-285.
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    Capacitance-type blade-tip clearance measurement system using a dual amplifier with ramp/dc inputs and integration (1992)
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    Publication Date: 2011-08-24
    Description: The analysis and prototype results of a dual-amplifier circuit for measuring blade-tip clearance in turbine engines are presented. The capacitance between the blade tip and mounted capacitance electrode within a guard ring of a probe forms one of the feedback elements of an operational amplifier (op amp). The differential equation governing the circuit taking into consideration the nonideal features of the op amp was formulated and solved for two types of inputs (ramp and dc) that are of interest for the application. Under certain time-dependent constraints, it is shown that (1) with a ramp input the circuit has an output voltage proportional to the static tip clearance capacitance, and (2) with a dc input, the output is proportional to the derivative of the clearance capacitance, and subsequent integration recovers the dynamic capacitance. The technique accommodates long cable lengths and environmentally induced changes in cable and probe parameters. System implementation for both static and dynamic measurements having the same high sensitivity is also presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Transactions on Instrumentation and Measurement (ISSN 0018-9456); 41; 5; p. 674-678.
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    Development and test of an IR camera for astronomical observation at the Palomar 200-in. observatory using the NICMOS II array (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: A NICMOS II array, a NIR (0.80 - 2.6 micron) imaging system, was integrated into the California Institute of Technology Palomar Observatory camera. The Palomar camera system which consists of six discrete subsystems including a focal plane, an electrical interface, data acquisition electronics, a dewar, dewar optics, and the software is described. The performance and calibration data for each subsystem are presented. Emphasis is placed on test data on the focal plane performance.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Infrared technology XVIII; Proceedings of the Meeting, San Diego, CA, July 19-22, 1992 (A93-32826 12-35); p. 444-460.
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    Development of the wake of an airfoil with riblets (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 30; 12; p. 2817, 2818. Abrid
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    Optimizing view/illumination geometry for terrestrial features using Space Shuttle and aerial polarimetry (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: This paper describes to relationship of polarimetric observations from orbital and aerial platforms and the determination optimum sun-target-sensor geometry. Polarimetric observations were evaluated for feature discrimination. The Space Shuttle experiment was performed using two boresighted Hasselblad 70 mm cameras with identical settings with linear polarizing filters aligned orthogonally about the optic axis. The aerial experiment was performed using a single 35 mm Nikon FE2 and rotating the linear polarizing filter 90 deg to acquire both minimum and maximum photographs. Characteristic curves were created by covertype and waveband for both aerial and Space Shuttle imagery. Though significant differences existed between the two datasets, the observed polarimetric signatures were unique and separable.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Polarization and remote sensing; Proceedings of the Meeting, San Diego, CA, July 22, 23, 1992 (A93-30026 11-35); p. 121-127.
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    Microstrip proportional counter development at MSFC (1992)
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    Publication Date: 2011-08-24
    Description: Microstrip detectors are an exciting new development in proportional counter design fabricated using integrated circuit-type photolithography techniques; they therefore offer very high spatial accuracy and uniformity. A development program is underway at NASA-Marshall to produce large-area microstrips for use in an X-ray detector balloon flight program and to investigate the general performance limits of these new devices. Microstrips tested so far have been fabricated both in-house using standard photolithographic techniques and by an outside contractor using electron beam technology. Various substrate materials have been tested along with different electrode configurations. The distributions of pickup on subdivided cathodes on both top and bottom surfaces of the microstrips are also being investigated for use as two-dimensional imaging detectors. Data from these tests in the development of a large-area device will be presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: EUV, X-ray, and gamma-ray instrumentation for astronomy III; Proceedings of the Meeting, San Diego, CA, July 22-24, 1992 (A93-29476 10-35); p. 125-132.
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    New definitions of pointing stability - ac and dc effects (1992)
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    Publication Date: 2011-08-24
    Description: For most imaging sensors, a constant (dc) pointing error is unimportant (unless large), but time-dependent (ac) errors degrade performance by either distorting or smearing the image. When properly quantified, the separation of the root-mean-square effects of random line-of-sight motions into dc and ac components can be used to obtain the minimum necessary line-of-sight stability specifications. The relation between stability requirements and sensor resolution is discussed, with a view to improving communication between the data analyst and the control systems engineer.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of the Astronautical Sciences (ISSN 0021-9142); 40; 4; p. 557-576.
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    Scanning electron acoustic microscopy of residual stresses in ceramics - Theory and experiment (1992)
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    Publication Date: 2011-08-24
    Description: The paper presents a three-dimensional mathematical model of signal generation and contrast in brittle materials and uses the model to simulate the effect of residual stress fields on the scanning electron acoustic microscopy (SEAM)-generated electron acoustic signal. According to the model, a positive (tensile) strain produces an increase in the output signal, whereas a negative (compressive) strain produces a decrease in the ouput signal. Dark field contrast conditions occur at a chopping frequency at which V2 - V1 is greater than 0 (where V2 = V is the SEAM output in a region of residual stresses, and V1 is the output in a stress-free region of the sample). Under ideal conditions (maximum contrast) V1 approaches zero. It was found that tensile strains of the order 0.2-0.3 percent, possible in brittle materials, would produce a variation of the acoustic output signal of the order 10 nV (about 1 percent), well within the image contrast and signal processing capability of the SEAM electronics.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: ; : Micro(
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    New technique for oil backstreaming contamination measurements (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The backstreaming contamination in the Space Power Facility, Ohio, was measured using small size clean silicon wafers as contamination sensors placed at all measurement sites. Two ellipsometric models were developed to measure the oil film with the contamination film refractive index of DC 705: a continuous, homogeneous film and islands of oil with the islands varying in coverage fraction and height. The island model improved the ellipsometric analysis quality parameter by up to two orders of magnitude. The continuous film model overestimated the oil volume by about 50 percent.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Vacuum Science and Technology A (ISSN 0734-2101); 10; 4; p. 2099-2104.
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    Crosstalk in solar polarization measurements (1992)
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    Publication Date: 2011-08-24
    Description: The instrumental crosstalk associated with the Marshall Space Flight Center Vector Magnetograph and the solar crosstalk created by the magnetic field are described and their impact on the reconstruction of the solar vector magnetic field is analyzed. It is pointed out that identifying and correcting the crosstalk is important in the development of realistic models describing the solar atmosphere. Solar crosstalk is spatially dependent on the structure of the magnetic field while instrumental crosstalk is dependent on the position of the analyzer.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Polarization analysis and measurement; Proceedings of the Meeting, San Diego, CA, July 19-21, 1992 (A93-33401 12-35); p. 281-294.
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    640 x 480 MWIR and LWIR camera system developments (1992)
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    Publication Date: 2011-08-24
    Description: The performance of a 640 x 480 PtSi, 3,5 microns (MWIR), Stirling cooled camera system with a minimum resolvable temperature of 0.03 is considered. A preliminary specification of a full-TV resolution PtSi radiometer was developed using the measured performance characteristics of the Stirling cooled camera. The radiometer is capable of imaging rapid thermal transients from 25 to 250 C with better than 1 percent temperature resolution. This performance is achieved using the electronic exposure control capability of the MOS focal plane array (FPA). A liquid nitrogen cooled camera with an eight-position filter wheel has been developed using the 640 x 480 PtSi FPA. Low thermal mass packaging for the FPA was developed for Joule-Thomson applications.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: Infrared technology XVIII; Proceedings of the Meeting, San Diego, CA, July 19-22, 1992 (A93-32826 12-35); p. 386-400.
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    Unsteady simulation of viscous flowfield around F-18 aircraft at large incidence (1992)
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 29; 6; p. 986-992.
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    Detecting X-rays with an optical imaging chamber (1992)
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    Publication Date: 2011-08-24
    Description: The light emitted by electron avalanches in a parallel plate chamber can be used to image the tracks of photoelectrons liberated by the interaction of an incident X-ray with the gas filling the chamber. The different morphologies of photoelectron tracks and minimum ionizing tracks can be used for charged particle rejection. The initial direction (before scattering) of the liberated photoelectron also contains information about the polarization of the incident radiation. We have built a small test chamber with which we have imaged photoelectron tracks using an intensified CCD camera. Our results show that optical imaging could be used in a hard X-ray imaging polarimeter useful for astronomy.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: EUV, X-ray, and gamma-ray instrumentation for astronomy III; Proceedings of the Meeting, San Diego, CA, July 22-24, 1992 (A93-29476 10-35); p. 252-261.
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    Performance of a multistep fluorescence-gated proportional counter for hard X-ray astronomy (1992)
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    Publication Date: 2011-08-24
    Description: Results from the first flight of our proportional counter in an imaging telescope led us to rebuild the detector. We have used a Penning gas mixture (xenon + 1 percent isobutylene) and introduced a preamplification region to improve the energy resolution. We have rebuilt the pressure vessel making novel use of molybdenum as the housing material in order to reduce the residual instrument background, particularly in the fluorescence-gated mode for which the detector design has been optimized. We have also increased the sensitive gas depth from 9 to 14 cm to further increase the sensitivity to both fluorescent pairs and conventional singles. Our calibrations have shown that the overall energy resolution of the detector has been enhanced by a factor of 2, and we predict that the sensitivity at float will increase by a factor of 3 in the 50-70 keV energy band.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: EUV, X-ray, and gamma-ray instrumentation for astronomy III; Proceedings of the Meeting, San Diego, CA, July 22-24, 1992 (A93-29476 10-35); p. 236-244.
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    Study on vortex flow control of inlet distortion (1992)
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: Journal of Propulsion and Power (ISSN 0748-4658); 8; 6; p. 1266-1272.
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    Nonintrusive spectroscopic techniques for supersonic/hypersonic aerodynamics and combustion diagnostics (1992)
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    Publication Date: 2011-08-24
    Description: This paper presents an overview of the primary nonintrusive diagnostic techniques being developed by the NASA Langley Research Center to address the validation needs of Computational Fluid Dynamic (CFD) codes. The techniques include absorption in the UV and IR, Laser Induced Fluorescence, electron beam fluorescence, and a number of scattering techniques including Rayleigh, spontaneous Raman, and several coherent Raman spectroscopies. Most of the techniques are highly specialized, require complex data interpretation, and can satisfy only a few of the CFD needs. For these reasons, the evolving trend in flowfield diagnostics appears to favor a mode in which the diagnostic researcher, the experimental aerodynamicist, and the CFD community jointly define experiments based on the aeronautical requirements and on available diagnostic techniques.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: In: ICAS, Congress, 18th, Beijing, China, Sept. 20-25, 1992, Proceedings. Vol. 1 (A93-14151 03-01); p. 722-727.
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    Navier-Stokes simulation of a close-coupled canard-wing-body configuration (1992)
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 29; 5, Se; 830-838
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    Aeroelastic effects of spoiler surfaces on a low-aspect-ratio rectangular wing (1992)
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 29; 5, Se; 768-773
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    Assessment of compressibility corrections to the k-epsilon model in high-speed shear layers (1992)
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 30; 10, O; 2369
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    Plasmadynamic effects in thermochemical nonequilibrium aerobrake flows (1992)
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 29; 3, Ma; 319-326
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    Computation of saddle point of attachment (1992)
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 30; 6, Ju; 1561-156
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    Transonic Navier-Stokes computations for an oscillating wing using zonal grids (1992)
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 29; 3, Ma; 326-335
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    Tangential, semisubmerged, and internal store carriage and separation (1992)
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    Publication Date: 2011-08-24
    Description: Accounts are presented of tangential, semisubmerged, and internal store carriage drag, as well as of the results to date of stores-separation investigations employing both computational and experimental methods. It is demonstrated that CFD can contribute to the data base needed for internal stores carriage design and trade studies. Attention is given to the case of an internally carried store separating from its bay at supersonic speeds, where various kinds of interference are encountered. A code is developed for the simulation of these unsteady flows through time-accurate computations; computation results are noted to closely reproduce experiment data.
    Keywords: AERODYNAMICS
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    Bodies with noncircular cross sections and bank-to-turn missiles (1992)
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    Publication Date: 2011-08-24
    Description: A development status evaluation is presented for the aerodynamics of missile configurations with noncircular cross-sections and bank-to-turn maneuvering systems, giving attention to cases with elliptical and square cross-sections, as well as bodies with variable cross-sections. The assessment of bank-to-turn missile performance notes inherent stability/control problems. A summary and index are provided for aerodynamic data on monoplanar configurations, including those which incorporate airbreathing propulsion systems.
    Keywords: AERODYNAMICS
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    Low aspect ratio wings at high angles of attack (1992)
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    Publication Date: 2011-08-24
    Description: A survey is conducted of the results of investigations into the flowfields and aerodynamic forces associated with low aspect ratio wings at high angles of attack. Attention is given to criteria for the cataloging of these flowfields, the phenomenon of vortex breakdown, with varying wing incidence and Mach number, and the effects of aspect ratio and compressibility. The planforms treated are of rectangular, clipped-delta, and strake-wing combination geometries. Extensive graphic representations of performance trends with varying parameters are furnished.
    Keywords: AERODYNAMICS
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    Identification and control of a multizone crystal growth furnace (1992)
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    Publication Date: 2011-08-24
    Description: This paper presents an intelligent adaptive control system for the control of a solid-liquid interface of a crystal while it is growing via directional solidification inside a multizone transparent furnace. The task of the process controller is to establish a user-specified axial temperature profile and to maintain a desirable interface shape. Both single-input-single-output and multi-input-multi-output adaptive pole placement algorithms have been used to control the temperature. Also described is an intelligent measurement system to assess the shape of the crystal while it is growing. A color video imaging system observes the crystal in real time and determines the position and the shape of the interface. This information is used to evaluate the crystal growth rate, and to analyze the effects of translational velocity and temperature profiles on the shape of the interface. Creation of this knowledge base is the first step to incorporate image processing into furnace control.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Crystal Growth (ISSN 0022-0248); 119; 3-4,
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    A new skin friction balance and selected measurements (1992)
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    Publication Date: 2011-08-24
    Description: A new skin friction balance with moving belt has been developed for measurement of the surface shear stress component in the direction of belt motion. The device is described in this paper with typical measurement results. This instrument is symmetric in design with small moving mass negligible internal friction. It is 3.8 cm high, 3.8 cm long and 2.1 cm wide, with the sensing surface 0.7 cm wide and 1.5 cm long, and it can be made in various sizes. The unique design of this instrument has reduced some of the errors associated with conventional floating-element balances. The instrument can use various sensing systems and the output signal is a linear function of the wall shear stress. Measurements show good agreement with data obtained by the floating element balances and flat plate prediction techniques. Dynamic measurements have been made in a limited range. The overall uncertainty of measurement is estimated to be +/- 2 percent.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Experiments in Fluids (ISSN 0723-4864); 12; 6, Ap; 401-406
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    Active dosimetric measurements on Shuttle flights (1992)
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    Publication Date: 2011-08-24
    Description: A tissue-equivalent proportional counter spectrometer capable of measuring the absorbed dose and dose distribution as a function of LET and time, for all penetrating radiation in space, is described. This instrument weighs about 0.7 kg and was flown on the STS-31 (28.5 deg x 620 km) flight of the Space Shuttle, 24-29 April 1990. The measured total dose is in excellent agreement with the calculations based on the AP8MAX model of the trapped radiation belt protons. The observed LET frequency distribution is also in excellent agreement with calculations based on this model. Active instruments can provide more detailed dosimetry for crew risk assessment than the thermoluminescent detectors or a plastic track detector system.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: International Journal of Radiation Applications and Instrumentation, Part D: Nuclear Tracks and Radiation Measurements (ISSN 0735-245X); 20; 1, Ja
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    Rayleigh-Brillouin scattering to determine one-dimensional temperature and number density profiles of a gas flow field (1992)
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    Publication Date: 2011-08-24
    Description: Rayleigh-Brillouin spectra for heated nitrogen gas were measured by imaging the output of a Fabry-Perot interferometer onto a CCD array. The spectra were compared with the theoretical 6-moment model of Rayleigh-Brillouin scattering convolved with the Fabry-Perot instrument function. Estimates of the temperature and a dimensionless parameter proportional to the number density of the gas as functions of position in the laser beam were calculated by least-squares deviation fits between theory and experiment.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 31; 15, M
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    Numerical study of the effects of reverse sweep on scramjet inlet performance (1992)
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: Journal of Propulsion and Power (ISSN 0748-4658); 8; 3, Ma; 714-719
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    Evaluation of a finite volume method for compressible shear layers (1992)
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 30; 5, Ma; 1214-121
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    A rotating tomographic imager for solar extreme-ultraviolet/soft X-ray emission (1992)
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    Publication Date: 2011-08-24
    Description: A concept is presented for a high-resolution EUV/soft-X-ray imager that has much in common with the medical imaging procedure of tomography. The resulting instrument is compatible with a simpler, less costly spin-axis-stabilized spacecraft. To demonstrate the fidelity of the reconstruction procedure, the observation and reconstruction is simulated to compare the results with the original image.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 389; L91-L93
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    Theoretical model for a thin cylindrical film optical fiber fluorosensor (1992)
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    Publication Date: 2011-08-24
    Description: The analytical treatment of power efficiency (P(eff) is undertaken for the case of a positively guiding optical fiber with a thin-film source distributed in the core-cladding interface. The approach adopts the exact solution of the cylindrical optical fiber with an infinite cladding to account for differences between the indices of refraction of the core and the cladding. The excitation of low-loss leaky modes by the cladding is ignored, and only the injection by the evanescent field is considered. The formulas permit the analysis of the power-injection efficiency of fibers with arbitrary differences in indices of refraction. P(eff) does not always increase with V number, but rather varies slightly with wavelength and fiber-core radius and varies significantly with the difference in the indices of refraction. The theoretical results of the work are of interest for designing an atomic-O chemical sensor based on evanescent-wave coupling.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering (ISSN 0091-3286); 31; 237-244
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    Application of the LAURA code for slender-vehicle aerothermodynamics (1992)
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4650); 29; 16-23
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    Implicit Navier-Stokes solver for three-dimensional compressible flows (1992)
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 30; 11; p. 2653-2659.
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    Comparison of algebraic turbulence models for afterbody flows with jet exhaust (1992)
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    Publication Date: 2011-08-24
    Description: Three-dimensional Navier-Stokes simulations have been done for transonic and low supersonic flow past a nonaxisymmetric nozzle typical of those advocated for advanced fighter airplanes. The jet exhaust is included in the calculations. The investigation compares the performance of the unmodified Baldwin-Lomax turbulence model with its performance when enhanced by the Degani-Schiff and the Goldberg modifications. Solutions are presented for Mach numbers of 0.80, 0.94, and 1.20 at 0-deg angle of attack and a Reynolds number of 20 x 10 to the 6th. The numerical results, which are compared to the wind-tunnel data, show that the three turbulence models predict considerably different shock locations, separated-flow regions, and flowfields.
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 30; 11; p. 2716-2722.
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  • 87
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    Application of an unsteady Navier-Stokes solver to transonic turbine design (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: Journal of Propulsion and Power (ISSN 0748-4658); 8; 5, Se; 1079-108
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  • 88
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    Gortler instability and supersonic quiet nozzle design (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 30; 8, Au; 2093
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  • 89
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    An evaluation of strain measuring devices for ceramic composites (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: A series of tensile tests were conducted on SiC/RBSN composites using different methods of strain measurement. The tests were used to find the optimum strain sensing device for use with continuous fiber reinforced ceramic matrix composites in ambient and high temperature environments. Bonded resistance strain gages were found to offer excellent performance for room temperature tests. The clip-on gage offers the same performance but significantly less time is required for mounting it to the specimen. Low contact force extensometers track the strain with acceptable results at high specimen temperatures. Silicon carbide rods with knife edges are preferred. The edges must be kept sharp. The strain measuring devices should be mounted on the flat side of the specimen. This is in contrast to mounting on the rough thickness side.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Testing and Evaluation (ISSN 0090-3973); 20; 4, Ju
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  • 90
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    Predicted pressure distribution on a prop-fan blade through Euler analysis (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 29; 4, Ju; 627-631
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  • 91
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    Navier-Stokes computations on swept-tapered wings, including flexibility (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 29; 4, Ju; 588-597
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  • 92
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    Navier-Stokes predictions for the F-18 wing and fuselage at large incidence (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 29; 4, Ju; 565-574
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  • 93
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    Aerothermodynamics of a 1.6-meter-diameter sphere in hypersonic rarefied flow (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 30; 7, Ju; 1789-179
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  • 94
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    Domain-decomposition algorithm applied to multielement airfoil grids (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 30; 6, Ju; 1457-146
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  • 95
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    Effect of acoustic excitation on stalled flows over an airfoil (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 30; 6, Ju; 1492-149
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  • 96
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    Tensile strain measurements of ceramic fibers using scanning laser acoustic microscopy (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: A noncontacting technique using scanning laser acoustic microscopy for making in situ tensile strain measurements of small diameter fibers was implemented for the tensile strain analysis of individual Nicalon SiC fibers (nominal diameter 15 microns). Stress vs strain curves for the fibers were plotted from the experimental data. The mean elastic modulus of the fibers was determined to be 185.3 GPa. Similar measurements were made for Carborundum SiC fibers (nominal diameter 28 microns) and Saphikon sapphire fibers (nominal diameter 140 microns).
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 13; 7-8,
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  • 97
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    Two- and three-dimensional grid generation by an algebraic homotopy procedure (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 30; 5, Ma; 1433
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  • 98
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    Navier-Stokes solution of transonic cascade flows using nonperiodic C-type grids (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: A new kind of C-type grid is proposed, this grid is non-periodic on the wake and allows minimum skewness for cascades with high turning and large camber. Reynolds-averaged Navier-Stokes equations are solved on this type of grid using a finite volume discretization and a full multigrid method which uses Runge-Kutta stepping as the driving scheme. The Baldwin-Lomax eddy-viscosity model is used for turbulence closure. A detailed numerical study is proposed for a highly loaded transonic blade. A grid independence analysis is presented in terms of pressure distribution, exit flow angles, and loss coefficient. Comparison with experiments clearly demonstrates the capability of the proposed procedure.
    Keywords: AERODYNAMICS
    Type: Journal of Propulsion and Power (ISSN 0748-4658); 8; 410-417
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  • 99
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    Navier-Stokes simulation of flow through a highly contoured subsonic diffuser (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The flow through a highly offset subsonic diffuser with cross-sectional profiles that varied from rectangular at the duct entrance to circular at the engine face was numerically simulated. A multizonal approach combined with a two-grid topology was used to represent both the internal and external flowfields, and an implicit, approximately-factored, partially flux-split finite-difference algorithm was used to solve the three-dimensional thin-layer Navier-Stokes equations. The computed static pressures along the inlet wall and total pressures on the engine face were compared with experimental data. In addition, the overall flowfield within the duct was examined in detail. Good agreement is shown between experiment and computations, with the limiting factor being the lack of a reliable turbulence model for internal flow problems.
    Keywords: AERODYNAMICS
    Type: International Journal for Numerical Methods in Engineering (ISSN 0029-5981); 34; 473-483
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  • 100
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    Enthalpy damping for high Mach number Euler solutions (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 30; 300
    Format: text
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