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  • Other Sources  (768)
  • NASA Technical Reports  (768)
  • FLUID MECHANICS AND HEAT TRANSFER  (327)
  • INSTRUMENTATION AND PHOTOGRAPHY  (258)
  • MECHANICAL ENGINEERING  (183)
  • 1985-1989
  • 1980-1984  (768)
  • 1975-1979
  • 1983  (768)
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  • Other Sources  (768)
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  • NASA Technical Reports  (768)
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  • 1985-1989
  • 1980-1984  (768)
  • 1975-1979
Year
  • 1
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    Si:Bi array detectors and astronomical applications of the Goddard 10 micron camera (1983)
    In:  CASI
    Details
    Publication Date: 2004-12-04
    Description: An improved 4 to 18 micron array camera system was developed at NASA Goddard SFC for astronomical photometry, using an Aerojet Electro Systems Corp. 16 x 16 Si:Bi accumulation mode charge injection device (AMCID) which could be suitable for eventual low-background spaceflight applications. An astronomical observing program using this device was carried out as a collaboration between NASA Goddard (Infrared and Radio Astronomy Branch and Micro Electronics Branch), the Harvard/Smithsonian Center for Astrophysics, and Steward Observatory of the University of Arizona. In 1983 the camera system was revised, and a new Aeroject Si:Bi array with 16 x 16 active pixels was obtained from NASA/Ames Research Center as part of a new scientific collaboration between the Ames and Goddard infrared array research groups. The 16 x 16 device had sufficiently good sensitivity, uniformity and noise characteristics to be used for successful observations at the Mt. Lemmon 60 and 61 inch telescopes in May 1983. Complete laboratory characterization of the 16 x 16 array was carried out in summer of 1983. Initial results indicate that this detector has sensitivity and noise characteristics comparable to other devices from the same generation of Aerojet arrays.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Ames Research Center, Infrared Detector Technology Workshop; 12 p
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  • 2
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    Solution adaptive grid generation (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Langley Research Center, Theoretical Aerodynamics Contractors' Workshop, Volume 2; p 651-68
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  • 3
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    Navier-Stokes solution for quasi-three dimensional flow (1983)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Langley Research Center, Theoretical Aerodynamics Contractors' Workshop, Volume 1; p 329-33
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  • 4
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    Vectorized, implicit Navier-Stokes solver for 2-D incompressible flows (1983)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Langley Research Center, Theoretical Aerodynamics Contractors' Workshop, Volume 1; p 273-31
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  • 5
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    Clebsch velocity decomposition for rotational conical flows (1983)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Langley Research Center, Theoretical Aerodynamics Contractors' Workshop, Volume 1; p 183-19
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  • 6
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    Influence of convection on the growth of crystals from solution (1983)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: This is a review of the influence of convection on the growth of crystals from solution. The growth rate is increased by convection up to the point where interface kinetics becomes rate controlling. Compositional inhomogeneity and morphological instability (inclusion formation) are probably worse for gentle convection than for either no convection or for vigorous stirring. Stirring, particularly of crystal suspensions, can cause an orders of magnitude increase in the rate of formation of new crystals. This is called 'secondary nucleation'.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Crystal Growth (ISSN 0022-0248); 65; 133-142
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  • 7
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    Heterodyne frequency measurements and frequency calibration standards for tunable diode lasers (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: New frequency calibration tables are required to keep abreast of the resolution attainable by currently available tunable lasers. One key to the generation of tables with requisite accuracy involves accurate heterodyne frequency measurements; another key consists of reliable fitting and analysis. Coordinated activity in NBS involves selection of suitable molecular calibration candidates, their frequency measurement and analysis, and dissemination of the results in the form of frequency calibration tables. Current status of these efforts is described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 8
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    Optogalvanic photodetachment spectroscopy (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A new extension to optogalvanic spectroscopy, in which electrons detached from negative ions formed in the discharge are observed as a function of incident laser wavelength, has been developed. The determination of the electron affinities of I(-) and Cl(-) atomic ions is described. The potential of the technique for studying the spectroscopy of molecular negative ions is also discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal de Physique (ISSN 0449-1947); 44; C7-461 t
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  • 9
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    Two-phase turbine staging (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Two-phase turbines would be useful in Rankine cycles using low-quality or saturated-liquid working fluids. The chief problem is low efficiency due to slip losses in nozzles and due to liquid impact and friction losses in rotors. To raise efficiency, a staging method was tested in which the first stage operated at high speed with low relative liquid velocity, and the second stage recovered the first-stage exit energy. The theoretical efficiency for an experimental turbine operating with Refrigerant-22 was raised from 55 percent to 66 percent, and the measured efficiency was raised from 52 percent to 57 percent.
    Keywords: MECHANICAL ENGINEERING
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  • 10
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    DOE/NASA Automotive Stirling Engine Project Overview 83 (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An overview of the DOE/NASA Automotive Stirling Engine Project is presented. The background and objectives of the project are reviewed. Project activities are described and technical progress and status are presented and assessed. Prospects for achieving the objective 30 percent fuel economy improvement are considered good. The key remaining technology issues are primarily related to life, reliability and cost, such as piston rod seals, and low cost heat exchanges. Previously announced in STAR as N83-27924
    Keywords: MECHANICAL ENGINEERING
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  • 11
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    Nd:YAG holographic interferometer for aerodynamic research (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A holographic interferometer system has been installed in the NASA Ames 2- by 2-Foot Transonic Wind Tunnel. The system incorporates a modern 10 pps, Nd:YAG pulsed laser which provides reliable operation and is easy to align. The spatial filtering requirements of the unstable resonator beam are described, as well as the integration of the system into the existing schlieren system. A two-plate holographic interferometer is used to reconstruct flow field data. For static wind tunnel models, the single exposure holograms are recorded in the usual manner; however, for dynamic models such as oscillating airfoils, synchronous laser hologram recording is used.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 12
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    The production of turbulent stress in a shear flow by irrotational fluctuations (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Attention is given to the way in which external turbulence affects an initially turbulence-free region in which there is a mean velocity gradient. External turbulence induces irrotational fluctuations in the sheared region which interact with the shear to produce rotational velocity fluctuations and mean Reynolds stresses. Since the actual front between the initial external turbulence and the shear flow is a randomly contorted surface, the turbulence near the front is intermittent, and is presently included in the form of a simple statistical model. In wind tunnel tests, turbulent shear stress was found to grow from zero to significant values in the interaction region. Observed stress magnitude and extent agrees with predictions, and it is concluded that turbulent stresses can be produced by irrotational fluctuations in a region of mean shear.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics (ISSN 0022-1120); 137; 307-329
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  • 13
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    Viscous thermocapillary convection at high Marangoni number (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A liquid, contained in a quarter plane, undergoes steady motion due to thermocapillary forcing on its upper boundary, a free surface separating the liquid from a passive gas. The rigid vertical sidewall has a strip whose temperature is elevated compared with the liquid at infinity. A boudnary-layer analysis is performed that is valid for large Marangoni numbers M and Prandtl numbers P. It is found that the Nusselt number N for the horizontal heat transport satisfies N proportional to min (M to the 1 2/7/power, M to the 1 1/5/power, M to the 1 1/10/power) Generalizations are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics (ISSN 0022-1120); 135; 175-188
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  • 14
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    Differential absorption lidar technique for measurement of the atmospheric pressure profile (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A new two-wavelength lidar technique for remotely measuring the pressure profile using the trough absorption region between two strong lines in the oxygen A band is described. The theory of integrated vertical path, differential ranging, and horizontal-path pressure measurements is given, with methods to desensitize and correct for temperature effects. The properties of absorption troughs are described and shown to reduce errors due to laser frequency jitter by up to two orders of magnitude. A general analysis, including laser bandwidth effects, demonstrates that pressure measurements with an integrated-vertical-path technique are typically fifty times more accurate than with a differential ranging technique. Simulations show 0.1-0.3 percent accuracy for ground and Shuttle-based pressure-profile and surface-pressure experiments.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; 3759-377
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  • 15
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    Stagnation-point ablation of carbonaceous flat disks. II Experiment (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Six flat-disk models made of carbon-carbon and carbon-phenolic materials were launched in an argon-filled track-range facility to test ablation characteristics in a radiation-dominated, massive-blowing environment. The shock standoff distances deduced from the shadowgraphs agree with theoretical predictions during the earlier portion of the flight, while the wall temperatures determined by the image-converter photographs agree with predictions during the later portion. The measured surface recessions exceed the calculated values by about 60 percent for carbon-phenolic and 30 percent for carbon-carbon. The discrepancies are attributed to spallation. The measured char thicknesses agree with theoretical predictions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 21; 1748-175
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  • 16
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    Continuation in a parameter - Experience with viscous and free surface flows (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The results of modifications in continuation methods applied to obtain solutions to the Navier-Stokes systems of equations for incompressible, two-dimensional, steady flows are reported. It is shown that parameter continuation permits prediction of accurate, initial estimates for iterative processing of nonlinear finite difference and finite element equations of motions. The new parameter steps are derived from values of the preceding parameter steps. The accuracy of the estimates is ensured with appropriate choices of the step size. The continuation predictor/iterative corrector is demonstrated to trace the branches of parameter space along which steady flow states are found, and techniques are available for tracing multiply branching paths. The techniques are applied to solving the Navier-Stokes equations for flow through a rotating square channel, the formation of a falling liquid curtain, and gyrostatic equilibria of rotating cylindrical drops.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 17
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    Modeling of transient two-component flow using a four-point implicit method (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The four-point, centered implicit scheme that is extensively used in open channel flow simulation is shown to be applicable to rapid and slow pressure transient problems in conduits with nearly single phase and two-phase flows. It is only necessary to choose the proper weighting factor value, theta, of the Courant number. For rapid pressure transients such as waterhammer, the implicit method can yield reasonable results with limited numerical dispersion and attenuation if theta is only slightly greater than the critical value of 0.5. For slower pressure gradients in single and two-phase flows, reasonable numerical solutions may be achieved for Courant number values as high as 20.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 18
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    Influence of unbalance on the nonlinear dynamical response and stability of flexible rotor-bearing systems (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: In this paper, some of the effects of unbalance on the nonlinear response and stability of flexible rotor-bearing systems is presented from both a theoretical and experimental standpoint. In a linear system, operating above its stability threshold, the amplitude of motion grows exponentially with time and the orbits become unbounded. In an actual system, this is not necessarily the case. The actual amplitudes of motion may be bounded due to various nonlinear effects in the system. These nonlinear effects cause limit cycles of motion. Nonlinear effects are inherent in fluid film bearings and seals. Other contributors to nonlinear effects are shafts, couplings and foundations. In addition to affecting the threshold of stability, the nonlinear effects can cause jump phenomena to occur at not only the critical speeds, but also at stability onset or restabilization speeds.
    Keywords: MECHANICAL ENGINEERING
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  • 19
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    The production of turbulent stress in a shear flow by irrotational fluctuations (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: This paper examines, both theoretically and experimentally, the effect produced by irrotational fluctuations, associated with a nearby turbulent field, in a region where the turbulence is initially very low but where there is a mean shear. Calculations are based on rapid distortion theory and experiments use linearized hot wire anemometers in an open circuit wind tunnel. Turbulent shear stress is observed to grow from zero to significant values in the interaction region. The magnitude and extent of this observed shear stress agree reasonably well with predictions of the analysis, when intermittency effects are included. It is concluded that turbulent stresses can be produced by irrotational fluctuations in a region of mean shear and that this effect can be estimated using rapid distortion theory if the overall strain ratio is not large.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 20
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    Ceramics potential in automotive powerplants (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The paper addresses the potential that ceramic materials can play an important role in future automotive powerplants - both advanced heat engines and advanced battery systems. A number of related experimental programs are reviewed including ceramics for gasoline and diesel piston engines, gas turbine and Stirling Engines and sodium-sulfur batteries. A strong integrated program to develop ceramics technology is recommended.
    Keywords: MECHANICAL ENGINEERING
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  • 21
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    Airborne detection of oceanic turbidity cell structure using depth-resolved laser-induced water Raman backscatter (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Airborne laser-induced, depth-resolved water Raman backscatter is useful in the detection and mapping of water optical transmission variations. This test, together with other field experiments, has identified the need for additional field experiments to resolve the degree of the contribution to the depth-resolved, Raman-backscattered signal waveform that is due to (1) sea surface height or elevation probability density; (2) off-nadir laser beam angle relative to the mean sea surface; and (3) the Gelbstoff fluorescence background, and the analytical techniques required to remove it. When converted to along-track profiles, the waveforms obtained reveal cells of a decreased Raman backscatter superimposed on an overall trend of monotonically decreasing water column optical transmission.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; 3778-378
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  • 22
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    A modified Dodge algorithm for the parabolized Navier-Stokes equations and compressible duct flows (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A revised version of Dodge's split-velocity method for numerical calculation of compressible duct flow was developed. The revision incorporates balancing of mass flow rates on each marching step in order to maintain front-to-back continuity during the calculation. The (checkerboard) zebra algorithm is applied to solution of the three dimensional continuity equation in conservative form. A second-order A-stable linear multistep method is employed in effecting a marching solution of the parabolized momentum equations. A checkerboard iteration is used to solve the resulting implicit nonlinear systems of finite-difference equations which govern stepwise transition. Qualitative agreement with analytical predictions and experimental results was obtained for some flows with well-known solutions. Previously announced in STAR as N82-16363
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal for Numerical Methods in Fluids (ISSN 0271-2091); 3; 493-506
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  • 23
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    Accuracy of approximations to the Navier-Stokes equations (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The systems of truncated differential equations that have been proposed to reduce the complexity and large computational costs of solutions to the full Navier-Stokes equations are considered. These systems are computationally efficient and capture all the physically relevant behavior. The systems follow a certain hierarchy: (1) the classical boundary-layer equations with specified edge properties (usually the streamwise pressure distribution); (2) the coupled boundary-layer/inviscid equations; (3) the so-called thin-layer equations that discard streamwise diffusion; and (4) the Navier-Stokes equations. Consideration is given to each of these approximations applied to an incompressible, laminar-separating flow at low and moderate Reynolds numbers. It is pointed out that for any flow or region of flow for which viscous-inviscid interaction effects are small, classical boundary-layer equations will provide a satisfactory description of the viscous flow at a fraction of the computational cost of any higher approximations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 21; 1759
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  • 24
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    Growth of Goertler vortices in compressible boundary layers along curved surfaces (1983)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An investigation of the growth of the three-dimensional, counter-rotating, longitudinal type vortices is considered in two-dimensional laminar compressible boundary-layer flow. The basic approximation of the disturbance equations that includes the terms due to boundary layer growth is considered and solved numerically. These terms are shown to have large local effects near the neutral stability region. The study shows that the instability of the boundary layer with respect to the three-dimensional vortices sets in at higher Goertler number as Mach number increases. Also the maximum amplitude ratio of the vortices is reduced by about 20 percent as Mach number increases from 0 to 5.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Engineering and Applied Sciences (ISSN 0191-9539); 2; 3, 19; 213-238
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  • 25
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    Into mesh lubrication of spur gears with arbitrary offset oil jet. I - For jet velocity less than or equal to gear velocity (1983)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An analysis was conducted for into mesh oil jet lubrication with an arbitrary offset and inclination angle from the pitch point for the case where the oil jet velocity is equal to or less than pitch line velocity. The analysis includes the case for the oil jet offset from the pitch point in the direction of the pinion and where the oil jet is inclined to intersect the common pitch point. Equations were developed for the minimum oil jet velocity required to impinge on the pinion or gear and the optimum oil jet velocity to obtain the maximum impingement depth.
    Keywords: MECHANICAL ENGINEERING
    Type: ASME; 713-718
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  • 26
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    Description and overview of an instrument designed to measure line-of-sight delay due to water vapor (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Eight dual channel microwave radiometers were constructed as a research and development effort for the Crustal Dynamics Project and the Deep Space Network. These instruments, known as water vapor radiometers, are primarily intended to demonstrate that the variable path delay imposed by atmospheric water vapor can be calibrated in microwave tracking and distance measuring systems but could also be used in other applications involving moist air meteorology and propagation studies. They are being deployed to various stations and observatories that participate in Very Long Baseline Interferometry experiments. The development history of these instruments are reviewed, the theory of operation and overall design considerations are outlined, and the instrumental parameters and performance characteristics are described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Telecommun. and Data Acquisition Rept.; p 1-19
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  • 27
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    Long term technology development program (1983)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In the Advanced Adiabatic Development program, the following technology were identified as critical: piston development for oil-less, adiabatic engine; positive displacement compounding and charge system; experimental evaluation of the preheat concept; combustion system with positive ignition assist; and ceramic manufacturing technology. Of these five areas, ceramic manufacturing technology is the pacing item, and is already being addressed by several organizations. Therefore the four remaining areas need immediate attention. Since the lead time involved in engine development and production is long, this technology development should be done concurrently with the AAD engine development. A four year program is outlined which will simultaneously study these first four areas. This program requires two test rigs; one single cylinder adiabatic engine; and one multicylinder adiabatic turbocompound engine.
    Keywords: MECHANICAL ENGINEERING
    Type: Advan. Automotive Diesel Assessment Program; 7 p
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  • 28
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    A.A.D. engine noise evaluation (1983)
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    Publication Date: 2011-08-19
    Description: A critique of the various characteristics of engine design influencing noise and attempts to indicator areas where attention is required to obtain noise acceptable engine for automobiles are discussed. It was concluded that the engine has a potential to be quiet beccause a ion rated speed is chosen. Problems with high gas pressure, the fuel injection pump, and the expander/compressor are discussed.
    Keywords: MECHANICAL ENGINEERING
    Type: Cummins Engine Co., Inc. Advan. Automotive Diesel Assessment Program; 29 p
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  • 29
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    Screw expander for light duty diesel engines (1983)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Preliminary selection and sizing of a positive displacement screw compressor-expander subsystem for a light-duty adiabatic diesel engine; development of a mathematical model to describe overall efficiencies for the screw compressor and expander; simulation of operation to establish overall efficiency for a range of design parameters and at given engine operating points; simulation to establish potential net power output at light-duty diesel operating points; analytical determination of mass moments of inertia for the rotors and inertia of the compressor-expander subsystem; and preparation of engineering layout drawings of the compressor and expander are discussed. As a result of this work, it was concluded that the screw compressor and expander designed for light-duty diesel engine applications are viable alternatives to turbo-compound systems, with acceptable efficiencies for both units, and only a moderate effect on the transient response.
    Keywords: MECHANICAL ENGINEERING
    Type: Cummins Engine Co., Inc. Advan. Automotive Diesel Assessment Program; 46 p
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  • 30
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    Thermal and mechanical analysis of major components for the advanced adiabatic diesel engine (1983)
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    Publication Date: 2011-08-19
    Description: The proposed design for the light duty diesel is an in-line four cylinder spark assisted diesel engine mounted transversely in the front of the vehicle. The engine has a one piece cylinder head, with one intake valve and one exhaust valve per cylinder. A flat topped piston is used with a cylindrical combustion chamber recessed into the cylinder head directly under the exhaust valve. A single ceramic insert is cast into the cylinder head to insulate both the combustion chamber and the exhaust port. A similar ceramic insert is cast into the head to insulate the intake port. A ceramic faceplate is pressed into the combustion face of the head to insulate the face of the head from hot combustion gas. The valve seats are machined directly into the ceramic faceplate for the intake valve and into the ceramic exhaust pot insert for the exhaust valve. Additional ceramic applications in the head are the use of ceramic valve guides and ceramic insulated valves. The ceramic valve guides are press fit into the head and are used for increased wear resistance. The ceramic insulated valves are conventional valves with the valve faces plasma spray coated with ceramic for insulation.
    Keywords: MECHANICAL ENGINEERING
    Type: Advan. Automotive Diesel Assessment Program; 65 p
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  • 31
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    Advanced automotive diesel engine system study (1983)
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    Publication Date: 2011-08-19
    Description: A conceptual study of an advanced automotive diesel engine is discussed. The engine concept selected for vehicle installation was a supercharged 1.4 liter, 4 cylinder spark assisted diesel of 14:1 compression ratio. A compounding unit consisting of a Lysholm compressor and expander is connected to the engine crankshaft by a belt drive. The inlet air charge is heated by the expander exhaust gas via a heat exchanger. Four levels of technology achievement on the selected engine concept were evaluated, from state-of-the-art to the ideal case. This resulted in the fuel economy increasing from 53.2 mpg to 81.7 mpg, and the 0-60 mph time decreasing from 17.6 seconds to 10.9 seconds.
    Keywords: MECHANICAL ENGINEERING
    Type: Cummins Engine Co., Inc. Advan. Automotive Diesel Assessment Program; 18 p
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    A study of the Armstrong Whitworth swing beam engine for automotive application (1983)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The introduction of ceramics to those parts suffering high thermal loading was successfully demonstrated, and there is no question that the 100 kw (134 hp) naturally aspirated engine of the future will be developed to produce up to 300 kw (402 hp) by the application of turbocharging or its equivalent. However, at the 60 - 80 kw (80 - 107 hp) size needed for the economic automotive engine, scaling down the 300 kw (402 hp) is beset by the laws of scale. The conventional four stroke diesel was not shown to be successful at the small high speed engine size. The opposed piston two stroke engine does not suffer the same laws of scale and engines in the low power range have already been marketed successfully. The half liter/cylinder Armstrong Whitworth Swing Beam Engine is the latest to be designed with the automotive market in mind. Its low noise structure and balanced linkage system coupled with advantages for easy start and potential use of low grade fuels, derived from its variable compression ratio and slow piston motion, qualifies it for the application.
    Keywords: MECHANICAL ENGINEERING
    Type: Cummins Engine Co., Inc. Advan. Automotive Diesel Assessment Program; 3 p
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    Roller crosshead analysis (1983)
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    Publication Date: 2011-08-19
    Description: An analysis of the frictional behavior of a roller crosshead configuration is given. This configuration consists of a piston which carries at the wristpin position a roller of large diameter which can roll on the cylinder liner surfaces. A preliminary assessment is given of whether the roller can roll on the cylinder liner without skidding, and what, if any, are the tribological implications of this approach to a dry lubricated design. The rotational speed of the roller must change during the stroke if it is not to slip on the cylinder liner. The maximum value of angular acceleration occurs at top dead center and bottom dead center. If the traction force on the rim of the roller, which is the product of the normal force due to piston side load and the coefficient of friction, is not sufficient to drive the roller through the necessary angular acceleration, sliding will occur. At 1,000 rpm, it appears that there will be a definite area of slip near each end of the stroke. The length of the area of slip may be of the order of 1/8 inch at each of these points.
    Keywords: MECHANICAL ENGINEERING
    Type: Advan. Automotive Diesel Assessment Program; 9 p
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    Advanced Automotive Diesel Assessment Program, executive summary (1983)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The objectives of this analytical study were: to select one advanced automotive diesel engine (AAD) concept which would increase the tank mileage of a 3,000 pound passenger car from the present 35 mpg to at least 52 mpg; to identify long term component research and development work required to bring the selected concept to fruition; and to prepare a development strategy that will bring the selected concept to a prototype testing phase. Cummins Engine Company has completed this study. The selected concept is a 4 stroke cycle, direct injection, spark assisted, advanced adiabatic diesel engine with positive displacement compounding plus expander and part load air preheating. The engine does not use a liquid coolant nor liquid lubricants. It is a 4 cylinder, in-line, 77 mm bore x 77 mm stroke, 1.434 liters displacement engine weighing 300 lb, and rated at 70 BHP at 3000 rpm. Installation dimensions are 621 mm length x 589 mm width x 479 mm height (24.4 inch x 22 inch x 18.9 inch).
    Keywords: MECHANICAL ENGINEERING
    Type: Advan. Automotive Diesel Assessment Program p; 59 p
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    Detailed performance analysis of the A.A.D. - concept B (1983)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: New concepts for engine performance improvement are seen through the adoption of heat regeneration techniques; advanced methods to enhance the combustion; and higher efficiency air handling machinery, such as the positive displacement helical screw expander and compressor. Each of these concepts plays a particular role in engine performance improvement. First regeneration has a great potential for achieving higher engine thermal efficiency through the recovery of waste energy. Although the concept itself is not new (this technique is used in the gas turbine), the application to reciprocating internal combustion engines is quite unusual and presents conceptual difficulties. The second important area is better control of the combustion process in terms of heat transfer characteristics, combustion products, and heat release rate. The third area for performance improvement is in the adoption of high efficiency air handling machinery. In particular, positive displacement helical expander and compressor exhibit an extremely high efficiency over a wide range of operating conditions.
    Keywords: MECHANICAL ENGINEERING
    Type: Advan. Automotive Diesel Assessment Program; 46 p
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    Spacelab high density digital recorders (1983)
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    Publication Date: 2011-08-18
    Description: The design and performance of the high-density digital recorder (HDDR) developed for use at the NASA centers (KSC, JSC, and GSFC) and at the JPL to store and retrieve 50-Mb/s PCM data streams from the Spacelab experiments are reported. The recording reproduction, and transport requirements are reviewed; and the design solutions adopted in the final version of the HDDR are described, incuding three-position-modulation and Y-phase encoding, microprocessor-controlled automatic bit synchronization and equalization, cyclic-redundancy-check error detection and correction, clock regeneration, data and clock variations, tape-speed control, and EEE-488 remote control. Reliable performance, with bit error rates 1 in 10 to the 10th forward and 1 in 10 to the 9th reverse or better and packing density up to 50 percent greater than that obtainable using conventional codes, is reported after 1.5 years of service.
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    Finite element calculation of buoyancy-driven convection near a melt/solid phase boundary (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Two iterative schemes based on the mixed finite element method are developed for analyzing steady natural convection in a melt adjacent to its solid phase. The simplest method decouples the calculation of the field variables and the shape of the melt/solid interface into two interlocked iterations that are performed successively. The second method uses Newton's iteration to solve simultaneously for both types of unknowns and has a quadratic convergence rate. Results for a model problem of melt and solid in a cylindrical ampoule show the Newton algorithm to be a factor of three more efficient.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    Design philosophy of the Jet Propulsion Laboratory infrared detector test facility (1983)
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    Publication Date: 2011-08-18
    Description: To support the development of advanced infrared remote sensing instrumentation using line and area arrays, a test facility has been developed to characterize the detectors. The necessary performance characteristics of the facility were defined by considering current and projected requirements for detector testing. The completed facility provides the desired level of detector testing capability as well as providing ease of human interaction.
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  • 39
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    Comparison of measurements by different instruments of the far-infrared reflectance of rough, optically black coatings (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Two comparisons of available specular infrared measurements using identical or very similar coatings reveal that specular BRDF (bidirectional reflectance distribution function) measurements of rough coatings are comparable but that simple measured reflectances are not. This is seen as indicating that the diffuse component of the measured specular reflectance is significantly larger than that of the specular component. It is noted that the diffuse component of the measurement is a convolution of the intrinsic directional reflectivity of the surface with the instrument function and that because the value of that function increases at the wavelengths under consideration, the diffuse component is larger than would otherwise be expected. The BRDF normalization is found to cause a primitive deconvolution of the instrument function and to produce a quantity that is approximately equal to the mean intrinsic directional reflectivity very near the specular direction. The analysis and comparison of data reveal that nonspecular BRDF measurements at angles well outside the instrument function can be calibrated as well by an image of the source upon the detector as by reference to a known surface.
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  • 40
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    Multiple-grid convergence acceleration of viscous and inviscid flow computations (1983)
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    Publication Date: 2011-08-18
    Description: A multiple-grid algorithm for use in efficiently obtaining steady solution to the Euler and Navier-Stokes equations is presented. The convergence of a simple, explicit fine-grid solution procedure is accelerated on a sequence of successively coarser grids by a coarse-grid information propagation method which rapidly eliminates transients from the computational domain. This use of multiple-gridding to increase the convergence rate results is substantially reduced work requirements for the numerical solution of a wide range of flow problems. Computational results are presented for subsonic and transonic inviscid flows and for laminar and turbulent, attached and separated, subsonic viscous flows. Work reduction factors as large as eight, in comparison to the basic fine-grid algorithm, were obtained. Possibilities for further performance improvement are discussed. Previously announced in STAR as N83-21847
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Applied Mathematics and Computation (ISSN 0096-3003); 13; 375-398
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  • 41
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    CO2 DIAL sensitivity studies for measurements of atmospheric trace gases (1983)
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    Publication Date: 2011-08-18
    Description: An analysis is presented of the accuracy of infrared differential absorption lidar (DIAL) measurements of trace constituents in the atmosphere. Expressions are derived for the signal-to-noise ratios applicable in the detection of a signal from a scattering cell for the cases of single-detection heterodyne detection and direct detection. Results of computer simulations of the expectation value of the measured return for various measurement conditions are presented which illustrate the sensitivities of plume measurements for horizontal range-resolved and vertical content measurements of NH3 in heterodyne and direct detection. Advantages for long-range measurements of the use of rare isotope laser frequencies, tuning by collision broadening, and closely spaced on and off frequencies are pointed out.
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    Coherent CO2 lidar systems for remote atmospheric measurements (1983)
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    Publication Date: 2011-08-18
    Description: Several examples of applications of coherent CO2 Doppler lidar systems are summarized to illustrate the potential of these systems. The applications discussed include the use of continuous-wave systems for detecting and tracking aircraft wake vortices, transverse velocity measurements, and measurements of mass flow rates of high stack emissions. The use of pulsed coherent lidars is illustrated by applications involving the measurement of thunderstorm gust fronts, the measurement of wind profiles, and clear air turbulence detection. Following a summary of previous efforts, some current programs are reviewed. These include investigations into two-dimensional wind field measurements, atmospheric backscatter measurements, transverse velocity measurements, and the feasibility of space operations.
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    The NASA/Goddard balloon borne lidar system (1983)
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    Publication Date: 2011-08-18
    Description: The present investigation represents a part of a NASA program which is concerned with a study regarding the seriousness of man-made stratospheric ozone depletion. Such a depletion could possibly be caused by exhaust gases of aircraft at high altitudes or the release of chlorofluorocarbons into the lower atmosphere. A balloon-borne optical radar system was employed to conduct ozone measurements in the altitude region from 21 to 36 km and hydroxyl radical measurements in the region from 33 to 36 km. The hydroxyl radical was determined by making use of a procedure which is based on fluorescence induced by laser radiation. The technique of differential absorption lidar (DIAL) was used to measure ozone. According to this technique, two wavelengths are transmitted simultaneously and their backscattered intensities are measured. the obtained results show that optical radar represents an effective tool for stratospheric investigations.
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  • 44
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    Signal averaging limitations in heterodyne- and direct-detection laser remote sensing measurements (1983)
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    Publication Date: 2011-08-18
    Description: The improvement in measurement uncertainty brought about by the averaging of increasing numbers of pulse return signals in both heterodyne- and direct-detection lidar systems is investigated. A theoretical analysis is presented which shows the standard deviation of the mean measurement to decrease as the inverse square root of the number of measurements, except in the presence of temporal correlation. Experimental measurements based on a dual-hybrid-TEA CO2 laser differential absorption lidar system are reported which demonstrate that the actual reduction in the standard deviation of the mean in both heterodyne- and direct-detection systems is much slower than the inverse square-root dependence predicted for uncorrelated signals, but is in agreement with predictions in the event of temporal correlation. Results thus favor the use of direct detection at relatively short range where the lower limit of the standard deviation of the mean is about 2 percent, but advantages of heterodyne detection at longer ranges are noted.
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  • 45
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    Atmospheric pressure and temperature profiling using near IR differential absorption lidar (1983)
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    Publication Date: 2011-08-18
    Description: The present investigation is concerned with differential absorption lidar techniques for remotely measuring the atmospheric temperature and pressure profile, surface pressure, and cloud top pressure-height. The procedure used in determining the pressure is based on the conduction of high-resolution measurements of absorption in the wings of lines in the oxygen A band. Absorption with respect to these areas is highly pressure sensitive in connection with the mechanism of collisional line broadening. The method of temperature measurement utilizes a determination of the absorption at the center of a selected line in the oxygen A band which originates from a quantum state with high ground state energy.
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    Remote detection of gases by gas correlation spectroradiometry (1983)
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    Publication Date: 2011-08-18
    Description: The present investigation is concerned with the application of a pressure modulated radiometer (PMR) to the remote sensing of trace amounts of gases in the atmospheres as well as to the direct measurement of upper atmospheric winds. The PMR operates as a gas correlation spectrometer. Compared to conventional gas correlation parameters, it has some advantages which are related to greater versatility and the employment of a simpler method for maintaining electrical/optical balance. The PMR has a high sensitivity in connection with its essentially very high effective resolution. It represents a passive system and emits no radiation. A PMR is flown on Nimbus 6 which was launched in 1975. The instrument has also been used on the Nimbus 7 satellite and the Tiros N satellite.
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    Airborne remote sensing measurements with a pulsed CO2 DIAL system (1983)
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    Publication Date: 2011-08-18
    Description: The present investigation is concerned with an optical radar instrument which has been developed for airborne remote sensing of atmospheric trace species at infrared wavelengths. The instrument makes use of compact, pulsed carbon dioxide lasers. It was designed for conducting differential absorption lidar (DIAL) measurements. The backscatter of laser pulse energy from the ocean and terrain surface is utilized to determine trace species column content. The instrument, which is carried by the NASA P3 aircraft, is used in a flight test program started in July 1981. The results obtained with the instrument in this program are discussed, taking into account ocean surface backscatter statistics, the ratio of ocean to terrain backscatter, the dual-wavelength correlation coefficient, the dual-wavelength cross-covariance, and the dependence of un-correlated noise variance on the mean backscatter signal.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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    Effect of variable thermal conductivity on isotherms in Bridgman growth (1983)
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    Publication Date: 2011-08-18
    Description: A change in thermal conductivity associated with melting or solidification can have a profound influence on the isotherms near the solidification interface if the material is being directionally solidified in an ampoule whose walls carry a substantial portion of the heat. This analysis was prompted by a recent discovery that the thermal conductivity of Hg(1-x)CD(x)Te increased dramatically as the material is heated above the solidus curve. An illustrative example is shown in which the sample is approximated as an infinite cylinder with constant but diffferent thermal properties in the solid and melt. The boundary conditions are fixed on the surface by a conductive ampoule in a two-zone Bridgman furnace with an adiabatic region separating the two zones. The effect of the adiabatic zone in this case is to intensify the curvature of the interface rather than to lessen it.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Crystal Growth (ISSN 0022-0248); 61; Apr
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  • 49
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    Practical small-scale explosive seam welding (1983)
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    Publication Date: 2011-08-18
    Description: A small-scale explosive seam welding process has been developed that can significantly contribute to remote metal joining operations under hazardous or inaccessible conditions, such as nuclear reactor repair and assembly of structure in space. This paper describes this explosive seam welding process in terms of joining principles, variables, types of joints created, capabilities, and applications. Very small quantities of explosive in a ribbon configuration are used to create narrow (less than 0.5 inch), long-length, uniform, hermetically sealed joints that exhibit parent metal properties in a wide variety of metals, alloys, and combinations. The practicality of this process has been demonstrated by its current acceptance, as well as its capabilities that are superior in many applications to the universally accepted joining processes, such as mechanical fasteners, fusion and resistance welding, and adhesives. Previously announced in STAR as N83-24896
    Keywords: MECHANICAL ENGINEERING
    Type: (ISSN 0025-6501)
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    Balloon-borne diode-laser absorption spectrometer for measurements of stratospheric trace species (1983)
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    Publication Date: 2011-08-18
    Description: An instrument has been designed for the measurement of stratospheric trace species which utilizes tunable infrared diode lasers as sources for sensitive in situ absorption spectroscopy in selected wavelength regions. This instrument, the Balloon-Borne Laser In Situ Sensor (BLISS), is a high-resolution absorption spectrometer designed to provide measurements of the concentrations of stratospheric species and their diurnal variations. The instrument employs second-harmonic detection of the absorption of tunable diode laser (TDL) radiation (3-30 microns) in a 1 km path length defined by a retroreflector lowered 0.5 km below the BLISS gondola. Retroreflector tracking under microprocessor control is obtained using a He-Ne laser and coaligned TV camera with CID imaging. Simultaneous measurements of molecular species in the 20-40 km altitude range will be performed using four TDLs, with the predicted minimum-detectable mixing ratio at 30 km being typically less than or equal to 0.1 ppbv.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; Sept. 1
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    New technological developments for the remote detection of atmospheric hydroxyl radicals (1983)
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    Publication Date: 2011-08-18
    Description: New developments in the areas of narrowband tunable excimer lasers, high-resolution high-rejection optical filters, and wavelength measurement devices are considered for application to the remote sensing of atmospheric hydroxyl radicals. The conclusion is that an increase in the SNR of 10,000 could readily be gained through the use of these new devices. Also, considerable reductions in size and electrical energy consumption could be realized.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; Sept. 1
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    Frequency-doubled CO2 lidar measurement and diode laser spectroscopy of atmospheric CO2 (1983)
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    Publication Date: 2011-08-18
    Description: A lidar instrument based on pulsed frequency-doubled carbon-dioxide lasers has been used at 4.88 microns for remote sensing of atmospheric carbon dioxide. A tunable-diode laser spectrometer provided the high-resolution spectroscopic data on carbon-dioxide line strength and line broadening needed for an accurate differential absorption measurement. Initial field measurements are presented, and instrument improvements necessary for accurate carbon dioxide measurement are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; Sept. 1
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    An all fiber-optic sensor for surface acoustic wave measurements (1983)
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    Publication Date: 2011-08-18
    Description: A surface acoustic wave (SAW) sensor constructed from single-mode fiber-optic components is described. An analysis of reciprocal and nonreciprocal modes of operation of the sensor is presented. Results from measurements on a variety of SAW devices illustrate the use of the sensor. The amplitude sensitivity is 0.0003 A for an integration time of 0.1 s.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Lightwave Technology (ISSN 0733-8724); LT-1; June 198
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  • 54
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    Environmental data display (1983)
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    Publication Date: 2011-08-18
    Description: Methods for using a combination of computer-generated color graphics and image processing techniques to display a large data base of environment information are described. The data source can be either field data or mathematical models, reduced to summary statistics that characterize the data field as a whole. Sharp gradients are plotted into contour plots, which can also feature shades, degree of brightness, and saturation levels for fine-tuning the image. The basic concepts of digital image processing are reviewed, including location of the pixels, intensity mapping operations, pseudocolor enhancements, neighborhood averaging, and smoothing. Sample applications are presented in terms of emissions and air quality distributions over the south coast air basin of southern California.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Environmental Science and Technology (ISSN 0013-936X); 17; Feb. 198
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  • 55
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    A nonintrusive laser interferometer method for measurement of skin friction (1983)
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    Publication Date: 2011-08-18
    Description: A method is described for monitoring the changing thickness of a thin oil film subject to an aerodynamic shear stress using two focused laser beams. The measurement is then simply analyzed in terms of the surface skin friction of the flow. The analysis includes the effects of arbitrarily large pressure and skin friction gradients, gravity, and time varying oil temperature. It may also be applied to three dimensional flows with unknown direction. Applications are presented for a variety of flows, including two dimensional flows, three dimensional swirling flows, separated flow, supersonic high Reynolds number flows, and delta wing vortical flows. Previously announced in STAR as N83-12393
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Experiments in Fluids (ISSN 0723-4864); 1; 1, 19; 1983
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    The function and response of an improved stratospheric condensation nucleus counter (1983)
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    Publication Date: 2011-08-18
    Description: An improved condensation nucleus counter (CNC) for use in the stratosphere is described. The University of Minnesota CNC (UMCNC) has a sequential saturator and condenser and uses n-butyl alcohol as the working fluid. The use of a coaxial saturator flow, with aerosol in the center and filtered, alcohol-laden air around it, speeds the response of this instrument and improves its stability as pressure changes. The counting efficiency has been studied as a function of particle size and pressure. The UMCNC provides an accurate measure of submicron aerosol concentration as long as the number distribution is not dominated by sub-0.02 micron diameter aerosol. The response of the UMCNC is compared with that of other stratospheric condensation nucleus counters, and the results of a (near) comparison with a balloon-borne condensation nucleus counter are presented. The UMCNC has operated 14 times on a NASA U-2 aircraft at altitudes from 8 to 21.5 km.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; Aug. 20
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  • 57
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    Analysis of coolant entrance boundary shape of porous region to control cooling along exit boundary (1983)
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    Publication Date: 2011-08-18
    Description: A cooled porous region has a plane surface exposed to a specified spatially varying heat flux. The coolant leaves the region through this surface, and it is desired to control the flow distribution to maintain a specified uniform surface temperature. This is accomplished by having the coolant entrance surface shaped to provide in the region the necessary variation of path length and, hence, flow resistance. The surface shape at the coolant entrance is found by solving a Cauchy boundary value problem. An exact solution is obtained that will deal with a wide variety of heating distributions for both two- and three-dimensional shapes.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASME, Transactions, Journal of Heat Transfer (ISSN 0022-1481); 105; Aug. 198
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    Gas flow through rotameters (1983)
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    Publication Date: 2011-08-18
    Description: Using data available for small rotameters that use spherical floats in gas flow, a linear relationship is derived. It is noted that the relationship provides a good fit for variable volumetric flow, density, and viscosity at constant flow height. With low Reynolds numbers (Re being less than 1), the product of the variable volumetric flow and the viscosity becomes constant; at high Reynolds numbers (Re being greater than 2000), the product of the variable volumetric flow and the square root of the density becomes constant. It is pointed out that the equation given here can be used to obtain an indirect calibration with any gas of known density and viscosity. The constancy of the product of the variable volumetric flow and viscosity at low variable volumetric flows is seen as suggesting the development of simple, inexpensive gas viscometers using rotameter technology.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: I & EC-Industrial and Engineering Chemistry, Fundamentals (ISSN 0196-4313); 22; 2, 19; 1983
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    The Airborne Laser Ranging System - Its capabilities and applications (1983)
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    Publication Date: 2011-08-18
    Description: The Airborne Laser Ranging System is a proposed multibeam short pulse laser ranging system on board an aircraft. It simultaneously measures the distances between the aircraft and six laser retroreflectors (targets) deployed on the earth's surface. Depending on the host aircraft and terrain characteristics, the system can interrogate hundreds of targets distributed over an area as large as 60,000 sq. km in a matter of hours. Potentially, a total of 1.3 million individual range measurements can be made in a 6 hr flight. The precision of these range measurements is approximately 1 cm. These measurements are then used in a procedure which is basically an extension of trilateration techniques to derive the intersite vector between the laser ground targets. By repeating the estimation of the intersite vector, strain and strain rate errors can be estimated. These quantities are essential for crustal dynamic studies which include determination and monitoring of regional strain in the vicinity of active fault zones, land subsidence, and edifice building preceding volcanic eruptions.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Bulletin Geodesique (ISSN 0007-4632); 57; 2, 19; 1983
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    Moire deflectometry with deferred analysis (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A simplified version of moire deflectometry for flow visualization is presented. The modification comprises replacement of the second grating, the ground glass screen, and the camera with a plate film holder to obtain a shadow picture. Postanalysis proceeds by placing a grid transparency of the same periodicity of the remaining glass grating on the negative for projection viewing. The rotational angle between the grating and the plate alters the moire fringe periodicity. Use of the method in studying flows is predicted to reveal weak density gradient areas and shocks.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 22; Mar. 1
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    Numerical solutions for spin-up from rest in a cylinder (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A set of three-dimensional flow-field data for the region around a cylinder impulsively spun-up from rest was derived with a numerical model based on the Navier-Stokes equations. Laser-Doppler anemometer data in the azimuthal direction was employed to test the model predictions, and data was developed for a flowfield with Ekman numbers from 9.18/1,000,000 to 9.18/10,000. The contributions of inviscid and viscous terms were determined as functions of radius and time. It was found that immediately after start-up viscous diffusion is the dominant factor, which is replaced by nonlinear radial advection. The Coriolis force dominates in the later stages of spin-up. The inward radial flow is a maximum near the front, where the vertical velocity is small, but features strong radial gradients, as it does at the edge of the Ekman layer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 127; Feb. 198
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    Lidar system analysis for measurement of atmospheric species (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Several important aspects of lidar are discussed, which pertain to a system analysis of the applicability of certain types of lidar to specific measurement objectives. The differential absorption lidar (DIAL) technique is emphasized. A brief treatment of the DIAL technique is followed by a discussion of the comparison of DIAL with other lidar measurement techniques. Sensitivity expressions are presented for DIAL with either direct or coherent (heterodyne) detection systems. A treatment of the fundamental similarities and differences in using the UV and IR spectral regions for species measurements, such as backscattering properties, spectral characteristics of the absorbing species, and factors relevant to the optimization of the DIAL measurement accuracy, is also included. Finally, results obtained from an existing ground-based DIAL system used to measure water vapor profiles are briefly discussed.
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    IR detectors - Heterodyne and direct (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Recent developments in the area of wide-bandwidth infrared detectors, both for direct and heterodyne detection, are reviewed with emphasis on the differences and tradeoffs between photodiodes and photoconductors. In the direct-detection mode, where amplifier noise is an important consideration, the state-of-the-art detection noise equivalent power is approximated by 500 (B/10 MHz) pW. At short wavelengths (less than 1.7 micron), avalanche photodiodes offer superior performance, with a detection noise equivalent power of about 50 (B/10 MHz) pW. In heterodyne operation, near-ideal sensitivities of about 0.3 (B/10 MHz) pW have been achieved with 77K photodiodes. At 10 microns, HgCdTe photoconductors offer very good heterodyne performance at elevated temperatures: 2 (B/10 MHz) pW at 195 K and potentially 3 (B/10 MHz) pW at 250 K.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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    The time-space relationships among data points from multispectral spatial scanners (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Multispectral scanner and thematic mapper (TM) data from Landsat satellites are discussed in terms of the perceived 'simultaineity' of the images, which are obtained by scanning techniques. Scanning the scenes ensures that the data points of the images are actually sequential, even if the scan is performed at rates that are fast relative to the motion of the spacecraft. The last datum gathered by the MSS is, in fact, taken 29 sec after the first, witih a 56 m distance being present between pixels. The spacing in uneven from band to band on the TM and analyses of the data to produce an image requires consideration of nonfixed time relationships for different locations on the scan within and among the bands. Additionally, corrective measures must be taken to compensate for instrument jitter and attitude changes.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: International Journal of Remote Sensing (ISSN 0143-1161); 4; July-Sep
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    X-ray imaging of extended objects using nonoverlapping redundant array (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A common problem associated with X-ray imaging using coded apertures is the reconstruction of low-intensity extended objects. In the decoding of such objects, the overlapping images from the multiple pinholes give rise to noise cross talk and, in many cases, also to signal cross talk. In this paper, an alternate approach is proposed based on the principle used in an earlier (Yin et al., 1980) laboratory device for the real-time viewing of X-ray objects. It is shown that with this approach, the nonoverlapping redundant array, the sidelobes in the point spread function are not eliminated but merely displaced through a suitable choice of geometry. In this manner, the sidelobes no longer contribute to the background in the vicinity of a reconstructed image, and both signal and noise cross talks are completely eliminated. It may now be possible to reconstruct extended X-ray objects in 3-D by simple optical correlation and tomographically by a computer.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; July 15
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    Supersonic-nitrogen flow-field measurements with the resonant Doppler velocimeter (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The application of the resonant Doppler velocimeter (RDV) for obtaining the mean velocity, temperature, and pressure measurements and flow-field visualization in a supersonic free nitrogen jet is reported. This method utilizes laser-induced fluorescence to determine the spectral absorption of an atomic or molecular species seeded into the flow. A narrow linewidth tunable laser is directed into the flow and the total fluorescence from any point is obtained as the laser is tuned. The velocity of the flow is obtained from the Doppler shifted absorption frequency, and the temperature and pressure of the gas are determined from line broadening measurements. Results are presented for the use of this technique to determine the velocity, temperature, and pressure of the flow of sodium atoms seeded into a supersonic nitrogen jet. It is concluded that the visible signal is sufficiently intense for spatially resolved flow visualization purposes.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Physics Letters (ISSN 0003-6951); 43; July 15
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    Procedure for generating ground wind environments for Shuttle liftoff studies (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Ground-wind environments for Monte Carlo simulations of Space Shuttle liftoff at KSC are developed. Input parameters include randomly selected 18.3-m-altitude peak wind speed (from which mean wind profile and turbulence intensity are calculated), randomly selected mean wind direction, and longitudinal and lateral turbulence components obtained from the Shuttle-simulation turbulence tapes (SSTT: Tatom et al., 1982). The steps in the simulation of turbulence time histories and horizontal wind fields are listed. It is found that separate statistical analysis of each hour-season pair, applying data on the time fraction of occurrence of peak winds and wind directions at KSC, will be necessary to interpret simulation results consistently.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Spacecraft and Rockets (ISSN 0022-4560); 20; July-Aug
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  • 68
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    Seven-hole cone probes for high angle flow measurement Theory and calibration (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previously cited in issue 08, p. 1219, Accession no. A82-22070
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: (ISSN 0001-1452)
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    A small, battery-operated fluoroscopic system - Lixiscope with X-ray generator (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A small, battery-operated X-ray generator has been developed to be used as part of a small-format fluoroscopic system, the Lixiscope (Low Intensity X-ray Imaging Scope). The X-ray generator consists of a grounded rod-anode X-ray tube with a 0.2 mm focal spot and a specially designed, battery-operated, 0 to -80 kV high-voltge supply. Total power consumption is about 10 W. The fine focal spot, in conjunction with the continuously variable X-ray intensity and spectral distribution, helps to extend both the versatility and the performance of the Lixiscope toward a much wider range of terrestrial and spacecraft applications. The complete fluoroscopic system is described, and some examples of possible applications are shown.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Materials Evaluation (ISSN 0025-5327); 41; June 198
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    Analysis method for Fourier transform spectroscopy (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A fast Fourier transform technique is given for the simulation of those distortion effects in the instrument line shape of the interferometric spectrum that are due to errors in the measured interferogram. The technique is applied to analyses of atmospheric absorption spectra and laboratory spectra. It is shown that the nonlinear least squares method can retrieve the correct information from the distorted spectrum. Analyses of HF absorption spectra obtained in a laboratory and solar CO absorption spectra gathered by a balloon-borne interferometer indicate that the retrieved amount of absorbing gas is less than the correct value in most cases, if the interferogram distortion effects are not included in the analysis.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 22; Mar. 15
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    The evolution of Tollmien-Schlichting waves near a leading edge (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The method of matched asymptotic expansions is used to study the generation of Tollmien-Schlichting waves by free-stream disturbances incident on a flat-plate boundary layer. Near the leading edge, the motion is governed by the unsteady boundary-layer equation, while farther downstream it is governed (to lowest order) by the Orr-Sommerfeld equation with slowly varying coefficients. It is shown that there is an overlap domain where the Tollmien-Schlichting wave solutions to the Orr-Sommerfeld equation and appropriate asymptotic solutions of the unsteady boundary-layer equation match, in the matched-asymptotic-expansion sense. The analysis explains how long-wavelength free-stream disturbances can generate Tollmien-Schlichting waves of much shorter wavelength. It also leads to a set of scaling laws for the asymptotic structure of the unsteady boundary layer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 127; Feb. 198
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  • 72
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    Sparger system for MMH-helium vents (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Based on a calculated vent flow rate and MMH concentration, a TI-59 program was run to determine total sparger hole area for a given sparger inlet pressure. Hole diameter is determined from a mass transfer analysis in the holding tank to achieve complete capture of MMH. In addition, based on oxidation kinetics and vapor pressure data, MMh atmospheric concentrations are determined 2 ft above the holding tank.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: The 1983 NASA(ASEE Summer Faculty Fellowship Research Program Research Reports; 17 p
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    An analysis of cryotrap heat exchanger performance test data (400 area) and recommendations for a system to handle Apollo RCS engines (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The current arrangement of a Platecoil heat exchanger which uses LN2 on the inside of parallel tubes, in counter flow to the test cell engine exhaust gases which are drawn through a box surrounding the plates by the existing vacuum blowers is examined. As a result of inadequate performance and special test data it was decided to redesign the system to accommodate an Apollo RCS engine.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: The 1983 NASA(ASEE Summer Faculty Fellowship Research Program Research Reports; 15 p
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    Jet array impingement heat transfer characteristics (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Two dimensional arrays of circular air jets impinging on a heat transfer surface parallel to the jet orifice plate are considered. The jet flow, after impingement, is constrained to exit in a single direction along the channel formed by the jet orifice plate and the heat transfer surface. In addition to the crossflow which originates from the jets following impingement, an initial crossflow is present which approaches the array through an upstream extension of the channel. The configurations considered are intended to model the impingement cooled midchord region of gas turbine airfoils in cases where an initial crossflow is also present. A major objective is determination of the effect of initial crossflow air temperature relative to jet array air temperature on impingement surface heat fluxes.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center Turbine Eng. Hot Sect. Technol. (HOST); p 117-128
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    Coolant passage heat transfer with rotation. A progress report on the computational aspects (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Turbine airfoils are subjected to increasingly higher heat loads which escalate the cooling requirements in order to satisfy life goals for the component materials. If turbine efficiency is to be maintained, however, cooling requirements should be as low as possible. To keep the quantity of cooling air bounded, a more efficient internal cooling scheme must be developed. One approach is to employ airfoils with multipass cooling passages that contain devices to augment internal heat transfer while limiting pressure drop. Design experience with multipass cooling passage airfoils has shown that a surplus of cooling air must be provided as a margin of safety. This increased cooling air leads to a performance penalty. Reliable methods for predicting the internal thermal and aerodynamic performance of multipass cooling passage airfoils would reduce or eliminate the need for the safety margin of surplus cooling air. The objective of the program is to develop and verify improved analytical methods that will form the basis for design technology which will result in efficient turbine components with improved durability without sacrificing performance. The objective will be met by: (1) establishing a comprehensive experimental data base that can form the basis of an empirical design system; (2) developing computational fluid dynamic techniques; and (3) analyzing the information in the data base with both phenomenological modeling and mathematical modeling to derive a suitable design and analysis procedure.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Lewis Research Center Turbine Eng. Hot Sect. Technol. (HOST); p 111-116
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    Unified Analysis for Antenna Pointing and Structural Errors. Part 1. Review (1983)
    In:  CASI
    Details
    Publication Date: 2014-09-10
    Description: A necessary step in the design of a high accuracy microwave antenna system is to establish the signal error budget due to structural, pointing, and environmental parameters. A unified approach in performing error budget analysis as applicable to ground-based microwave antennas of different size and operating frequency is discussed. Major error sources contributing to the resultant deviation in antenna boresighting in pointing and tracking modes and the derivation of the governing equations are presented. Two computer programs (SAMCON and EBAP) were developed in-house, including the antenna servo-control program, as valuable tools in the error budget determination. A list of possible errors giving their relative contributions and levels is presented.
    Keywords: MECHANICAL ENGINEERING
    Type: The Telecommun. and Data Acquisition Rept.; p 40-59
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    Laboratory Automation of a Quadrupole Mass Spectrometer (1983)
    In:  CASI
    Details
    Publication Date: 2014-09-11
    Description: Efforts directed toward interfacing an LSI II bus of a PDP 11/23 desktop computer with a quadrupole mass spectrometer for the purpose of providing a convenient system whereby mass spectral data, of the products of thermal decomposition, may be rapidly acquired and processed under programmed conditions are described. The versatility and operations of the quadrupole mass spectrometer are discussed as well as the procedure for configurating the LSI II bus of the PDP 11/23 desktop computer for interfacing with the quadrupole mass spectrometer system. Data from the mass filter and other units of the spectrometer are digitally transferred to the computer whereupon mass spectral data and related data are generated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Alabama Univ. Res. Rept.: 1983 NASA(ASEE Summer Faculty Fellowship Program; 26 p
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    A Study of Accretion in Compact Sources: Disk Precession and Jet Helicity (1983)
    In:  CASI
    Details
    Publication Date: 2014-09-11
    Description: The effect of adiabatic expansion on the propagation and growth of helical twisting on a supersonic jet is investigated. Cooling of the jet material increases the jet's Mach number and increases the jet's density relative to that of the external medium. This has the effect of decreasing the maximum rate of growth and increasing the maximally unstable wavelength relative to the jet's radius. Propagation effects cause the wavelength of helical waves to change at a rate different from that of the maximally unstable wavelength with the result that the characteristic wavelength of helical twisting is not equal to this wavelength. The most rapidly growing helical wave will have a wavelength as much as a factor of 2 different from the instantaneous maximally unstable wavelength.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Res. Rept.: 1983 NASA(ASEE Summer Faculty Fellowship Program; 39 p
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    A Numerical Investigation of the Multiple Vortex Phenomenon: Vortex Number and Structure as a Function of Swirl Ratio (1983)
    In:  CASI
    Details
    Publication Date: 2014-09-12
    Description: A numerical investigation of the multiple vortex phenomenon (MVP) for tornado like flows is conducted to determine the conditions for when a vortex becomes unstable and divides into smaller subsidiary vortices, as well as to determine the structure of these vortices. A three dimensional numerical model developed by Rotunno (1983) is utilized which has been demonstrated to successfully simulate MVP with properties observed both in natural as well as laboratory tornado like vortices. The MVP is generated for several swirl ratio conditions in order to determine the number of vortices generated for those flow configurations. These results are then compared to experimental measurements to validate the numerical model. The number of vortices produced is consistent with observational results made in the Purdue tornado vortex chamber. Furthermore, horizontal and vertical cross sections are taken through the vortices to determine the structure of MVP. Preliminary results indicate that tangential velocities within these smaller asymmetric vortices increase by 20% over values observed in a single axisymmetric vortex at the same swirl ratio.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. Res. Rept.: 1983 NASA(ASEE Summer Faculty Fellowship Program; 28 p
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    Simultaneous multiple-point velocity measurements using laser-induced iodine fluorescence (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A technique is demonstrated for measuring velocity at multiple locations in a plane of a gaseous flowfield using Doppler-shifted absorption with fluorescence detection from iodine molecules, excited by a sheet of tunable single-axial-mode argon-ion laser radiation at 514.5 nm. Measurements were made simultaneously at 10,000 points in an iodine-seeded supersonic flow field with a 100 x 100 element photodiode array camera and were found to agree well with a numerical solution for the velocity field. The accuracy with which a component of velocity can be measured is limited, in the current approach, by the iodine linewidth to about 5 m/sec.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optics Letters; 8; Jan. 198
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    Laboratory analysis of techniques for remote sensing of estuarine parameters using laser excitation (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The theoretical concepts underlying remote sensing of estuarine parameters using laser excitation are examined. The concepts are extended to include Mie scattering as a measure of the total suspended solids and to develop the water Raman signal as an internal standard. Experimental validation of the theory was performed using backscattered laser light from a laboratory tank to simulate a remote-sensing geometry. Artificially prepared sediments and biological cultures were employed to check specific aspects of the theory under controlled conditions. Natural samples gathered from a variety of water types were also analyzed in the tank to further enhance the simulation. The results indicate that it should be possible to remotely quantify total suspended solids, dissolved organics, attenuation coefficient, chlorophyll a, and phycoerythrin in estuarine water using laser excitation.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 22; Jan. 1
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    A comparative study of time-marching and space-marching numerical methods (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Menees (1981) has conducted an evaluation of three different flowfield codes for the Jupiter entry conditions. However, a comparison of the codes has been made difficult by the fact that the three codes use different solution procedures, different computational mesh sizes, and a different convergence criterion. There are also other differences. For an objective evaluation of the different numerical solution methods employed by the codes, it would be desirable to select a simple no-blowing perfect-gas flowfield case for which the turbulent models are well established. The present investigation is concerned with the results of such a study. It is found that the choice of the numerical method is rather problem dependent. The time-marching and the space-marching method provide both comparable results if care is taken in selecting the appropriate mesh size near the body surface.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 21; Jan. 198
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    Multiwavelength analyzer for the determination of diffusion lengths (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The minority carrier diffusion length Ln in the base or substrate region is an important parameter which governs a solar cell's performance. The present investigation is concerned with the development of a multiwavelength analyzer (MWA) technique for the nondestructive spatial testing of polycrystalline solar cells. The MWA method is based on the utilization of the short-circuit current generated by two or more light-emitting diodes (LEDs) operating at different wavelengths and modulated 180 deg out-of-phase. For a determination of Ln by the MWA technique, it is necessary to know the value of the absorption coefficient.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Solar Cells (ISSN 0379-6787); 9; Sept
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    Remote sensing of OH in the atmosphere using the technique of laser-induced fluorescence (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The use of a laser-induced fluorescence technique for the sensitive measurement of the atmospheric hydroxyl radical is discussed. Results of laboratory studies of the fluorescence and other spectroscopic properties of OH which allow the calculation of OH concentrations from the returned signals for various altitudes, water vapor contents and temperatures are presented. The experimental setup used for airborne OH measurements is then described, with particular attention given to the use of a telescope for excitation and light collection in a coaxial configuration and the periodic tuning of the exciting radiation necessary to obtain an OH signal in the presence of strong solar and nonresonant fluorescence backgrounds. The best detection limit obtained to date with the system is noted to be about 700,000 OH/cu cm, and it is expected that, with planned improvements in detection and tuning schemes, limits in the neighborhood of 1,000,000 OH/cu cm will be achieved routinely.
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    On the structure of wall-bounded turbulent flows (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The variable-interval time-averaging (VITA) technique developed by Blackwelder and Kaplan is applied to data obtained from large-eddy simulation of turbulent channel flow in an investigation of the organized structures associated with the bursting phenomenon in the near-wall region. Conditionally averaged velocities, shear stress, pressure, and vorticity are discussed in conjunction with the bursting phenomenon detected by the VITA technique. The conditionally averaged pressure reveals that the ejection process is associated with a localized adverse pressure gradient. In the plane perpendicular to the flow direction, the conditionally averaged vorticity field indicates that a pair of counterrotating streamwise vorticity is being lifted through the ejection process. Previously announced in STAR as N83-17832.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 26; Aug. 198
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    Coherent anti-Stokes Raman spectroscopic modeling for combustion diagnostics (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The status of modelling the coherent anti-Stokes Raman spectroscopy (CARS) spectra of molecules important in combustion, such as N2, H2O, and CO2, is reviewed. It is shown that accurate modelling generally requires highly precise knowledge of line positions and reasonable estimates of Raman linewidths, and the sources of these data are discussed. CARS technique and theory is reviewed, and the status of modelling the phenomenon of collisional narrowing at pressures well above atmospheric for N2, H2O, and CO2 is described. It is shown that good agreement with experiment can be achieved using either the Gordon rotational diffusion model or phenomenological models for inelastic energy transfer rates.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering (ISSN 0091-3286); 22; May-June
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    X-ray spectrograph design (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An aberration theory is applied to spectrograph design. The initial system considered has a toroidal mirror in front of a concave grating spectrograph, giving spatial resolution perpendicular to the dispersion direction. The accuracy of the theory is shown by comparison of spot diagrams obtained from the aberrations with those produced by raytracing. The major aberrations affecting the vignetting at the intermediate slit and the spatial resolution are identified. A new system, using a holographic grating to give a flat focal plane, is then designed and optimized. It has increased spatial resolution over the wavelength range and is particularly suitable for microchannel array detectors.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; May 15
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    Electron-photon coincidence technique for the absolute calibration of VUV detectors (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A method is described whereby VUV photon detectors can be accurately calibrated. This method is illustrated by taking the 58.4-nm transition of He as an example. The technique consists of crossing a monoenergetic electron beam with a beam of He atoms. When inelastically scattered electrons which have excited the 2 1P state are detected in coincidence with the 58.4-nm photons emitted in the decay of the excited state, the interaction volume formed by the crossed beams constitutes a standard source of photons. By comparing the number of detected coincidences with the predicted number the calibration can be made. A total detector efficiency of 0.024 + or - 0.003 is obtained for a Galileo 4830 channeltron.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; May 15
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    Coherent structures - Reality and myth (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Large-scale coherent structures (CS) in turbulent shear flows are characterized, reviewing recent theoretical and experimental investigations. The use of computers as a research tool and the flow-visualization experimental technique are introduced, CS are defined, the history of their discovery is traced, and their main characteristics are listed. Topics discussed and illustrated include the initial condition of the free shear layer, triple and double decomposition, topological features of CS, detection and eduction of CS, phase alignment via cross correlation, induced versus natural structures, the bursting phenomenon, turbulent spot, streaks, bursting frequency, the axisymmetric mixing layer, vortex pairing in an axisymmetric jet, CS and jet noise, broadband noise amplification via pure-tone excitation, CS interaction in a plane-jet near field, the Taylor hypothesis applied to CS, negative production, and the validity of the Reynolds-number similarity hypothesis. It is found that the coherent Reynolds stress, vorticity, and production are not much greater than the time-averaged values for fully developed flows with significant incoherent turbulence, suggesting that the importance of CS may have been exaggerated in some recent studies.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids (ISSN 0031-9171); 26; 2816-285
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  • 90
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    Ferrographic and spectrometer oil analysis from a failed gas turbine engine (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An experimental gas turbine engine was destroyed as a result of the combustion of its titanium components. It was concluded that a severe surge may have caused interference between rotating and stationary compressor parts that either directly or indirectly ignited the titanium components. Several engine oil samples (before and after the failure) were analyzed with a Ferrograph, and with plasma, atomic absorption, and emission spectrometers to see if this information would aid in the engine failure diagnosis. The analyses indicated that a lubrication system failure was not a causative factor in the engine failure. Neither an abnormal wear mechanism nor a high level of wear debris was detected in the engine oil sample taken just prior to the test in which the failure occurred. However, low concentrations (0.2 to 0.5 ppm) of titanium were evident in this sample and samples taken earlier. After the failure, higher titanium concentrations (2 ppm) were detected in oil samples taken from different engine locations. Ferrographic analysis indicated that most of the titanium was contained in spherical metallic debris after the failure. The oil analyses eliminated a lubrication system bearing or shaft seal failure as the cause of the engine failure. Previously announced in STAR as N83-12433
    Keywords: MECHANICAL ENGINEERING
    Type: Wear (ISSN 0043-1648); 90; 239-249
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  • 91
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    Stagnation-point ablation of carbonaceous flat disks. I Theory (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The process of ablation is calculated for the stagnation region of a flat disk in a radiation-dominated, massive-blowing environment produced in a ballistic range filled with argon. Flow environments are determined by solving the boundary-layer equations while radiative transfer is calculated through a line-by-line spectral computation. The resulting wall heat-transfer rates are coupled with an existing material's response code to determine surface recession and char thickness. The calculation is performed for six 5-cm-diam models made of carbon-phenolic and carbon-carbon composite launched in the Track-G facility at the Arnold Engineering Development Center. Significant surface recessions are predicted to occur for these models due mostly to radiative heating.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 21; 1588-159
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  • 92
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    A spectral numerical method for the Navier-Stokes equations with applications to Taylor-Couette flow (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A new spectral method for solving the incompressible Navier-Stokes equations in a plane channel and between concentric cylinders is presented. The method uses spectral expansions which inherently satisfy the boundary conditions and the continuity equation and yield banded matrices which are efficiently solved at each time step. In addition, the number of dependent variables is reduced, resulting in a reduction in computer memory requirements. Several test problems have been computed for the channel flow and for flow between concentric cylinders, including Taylor-Couette flow with axisymmetric Taylor vortices and wavy vortices. In all cases, agreement with available experimental and theoretical results is very good.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics (ISSN 0021-9991); 52; 524-544
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  • 93
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    dc discharge cell for laser optogalvanic spectroscopy (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A dc electrical discharge cell for laser optogalvanic spectroscopy has been designed and tested. Signal optimization is achieved through the use of adjustable electrode positions and an orthogonal geometry between the probe laser and the discharge axis. Results are presented for visible dye laser and infrared diode laser studies of selected neutral, radical, and ion species.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments (ISSN 0034-6748); 54; 1454-145
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  • 94
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    Numerical computation of transonic flow governed by the full-potential equation (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Basic concepts associated with the numerical solution of elliptic partial differential equations are introduced, and procedures used to solve the full potential equation for transonic flow fields are discussed. Governing equations, classical relaxation schemes and concepts regarding transonic, full potential equation algorithms are covered. The equation transformation and grid generation procedures; full potential spatial differencing schemes; full potential iteration schemes, emphasizing convergence acceleration; and three dimensional applications are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Von Karman Inst. for Fluid Dynamics Computational Fluid Dyn., Vol. 2; 110 p
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  • 95
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    A modified Dodge algorithm for the parabolized Navier-Stokes equations and compressible duct flows (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A revised version of Dodge's split-velocity method for numerical calculation of compressible duct flow has been developed. The revision incorporates balancing of massflow rates on each marching step in order to maintain front-to-back continuity during the calculation. Qualitative agreement with analytical predictions and experimental results has been obtained for some flows with well-known solutions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 96
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    Submillimeter-wave receivers - A status report (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A development status assessment is presented for the work of U.S. and Western European research groups on heterodyne sub-mm receivers in the 300-1000 GHz frequency range. The applications driving sub-mm receiver and local oscillator source technologies are radio astronomy, atmospheric measurements, plasma diagnostics, and laboratory spectroscopy. Progress is concentrated in two areas, cooled Schottky diode mixers and solid state local oscillators employing frequency multipliers.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Transactions on Microwave Theory and Techniques (ISSN 0018-9480); MTT-31; 873-878
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  • 97
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    Frequency standards for VLBI, present and future (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: During the last several years, J.P.L. has evaluated a number of different types of frequency standards. These evaluations include measurement of environmetal susceptibilities (barometric pressure, humidity, temperature and magnetic field) and evaluation of stability. Data from these tests are presented for quartz oscillators, rubidium vapor standards, cesium beam standards, hydrogen masers (active and passive) and a superconducting cavity stabilized oscillator. Data on reliability and mechanical ruggedness based on actual field use is also presented. A survey of new frequency standards, their likely performance and environmental characteristics is presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 98
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    Boundary conditions for the solution of compressible Navier-Stokes equations by an implicit factored method (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A method is presented for formulating the boundary conditions in implicit finite-difference form needed for obtaining solutions to the compressible Navier-Stokes equations by the Beam and Warming implicit factored method. The usefulness of the method was demonstrated (a) by establishing the boundary conditions applicable to the analysis of the flow inside an axisymmetric piston-cylinder configuration and (b) by calculating velocities and mass fractions inside the cylinder for different geometries and different operating conditions. Stability, selection of time step and grid sizes, and computer time requirements are discussed in reference to the piston-cylinder problem analyzed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics (ISSN 0021-9991); 52; 54-79
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  • 99
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    Computation of transonic viscous-inviscid interacting flow (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Transonic viscous-inviscid interaction is considered using the Euler and inverse compressible turbulent boundary-layer equations. Certain improvements in the inverse boundary-layer method are mentioned, along with experiences in using various Runge-Kutta schemes to solve the Euler equations. Numerical conditions imposed on the Euler equations at a surface for viscous-inviscid interaction using the method of equivalent sources are developed, and numerical solutions are presented and compared with experimental data to illustrate essential points. Previously announced in STAR N83-17829
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    Metal shell technology (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Metallic shells are fabricated for a size range from several millimeters down to less than 500 microns in diameter. The technology, developed at JPL, is based on the hollow-jet instability for the large-shell formation, and in addition, on the Bernoulli's force for the microbubble generation. Various materials were processed into hollow spheres, such as AL1100, tin, lead, and a metallic glass-forming alloy, AuPbSb. They exhibited a range of contrasting solidification behaviors and surface characteristics. Some of their potential applications will be explored in this paper.
    Keywords: MECHANICAL ENGINEERING
    Type: SAMPE Journal (ISSN 0091-1062); 19; 7-11
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