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  • 1985-1989  (14)
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  • 1
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    Application of optical interferometry in compressible flows (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Interferometry methods were applied to the investigation of steady and unsteady flows in large scale transonic wind tunnels. Holographic interferometry was demonstrated to provide reliable flow visualization and quantitative results for a number of two-dimensional flows. These conclusions were based on extensive comparisons with results obtained by other means. Data obtained on a NACA 64A010 airfoil with an oscillating flap installed in the Ames 11-foot transonic tunnel are presented. Interferograms were recorded at a free stream Mach number of 0.8, flap frequency of 30 Hertz and chord Reynolds numbers of 6.6 x 10 to the 6th and 12.3 x 10 to the 6th. The interferometric results were reduced to dynamic surface pressures, Mach contours and wake flow profiles. A new interferometry method that is capable of providing real-time interferometry data is also discussed.
    Keywords: AERODYNAMICS
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Transonic, turbulent boundary-layer separation generated on an axisymmetric flow model (1986)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Experimental data describing the transonic, turbulent, separated flow generated by an axisymmetric flow model are presented. The model consisted of a circular-arc bump affixed to a straight, circular cylinder aligned with the flow direction. Measurements of the mean velocity, turbulence intensity, and Reynolds shear-stress profiles were made in the separated flow. These data revealed dramatic changes in the shear-stress levels as the flow passed through the interaction to reattachment. Behavior of the turbulence reaction to the imposed pressure gradients was examined in terms of the mixing length and the excursions of the turbulence from equilibrium.
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 24; 437-443
    Format: text
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  • 3
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    Spray drop size and velocity measurements using the Phase/Doppler Particle Analyzer (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Detailed measurements of the drop size and velocity distributions were obtained for a swirl chamber pressure atomizer. These data were obtained with the Phase/Doppler Particle Analyzer manufactured by Aerometrics, Inc. Direct measurements of the size distributions revealed the evolving characteristics of the spray. Size velocity correlations were used to evaluate the effect of velocity relaxation on the size distributions. The simultaneous measurement of drop size and velocity was of major importance in accurately describing the changes in the local drop size distributions and mass flux.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal of Turbo and Jet-Engines (ISSN 0334-0082); 4; 3-4,; 207-215
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Optical interferometry in fluid dynamics research (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Optical interferometry techniques have been applied to the investigation of transonic airfoil flow fields in large-scale wind tunnels. Holographic interferometry techniques were used in the study of two-dimensional symmetric NACA 64A010 and Douglas Aircraft Company DSMA671 supercritical airfoil performance in the NASA Ames 2 ft x 2 ft transonic wind tunnel. Quantitative data obtained from the interferograms were compared to the surface pressure data. The excellent agreement obtained verified the accuracy of the flow visualization and demonstrated the potential for acquiring quantitative scalar results. Measurements of the inviscid flow speed and the boundary layer and wake velocity profiles were extracted from the interferograms and compared to laser Doppler velocimeter measurements. These results were also in good agreement. A method for acquiring real-time interferometric data in large-scale facilities was developed. This method, based on the point diffraction interferometer, was successfully tested in the Ames 2 ft x 2 ft transonic wind tunnel. The holographic and real-time interferometry methods were applied to the investigations of circulation control airfoils utilizing the Coanda effect. These results revealed the details of the jet interaction with the trailing edge boundary layer and the other parameters affecting the lift augmentation.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering (ISSN 0091-3286); 24; 455-461
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  • 5
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    Optical interferometry in fluid dynamics research (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Optical interferometry techniques were applied to the investigation of transonic airfoil flow fields in large wind tunnels. Holographic interferometry techniques were used to study 2 dimensional symmetric NACA 64A010 and Douglas Aircraft Co. DSMA671 supercritical airfoil performance in the NASA Ames 2 x 2 ft transonic wind tunnel. Quantitative data obtained from the interferograms were compared to the surface pressure data. The agreement obtained verified the accuracy of the flow visualization and demonstrated the potential for acquiring quantitative scalar results. Measurements of the inviscid flow speed and the boundary layer and wake velocity profiles were extracted from the interferograms and compared to laser Doppler velocimeter measurements. These results were also in good agreement. A method for acquiring real time interferometric data in large scale facilities was developed. This method, based on the point diffraction interferometer, was successfully tested in the 2 x 2 ft transonic wind tunnel. The holographic and real time interferometry methods were applied to the investigations of circulation control airfoils utilizing the Coanda effect. These results reveals the details of the jet interacting with the trailing edge boundary layer and the other parameters affecting the lift augmentation.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Ames Research Center, Automated Reduction of Data from Images and Holograms; p 193-247
    Format: application/pdf
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  • 6
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    Improved Skin Friction Interferometer (1986)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An improved system for measuring aerodynamic skin friction which uses a dual-laser-beam oil-film interferometer was developed. Improvements in the optical hardware provided equal signal characteristics for each beam and reduced the cost and complexity of the system by replacing polarization rotation by a mirrored prism for separation of the two signals. An automated, objective, data-reduction procedure was implemented to eliminate tedious manual manipulation of the interferometry data records. The present system was intended for use in two-dimensional, incompressible flows over a smooth, level surface without pressure gradient, but the improvements discussed are not limited to this application.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-TM-88216 , A-86138 , NAS 1.15:88216
    Format: application/pdf
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  • 7
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    Experiments on spray interactions in the wake of a bluff body (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The dynamics of spray drop interaction within the turbulent wake of a bluff body were investigated using the Aerometrics Phase Doppler Particle Analyzer that determines both drop size and velocity. Detailed measurements obtained included spray drop size, axial and radial velocity, angle of trajectory, and size-velocity correlations. The gas-phase flow field was also ascertained via the behavior of the smallest drops. Results showed dramatic differences in drop behavior when interacting with turbulence for the various size classes. Small drops were recirculated in a pair of toroidal vortices located behind the bluff body, whereas the larger drops followed the general direction of the spray cone angle. The spray field interaction illustrated by these data casts some doubt on attempts to describe sprays via simple integral quantities such as the Sauter mean diameter.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASME PAPER 87-GT-48
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  • 8
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    Time analysis of polydisperse sprays in complex turbulent environments (1989)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The two-phase flow field of a small swirl-stabilized burner has been investigated, using a phase Doppler particle analyzer to obtain the velocity, drop size, and time of arrival components. Water/kerosene comparisons were made for the case of nonreacting flow. It is found that the spray flow field is strongly influenced by the aerodynamic flow field and by the reaction and fluid properties. It is noted that vortex shedding produces clusters of drops.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 89-0052
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  • 9
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    Diagnostics development for spray characterization in complex turbulent flows (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The present work reports a detailed investigation of air-liquid interaction in sprays along with particle number density and mass flux measurements in complex turbulent flows such as those present in gas turbines and rocket combustors. Data have been obtained for the characterization of sprays in complex flows which include detailed drop size and drop velocity distributions, size-velocity correlations, mass flux, and particle number density. Key factors affecting the measurement of the sample volume size are discussed in detail since an accurate estimation of it is essential to the particle number density and volume flux determined by the instrument. The discrimination of refraction and reflective scattering components and their influence on the measurements are also discussed. Data comparing the phase Doppler results to alternate methods of measuring number density and volume flux are also presented. These results showed agreement to within 15 percent in most cases for realistic flow configurations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: ASME PAPER 88-GT-241
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  • 10
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    Measurements of droplet drag coefficients in a polydispersed turbulent flow field (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Measurements of drag coefficient versus Reynolds number were obtained in a polydispersed turbulent flow field for three turbulence velocities and for freestream turbulence intensities between 3 and 12 percent. Results are presented for a single nozzle with low number density and a twin nozzle with higher number density. The results for drops smaller than 30 microns showed strong differences from existing low turbulence results. The drag relation was found to be weakly affected by the freestream velocity and to be strongly affected by the velocity fluctuation levels of individual size classes. A drag effect with the drop-drop interaction may also be possible.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 88-0235
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