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Book Application of a Novel Laser Doppler Velocimeter for Turbulence Structural Measurements in Turbulent Boundary Layers

Download or read book Application of a Novel Laser Doppler Velocimeter for Turbulence Structural Measurements in Turbulent Boundary Layers written by and published by . This book was released on 2006 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt: An advanced laser-Doppler velocimeter (LDV), deemed the 'comprehensive LDV', is designed to acquire fully-resolved turbulence structural measurements in high Reynolds number two- and three-dimensional turbulent boundary layers. The new instrument combines, for the first time, new techniques allowing for the direct measurement of particle acceleration and sub-measurement-volume-scale position resolution so that second-order 3D particle trajectories may be measured at high repetitions. Using these measurements, several terms in the Reynolds stress transport equations may be directly estimated, giving new data for modeling and understanding the processes leading to the transport of turbulence in boundary layer flows. Measurements utilizing the CompLDV technologies are presented and include turbulence dissipation rate and fluctuating velocity-pressure gradient correlations that have been measured in 2D and 3D turbulent boundary layers using the unique capabilities of the 'comprehensive' LDV. Many of these measurements are the first of their kind ever acquired in high Reynolds number turbulent flows. The flat-plate turbulent boundary layer is studied at several Reynolds numbers up to Re-theta ~7500 to examine Reynolds numbers effects on terms such as the velocity-pressure gradient correlation and the dissipation rate in the Reynolds transport equations. Measurements are also presented in a pressure-driven three-dimensional turbulent boundary layer created upstream from a wing-body junction. The current results complement the extensive data from previous studies and provide even richer depth of knowledge on the most completely-documented 3D boundary layer flow in existence. Further measurements include the effects of high free-stream turbulence on flat plate turbulent boundary layers and a wing/body junction flow that is similar to a gas turbine flow.

Book Laser Doppler Velocimeter Measurements of Boundary Layer Velocity and Turbulent Intensities in Mach 2 5 Flow

Download or read book Laser Doppler Velocimeter Measurements of Boundary Layer Velocity and Turbulent Intensities in Mach 2 5 Flow written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-05 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, the interest in developing a high-speed civil transport has increased. This has led to an increase in research activity on compressible supersonic flows, in particular the boundary layer. The structure of subsonic boundary layers has been extensively documented using conditional sampling techniques which exploit the knowledge of both u and v velocities. Researchers using these techniques have been able to explore some of the complex three-dimensional motions which are responsible for Reynolds stress production and transport in the boundary layer. As interest in turbulent structure has grown to include supersonic flows, a need for simultaneous multicomponent velocity measurements in these flows has developed. The success of conditional analysis in determining the characteristics of coherent motions and structures in the boundary layer relies on accurate, simultaneous measurement of two instantaneous velocity components. Sewell, Jesse and Chew, Larry Unspecified Center NAG1-1402...

Book Experimental Investigation of Turbulent Boundary Layer with Uniform Blowing at Moderate and High Reynolds Numbers

Download or read book Experimental Investigation of Turbulent Boundary Layer with Uniform Blowing at Moderate and High Reynolds Numbers written by Gazi Hasanuzzaman and published by Cuvillier Verlag. This book was released on 2022-01-18 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental investigation in turbulent boundary layer flows represents one of the canonical geometries of wall bounded shear flows. Utmost relevance of such experiments, however, is applied in the engineering applications in aerospace and marine industries. In particular, continuous effort is being imparted to explore the underlying physics of the flow in order to develop models for numerical tools and to achieve flow control. Flow control experiments have been widely investigated since 1930’s. Several flow control technique has been explored and have shown potential benefit. But the choice of control technique depends largely on the boundary condition and the type of application. Hence, friction drag of subsonic transport aircraft is intended to be reduced within the scope of this Ph. D. topic. Therefore, application of active control method such as microblowing effect in the incompressible, zero pressure gradient turbulent boundary layer was investigated. A series of experiments have been performed in two different wind tunnel facilities. Wind tunnel from Department of Aerodynamics and Fluid Mechanics (LAS) was used for the measurements for moderate Reynolds number range in co-operation with the wind tunnel from Laboratoire de M´ecanique de Feiret Lille for large Reynolds number range. Measurements are conducted with the help of state-of-the-art techniques such as Laser Doppler Anemometry, Particle Image Velocimetry and electronic pressure sensors.

Book Turbulence Measurements with a Laser Doppler Velocimeter

Download or read book Turbulence Measurements with a Laser Doppler Velocimeter written by William Joseph Yanta and published by . This book was released on 1973 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulence measurements with a Laser Doppler Velocimeter (LDV) using the dual scatter or differential Doppler mode have been made in a subsonic, fully developed channel flow. The measurements were made using only those light scattering particles occurring naturally in air. Results include mean velocity profiles, turbulence intensities, Reynolds stress distributions and a skewness measurement of the velocity distribution function across the channel. Statistical techniques were used to obtain the various turbulence parameters. Guidelines have been established for the amount of data needed to obtain results with a specified accuracy and confidence level. Measurements have also been made to determine the particle-size distribution. An aerodynamic means was used to determine the size distribution, in contrast to the usual optical procedures. (Modified author abstract).

Book An Analysis of the Laser Doppler Velocimeter and Its Application to the Measurement of Turbulence

Download or read book An Analysis of the Laser Doppler Velocimeter and Its Application to the Measurement of Turbulence written by William K George (Jr) and published by . This book was released on 1971 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: An operational Laser-Doppler Velocimeter is described and measurements of spectra in both laminar and turbulent flow are presented. (Author).

Book Multi Structure Turbulence in a Boundary Layer with a Uniformly Sheared Free Stream

Download or read book Multi Structure Turbulence in a Boundary Layer with a Uniformly Sheared Free Stream written by Curtis Livingston and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A turbulent boundary layer (TBL), generated in a water tunnel, extended to a highly turbulent and anisotropic "free stream" that consisted of a uniformly sheared flow (USF) with a mean shear that was in the opposite direction to that in the TBL. Extensive measurements of the fluctuating velocity were taken with the use of hot-film anemometry, laser Doppler velocimetry and particle image velocimetry. On either side of the TBL edge, defined as the location of maximum velocity, the turbulence relaxed to its canonical structures in TBL and USF, respectively, but, in the vicinity of the edge, the turbulence was multi-structure and exhibited strong departures from canonical behaviour. Of particular interest was the variation of the dissipation parameter, which, in contrast to its near-constancy in well-developed canonical flows, varied inversely proportionally to the turbulence Reynolds number. The entire flow contained horseshoe-shaped coherent structures, whose properties, however, varied from the TBL, across the multi-structure region and into the USF.

Book The Use of a Laser Doppler Velocimeter in Supersonic Flow

Download or read book The Use of a Laser Doppler Velocimeter in Supersonic Flow written by William Joseph Yanta and published by . This book was released on 1971 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results are presented for an experimental program which investigated the application of an LDV technique in supersonic flows. This paper presents an analysis of the behavior of light-scattering particles in rapidly accelerating or shock decelerated flows, an evaluation of particle production techniques and the results of several velocity measurements. Measurements included the velocity distribution along the nozzle centerline and flow over a diamond airfoil in a Mach 3 tunnel and velocity profiles for a turbulent boundary layer in a Mach 4.8 facility. It is demonstrated that LDV measurements can be made consistently with errors of less than five percent if the particle lag is considered. (Author).

Book Turbulence Measurements with a Laser Doppler Velocimeter

Download or read book Turbulence Measurements with a Laser Doppler Velocimeter written by William J. Yanta and published by . This book was released on 1973 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulence measurements with a Laser Doppler Velocimeter (LDV) using the dual scatter or differential Doppler mode have been made in a subsonic, fully developed channel flow. The measurements were made using only those light scattering particles occurring naturally in air. Results include mean velocity profiles, turbulence intensities, Reynolds stress distributions and a skewness measurement of the velocity distribution function across the channel. Statistical techniques were used to obtain the various turbulence parameters. Guidelines have been established for the amount of data needed to obtain results with a specified accuracy and confidence level. Measurements have also been made to determine the particle-size distribution. An aerodynamic means was used to determine the size distribution, in contrast to the usual optical procedures. (Modified author abstract).

Book Application of Laser Doppler Velocimeter to Chemical Vapor Laser System

Download or read book Application of Laser Doppler Velocimeter to Chemical Vapor Laser System written by Luther R. Gartrell and published by . This book was released on 1993 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book The Effects of Expansion Regions on the Turbulence Structure of a Supersonic Boundary Layer

Download or read book The Effects of Expansion Regions on the Turbulence Structure of a Supersonic Boundary Layer written by and published by . This book was released on 1996 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: A fully-developed high Reynolds number Mach 3 turbulent boundary layer and the effects of four expansion regions (centered and gradual expansions of 7 deg and 14 deg) on the boundary layer were investigated by utilizing 1) multi-point instantaneous surface pressure measurements, 2) instantaneous single- and double-pulse flow visualizations based on Filtered Rayleigh Scattering (FRS), 3) two-component planar velocity measurements using Filtered Planar Velocimetry (FPV), and 4) detailed turbulence measurements using Laser Doppler Velocimetry (LDV). Flow visualization results indicate that the upper half of the fully developed turbulent boundary layer is populated with elongated longitudinal structures of considerable streamwise but very limited spanwise extent. These structures are randomly distributed in space and time and survive even the 14 deg centered expansion. The visualizations also show that large scale structures increase both in size and angle and small scale structures are quenched across the expansions. The angle of large scale structures return to the flat plate value further downstream of the expansions. The normalized power spectra of pressure fluctuations downstream of the expansions are more concentrated at lower frequencies than their upstream counterparts, confirming the small scale quenching shown by flow visualizations.

Book A Comparison of Diode Laser Doppler Velocimeter and Medium Resolution Turbulence Cluster Measurements in MIZEX 84

Download or read book A Comparison of Diode Laser Doppler Velocimeter and Medium Resolution Turbulence Cluster Measurements in MIZEX 84 written by Miles G. McPhee and published by . This book was released on 1985 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the MIZEX 84 Experiment two prototype Diode-Laser-Doppler Velocimeters were tested in the oceanic boundary layer under a drifting ice floe. Part of the testing included a comparison of turbulent flow measured with the DLDV instruments and with a so-called Medium Resolution Cluster of small partially ducted rotors mounted along orthogonal axes, used in a separate boundary-layer experiment. This report presents data from 15 runs in which the two systems, suspended on the same inverted mast but separated vertically by about half a meter, measured the flow simultaneously. One-second averages of the DLDV and MRC output are presented, along with statistics of flow measured by each system, direct comparison of the horizontal and 45-degree components, and autospectra and squared coherency calculated from each of 12 fourteen-minute runs. Overall, flow measurements made with the DLDV instruments compare favorably with those of the MRC.

Book Reportnr ISL CO 219 87

Download or read book Reportnr ISL CO 219 87 written by G. Smeets and published by . This book was released on 1987 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: