Download or read book Laser Velocimeter Measurements in Turbulent and Mixing Flows Part II written by and published by . This book was released on 1980 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental and analytical study of subsonic flow over a rearward facing step is reported. A major emphasis of the work is the investigation of bias errors in mean velocities obtained from laser doppler velocimeter (LDV) measurements in such highly turbulent flows. Optical alignment of the specially designed LDV used in the study is described in detail. An analysis of the biasing problem is presented and preliminary measurements which appear to confirm previously predicted velocity bias errors are reported. Results of a computer model developed to describe the flow are presented together with preliminary static pressure measurements made in the flow facility. (Author).
Download or read book Laser Velocimeter Measurements in Turbulent and Mixing Flows written by Warren H. Stevenson and published by . This book was released on 1981 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental and analytical studies of subsonic flow over a backward facing 2-D step and in a cylindrical simulated dump combustor were conducted. A laser velocimeter was used to obtain mean velocities and turbulence quantities. A method for detecting and eliminating velocity bias errors in such measurements was developed. The 2/E/FIX computer code used for numerical modeling predicted the mean velocity field satisfactorily, but was less effective in computing turbulence quantities. (Author).
Download or read book Laser Velocimeter Measurements in Turbulent and Mixing Flows written by Warren H. Stevenson and published by . This book was released on 1979 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental and analytical study of subsonic flow over a rearward facing step is reported. A major emphasis of the work is the investigation of bias errors in mean velocities obtained from laser doppler velocimeter (LDV) measurements in such highly turbulent flows. Optical alignment of the specially designed LDV used in the study is described in detail. An analysis of the biasing problem is presented and preliminary measurements which appear to confirm previously predicted velocity bias errors are reported. Results of a computer model developed to describe the flow are presented together with preliminary static pressure measurements made in the flow facility. (Author).
Download or read book Laser Velocimetry in Fluid Mechanics written by Alain Boutier and published by John Wiley & Sons. This book was released on 2013-01-09 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: In fluid mechanics, velocity measurement is fundamental in order to improve the behavior knowledge of the flow. Velocity maps help us to understand the mean flow structure and its fluctuations, in order to further validate codes. Laser velocimetry is an optical technique for velocity measurements; it is based on light scattering by tiny particles assumed to follow the flow, which allows the local fluid flow velocity and its fluctuations to be determined. It is a widely used non-intrusive technique to measure velocities in fluid flows, either locally or in a map. This book presents the various techniques of laser velocimetry, as well as their specific qualities: local measurements or in plane maps, mean or instantaneous values, 3D measurements. Flow seeding with particles is described with currently used products, as well as the appropriate aerosol generators. Post-processing of data allows us to extract synthetic information from measurements and to perform comparisons with results issued from CFD codes. The principles and characteristics of the different available techniques, all based on the scattering of light by tiny particles embedded in the flow, are described in detail; showing how they deliver different information, either locally or in a map, mean values and turbulence characteristics.
Download or read book Fluid Mechanics Measurements written by R. Goldstein and published by Routledge. This book was released on 2017-11-13 with total page 740 pages. Available in PDF, EPUB and Kindle. Book excerpt: This revised edition provides updated fluid mechanics measurement techniques as well as a comprehensive review of flow properties required for research, development, and application. Fluid-mechanics measurements in wind tunnel studies, aeroacoustics, and turbulent mixing layers, the theory of fluid mechanics, the application of the laws of fluid mechanics to measurement techniques, techniques of thermal anemometry, laser velocimetry, volume flow measurement techniques, and fluid mechanics measurement in non-Newtonian fluids, and various other techniques are discussed.
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).
Download or read book A Scanning Laser Velocimeter for Turbulence Research written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-20 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulent and unsteady separated flows occur on most practical flight vehicles, but are not yet sufficiently understood for designs to provide safe margins of performance without recourse to extensive experiment and computation. In date, reliable experimental data for even basic flows is severely limited and does not yet provide a satisfactory data base with which to assess current design and calculation methods. Although the laser velocimeter (LV) has become a proven, nonintrusive instrument for the measurement of local mean velocities and turbulence properties, measurements have been of a mean, statistical nature derived from averages accumulated independently at different positions in the flow. Thus, the measurements do not give an instantaneous dynamic, picture of the flow-field structures. Accordingly, a new technique for rapid LV scans of turbulent flow fields was proposed. The potential of this new instrument for fundamental fluid mechanical measurements of turbulent flows has been demonstrated. The results clearly show that significant unsteady flow features are hidden by conventional measurements and that the scanning laser velocimeter should prove an invauable tool in future studies of the structure of turbulent flows. Duen, F. K. Unspecified Center NASA-CR-172493, NAS 1.26:172493 NAS1-17572; RTOP 324-01-00-01...
Download or read book Application of a Dual Beam Laser Velocimeter to Turbulent Flow Measurements written by V. A. Cline and published by . This book was released on 1974 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: A dual beam laser velocimeter (LV) system has been applied to the measurements of mean velocity and turbulence intensity. The basic theory of the LV is described in terms of both Doppler and fringe models. A statistical analysis predicting the number of data points required to ensure a given accuracy is developed. Experimental verification of the analysis is given. A theoretical analysis of the LV counting process is proposed which predicts the biases to be found in velocity and turbulent intensity estimators. The two most common methods of averaging are compared for biases in the estimators for a one-dimensional model. Finally, experimental LV data are presented, taken from a coaxial free-jet-mixing facility. (Modified author abstract).
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...
Download or read book Laser Velocimeter Measurements and Analysis in Turbulent Flows with Combustion Part 3 A Correction Lens for Laser Doppler Measurements in a Cylindrical Tube written by H. D. Thompson and published by . This book was released on 1984 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: A lens was designed using analytical ray tracing techniques to correct aberrations caused by a cylindrical tube wall when measurements are made off the plane of symmetry with a Laser Doppler Velocimeter. The single element correction lens was found to work well and good results were obtained out to a normalized tube radius of r/R = 0.83. LDV measurements were made in three axisymmetric flow geometries: a turbulent flow in a straight pipe, a sudden expansion with diameter ratio 1.90:1, and a second sudden explosion with diameter ratio 2.70:1. Mean velocity and turbulence intensity were measured as well as Reynolds stress and turbulence kinetic energy. Numerical predictions of the flow field using the k-epsilon turbulence model were compared to the experimental measurements in the 1:90:1 sudden expansion. In the 2.70:1 sudden expansion, the presence of a secondary recirculation zone in the corner of the step was confirmed and velocity measurements were made in this region. (Author).
Download or read book The Measurements of Axisymmetric Air Turbulent Jet Flow with an Individual Realization Laser Velocimeter System written by X. Shen and published by . This book was released on 1985 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper describes the measurements of axisymmetric air turbulent jet flow with the use of an IRLV system. The distributions of axial mean velocity, turbulent intensity and probability density functions of velocity in the initial region of jet flow were obtained. The data from LV were sampled and processed automatically by a microprocessor. The experiments show that the velocity measurements can be realized even with the air particles in their natural state. The measurements of the mean velocity were also simultaneously made with aa hot wire anemometer in order to compare with those made with a LV. Their results were in good coincidence in the core flow region. The velocity bias was increased with the decrease of data rate and increase of turbulent intensity in the mixing boundary layer. Keywords: Laser velocimeters (LV); Velocity measurements. (Translations).
Download or read book Laser Velocimeter Measurements and Analysis in Turbulent Flows with Combustion Part 4 Two Component Cold Flow Measurements written by H. D. Thompson and published by . This book was released on 1986 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: A unique two component, two color Laser doppler Velocimeter (LDV) has been designed and built. The system includes Bragg cell modulators in all four beams, and a correction lens system to correct for the aberration induced by the cylindrical quartz test section. A dedicated PDP 11/40 mini-computer with DMA capability is used for data collection, storage, and processing. Two component (axial and radial) velocity measurements have been made in the turbulent flow field following an axisymmetric sudden expansion. Mean streamwise and radial velocity and turbulence intensity measurements were made. Reynolds stresses were computed. Keywords: Turbulent measurements; Laser velocimeter; Bias errors; Recirculating flows.
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).
Download or read book Combined LDV Laser Doppler Velocimetry and Rayleigh Measurements in a Complex Turbulent Mixing Flow written by W. A. De Groot and published by . This book was released on 1987 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The cold flow behind a backward facing step with injection of a foreign bleed gas was investigated using a simultaneous laser Doppler velocimetry-Rayleigh scattering technique. The facility simulates the flow field in the flame stabilization region in a solid fueled ramjet. Velocities and bleed gas concentrations and the resulting mixing pattern were measured. Particular attention was paid to the covariance of the velocity and bleed gas concentration which is a measure of the turbulent mass transport in the flow field. A novel reduction technique was utilized in the reported measurements.
Download or read book Laser Velocimeter Measurements and Analysis in Turbulent Flows with Combustion written by Howard Doyle Thompson and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Laser Doppler Velocimeter Measurements in a Turbulent Jet Exiting Into a Cross Flow written by Dennis K. McLaughlin and published by . This book was released on 1972 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements were made of horizontal and vertical velocity components along the center line plane of a turbulent jet exiting into a cross flow. The dual scatter laser Doppler velocimeter was used in both the continuous wave mode and the individual realization mode. In the latter case, numerical averaging over many individual measurements was used to compute the average velocity components. Encouraging results were obtained which indicate that the laser Doppler velocimeter will become an important tool in the field of experimental fluid mechanics. (Author).
Download or read book A Method for the Measurement of Mixing Properties in a Turbulent Jet Flow written by C. Borrego and published by . This book was released on 1979 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:
