Download or read book Effect of Particle Dynamics on Turbulence Measurements with the Laser Doppler Velocimeter written by R. H. Nichols and published by . This book was released on 1986 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: A numerical model for evaluating seed requirements for accurate turbulence measurements with the LV has been developed. A Monte Carlo turbulence model was developed which included an elementary description of the internal structure of an eddy. The model was applied to two simple turbulent flows, grid generated turbulence and a subsonic axisymmetric jet, to evaluate particle response and to establish particle size requirements for accurate LV measurements in these flows. Large monodisperse particles were found to cause the turbulence quantities to be underestimated, leading to a requirement for very small particles for meaningful turbulence measurements with the L.V. Rule of thumb criteria for particle size selection are developed. Keywords: Velocity data; Computer code; Turbulence measurements; laser velocimeter.

Download or read book The Effect of Particle Dynamics on Turbulence Measurements with the Laser Doopler Velocimeter written by Robert H. Nichols and published by . This book was released on 1986 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 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 Laser Velocimetry Measurements of Vortex Flows on a Delta Wing at Mach 1 9 written by Linda G. Smith and published by . This book was released on 1993 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: Off-body flow visualizations and fluid velocity measurements are conducted in a supersonic vortex flow. Three-dimensional laser velocimetry measurements are made in the leeward flowfield over a simple sharp-edged delta wing with 75 degree sweep angle. Tests are conducted at Mach 1.9 and Reynolds number of 2.4 x 10(exp 6) based on model root chord. Measurements are made at 40% and 80% chord positions for 20 and 30 degree angles of attack and at 40% chord for 35 degrees. Mean velocities and turbulence intensities are measured on the five planes. Measurement accuracy is discussed in detail. The measurements define the location of the vortex core and provide the flowfield velocities surrounding the vortex. The difficulties inherent with seeding high velocity vortex flows are discussed ... Laser Velocimetry Measurement of Vortical Flowfields.

Download or read book A Laser Doppler Velocimeter Approach for Near wall Three dimensional Turbulence Measurements written by and published by . This book was released on 1990 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book New Trends in Instrumentation for Hypersonic Research written by A. Boutier and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt: Because of the growing interest in hypersonic flows, the AGARD Fluid Dynamics Panel initiated a sub-working group on instrumentation for hypersonics in 1989. This sub-group, chaired by J. WENDT (VKI -Belgium), was composed of: A. BOUTIER (ONERA -France), K. BUTEFISCH (DLR -Germany), R. CATTOLICA (SANDIA Lab. -USA), V. CLINE (AEDC -USA), A. GIRARD (ONERA -France), R. McKENZIE (NASA Ames -USA), S. OCHELTREE (NASA Langley -USA) and G. SMEETS (ISL -Franco-German Inst.). As a result of several meetings, the idea came to organize this workshop, 27th April - 1st May 1992, on "New Trends in Instrumentation for Hypersonic Research", at Le Fauga-Mauzac ONERA center, in France, where the new hot-shot arc-heated facility F4, as well as a new conference building, were recently completed. This workshop has been organized in close connection with the AGARD FDP Symposium to be held in Torino 4 - 8 May 1992 on "Theoretical and Experimental Methods in Hypersonic Flows": the main conclusions and ideas expressed by the papers and during the discussions of this workshop are reported in session 7 and have been presented in Torino in a special Instrumentation session. As chairman of this workshop, I express many thanks to the Organizing Committee composed of Karl BUTEFISCH, Andre GIRARD, Stewart OCHELTREE and John WENDT for their very constructive help, leading to a meeting that was recognized to be very fruitful for all the participants.

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).

Download or read book Advances in Hypersonics written by BALLMAN and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: These three volumes entitled Advances in Hypersonics contain the Proceedings of the Second and Third Joint US/Europe Short Course in Hypersonics which took place in Colorado Springs and Aachen. The Second Course was organized at the US Air Force Academy, USA in January 1989 and the Third Course at Aachen, Germany in October 1990. The main idea of these Courses was to present to chemists, com puter scientists, engineers, experimentalists, mathematicians, and physicists state of the art lectures in scientific and technical dis ciplines including mathematical modeling, computational methods, and experimental measurements necessary to define the aerothermo dynamic environments for space vehicles such as the US Orbiter or the European Hermes flying at hypersonic speeds. The subjects can be grouped into the following areas: Phys ical environments, configuration requirements, propulsion systems (including airbreathing systems), experimental methods for external and internal flow, theoretical and numerical methods. Since hyper sonic flight requires highly integrated systems, the Short Courses not only aimed to give in-depth analysis of hypersonic research and technology but also tried to broaden the view of attendees to give them the ability to understand the complex problem of hypersonic flight. Most of the participants in the Short Courses prepared a docu ment based on their presentation for reproduction in the three vol umes. Some authors spent considerable time and energy going well beyond their oral presentation to provide a quality assessment of the state of the art in their area of expertise as of 1989 and 1991.

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:

Download or read book Combustion Measurements written by Norman Chigier and published by CRC Press. This book was released on 1991-04-01 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book begins with an introduction to the general problems of making measurements in high temperature and a presentation of chemically reacting flow systems. It describes each instrument with the various diagnostic techniques and discusses measurements that have been made in furnaces, flames, and rocket engines. The detailed measurement techniques described in this book cover a wide spectrum of applications in combustion systems, including gas turbine, rocket measurement techniques that were developed in laboratories. Information obtained on detailed temperature, velocity, particle size, and gas concentration distribution is leading to improve understanding of the chemical combustion process and to design imporvements in combustors.

Download or read book Second Microgravity Fluid Physics Conference written by and published by . This book was released on 1994 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Seeding Particle Impact on Laser Doppler Velocimetry In cylinder Flow Measurement written by Zhenzhi Shao and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This project studies the influence of seeding particle on the Laser Doppler Velocimetry (LDV) measurement of engine flow. A CFR engine with underhead valve construction was used for the measurement. A quartz window located in the cylinder head allow the use of LDV in the backscatter arrangement. The flow velocities were measured at three positions in the combustion chamber: at the combustion chamber center, by the intake valve and by the exhaust valve. Three different seeding particles (0.2 $\mu$m TiO$\sb2,$ 1 $\mu$m TiO$\sb2,$ 3 $\mu$m $\rm Al\sb2O\sb3)$ were used to seed the flow. Experimental results provide the Ensemble mean velocities, Ensemble mean turbulence, autocorrelation and Power Spectrum Density (PSD) of the flow at all measured positions. For the Ensemble mean velocities, significant differences could be found between different seeding particles, the differences are associated with the accelerations and decelerations of the measured velocity components during intake and exhaust strokes. Less significant differences between different seeding particles were found in the turbulence, autocorrelation and PSD of the flow. From Basset's equation (1888), the motion of a suspended particle in the fluid can be described. By applying the condition of LDV in-cylinder flow measurement, particle density/fluid density $\gg$ 1, Basset's equation can be simplified and the velocity difference between seeding particles and fluid can be calculated by knowing the particle acceleration, particle diameter, particle density and fluid viscosity. The differences are related to the particle acceleration, particle diameter, particle density and fluid viscosity. Experimental data were used to verify this model and there is reasonably good agreement. By applying this model, the slip velocity between seeding particle and fluid in LDV in-cylinder flow measurement can be calculated. (Abstract shortened by UMI.).

Download or read book Technical Reports Awareness Circular TRAC written by and published by . This book was released on 1988-06 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of a Laser Doppler Velocimetry System for Supersonic Jet Turbulence Measurements written by Alex Karns and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of military style exhaust nozzles to further understand their acoustic characteristics has been the recent focus of the Pennsylvania State University high-speed jet aeroacoustics facility. Advanced measurement techniques are required to study the turbulence characteristics of the flow field. Development of a laser Doppler velocimetry system would allow for these measurements to be made non-intrusively.Development of the laser Doppler velocimetry system required research and testing of each component as it was placed into the system. Development was split into two portions: fundamental or basic concepts and components, and advanced components. During these stages, many components, such as the transmitting and receiving probes, were fabricated, procedures were developed, and calibration of the transmitting probe was completed.Once the development stages were complete, the laser Doppler velocimetry system was used to measure subsonic flows of a cold air exhaust jet. Velocity measurements proved to be accurate to within 2% of calculated jet Mach numbers with discrepancies of up to 6% at Mach numbers approaching 1 at x/D of 2. Comparison of axial turbulence intensity data to previous studies yielded less favorable result possibly due to use of the exhaust fan, but this hypothesis cannot be proven without more experiments.Parametric studies were also on the ratio of the injection pressure ratio to the nozzle pressure ratio and the exhaust fan power determine their effects of seeding on measurement values. It was determined that ratio of the injection pressure ratio to the nozzle pressure ratio had negligible effect on the measurements except at a value of 1 where the axial turbulence intensity was up to 6% different than the other measurements. However, the ratio was found to have an inverse relationship to the number of validated burst particles per unit time. The power of the exhaust fan created differences in the measurement of up to 3% at x/D greater than 6, with higher values of Mach number and lower values of axial turbulence intensity at the exhaust fan power of 15%. However, it is difficult to draw conclusions with only two sets of data.

Download or read book 30th Aerospace Sciences Meeting and Exhibit 92 0760 92 0809 written by and published by . This book was released on 1992 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt: