Download or read book The Development of a Laser Doppler Velocimetry System for Unsteady Separated Flow Research written by R. A. Kadlec and published by . This book was released on 1978 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Frank J. Seiler Research Laboratory (FJSRL) at the U.S. Air Force Academy is conducting a comprehensive experimental research program to study unsteady, separated flows and, in particular, the dynamic stall of oscillating airfoils. The aim of this study is to achieve a clearer understanding into the physical mechanisms responsible for dynamic stall and to capitalize on these unique stall features by using them to improve the turn performance and maneuverability of flight vehicles. The objective of one phase of this experimental research program has been to adapt a general purpose Laser Doppler VElocimetry (LDV) two velocity component system to dynamic stall experiments in the Subsonic Wind Tunnel at the USAFA. The preliminary design of the LDV system, its special constraints and the characterization of system signal and noise parameters are described. Results presented for the initial operation of the LDV system demonstrate its performance capabilities. It has been observed that accurate measurements in the wind tunnel environment can be achieved only when optical noise produced by scattered laser light from wind tunnel surfaces is minimized. While the LDV system configuration satisfies all constraints related to the USAFA Subsonic Wind Tunnel geometry and is capable of accurate velocity measurements in the two-dimensional flow field surrounding an airfoil, a reconfiguration of the system is suggested to improve optical alignment procedures and overall system signal-to-noise ratio. (Author).
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Unsteady Flow Field Measurements Using LDV written by Steven Dale Hedrick and published by . This book was released on 1987 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary goal of this thesis was the development of an experimental technique, and supporting software, for the acquisition and analysis of unsteady velocity data generated by an oscillating airfoil. This research was in support of a major investigation of the compressibility effects on dynamic stall. The experimental procedure involved schlieren flow visualization for comparison of steady and unsteady flow fields, and for determination of parameters for further study. Laser Doppler velocimetry was employed for obtaining velocity data in the airfoil wake. For unsteady data, the airfoil was oscillated in pitch about its quarter chord. The data analysis produced wake profile plots representing the flow field distributed by the airfoil. Results were obtained for steady and unsteady conditions. Keywords: Laser doppler velocimetry, Schlieren flow visualization, Dynamic stall.
Download or read book Government reports annual index written by and published by . This book was released on 199? with total page 906 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development and Testing of the Virginia Tech Doppler Global Velocimeter written by and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new laser based flow interrogation system, capable of simultaneous measurement of planar three-component velocity data, was constructed and tested. The Virginia Tech Doppler Global Velocimeter (DGV) system was designed for use in the Virginia Tech Stability Wind Tunnel as a tool for investigating complex three-dimensional separated flow regions. The systems was designed for robustness, ease of use, and for acquisition of low uncertainty velocity data. A series of tests in the Stability Tunnel were conducted to determine the how well the new DGV system met these goals. Extensive calibration tests proved the system is capable of measuring the frequency shifts of scattered laser light, and therefore velocity. However, equipment failures and inadequate flow seed density prevented accurate velocity measurements in the separated wake region behind a 6:1 prolate spheroid. Detailed uncertainty analysis techniques demonstrated that, under the proper conditions, the system is capable of making velocity measurements with approximately +/- 2m/s uncertainty.
Download or read book Research in Progress written by and published by . This book was released on 1992 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy a Continuing Bibliography with Indexes written by and published by . This book was released on 1979 with total page 666 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 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 Development of a Laser Doppler Velocimeter written by Le-cong Phung and published by . This book was released on 1976 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Annual Index Keyword A L written by and published by . This book was released on 1987 with total page 1260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Development of Laser Speckle Velocimetry for the Study of Vortical Flows written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-11-14 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: A research program was undertaken to develop a new experimental technique commonly known as particle image displacement velocity (PIVD) to measure an instantaneous two dimensional velocity field in a selected plane of flow field. This technique was successfully developed and applied to the study of several aerodynamic problems. A detailed description of the technique and a broad review of all the research activity carried out in this field are reported. A list of technical publications is also provided. The application of PIDV to unsteady flows with large scale structures is demonstrated in a study of the temporal evolution of the flow past an impulsively started circular cylinder. The instantaneous two dimensional flow in the transition region of a rectangular air jet was measured using PIDV and the details are presented. This experiment clearly demonstrates the PIDV capability in the measurement of turbulent flows. Preliminary experiments were also conducted to measure the instantaneous flow over a circular bump in a transonic flow. Several other experiments now routinely use PIDV as a non-intrustive measurement technique to obtain instantaneous two dimensional velocity fields. Krothapalli, A. Unspecified Center FLOW DISTRIBUTION; LASERS; SPECKLE PATTERNS; TURBULENT FLOW; TWO DIMENSIONAL FLOW; UNSTEADY FLOW; VELOCITY MEASUREMENT; AIR JETS; CIRCULAR CYLINDERS; DISPLACEMENT; PARTICLE IMAGE VELOCIMETRY; TRANSONIC FLOW; VELOCITY DISTRIBUTION; VORTICES...
Download or read book Doppler Global Velocimetry Development of a Flight Research Instrumentation System for Application to Non intrusive Measurements of the Flow Field written by and published by . This book was released on 1994 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Technical Abstract Bulletin written by and published by . This book was released on 1979 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA SP written by and published by . This book was released on 1993 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt:
