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1 edition of Laser Doppler velocimetry measurements across a normal shock in transonic flow found in the catalog.

Laser Doppler velocimetry measurements across a normal shock in transonic flow

David Arthur Perretta

Laser Doppler velocimetry measurements across a normal shock in transonic flow

by David Arthur Perretta

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Published by Naval Postgraduate School, Available from National Technical Information Service in Monterey, Calif, Springfield, Va .
Written in English


About the Edition

One-dimensional laser-Doppler velocimetry measurements were taken with standard optics in back scatter mode across a normal shock at a Mach number of 1.35. Back pressure on a blow-down supersonic tunnel was controlled to place a normal shock in a 4 by 4 inch test section and schlieren visualization techniques were used to verify and record shock position and behavior. Velocity surveys were taken across the shock, using various filtering techniques, in an attempt to quantify shock unsteadiness. Additional surveys were performed to further characterize the flow in the test section. The velocity surveys upstream and downstream of the shock compared favorably with pressure and temperature data and normal shock relations. Surveys across the shock indicated distinct and repeatable velocity patterns, and the measured location of the shock matched schlieren photographs.

Edition Notes

StatementDavid A. Perretta
The Physical Object
Pagination111 p. ;
Number of Pages111
ID Numbers
Open LibraryOL25458825M

LASER DOPPLER VELOCIMETRY APPLICATION IN THE LANGLEY METER TRANSONIC CRYOGENIC TUNNEL (contributors to the flow velocity measurement) are smaller than the fringe spacing (=6 urn) for the test conditions shown in figure 8. The velocity survey across the shock using a laser transient anemometer (LTA) revealed a percent velocity change. What is laser doppler velocimetry? This is a technique to determine the local velocity of a flow by fine particles in the air with high temporal resolution and in a non-intrusive way. The particles within the flow pass through interference fringes created by interaction between two coherent laser beams.

Shepherd AP, Riedel GL. Continuous measurement of intestinal mucosal blood flow by laser-Doppler velocimetry. Am J Physiol. Jun; (6):G–G Karanfilian RG, Lynch TG, Lee BC, Long JB, Hobson RW., 2nd The assessment of skin blood flow in peripheral vascular disease by laser Doppler velocimetry. Am Surg. Dec; 50 (12)– 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.

  Three-dimensional unsteady calculations were found to agree with fast response pressure probe measurements at the rotor exit of a low speed test turbine. The second part of the paper shows that increasing the injected coolant swirl angle reduced the secondary flow penetration depth, improves the coolant distribution on the rotor hub, and Cited by. Laser Doppler velocimetry (LDV) is a non-intrusive technique for measuring the velocity of flows and solid surfaces using laser light proposed by Yeh and Cummins in [1]. By illuminating the flow or object with a laser light and measuring the scattering caused by movement, it .


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Laser Doppler velocimetry measurements across a normal shock in transonic flow by David Arthur Perretta Download PDF EPUB FB2

Calhoun: The NPS Institutional Archive Theses and Dissertations Thesis Collection Laser Doppler velocimetry measurements across a normal shock in transonic flow. Laser Doppler velocimetry, also known as laser Doppler anemometry, is the technique of using the Doppler shift in a laser beam to measure the velocity in transparent or semi-transparent fluid flows or the linear or vibratory motion of opaque, reflecting surfaces.

The measurement with laser Doppler anemometry is absolute and linear with velocity and requires no pre-calibration.

II Title (include security classification) Laser Doppler Velocimetry Measurements Across a Normal Shock in Transonic Flow 12 Personal Author(s) Perretta, David A. 13a Type of Report 13b Time Covered 14 Date of Report (year, month, day) Page Count Master's Thesis Frcm To Author: David Arthur Perretta.

The Laser-Doppler-Velocimetry (LDV) is an optical method to measure local flow parameters of transparent gaseous or liquid flows.

Without explaining in more detail it should be noted that in a modified version the same technique can be applied to velocity measurements of surfaces of by: 4. Laser Doppler velocimetry (LDV) is a technique to measure the velocity of a flow based on the measurement of light scattering caused by particles in the flow [53,54].

According to the Doppler effect, the frequency of reflected radiation from a flowing particle is shifted from that of the incident light.

Laser Doppler velocimetry measurements across a normal shock in transonic flow. -dimensional laser-Doppler velocimetry measurements were taken with standard optics in back scatter mode across a normal shock at a Mach number of Back pressure on a blow-down supersonic tunnel was controlled to place a normal shock in a 4 by.

Christian M. Pettker, Katherine H. Campbell, in Avery's Diseases of the Newborn (Ninth Edition), Doppler. Doppler velocimetry shows the direction and characteristics of blood flow, and it can be used to examine the maternal, uteroplacental, or fetal circulations.

Because of placental capacitance, the umbilical artery is one of the few arteries that normally has forward diastolic flow. The image below shows laser Doppler flow measurements during a cardiac surgery.

Flowmetry during cardiac surgery. The arrow indicated the fiber used for Doppler flowmetry. Courtesy insidan. Retinal Blood Flow.

Retinal blood flow can still be imaged with visible light as the eye is transparent to the visible region. The objective is to. A total of 11 wall normal velocity measurements hav e been performed using LDV around the shock w ave in order to characterise the SBLI. The local Mach number contours are shown in Figure 6, along.

The purpose of the present study is to investigate two-dimensional unsteady transonic flows in a channel with a sonic throat and a moderately strong normal shock downstream of the throat.

The aim of the present work is to obtain a precise description of the unsteady flow in order to characterize the evolution of the boundary layer and the shock.

Laser Doppler velocimetry was used to measure the mean velocity components, turbulence levels and shear stresses. Measurements Across A Normal Shock In Transonic Flow.

Enhanced delayed DES of shock wave/boundary layer interaction in a planar transonic nozzle International Journal of Heat and Fluid Flow, Vol. 77 Effects of fluid type and pressure order on performance of convergent-divergent nozzles: An efficiency model for supersonic separation.

Laser Doppler Velocimetery (LDV) is a technique used to measure the instantaneous velocity of a flow field. This technique, like PIV is non-intrusive and can measure all the three velocity components.

The laser Doppler velocimeter sends a monochromatic laser beam toward the target and collects the reflected radiation. Laser Doppler Velocimetry This technique uses small tracer particles added to the flow (particles with diameter below 1 micrometer, e.g.

oil). These particles scatter light projected by two laser beams into a small measurement volume. In this volume these laser-beams interfere producing interference planes (tiny planes of light one behind the.

Velocity component normal to the shock (m s−1) u 1 Velocity upstream of the shock (m s−1) u 2 Velocity downstream of the shock (m s−1) * Normalized velocity across the shock U j Jet peak exit velocity (m s−1) Measurement Science and Technology A high temperature seeding technique for particle image velocimetry Mark P Wernet1 and Judith.

a laser Doppler velocimeter and study the characteristics of di erent ow patterns to evaluate the potential of this method. 2 Laser Doppler Velocimetry Theory The experiment uses the Doppler e ect to calculate the velocity of particles in uids.

Light scattered on moving particles experi-ences a shift in frequencies according to f r = f b 1. The equipment is from Dantec Dynamics and it is actually capable of 1D velocimetry measurements only.

This LDA system is based on Argon ions laser (Innova 70 Coherent, nominal power of 4 W), which is refrigerated by air with a backscattering configuration. The BSA Flow Software, from the same company, was also used.

Laser-Doppler-Velocimetry (LDV) Laser Doppler Velocimetry (LDV) is a technique which allows the measurement of velocity at a point in a seeded flow field with a high temporal resolution. Laser doppler velocimetry (LDV) is a technique in which the velocity of a fluid is calculated from the measured doppler frequency shift of a laser beam scattering from tracer particles in the fluid.

The relativistic doppler shift is given, for particles traveling much less than the speed of light, by fd= f0 1− vpr c = f0 vprb c =f0 vprb 0. Laser Doppler Velocimetry for Joint Measurements of Acoustic and Mean Flow Velocities: LMS-based Algorithm and CRB Calculation I.

INTRODUCTION Laser Doppler Velocimeter (LDV) is an optical technique allowing direct measurement of local and instantaneous fluid velocity. The newest appiication of the ubiquitous Doppler principle, laser-Doppler velocimetry, has been used to measure blood ftow in tissue for just a few years, but we perceived that, like most new techniques, the birth of laser-Doppler blood ftowmetry was not easy, nor was it likely to pass through infancy and reach maturity without difficulty.niques of laser Doppler velocimetry (LD) and transcutaneous oxygen tension monitoring (tcPo2) to quantitatively measure skin blood flow in the distal foot.

Fifty-nine limbs were studied (48 patients), of which 37 (63%) were in diabetic and 22 (37%) in nondiabetic patients. All patients were admitted with ischemic ulcerations or gangrenous.A theory is developed which relates quasi-elastic light scattering measurements to blood flow in tissue microvasculature.

We assume that the tissue matrix surrounding the blood cells is a strong diffuser of light and that moving erythrocytes, therefore, are illuminated by a spatially distributed source.

Because the surrounding tissue is considered to be stationary, Doppler shifts in the.