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Application of Spectroscopic Doppler Velocimetry for Measurement of Streamwise VorticityA spectroscopic Doppler velocimetry technique has been developed for measuring two transverse components of velocity and hence streamwise vorticity in free jet flows. The nonintrusive optical measurement system uses Mie scattering from a 200 mW green continuous-wave laser interacting with dust and other tracer particulates naturally present in the air flow to measure the velocities. Scattered light is collected in two opposing directions to provide measurements of two orthogonal velocity components. An air-spaced Fabry-Perot interferometer is used for spectral analysis to determine the optical frequency shift between the incident laser light and the Mie scattered light. This frequency shift is directly proportional to the velocity component in the direction of the bisector of the incident and scattered light wave propagation vectors. Data were acquired for jet Mach numbers of 1.73 and 0.99 using a convergent 1.27-cm diameter round nozzle fitted with a single triangular "delta-tab". The velocity components and the streamwise vorticity calculated from the measurements are presented. The results demonstrate the ability of this novel optical system to obtain velocity and vorticity data without any artificial seeding and using a low power laser system.
Document ID
Document Type
Conference Paper
Fagan, Amy
(NASA Glenn Research Center Cleveland, OH, United States)
Zaman, Khairul B.
(NASA Glenn Research Center Cleveland, OH, United States)
Elam, Kristie A.
(Jacobs Sverdrup Technology, Inc. Cleveland, OH, United States)
Clem, Michelle M.
(NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
August 27, 2013
Publication Date
January 7, 2013
Subject Category
Report/Patent Number
Meeting Information
Meeting: 51st AIAA Aerospace Sciences Meeting
Location: Grapevine, TX
Country: United States
Start Date: January 7, 2013
End Date: January 10, 2013
Sponsors: American Inst. of Aeronautics and Astronautics
Funding Number(s)
WBS: WBS 475122.
Distribution Limits
Public Use Permitted.
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