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Combined filtered Rayleigh and Mie scattering for simultaneous planar temperature and velocity measurements

Stockhausen, Guido and Doll, Ulrich and Strehlau, Tobias and Willert, Christian (2010) Combined filtered Rayleigh and Mie scattering for simultaneous planar temperature and velocity measurements. 15th Internation Symposium on Applications of Laser Techniques to Fluid Mechanics, 05-08 Jul 2010, Lisbon, Portugal.

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Official URL: http://ltces.dem.ist.utl.pt/lxlaser/lxlaser2010/default.asp

Abstract

The combination of planar Doppler velocimetry (PDV) and FRS offers a promising way to obtain simultaneously 3 component velocity in a plane and corresponding scalar temperature maps. Implementation wise the two techniques are closely related since they both make use of a molecular absorption filter. This makes it possible to combine the necessary equipment using a single laser to illuminate a plane of interest that is observed simultaneously by multiple viewing directions. While PDV determines the frequency shift utilizing an absorption measurement with the laser light stabilized on the slope of an iodine line FRS measures the residual light passing through the molecular filter with the laser frequency tuned to the absorption minimum. The main challenge arises from the fact that PDV relies on the scattered light by micron-sized particles added to the flow. The intensity of this Mie scattered light is orders of magnitude higher than the light scattered by molecules of the gas flow itself known as Rayleigh scattering. In order to be able to record both signals both simultaneously but separately two iodine cells with different operation conditions were used for each camera system. The necessary criteria for successful measurements is the sufficient suppression of the Mie scattered light by the FRS camera while maintaining a proper dynamic range for the Doppler shifted light recorded by the PDV camera system.The combined PDV – FRS system was optimized by arranging the observation directions for the velocity and temperature measurements separately. An evaluation of the combined system was performed with an analysis of measurements taken on a hot free jet. Although the PDV velocity data agree reasonably with the calculated value the performance of FRS system suffered from technical problems.

Document Type:Conference or Workshop Item (Paper)
Title:Combined filtered Rayleigh and Mie scattering for simultaneous planar temperature and velocity measurements
Authors:
AuthorsInstitution or Email of Authors
Stockhausen, Guidoguido.stockhausen@dlr.de
Doll, Ulrichulrich.doll@dlr.de
Strehlau, TobiasUNSPECIFIED
Willert, Christianchris.willert@dlr.de
Date:May 2010
Refereed publication:Yes
In ISI Web of Science:No
Status:Published
Keywords:Rayleigh scatter, Doppler velocimetry, flow field measurement, flow diagnostics, temperature field, iodine filter, molecular absorption filter
Event Title:15th Internation Symposium on Applications of Laser Techniques to Fluid Mechanics
Event Location:Lisbon, Portugal
Event Type:international Conference
Event Dates:05-08 Jul 2010
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Propulsion Systems
DLR - Research area:Aeronautics
DLR - Program:L ER - Engine Research
DLR - Research theme (Project):L - Virtual Engine and Validation Methods
Location: Köln-Porz
Institutes and Institutions:Institute of Propulsion Technology > Engine Measurement Systems
Deposited By: Dr.phil. Christian Willert
Deposited On:16 May 2011 12:45
Last Modified:12 Dec 2013 21:16

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