Open AccessRaman mixture composition and flow velocity imaging with high repetition rates
Author(s) -
Andreas Braeuer,
Sascha R. Engel,
Stefan Dowy,
S. Luther,
Jürgen Goldlücke,
Alfred Leipertz
Publication year - 2010
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.18.024579
Subject(s) - raman spectroscopy , optics , mixing (physics) , materials science , temporal resolution , raman scattering , signal (programming language) , volumetric flow rate , image resolution , flow velocity , tracer , laser , flow (mathematics) , physics , mechanics , quantum mechanics , computer science , nuclear physics , programming language
A novel and completely tracer free strategy to image composition and velocity fields during the mixing process of two liquids is introduced. The achieved temporal resolution, spatial resolution and sampling rate of 30 ns, 54 x 54 µm2 and 10 kHz, respectively, are sufficient to resolve Kolmogorov time and length scales as well as transient mixing phenomena of many technical mixing processes. During the injection of liquid water into liquid ethanol, mixing was quantitatively observed by means of high repetition rate Raman imaging using a laser cluster for the excitation of the Raman process with 8 successive light sheet pulses. One high speed camera was used to detect the CH-vibration Raman band signal of ethanol, while a second one was used to detect the OH-vibration Raman band signal of water and ethanol. From the ratio of both, the mixture composition field was computed. The dense flow field was determined by processing the mixture composition images with a variational optical flow method.