Abstract
In the present study, Long-range Microparticle Image Velocimetry (\(\upmu\)PIV) and Differential Interferometry (DI) are combined in a novel manner to enable both velocity and depth-integrated density gradient field measurements using the same laser pulse for both recordings. In the present work, temperature-driven boundary layer flows could be successfully determined to an accuracy of \(\Updelta T=0.17\,\hbox {K}\) with a spatial resolution of \(405\,\upmu \hbox {m}\) for interference and \(101\,\upmu \hbox {m}\) for \(\upmu\)PIV measurements. The DI measurements are refraction compensated, and both temperature and velocity fields are compared with results from numerical simulations.
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Abbreviations
- \(\alpha\) :
-
Fringe orientation angle
- \(\bar{\rho }\) :
-
Depth-averaged density
- \(\beta\) :
-
Divergence angle of Wollaston Prism
- \(\delta\) :
-
Standard deviation
- \(\delta _{ref}\) :
-
Deviation related to reference density gradient
- \(\eta ,\zeta\) :
-
Cartesian coord. aligned with reference fringes
- \(\lambda\) :
-
Wavelength of light
- \(\rho\) :
-
Density
- \(\Updelta S\) :
-
Fringe shift
- \(\Updelta x\) :
-
Distance along x-axis
- \(\Updelta x_{r}\) :
-
Refraction-induced light ray shift
- \(\Updelta y\) :
-
Distance along y-axis
- b :
-
Measurement volume thickness
- d :
-
Neighbouring light ray distance
- dt :
-
Interframing time
- f :
-
Focal length
- I :
-
Laser intensity
- K :
-
Gladstone Dale constant
- L :
-
Distance between test section and lens
- Nu :
-
Nusselt number
- p :
-
Pressure
- S :
-
Homogeneous fringe spacing
- T :
-
Temperature
- t :
-
Time
- v :
-
Velocity
- W :
-
Distance between Wollaston prism and focal point
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This research was financially supported by DFG (HU 2264/1-1).
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An erratum to this article can be found at http://dx.doi.org/10.1007/s00348-016-2259-9.
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Kordel, S., Nowak, T., Skoda, R. et al. Combined density gradient and velocity field measurements in transient flows by means of Differential Interferometry and Long-range \(\varvec{\upmu }\)PIV. Exp Fluids 57, 138 (2016). https://doi.org/10.1007/s00348-016-2224-7
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DOI: https://doi.org/10.1007/s00348-016-2224-7