Doppler global velocimetry (DGV) is considered to be a useful optical measurement tool for acquiring flow velocity fields. Often near-wall measurements are required, which is still challenging due to errors resulting from background scattering and multiple-particle scattering. Since the magnitudes of both errors are unknown so far, they are investigated by scattering simulations and experiments. Multiple-particle scattering mainly causes a stochastic error, which can be reduced by averaging. Contrary to this, background scattering results in a relative systematic error, which is directly proportional to the ratio of the background scattered light power to the total scattered light power. After applying a correction method and optimizing the measurement arrangement, a subsonic flat plate boundary layer was successfully measured achieving a minimum wall distance of with a maximum relative error of 6%. The investigations reveal the current capabilities and perspectives of DGV for near-wall measurements.
© 2011 Optical Society of AmericaFull Article | PDF Article
OSA Recommended Articles
Appl. Opt. 39(10) 1505-1510 (2000)
Christian Cierpka, Sven Scharnowski, and Christian J. Kähler
Appl. Opt. 52(12) 2923-2931 (2013)
Robert L. McKenzie
Appl. Opt. 35(6) 948-964 (1996)