Imaging laser Doppler velocimetry

Meier, Alexander; Roesgen, T.

doi:10.1007/s00348-011-1192-1

Cited by 17 publications

(13 citation statements)

References 13 publications

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“…Standard LDA systems yield a point-wise measurement, which objects the requirement of an imaging technique. Enhanced LDA sensor principles with a linear (known as profile sensor) and planar (known as field sensor) measurement volume have been presented (Voigt et al, 2008;Meier and Roesgen, 2012). However, for all LDA principles the measurement rate equals the random particle rate passing the measurement volume observed by one detector element.…”

Section: State Of the Artmentioning

confidence: 99%

High-speed camera-based measurement system for aeroacoustic investigations

Gürtler

Haufe

Schulz

et al. 2016

J. Sens. Sens. Syst.

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Abstract. The interaction of sound and flow enables an efficient noise damping. Inevitable for understanding of this aeroacoustic damping phenomenon is the simultaneous measurement of flow and sound fields. Optical sensor systems have the advantage of non-contact measurements. The necessary simultaneous determination of sound levels and flow velocities with high dynamic range has major hurdles. We present an approach based on frequency-modulated Doppler global velocimetry, where a high-speed CMOS camera with data rates over 160 MSamples s −1 of velocity samples is employed. Using the proposed system, two-component flow velocity measurements are performed in a three-dimensional region of interest with a spatial resolution of 224 µm, based on single-pixel evaluation, and a measurement rate of 10 kHz. The sensor system can simultaneously capture sound and turbulent flow velocity oscillations down to a minimal power density of 40.5 (mm s −1 ) 2 Hz −1 in a frequency range up to 5 kHz. The presented measurements of the interaction of sound and flow support the hypothesis that the sound energy is transferred into flow energy.

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Section: State Of the Artmentioning

confidence: 99%

High-speed camera-based measurement system for aeroacoustic investigations

Gürtler

Haufe

Schulz

et al. 2016

J. Sens. Sens. Syst.

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“…Measurements of phase [3][4][5], beam deflection [6,7], pulse arrival time [8], Doppler shift [9,10], and velocity [11][12][13][14] are all fundamentally bounded by a CRB. If a measurement technique reaches the CRB, its estimator is said to be efficient.…”

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confidence: 99%

Weak-values technique for velocity measurements

et al. 2013

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In a recent Letter, Brunner and Simon proposed an interferometric scheme using imaginary weak values with a frequency-domain analysis to outperform standard interferometry in longitudinal phase shifts [Phys. Rev. Lett105, 010405 (2010)]. Here we demonstrate an interferometric scheme combined with a time-domain analysis to measure longitudinal velocities. The technique employs the near-destructive interference of non-Fourier limited pulses, one Doppler shifted due to a moving mirror in a Michelson interferometer. We achieve a velocity measurement of 400 fm/s and show our estimator to be efficient by reaching its Cramér-Rao bound.

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“…In order to overcome this drawback and to yield 2d flow measurements, an imaging optic with a high-speed camera or a smart pixel detector array for the photo detection can be applied together with intersecting light sheets for the illumination. This technique was introduced as imaging laser Doppler velocimetry (ILDV) by Meier and Rösgen in 2012 [96]. The experimental setup is similar to the HDGV experiments.…”

Section: Frequency-based Signal Evaluationmentioning

confidence: 99%

Imaging Flow Velocimetry with Laser Mie Scattering

Fischer

2017

Applied Sciences

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Abstract:Imaging flow velocity measurements are essential for the investigation of unsteady complex flow phenomena, e.g., in turbomachines, injectors and combustors. The direct optical measurement on fluid molecules is possible with laser Rayleigh scattering and the Doppler effect. However, the small scattering cross-section results in a low signal to noise ratio, which hinders time-resolved measurements of the flow field. For this reason, the signal to noise ratio is increased by using laser Mie scattering on micrometer-sized particles that follow the flow with negligible slip. Finally, the ongoing development of powerful lasers and fast, sensitive cameras has boosted the performance of several imaging methods for flow velocimetry. The article describes the different flow measurement principles, as well as the fundamental physical measurement limits. Furthermore, the evolution to an imaging technique is outlined for each measurement principle by reviewing recent advances and applications. As a result, the progress, the challenges and the perspectives for high-speed imaging flow velocimetry are considered.

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Imaging laser Doppler velocimetry

Cited by 17 publications

References 13 publications

High-speed camera-based measurement system for aeroacoustic investigations

High-speed camera-based measurement system for aeroacoustic investigations

Weak-values technique for velocity measurements

Imaging Flow Velocimetry with Laser Mie Scattering

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