Analysis of free jet turbulence with cross-correlation light-in-flight holography

Geiger, Mark L.; Herrmann, Sven F; Peinke, Joachim; Hinsch, Klaus D.

doi:10.1002/1617-7061(200203)1:1<304::aid-pamm304>3.0.co;2-r

Cited by 3 publications

(2 citation statements)

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“…The exact spatial orientation and depth position of each of the 2D2C velocity maps is obtained from a reference hologram of a regular planar grid placed under a tilted angle, thus all maps can be rearranged into a single 3D2C map. First results have been obtained in a free jet in air during measurements in the region of transition to turbulence (Geiger et al 2000). Up to 21 planes were obtained from which the inner 18 were used to evaluate 64.800 velocity vectors.…”

Section: Double-pulse Ruby Laser: Cross-correlation Evaluationcontrasting

confidence: 41%

Advances in Light-in-Flight HPIV for the Study of Wind Tunnel Flows

Herrmann

Hinsch

2004

Particle Image Velocimetry: Recent Improvements

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The concept of light-in-flight holographic particle image velocimetry (LiF-HPIV) has been demonstrated successfully for ruby laser light illumination and virtual-image reconstruction. To circumvent the many disadvantages of ruby lasers the method was transferred to illumination with pulsed second-harmonic Nd:YAG-laser light. Furthermore, real-image interrogation was employed to minimize alignment and calibration problems. By using cw Nd:YAG lasers it is possible to design an optical setup for the reconstruction that is separate from the recording equipment. Thus, the time-consuming interrogations no longer block the flow measurements.

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Section: Double-pulse Ruby Laser: Cross-correlation Evaluationcontrasting

confidence: 41%

Advances in Light-in-Flight HPIV for the Study of Wind Tunnel Flows

Herrmann

Hinsch

2004

Particle Image Velocimetry: Recent Improvements

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“…The background of holographic particle images is therefore reduced considerably. This method has been applied successfully to the investigation of flows in a small wind tunnel (Hinrichs et al 1998) and in the transition region of a free air jet (Geiger et al 2000). These experiments have been performed with a double-pulsed ruby laser-a light source of high energy but which has many disadvantages.…”

Section: Light-in-flight Holography For Flow Analysismentioning

confidence: 99%

Light-in-flight holographic particle image velocimetry for wind-tunnel applications

Herrmann

Hinsch

2004

Meas. Sci. Technol.

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Holographic particle imaging techniques for air-flow investigations are mainly limited to small-scale laboratory experiments. The two main reasons are the limited light power available in conjunction with small tracer-particle sizes, which must be in the order of 1 µm to properly probe air flows, and the increased background noise from out-of-focus particles in deep volumes preventing investigations with higher particle densities. To ensure a good accuracy of the velocity measurements by faithful reconstruction geometry, the evaluation of particle images is often conducted in the original recording setup. The time-consuming scanning process, however, blocks the flow facility during evaluation-a disadvantage for measurements in costly industrial wind tunnels. For an alternative, we have introduced off-site reconstruction and evaluation. In recent papers (

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Holographic Particle Image Velocimetry

Hinsch¹,

Herrmann²

2004

Meas. Sci. Technol.

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The articles in this special feature of Measurement Science and Technology are devoted to an exciting area of fluid metrology pursuing the registration of flow velocities in three dimensions by particle holography—commonly termed holographic particle image velocimetry (HPIV) (Hinsch 2002). Already in 1993 this technique was considered to 'revolutionize the acquisition of velocity data in much the same way as did the inventions of hot wire anemometry and laser Doppler velocimetry' as E P Rood states in his foreword to the proceedings of the first workshop dedicated to the topic at the Washington ASME Fluid Engineering Conference (Rood 1993). The big step forward is to eliminate most of the depth-of-focus restrictions of classical PIV by a holographic recording of tracer particles. Thus, even non-stationary flows can be registered in a single record.A central concern of the early days was to explore optical set-ups suitable for improving particle-position resolution by using large recording apertures and for suppressing coherent noise. Furthermore, the evaluation of the holographic images required efficient hardware and software to scan and process the coordinates of particle images in a reasonable time. A sophisticated system relying on the state-of-the art experience and the utmost in processing hardware was producing first fields of thousands of three-dimensional velocity vectors (Barnhart et al 1994). Much profound research work on the main issues has been carried out in the meantime. Advances toward practical systems, however, needed fuelling by the recent technological developments of high-energy pulsed lasers and electronic image acquisition as well as the increasing performance of digital image processing.This recent progress led to a session on HPIV during the international PIV'01 conference at Göttingen, Germany (Kompenhans 2001), the creation of a worldwide working group (photon.physik.uni-oldenburg.de/hpiv) and in May 2003 an international workshop on holographic metrology in fluid mechanics at Loughborough University, UK (Coupland 2003). These workshop presentations have been elaborated and supplemented in the present special feature.The holographic velocimetry work presented here can be grouped into two sections according to the type of hologram recording—using either a physical carrier material or an electronic image sensor. Most researchers still use the somewhat anachronistic silver-halide emulsion of photographic film, especially when high resolving power is needed as in several application-specific topics. It offers still an unequalled resolution of up to 5000 line-pairs/mm at reasonable sensitivities to record even the low-power light scattered by tiny tracer particles, yet it requires laborious wet chemical processing.A good impression of the huge amount of data that can be stored on photographic film and the immense effort needed to analyse the reconstructed holographic images is given in the paper by E Malkiel et al. A straightforward in-line recording layou...

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Analysis of free jet turbulence with cross-correlation light-in-flight holography

Cited by 3 publications

References 1 publication

Advances in Light-in-Flight HPIV for the Study of Wind Tunnel Flows

Advances in Light-in-Flight HPIV for the Study of Wind Tunnel Flows

Light-in-flight holographic particle image velocimetry for wind-tunnel applications

Holographic Particle Image Velocimetry

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