Three Component Laser-Doppler-Velocimeter Development for Large Wind Tunnel

Seelhorst, U.; Bütefisch, K.-A.; Sauerland, K.

doi:10.1109/iciasf.1993.687676

Cited by 8 publications

(5 citation statements)

References 1 publication

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“…7 (Refs. 19,20). Each of the laser beams was divided into two individual beams with similar intensity, one of them superimposed with a Bragg shift in the MHz range, to determine both velocity modulus and direction of each velocity component.…”

Section: Laser Doppler Velocimetry (Ldv) Measurementsmentioning

confidence: 99%

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Key Results From a Higher Harmonic Control Aeroacoustic Rotor Test (HART)

Splettstoesser¹,

Kube²,

Wagner³

et al. 1997

j am helicopter soc

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In a major cooperative research program within existing US-Gennan and US-French Memoranda of Understandings (MoU's) a comprehensive experimental study was conducted with a 40-percent geometrically and dynamically scaled B0-105 main rotor operated in the open-jet anechoic test section of the German-Dutch Wind Tunnel (DNW). The objectives of the program were to improve the physical understanding and the mathematical modelling of the effects of the higher harmonic blade pitch control technique on blade-vortex interaction (BY!) impulsive noise and vibration reduction. A unique set of acoustic, aerodynarnic, dynamic response, performance, and rotor wake data were acquired with a pressure and strain gauge instrumented blade and by application of non~intrusive measurement techniques.

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Section: Laser Doppler Velocimetry (Ldv) Measurementsmentioning

confidence: 99%

“…Other techniques (e.g. LDV) had to be improved with respect to extended measurement range and/or 3D capability and had to prove its functionality during wind tunnel pre-tests (Refs 19,20)…”

mentioning

confidence: 99%

Key Results From a Higher Harmonic Control Aeroacoustic Rotor Test (HART)

Splettstoesser¹,

Kube²,

Wagner³

et al. 1997

j am helicopter soc

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“…11,12 The measured data will be used to validate the prediction methodology and to set the future direction for code improvement.…”

Section: Introductionmentioning

confidence: 99%

Prediction and Measurement of Blade - Vortex Interaction

Tung

Kube

Brooks

et al. 1998

Journal of Aircraft

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An extensive quantity of airload measurements was obtained for a pressure-instrumented model of the BO-105 main rotor for a large number of higher harmonic control settings at Duits-Nederlandse Wind Tunnel. The wake geometry, vortex strength, and vortex core size were also measured through a laser light sheet technique and laser Doppler velocimetry. These results are used to verify the blade-vortex interaction (BVI) airload prediction methodologies developed by Army Aero ightdynamics Directorate, Deutsche Forschungsanstalt fur Luft-und Raumfahrt, NASA Langley Research Center, and the Of ce National d'Etudes et de Recherches Aerospatiales. The comparisons show that an accurate prediction of the blade motion and the wake geometry is the most important aspect of the BVI airload predictions. IntroductionA LTHOUGH the current civil helicopter has been used extensively because of its excellent hover and low-speed forward-ight capability, the civil helicopter eet continues to be too noisy for community acceptance, preventing it from reaching its full potential of utilization. One of the major noise sources comes from the rotor blade cutting through its own wake. This phenomenon is known as blade-vortex interaction (BVI). It occurs mostly during descent ight for landing.Over the last decade many experimental studies from fullscale ight tests 1,2 to model-scale tests 3-5 have been performed to investigate this BVI phenomenon. It was found that the BVI noise can be scaled 6,7 and expensive ight tests can be simulated by model rotor tests. The development of BVI prediction methodology lagged behind the experimental studies because no comprehensive rotor code had enough azimuthal (or time) resolution to predict the BVI event. However, several analytical methods 8,9 were developed with limited success as compared with measured blade surface pressure distributions and acoustic signatures. References 8 and 9 indicate that the wake geometry and vortex strength are two major parameters affecting the BVI noise signatures. The information of the wake geometry and vortex strength was not measured in most tests.An international cooperative test, called the higher-harmonic-control aeroacoustic rotor test (HART) was conducted by the Army Aero ightdynamics Directorate (AFDD), Deutsche Forschungsanstalt fur Luft-und Raumfahrt (DLR), Duits-Nederlandse Wind Tunnel (DNW), and the Of ce National d'Etudes et de Recherches Aerospatiales at DNW to measure not only the blade surface pressure distributions, the Presented as Paper 95-021 at the AIAA/CEAS 1st Joint blade deformation, and the acoustic signatures, but also the wake geometry using the laser light sheet (LLS) technique 10 and the vortex strength using the laser Doppler velocimetry (LDV ) method. 11,12 The measured data will be used to validate the prediction methodology and to set the future direction for code improvement.Analytical predictions of BVI events by AFDD, DLR, NASA, and ONERA were performed before the HART test. The predicted wake geometry served as a guide for the LLS and...

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“…The 3D-LDV system of the DLR Institute for Fluid Mechanics was operated in a back scatter, off-axis mode' 18 '. A 6 Watt argon-ion laser was used as a light source of which the three most intensive laser lines (476-5 nm, 488 nm, 514-5 nm) were utilised to distinguish the different velocity components (Fig.…”

Section: D-ldv Set-upmentioning

confidence: 99%

Vortical flow structures at a helicopter rotor model measured by LDV and PIV

Raffel

Seelhorst²,

Willert³

1998

Aeronaut. j.

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Flowfield measurements of the blade tip vortices from a rotating helicopter rotor model were performed by three component laser-Doppler velocimetry (3D-LDV) and conventional (two component) particle image velocimetry (PIV). In general, the results are in good correspondence, but also illustrate the different properties of both techniques: LDV offers the capability of three-component measurements, whereas PIV captures the unsteadyness of the flowfield.

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Three Component Laser-Doppler-Velocimeter Development for Large Wind Tunnel

Cited by 8 publications

References 1 publication

Key Results From a Higher Harmonic Control Aeroacoustic Rotor Test (HART)

Key Results From a Higher Harmonic Control Aeroacoustic Rotor Test (HART)

Prediction and Measurement of Blade - Vortex Interaction

Vortical flow structures at a helicopter rotor model measured by LDV and PIV

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