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Anemometry

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A. Rieu – One of the best experts on this subject based on the ideXlab platform.

  • frequency modulated multifunction lidar for Anemometry range finding and velocimetry 1 theory and signal processing
    Applied Optics, 2017
    Co-Authors: Patrick Feneyrou, Luc Leviandier, J. Minet, Grégoire Pillet, A. Martin, Daniel Dolfi, Jean-pierre Schlotterbeck, Philippe Rondeau, Xavier Lacondemine, A. Rieu

    Abstract:

    Original waveforms and optimized signal processing are proposed for frequency-modulated continuous-wave lidar for range finding, velocimetry, and laser Anemometry. For range finding, the aim of this signal processing is to extend lidar range and reduce ambiguities. Moreover, the effect of moderate atmospheric turbulence on lidar efficiency is analyzed for infinite and finite targets, taking into account wind-induced bistatism. For laser Anemometry, the aim is to measure air speed at the shortest distance farther than the rotor-induced turbulent volume around the helicopter and to avoid parasitic echoes coming from clouds or hard targets in the vicinity of a helicopter.

  • Frequency-modulated multifunction lidar for Anemometry, range finding, and velocimetry-2. Experimental results.
    Applied Optics, 2017
    Co-Authors: Patrick Feneyrou, Luc Leviandier, J. Minet, Grégoire Pillet, A. Martin, Daniel Dolfi, Jean-pierre Schlotterbeck, Philippe Rondeau, Xavier Lacondemine, A. Rieu

    Abstract:

    Frequency-modulated continuous-wave lidar is evaluated for range finding, velocimetry, and laser Anemometry. An original signal processing and waveform calibration for range finding leads to a reduction of computational effort while preserving capability for long-range measurement. Multiple target distance measurement is also demonstrated. For laser Anemometry, the aim is to avoid parasitic echoes in the vicinity of a helicopter and to measure the air speed at the shortest distance farther than the rotor-induced turbulent volume around the helicopter. Flight tests of this functionality and vortex ring state warning are demonstrated.

  • Frequency-modulated multifunction lidar for Anemometry, range finding, and velocimetry–1. Theory and signal processing
    Applied Optics, 2017
    Co-Authors: Patrick Feneyrou, Luc Leviandier, J. Minet, Grégoire Pillet, A. Martin, Daniel Dolfi, Jean-pierre Schlotterbeck, Philippe Rondeau, Xavier Lacondemine, A. Rieu

    Abstract:

    Original waveforms and optimized signal processing are proposed for frequency-modulated continuous-wave lidar for range finding, velocimetry, and laser Anemometry. For range finding, the aim of this signal processing is to extend lidar range and reduce ambiguities. Moreover, the effect of moderate atmospheric turbulence on lidar efficiency is analyzed for infinite and finite targets, taking into account wind-induced bistatism. For laser Anemometry, the aim is to measure air speed at the shortest distance farther than the rotor-induced turbulent volume around the helicopter and to avoid parasitic echoes coming from clouds or hard targets in the vicinity of a helicopter.

Detlef Lohse – One of the best experts on this subject based on the ideXlab platform.

  • phase sensitive constant temperature Anemometry
    Macromolecular Materials and Engineering, 2011
    Co-Authors: Thomas H. Van Den Berg, Stefan Luther, Willem D Wormgoor, Detlef Lohse

    Abstract:

    Hot-film measurements in bubbly flows provide time series that contain information about the liquid and the gas phase. Signal classification is required to disentangle the corresponding segments. The classification algorithms are prone to detection bias, which makes hot-film measurements in two-phase flows very difficult. We present a new phase-sensitive hot-film probe that provides velocity data and optical phase classification in a single device. We report a proof of concept of this method and demonstrate its accuracy and robustness. Furthermore, we discuss its application to turbulent bubbly flows

  • Data analysis for hot-film Anemometry in turbulent bubbly flow
    Experimental Thermal and Fluid Science, 2005
    Co-Authors: Stefan Luther, J.m. Rensen, Thomas H. Van Den Berg, Detlef Lohse

    Abstract:

    We report on a new method for the analysis of hot-film Anemometry in turbulent bubbly flows based on stochastic pattern recognition summarizing our results of [J.M. Rensen, S. Luther, J. de Vries, D. Lohse, Hot-film Anemometry in bubbly flow I: bubble–probe interaction, in press; S. Luther, J. Rensen, Hot-film Anemometry in bubbly flow II: local phase discrimination, in press; J.M. Rensen, S. Luther, D. Lohse, Velocity structure functions in turbulent two-phase flows, J. Fluid Mech., in press]. It consists of an optimal signal decomposition using an adaptive wavelet transform and neural network based classification. We discuss the application of autoregressive models to obtain energy spectra for gapped time series.

Fabrice Onofri – One of the best experts on this subject based on the ideXlab platform.

  • Glare Spot Phase Doppler Anemometry
    AIP Conference Proceedings, 2007
    Co-Authors: Camille Hespel, Kuan Fang Ren, Gérard Gréhan, Fabrice Onofri

    Abstract:

    The Phase Doppler Anemometry has been developed to measure simultaneously the velocity and the size of droplets. The measurement of the refractive index would be also interesting since it depends on the temperature and the composition of the particle and its measurement permits both to increase the quality of the diameter measurement and to obtain information on the temperature and/or the composition of the droplets. In this paper, we introduce a Glare Spot Phase Doppler Anemometry which uses two large beams. In this case, the images of the particle formed by the reflected and refracted light, known as glare spots, are separated in space. When a particle passes in the probe volume, the two parts in a signal obtained by a detector in forward direction are then separated in time. If two detectors are used the phase differences between two signals, the distance and the intensity ratio of reflected and refracted parts can be obtained and they provide rich information about the particle diameter and its refrac…

  • Glare Spot Phase Doppler Anemometry
    , 2006
    Co-Authors: Camille Hespel, Kuan Fang Ren, Gérard Gréhan, Fabrice Onofri

    Abstract:

    The Phase Doppler Anemometry has been developed to measure simultaneously the velocity and the size of droplets. The measurement of the refractive index is also necessary since it depends on the temperature and the composition of the particle and its measurement permits both to increase the quality of the diameter measurement and to obtain information on the temperature and/or the composition of the droplets. In this paper, we introduce a Glare Spot Phase Doppler Anemometry which uses two large beams. In this case, the images of the particle formed by the reflected and refracted light, known as glare spots, are separated in space. When a particle passes in the probe volume, the two parts in a signal obtained by a detector in forward direction are then separated in time. If two detectors are used the phase differences between two signals, the distance and the intensity ratio of reflected and refracted parts can be obtained and they provide rich information about the particle diameter and its refractive index, as well as its velocity. This paper is devoted to the numerical study of such a configuration with two theoretical models: geometrical optics and rigorous electromagnetism solution.