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Nozay, France

Milanovic I.M.,University of Hartford | Hammad K.J.,Dantec Dynamics Inc.
American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FEDSM | Year: 2010

Turbulent jets have been extensively studied in the past due to their fundamental importance and wide spread usage in numerous industrial processes to enhance momentum, heat and mass transfer. Most previous work focused on the far-field or self-similar region of the flow. However, the initial development region, where the flow is dominated by streamwise and large-scale, Kelvin-Helmholtz-type, structures, received far less attention. In the current study, Particle Image Velocimetry (PIV) was used to obtain reliable statistics in the near-field region of a turbulent submerged jet. The jet issued from an 84 diameter, D, long pipe which ensured fullydeveloped turbulent flow conditions at the outlet. The twodimensional flow field in the plane containing the jet axis was measured in the initial 8D region, for three Reynolds numbers: 14,602, 19,135, and 24,685. The selected Reynolds numbers overlap with the previously identified critical Reynolds number range, 10,000-20,000, where flow characteristics of a jet undergo a dramatic transition to a much more chaotic and wellmixed state or fully developed turbulence. Copyright © 2010 by ASME. Source

Hammad K.J.,Central Connecticut State University | Hammad K.J.,Dantec Dynamics Inc. | Milanovic I.,University of Hartford
Journal of Fluids Engineering, Transactions of the ASME | Year: 2011

An experimental investigation was performed to study the flow structure of a submerged water jet impinging normally on a smooth and flat surface using particle image velocimetry (PIV). The jet issued from a 112 diameter long pipe which ensured fully developed turbulent flow conditions at the outlet. A semiconfined setting provided properly characterized flow boundary conditions. The Reynolds number based on jet mean exit velocity was Re = 15,895. The pipe-to-plate separation was varied between 1 and 8 pipe diameters. The current study focused on characterizing the flow structure close to the pipe outlet, in the impingement and wall-jet regions. Statistically averaged mean and RMS velocities are reported for a 6D wide and 1D high, near-plate, rectangular region. © 2011 American Society of Mechanical Engineers. Source

Schreyer A.-M.,French National Center for Space Studies | Lasserre J.J.,Dantec Dynamics Inc. | Dupont P.,Aix - Marseille University
Experiments in Fluids | Year: 2015

A new Dual-particle image velocimetry (Dual-PIV) system for application in supersonic flows was developed. The system was designed for shock wave/turbulent boundary layer interactions with separation. This type of flow places demanding requirements on the system, from the large range of characteristic frequencies O(100 Hz–100 kHz) to spatial and temporal resolutions necessary for the measurement of turbulent quantities (Dolling in AIAA J 39(8):1517–1531, 2001; Dupont et al. in J Fluid Mech 559:255–277, 2006; Smits and Dussauge in Turbulent shear layers in supersonic flow, 2nd edn. Springer, New York, 2006). While classic PIV systems using high-resolution CCD sensors allow high spatial resolution, these systems cannot provide the required temporal resolution. Existing high-speed PIV systems provide temporal and CMOS sensor resolutions, and even laser pulse energies, that are not adapted to our needs. The only obvious solution allowing sufficiently high spatial resolution, access to high frequencies, and a high laser pulse energy is a multi-frame system: a Dual-PIV system, consisting of two synchronized PIV systems observing the same field of view, will give access to temporal characteristics of the flow. The key technology of our system is frequency-based image separation: two lasers of different wavelengths illuminate the field of view. The cross-pollution with laser light from the respective other branches was quantified during system validation. The overall system noise was quantified, and the prevailing error of only 2 % reflects the good spatial and temporal alignment. The quality of the measurement system is demonstrated with some results on a subsonic jet flow including the spatio-temporal inter-correlation functions between the systems. First measurements in a turbulent flat-plate boundary layer at Mach 2 show the same satisfactory data quality and are also presented and discussed. © 2015, Springer-Verlag Berlin Heidelberg. Source

A velocimetry system for measuring the velocity of a moving body propagating through a measurement volume includes a light source for emitting a light beam, a controller for generating a modulation pattern corresponding to a desired set of fringes to be generated in the measurement volume, and a spatial light modulator operatively connected to the controller to receive therefrom the modulation pattern. The spatial light modulator is configured to spatially modulate the light beam according to the modulation pattern in order to generate the desired set of fringes in the measurement volume. Also provided are a light detector for measuring the energy of the light scattered by the moving body as it intersects the fringes, and a data analysis unit operatively connected to the light detector and adapted to determine the velocity of the moving body from at least one fringe characteristic and the energy of the scattered light measured.

Dantec Dynamics Inc. | Date: 2014-09-30

Particle dynamics analyzer systems and components thereof namely lenses, filters and photomultipliers, electronic and electro-mechanical components.

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