scholarly journals Spatio-Temporal Changes in the Turbulent Kinetic Energy of a Rectangular Jet Impinging on a Slotted Plate Analyzed with High Speed 3D Tomographic-Particle Image Velocimetry

2019 ◽  
Vol 37 (4) ◽  
pp. 1071-1079 ◽  
Author(s):  
Hassan Assoum ◽  
Jana Hamdi ◽  
Kamel Abed-Meraïm ◽  
Marwan Al Kheir ◽  
Tarek Mrach ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
High Speed ◽  
Particle Image ◽  
Temporal Changes ◽  
Tomographic Particle Image Velocimetry ◽  
Rectangular Jet ◽  
Image Velocimetry ◽  
Spatio Temporal

scholarly journals Turbulent kinetic energy and self-sustaining tones: Experimental study of a rectangular impinging jet using high Speed 3D tomographic Particle Image Velocimetry

2020 ◽  
Vol 14 (1) ◽  
pp. 6322-6333
Author(s):  
Hassan Hasan Assoum ◽  
Jana Hamdi ◽  
Mouhammad El Hassan ◽  
Kamel Abed-Meraim ◽  
M. El Kheir ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Energy Transfer ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Acoustic Signal ◽  
Particle Image ◽  
Tomographic Particle Image Velocimetry ◽  
Rectangular Jet ◽  
Image Velocimetry ◽  
Slotted Plate

Impinging jets are widely used in ventilation systems to improve the mixing and diffusion of airflows. When a rectangular jet hits a slotted plate, an acoustic disturbance can be generated and self-sustained tones produced. Few studies have looked at the Turbulent Kinetic Energy (TKE) produced by the aerodynamic field in such configurations and in the presence of self-sustaining tones. The aim of this work is to investigate the energy transfer between the aerodynamic and acoustic fields generated in a rectangular jet impinging on a slotted plate. The present paper methodology is based on experimental data measurements using 3D tomographic Particle Image Velocimetry (PIV) technique and microphones. It was found that the spectrum of the TKE for Re=5294 (configuration of self-sustained tones) is    which is smaller than that of the acoustic signal . A negative peak of correlation  is obtained between the acoustic signal and TKE for   These results may lead to conclude that the acoustic cycle should be covered by the TKE period and the two signals of both fields are in opposition of phase in order to obtain an optimal configuration for energy transfer.

scholarly journals Tomographic particle image velocimetry of desert locust wakes: instantaneous volumes combine to reveal hidden vortex elements and rapid wake deformation

2012 ◽  
Vol 9 (77) ◽  
pp. 3378-3386 ◽  
Author(s):  
Richard J. Bomphrey ◽  
Per Henningsson ◽  
Dirk Michaelis ◽  
David Hollis
Keyword(s):  
Particle Image Velocimetry ◽  
High Speed ◽  
Particle Image ◽  
Aerodynamic Force ◽  
Three Dimensional ◽  
Flow Fields ◽  
Diagnostic Methods ◽  
Tomographic Particle Image Velocimetry ◽  
Image Velocimetry ◽  
Spatio Temporal

Aerodynamic structures generated by animals in flight are unstable and complex. Recent progress in quantitative flow visualization has advanced our understanding of animal aerodynamics, but measurements have hitherto been limited to flow velocities at a plane through the wake. We applied an emergent, high-speed, volumetric fluid imaging technique (tomographic particle image velocimetry) to examine segments of the wake of desert locusts, capturing fully three-dimensional instantaneous flow fields. We used those flow fields to characterize the aerodynamic footprint in unprecedented detail and revealed previously unseen wake elements that would have gone undetected by two-dimensional or stereo-imaging technology. Vortex iso-surface topographies show the spatio-temporal signature of aerodynamic force generation manifest in the wake of locusts, and expose the extent to which animal wakes can deform, potentially leading to unreliable calculations of lift and thrust when using conventional diagnostic methods. We discuss implications for experimental design and analysis as volumetric flow imaging becomes more widespread.

Experimental Investigation of Unsteady Flow Field Within a Two Stage Axial Turbomachine Using Particle Image Velocimetry

2002 ◽  
Author(s):  
Oguz Uzol ◽  
Yi-Chih Chow ◽  
Joseph Katz ◽  
Charles Meneveau
Keyword(s):  
Particle Image Velocimetry ◽  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Particle Image ◽  
Energy Levels ◽  
Shear Stresses ◽  
Image Velocimetry ◽  
Entire Flow ◽  
The Difference

Detailed measurements of the flow field within the entire 2nd stage of a two stage axial turbomachine are performed using Particle Image Velocimetry. The experiments are performed in a facility that allows unobstructed view on the entire flow field, facilitated using transparent rotor and stator and a fluid that has the same optical index of refraction as the blades. The entire flow field is composed of a “lattice of wakes”, and the resulting wake-wake and wake-blade interactions cause major flow and turbulence non-uniformities. The paper presents data on the phase averaged velocity and turbulent kinetic energy distributions, as well as the average-passage velocity and deterministic stresses. The phase-dependent turbulence parameters are determined from the difference between instantaneous and the phase-averaged data. The distributions of average-passage flow field over the entire stage in both the stator and rotor frames of reference are calculated by averaging the phase-averaged data. The deterministic stresses are calculated from the difference between the phase-averaged and average-passage velocity distributions. Clearly, wake-wake and wake-blade interactions are the dominant contributors to generation of high deterministic stresses and tangential non-uniformities, in the rotor-stator gap, near the blades and in the wakes behind them. The turbulent kinetic energy levels are generally higher than the deterministic kinetic energy levels, whereas the shear stress levels are comparable, both in the rotor and stator frames of references. At certain locations the deterministic shear stresses are substantially higher than the turbulent shear stresses, such as close to the stator blade in the rotor frame of reference. The non-uniformities in the lateral velocity component due to the interaction of the rotor blade with the 1st stage rotor-stator wakes, result in 13% variations in the specific work input of the rotor. Thus, in spite of the relatively large blade row spacings in the present turbomachine, the non-uniformities in flow structure have significant effects on the overall performance of the system.

scholarly journals Single sensor fiber-based high-speed tomographic particle image velocimetry

2019 ◽  
Vol 44 (11) ◽  
pp. 2748 ◽  
Author(s):  
Jonathan Reyes ◽  
Darin Knaus ◽  
Danny Micka ◽  
Brynmor Davis ◽  
Vincent Belovich ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
High Speed ◽  
Particle Image ◽  
Tomographic Particle Image Velocimetry ◽  
Image Velocimetry ◽  
Single Sensor

Scaled Room Three-Dimensional Velocity Measurements Using Particle Image Velocimetry

2002 ◽  
Author(s):  
Steven P. O’Halloran ◽  
B. Terry Beck ◽  
Mohammad H. Hosni ◽  
Thomas P. Gielda
Keyword(s):  
Particle Image Velocimetry ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Particle Image ◽  
Three Dimensional ◽  
Stereoscopic Particle Image Velocimetry ◽  
Measurement Information ◽  
Velocity Measurements ◽  
Image Velocimetry ◽  
Equipment Configuration

A stereoscopic particle image velocimetry (PIV) system was used to measure flow within a one-tenth-scale room. The dimensions of the scaled room were 732 × 488 × 274 mm (28.8 × 19.2 × 10.8 in.). The measurements were made under isothermal conditions and water was used as the fluid instead of air. Six equally spaced vertical planes along the length of the room were captured and symmetry was utilized so that measurements were only made on one side of the room. A sample size of 50 pairs of PIV images were collected and averaged to determine average velocity. Turbulent kinetic energy was also calculated from the collected data. The equipment configuration, measurement information and the velocity and turbulent kinetic energy results are presented in this paper. The measurements provide detailed three dimensional velocity profiles that could be used to validate numerical simulations.

Turbulence Measurements at the Inlet of an Automotive Turbocharger Compressor using Stereoscopic Particle Image Velocimetry

2021 ◽  
pp. 1-50
Author(s):  
Deb Banerjee ◽  
Rick Dehner ◽  
Ahmet Selamet
Keyword(s):  
Particle Image Velocimetry ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Mass Flow ◽  
Particle Image ◽  
Stereoscopic Particle Image Velocimetry ◽  
Flow Rates ◽  
Image Velocimetry ◽  
Compressor Inlet ◽  
The Mean

Abstract The present work uses Stereoscopic Particle Image Velocimetry (SPIV) to analyze the compressor inlet flow field, with specific emphasis on its turbulence characteristics during flow reversal in order to gain further insight into the inlet flow structures. SPIV experiments were carried out at the inlet of a centrifugal compressor without any recirculation channel at four different rotational speeds (from 80 to 140 krpm) and over the entire mass flow range (from choke to surge) at each speed. Detailed analyses have been carried out for the mean velocity field, the mean vorticity field, and the turbulent statistics including turbulent kinetic energy, Reynolds stress, and the one-dimensional energy spectra. The turbulent kinetic energy at the compressor inlet was observed to increase rapidly along a speed line with decreasing mass flow rate once flow separation started, and the turbulence became more anisotropic. As the flow rate was reduced (along a speed line), the zone with maximum turbulent kinetic energy moved from the periphery toward the center of the inlet duct and also occurred further upstream from the impeller. The Reynolds stress distributions suggest that the Boussinesq assumption of an isotropic eddy viscosity may not be appropriate after the detection of flow reversal. The Reynolds shear stresses were observed to change signs with their corresponding velocity gradients at the tested mass flow rates at different rotational speeds. At the investigated flow rates, the radial gradients in the axial and tangential velocities were found to be most dominant.

Experimental Investigation of Unsteady Flow Field Within a Two-Stage Axial Turbomachine Using Particle Image Velocimetry

2002 ◽  
Vol 124 (4) ◽  
pp. 542-552 ◽  
Author(s):  
Oguz Uzol ◽  
Yi-Chih Chow ◽  
Joseph Katz ◽  
Charles Meneveau
Keyword(s):  
Particle Image Velocimetry ◽  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Particle Image ◽  
Energy Levels ◽  
Shear Stresses ◽  
Image Velocimetry ◽  
Entire Flow ◽  
The Difference

Detailed measurements of the flow field within the entire 2nd stage of a two-stage axial turbomachine are performed using particle image velocimetry. The experiments are performed in a facility that allows unobstructed view on the entire flow field, facilitated using transparent rotor and stator and a fluid that has the same optical index of refraction as the blades. The entire flow field is composed of a “lattice of wakes,” and the resulting wake-wake and wake-blade interactions cause major flow and turbulence nonuniformities. The paper presents data on the phase averaged velocity and turbulent kinetic energy distributions, as well as the average-passage velocity and deterministic stresses. The phase-dependent turbulence parameters are determined from the difference between instantaneous and the phase-averaged data. The distributions of average passage flow field over the entire stage in both the stator and rotor frames of reference are calculated by averaging the phase-averaged data. The deterministic stresses are calculated from the difference between the phase-averaged and average-passage velocity distributions. Clearly, wake-wake and wake-blade interactions are the dominant contributors to generation of high deterministic stresses and tangential nonuniformities, in the rotor-stator gap, near the blades and in the wakes behind them. The turbulent kinetic energy levels are generally higher than the deterministic kinetic energy levels, whereas the shear stress levels are comparable, both in the rotor and stator frames of references. At certain locations the deterministic shear stresses are substantially higher than the turbulent shear stresses, such as close to the stator blade in the rotor frame of reference. The nonuniformities in the lateral velocity component due to the interaction of the rotor blade with the 1st-stage rotor-stator wakes, result in 13 percent variations in the specific work input of the rotor. Thus, in spite of the relatively large blade row spacings in the present turbomachine, the nonuniformities in flow structure have significant effects on the overall performance of the system.

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