Simultaneous PIV/PTV velocimetry technique in a turbulent particle-laden flow

Elhimer, Mehdi; Praud, Olivier; Marchal, Moïse; Cazin, Sébastien; Bazile, R.

doi:10.1007/s12650-016-0397-z

Cited by 25 publications

(9 citation statements)

References 34 publications

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“…Experimental observations and numerical simulations of particle settling in homogeneous and isotropic turbulence with a vanishing mean flow velocity have evidenced that the turbulence is to enhance the terminal fall velocity [81][82][83][84][85][86][87][88][89]. However, a few studies reported that the terminal fall velocity reduces in moderately weak turbulence [90][91][92].…”

Section: (B) Effects Of Hindered Settlingmentioning

confidence: 99%

Terminal fall velocity: the legacy of Stokes from the perspective of fluvial hydraulics

2019

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This review article, dedicated to the bicentenary celebration of Sir George Gabriel Stokes' birthday, presents the state-of-the-science of terminal fall velocity, highlighting his rich legacy from the perspective of fluvial hydraulics. It summarizes the fluid drag on a particle and the current status of the drag coefficient from both the theoretical and empirical formulations, highlighting the three major realms-Stokesian, transitional and Newtonian realms. The force system that drives the particle motion falling through a fluid is described. The response of terminal fall velocity to key factors, which include particle shape, hindered settling and turbulence (nonlinear drag, vortex trapping, fast tracking and effects of loitering), is delineated. The article puts into focus the impact of terminal fall velocity on fluvial hydraulics, discussing the salient role that the terminal fall velocity plays in governing the hydrodynamics of the sediment threshold, bedload transport and suspended load transport. Finally, an innovative perspective is presented on the subject's future research track, emphasizing open questions.

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Section: (B) Effects Of Hindered Settlingmentioning

confidence: 99%

Terminal fall velocity: the legacy of Stokes from the perspective of fluvial hydraulics

2019

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“…The goal of this work is to simultaneously measure the gas and particle velocities using particle image velocimetry (PIV) and particle tracking velocimetry (PTV), which has been conducted before in incompressible flows. Previous simultaneous PIV/PTV measurements have used dual-camera systems with optical discrimination Elhimer et al (2016) and single-camera systems with image segmentation of raw images Kiger and Pan (2000) to obtain both particle and velocity fields. Using our ultra-high-speed diagnostics systems, we plan to extend the simultaneous PIV/PTV technique to the compressible flow regime.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous two-phase flow measurements in a high-speed particle-laden under-expanded jet

Diaz-Lopez¹,

Rubio²,

Ni³

2021

ISPIV21

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The objective of this study is to understand the dynamics of a high-speed particle-laden under-expanded jet, motivated by landings on extraterrestrial bodies. In this setup, inertial particles are entrained and accelerated by an under-expanded jet. But, due to their inertia, the particle velocity is significantly lower than that of the surrounding gas close to the nozzle, so the two phases are coupled through aerodynamic drag. Sub-micron oil droplets are dispensed upstream to serve as tracers, whose velocity is determined through a PIV system; inertial particles, after image segmenting is performed to separate them from PIV data, will be tracked over time with a PTV system. This was accomplished with a single laser pulse and the camera straddle time to produce image pairs and shorten the pulse width. The results will help to understand particle-laden flow in a new regime where the background flow is compressible and the Mach number based on the slip velocity is not negligible, which may help to pave a foundation for future studies in compressible multiphase flows.

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“…In the most general case, a two-wavelength illumination and imaging would be necessary to distinguish between the two phases (Elhimer et al, 2017;Poelma et al, 2006). However, in this case the particles are much larger as compared to the flow tracers, and a simple PIV system is sufficient to separate the particles and fluid tracers (Khalitov and Longmire, 2002;Hwang and Eaton, 2006).…”

Section: Introductionmentioning

confidence: 99%

Particle-turbulence interaction of high Stokes number irregular shape particles in accelerating flow: A rocket-engine model

Kalenko

Liberzon

2020

International Journal of Multiphase Flow

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Metal particles in solid propellants enhance rocket engines performance. An interaction of particles with a high Reynolds number turbulent gas flow accelerating to a nozzle, has not been characterized thoroughly. We study the particleturbulence interactions in a two-dimensional model of a rocket engine. Twophase particle image/tracking velocimetry provides the flow velocity simultaneously with the velocities of irregularly shaped inertial particles (d p ∼ 320µm, Stokes St ∼ 70, particle Reynolds number Re p ∼ 300). We reveal the local augmentation of turbulent fluctuations in the particle wakes (up to 5 particle diameters downstream the particle). Despite the low mass fraction, the large response time of the particles leads to an increase of turbulent kinetic energy (TKE) everywhere in the chamber. The increase of local particle mass fraction near the nozzle, due to the mass conservation and converging streamlines, compensates for the dampening effect of the strong mean flow acceleration and further augments TKE at the nozzle inlet. Furthermore, this is accompanied by unexpectedly isotropic fluctuations in the proximity of the nozzle. The phenomenon of the isotropic, strongly enhanced turbulence in the proximity of the engine nozzle achievable with the low mass fraction of high St, Re p particles, can be used to improve the design of solid propellant rocket engines.

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Simultaneous PIV/PTV velocimetry technique in a turbulent particle-laden flow

Abstract: OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

Cited by 25 publications

References 34 publications

Terminal fall velocity: the legacy of Stokes from the perspective of fluvial hydraulics

Terminal fall velocity: the legacy of Stokes from the perspective of fluvial hydraulics

Simultaneous two-phase flow measurements in a high-speed particle-laden under-expanded jet

Particle-turbulence interaction of high Stokes number irregular shape particles in accelerating flow: A rocket-engine model

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