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Multi-spatio-temporal scales PIV applied to a turbulent buoyant jet in a stratified environment

  • December 04, 2017
  • 4:00 p.m.
  • 117A Surge Building
  • Dr. Philippe Bardet, George Washington University,
  • Faculty Host: Dr. Christine Gilbert

Abstract: An overview of the laser diagnostics development in the Thermo-Fluids Laboratory (TF Lab) of Dr. Bardet will be presented.  The TFL is focused on Multiphysics diagnostics for harsh, in-situ environments.  Practical aspects of the deployment of tunable diode laser absorption spectroscopy (TDLAS) and molecular tagging velocimetry (MTV) in high temperature and elevated pressure facilities will be presented before focusing on an ongoing experimental campaign in the TF Lab.

A turbulent buoyant jet discharging in a stratified environment is studied experimentally.  To enable the deployment of optical diagnostics in this flow, the jet and stratified environment are established with index matched solutions that allow up to a linear response with up to 5% difference in density.  The mixtures were selected so that the dynamic viscosity of the fluids is also matched.  The jet of diameter D is injected vertically in a tank that 144 D × 144 D × 124 D to minimize confinement effects on the flow.  The main parameters are Reynold number, Re = 2.00 × 104, and Froude number, Fr = 7.67.

Turbulent velocity field is resolved with multi-spatio-temporal scales particle image velocimetry (PIV).  A combination of 5 laser planes and 12 cameras are deployed simultaneously to probe the flow.  Cameras all record in a time-resolved manner and have long recording time, which allows resolving turbulence statistics, while also capturing the evolution of flow structures.  The velocity is measured from over a range of scales from ~ 100 µm up to 1 m.  Likewise, the recorded frequencies scale from 0.1 to 2 kHz.  Details of the experimental setup and data integration will be presented.  Insights in the evolution of this turbulent jet will also be discussed.

Bio: Philippe Bardet is an Associate Professor at the George Washington University (GW).  He holds a primary appointment in Mechanical and Aerospace Engineering Department with a courtesy appointment in the Elliott School of International Affairs.  He received his Ph.D. in nuclear engineering from the University of California at Berkeley in 2006 under the joint supervision of Profs. Per F Peterson in Nuclear Eng. and Ömer Savaş in Mechanical Eng.  After his doctoral studies, Dr. Bardet was a lecturer and postdoctoral fellow at UC Berkeley, before postdoctoral training at the California Institute of Technology.  He joined the Faculty at GW in August 2010.  His current research aims at uncovering complex physical phenomena through the development and deployment of laser diagnostics and experimental facilities.  His multiphase flow research is focused on free surface turbulence, interface shear at liquid-gas interface, and mass transfer.  He is also active in Fluid-Structure Interactions in nuclear and maritime environments, stratified flows, and accident scenarios of the Very High-Temperature Gas cooled Reactor.  His research group is currently developing non-intrusive laser based velocimetry techniques, both particle based and seedless as well as spectroscopic techniques to measure water vapor temperature and pressure and dissolved gas concentration in liquids.  Dr. Bardet teaches courses in Fluid Mechanics, Thermodynamics, Experimental Methods, and Optics.