Seminar: Pulse-Burst PIV in High-Speed Flows
Time-resolved particle image velocimetry (TR-PIV) has been achieved in a high-speed wind tunnel and a shock tube, providing velocity field movies of compressible turbulence events. The requirements of high-speed flows demand greater energy at faster pulse rates than possible with the TR-PIV systems developed for low-speed flows. This has been realized using a pulse-burst laser to obtain movies at up to 50 kHz with higher speeds possible at the cost of spatial resolution. Pulse-burst PIV has been demonstrated in a supersonic jet exhausting into a transonic crossflow, in transonic flow over a rectangular cavity and supersonic unsteady shock motion in a hemisphere wake. The velocity field sequences reveal the passage of turbulent structures and can be used to find velocity power spectra at every point in the field, providing spatial distributions of acoustic modes and revealing turbulence scaling laws. Additional applications in a shock tube show the transient onset of a von Kármán vortex street shed from a cylinder and particle drag in a shocked dense gas-solid flow. The present work represents the first use of TR-PIV in a high-speed ground test facility.
About the speaker
Steven J. Beresh is a Distinguished Member of the Technical Staff at Sandia National Laboratories in Albuquerque, New Mexico, U.S.A., where he has worked since 1999 and leads the Experimental Aerosciences Facility. He received his BS in mechanical engineering from Michigan State University in 1994 and his PhD in aerospace engineering from The University of Texas at Austin in 1999. His research interests emphasize the use of optical diagnostics for compressible aerodynamics, particularly particle image velocimetry, but utilize a variety of laser-based instrumentation techniques and high-frequency surface sensors. He also is responsible for a wide range of wind tunnel testing and facility operation. He is an Associate Fellow of the American Institute for Aeronautics and Astronautics, has served as chair for the AIAA Aerodynamic Measurement Technology Technical Committee and is a past president of the Supersonic Tunnel Association International.
Hosted by Professor Datta Gaitonde.