MRI: Development of a Three-differential-velocity-component Fiber-optic Laser-Doppler Velocimeter for Measuring the Instantaneous Rate-of-strain and Vorticity for Turbulent Flows

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CTS-0079638R. Simpson, VA Polytechnic & State UnivAbstractThe proposed Instrument Development is to produce a unique laser doppler differential velocimeter system for fine- spatial-resolution instantaneous measurements of the complete rate-of-strain and vorticity tensors in complex turbulent flows. This rate-of-strain and vorticity measuring LDV (ROSVOR LDV) will be a unique system providing measurements of the turbulent kinetic energy dissipation rate and the enstrophy without simplifying assumptions. Such measurements are needed for the further development of turbulence models.The innovations in LDV technologies to be used here are: (1) the direct measurement of low uncertainty velocity differences from four closely spaced (100microns x 20microns) volumes, (2) the use of polarization-preserving fiber optics and beam combiners in a compact design, and (3) signal processing and data handling techniques for 9 velocity-component differences simultaneously.The goals of the Virginia Tech graduate program are to provide strong M.S. and Ph.D. education and to conduct research in state-of-the-art-facilities. Research opportunities are available for all qualified persons. In the past, there have been 3 women graduate students involved in this turbulence research program. Currently there is one woman graduate student. It is expected that, the proposed ROSVOR LDV will provide a new international standard for experimentally measuring the instantaneous rate-of-strain and vorticity tensors and determining the anisotropic contributions to the turbulent kinetic energy dissipation rate. These data are expected to guide the development of refined turbulence models that will be used throughout the modern CFD community.