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

CTS-0079638R。Simpson，VA Polytechnic State Universtabstract提出的仪器开发是为了产生一个独特的激光多普勒差分速度计系统，用于复杂湍流中完整应变率和涡量张量的精细空间分辨率瞬时测量。这种应变率和涡度测量LDV（ROSVOR LDV）将是一个独特的系统，提供测量的湍流动能耗散率和涡度拟能不简化的假设。湍流模型的进一步发展需要这种测量。这里使用的LDV技术创新包括：（1）直接测量四个紧密间隔的低不确定度速度差（100微米× 20微米）体积，（2）在紧凑设计中使用保偏光纤和光束组合器，（3）同时处理9个速度分量差的信号处理和数据处理技术。和博士教育和开展研究的国家的最先进的设施。所有合格人员均可获得研究机会。在过去，有3名女研究生参与了这项湍流研究计划。目前有一名女研究生。预计，拟议的ROSVOR LDV将提供一个新的国际标准，实验测量的瞬时应变率和涡量张量，并确定各向异性的贡献湍流动能耗散率。这些数据有望指导将在整个现代CFD社区中使用的精细湍流模型的开发。

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.