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 - 0079638 r。摘要提出的仪器开发是为了生产一种独特的激光多普勒差分测速仪系统，用于复杂湍流中完整的应变速率和涡量张量的精细空间分辨率瞬时测量。这种应变速率和涡量测量LDV （ROSVOR LDV）将是一种独特的系统，可以在不简化假设的情况下测量湍流动能耗散率和熵。这种测量对于湍流模型的进一步发展是必要的。这里使用的LDV技术的创新是：(1)直接测量四个紧密间隔（100微米x 20微米）体积的低不确定度速度差，(2)在紧凑设计中使用保偏振光纤和光束合并器，以及(3)同时处理9个速度分量差异的信号处理和数据处理技术。弗吉尼亚理工大学研究生项目的目标是提供强大的硕士和博士教育，并在最先进的设施中进行研究。所有有资格的人都有研究机会。在过去，有3名女研究生参与了这个湍流研究项目。目前有一名女研究生。预计所提出的ROSVOR LDV将为实验测量瞬时应变率和涡量张量以及确定各向异性对湍流动能耗散率的贡献提供新的国际标准。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发展。

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.