REG: Advanced Imaging Capability: Vorticity as Seen by a Moving Particle

点击翻译按钮获取中文摘要

Abstract CTS-9610340 Chris Rogers Tufts University The main goal is to develop instrumentation for the measurement of instantaneous, two dimensional fluid velocity fields from the viewpoint of a moving particle. A Kodak camera, imaging frame grabber and accessory equipment will be purchased. In order to accurately predict the behavior of a solid particle in a turbulent air flow, one must be able to predict the fluid turbulence experienced by the particle: that is in the particle Lagrangian reference frame. Most conventional models and simulations give information in the stationary Eulerian reference frame or in the Lagrangian reference frame. Since the particle has a gravitational drift and inertia, its path is different from that of a fluid point (Lagrangian) or a stationary point (Eulerian). The turbulence to which the particle responds is dependent on the physical particle properties and on its previous history of surrounding turbulence. The PI is modeling a transformation from an Eulerian coordinate system to the particleıs coordinate system for single point measurements, such as fluid velocity autocorrelation. For some particles, however, their path is dictated by local fluid vorticity. Vortices tend to throw particles out into straining regions. To model this behavior, one needs to be able to measure the local instantaneous vorticity along the particle path. One can approximate the vorticity using digital particle image velocimetry, measuring the 2-D fluid velocity field in the reference frame of the moving particle. The current difficulty is spatial and temporal resolution, both of which are addressed here. The equipment will also be used by a number of other projects, both with industry and government agencies.