An Investigation of Turbulence Scales that Affect Particle Motion

摘要CTS-9612747 C.罗杰斯塔夫茨大学主要目的是测量悬浮在气流中的粒子所看到的湍流的统计特性，并确定粒子分散的机制。提出了一种实验与数值相结合的方法来确定运动粒子参照系中的流体湍流。双分量激光多普勒测速仪（LDV）测量瞬时流体速度，然后计算一个假想粒子的加速度，LDV测量体积跟随该粒子。流体中的瞬时涡量和能量耗散率。利用数字粒子图像测速法（DPIV）估计了湍流长度尺度和色散特性。研究将包括低和中等雷诺数流动，在强迫和非强迫湍流情况下，与二维和三维流动相关。这是塔夫茨大学的C·罗杰斯教授和j·伊顿教授以及他在斯坦福大学的一名学生之间的合作项目，他们将在颗粒流动的直接数值模拟方面进行合作。本文将对分离剪切层中颗粒优先浓度、近各向同性湍流、颗粒浓度和颗粒定向运动进行几组实验。期望提高对流体湍流-粒子相互作用的基本理解。

Abstract CTS-9612747 C. Rogers Tufts University The main objective is to measure statistical properties of turbulence as seen by a particle suspended in air flow, and to determine the mechanisms responsible for particle dispersion. A combined experimental-numerical approach is suggested to determine the fluid turbulence in the reference frame of a moving particle. A two-component laser Doppler velocimeter (LDV) measure the instantaneous fluid velocity, then one calculates the acceleration of an imaginary particle, and the LDV measuring volume follows that particle. The instantaneous vorticity and energy dissipation rate in the fluid. The turbulence length scales and the dispersion characteristics are estimated using digital particle image velocimetry (DPIV). The investigation will include low and moderate Reynolds number flows, in forced and unforced turbulence situations, with relevance for two- and three-dimensional flows. This a collaborative project between Prof. C, Rogers of Tufts University and Prof. J. Eaton and one of his students at Stanford University who will collaborate particularly in the direct numerical simulation of particle-laden flows. Several sets of experiments will be performed concerning preferential particle concentration near-isotropic turbulence, particle concentration and directed particle motion in a separated shear layer. Improved fundamental understanding of fluid turbulence-particle interaction is expected.