Research on the Structure of Complex 3-D Turbulent Flows Using the Comprehensive Laser-Doppler Velocimeter

建议编号：CBET-0730774首席研究员：辛普森，罗杰·L机构：弗吉尼亚理工学院和州立大学表面驱动液体流动及其在纳米结构中的应用在这项研究计划中，新的综合激光多普勒测速仪(CompLDV)实验技术将以每秒至少100,000个样本的高数据速率，同时精确地测量高雷诺数三维湍流科尔莫戈洛夫尺度内亚微米尺寸颗粒的瞬时矢量速度、加速度和位置。CompLDV的新颖设计叠加了会聚和发散条纹图案，可以在5微米的不确定度内确定通过200微米直径测量体积的给定颗粒的三维位置。可以在实心墙的5微米范围内进行测量，以确定表面的表面摩擦。对于三维流动，这些输运方程需要考虑：(1)涡粘性的可变各向异性，(2)平均流动和湍流场之间的滞后，以及(3)重要剪应力和速度脉动之间的强烈关系(Simpson，1996)。这里计划的工作将研究这种机翼/机身试验样机流动和涡生成流的马蹄形涡旋结构，以提供定量数据，以更好地解释和模拟实际应用中常见的嵌入平均流方向涡流的三维湍流结构。此外，在这项研究中，需要关于流动的全球不稳定性和各种尺寸涡流的长度尺度的实验统计信息，并将使用多点LDV测量获得这些信息，以与大涡模拟(LES)进行比较，这些数据和结果将与欧洲流体、湍流和燃烧研究共同体(ERCOFTAC)和其他合作者共享。这项计划中的研究的更广泛的影响通过继续开发一种新型的仪器来促进发现和理解，并加强湍流研究的基础设施，该仪器可以首次提供关于明确定义的高雷诺数三维湍流边界层的湍流能量耗散率和速度/压力-梯度关联以及其他以前未测量的量的基本的低不确定性信息。PI和湍流模型器之间的合作已经建立。计划中的研究生还将与这些研究人员互动，帮助根据数据建立湍流模型。来自德国的研究生和其他建模研究人员预计将参与这些结果的讨论。从计划的三维流动中获得的知识和见解将使高雷诺数下的速度/压力-梯度关联和耗散率的模型更加可信，这是天气预报和更好地估计湍流产生的气声噪声源所必需的。

PROPOSAL NO.: CBET - 0730774 PRINCIPAL INVESTIGATOR: SIMPSON, ROGER L. INSTITUTION: VIRGINIA POLYTECHNIC INSTITUTE AND STATE UNIVERSITYNANOFLUIDICS OF SURFACE-DRIVEN LIQUID FLOW AND ITS APPLICATION FOR NANOFABRICATIONIn this research program, the new comprehensive laser-Doppler velocimeter (CompLDV) experimental technique will measure simultaneously and precisely the instantaneous vector velocity, acceleration, and position of submicron-sized particles within the Kolmogorov scales of high Reynolds number 3-D turbulent flows at a high data rate of at least 100,000 samples per second. The CompLDV novel design superimposes converging and diverging fringe patterns to determine the 3-D location of a given particle passing through the 200 micron diameter measurement volume within 5 microns uncertainty. Measurements can be made within 5 microns of a solid wall to determine the surface skin friction. For 3-D flows, these transport equations are required to account for: (1) the variable anisotropy of the eddy viscosities, (2) the lags between the mean flow and the turbulence field, and (3) the strong relation between the important shearing stresses and velocity fluctuations (Simpson, 1996). Work planned here will examine the horseshoe vortex structure for this wing/body test case flow and for a vortex generator flow to provide quantitative data to better explain and model the 3-D turbulence structure of embedded mean stream-wise vortices common in practical applications. In addition, in this research experimental statistical information on the global unsteadiness of the flow and the length scales of the various sized eddies are needed and will be obtained using multi-point LDV measurements to compare with large-eddy simulations (LES), These data and results will be shared with European Research Community on Fluids, Turbulence and Combustion (ERCOFTAC) and other collaborators. The broader impacts of this planned research advances discovery and understanding and enhances the infrastructure of turbulence research by continuing to develop a new type of instrument that can provide fundamental low uncertainty information for the first time on the turbulence energy dissipation rate and the velocity/pressure-gradient correlation and other previously unmeasured quantities for well-defined high Reynolds number three-dimensional turbulent boundary layers. Collaborations between the PI and turbulence modelers have already been established. The planned graduate student will interact with these researchers also in helping to develop turbulence models from the data. Graduate students from Germany and other modeling researchers are expected to be involved in the discussions of these results. The knowledge and insights gained from the planned three-dimensional flows will permit more credible models for the velocity/pressure-gradient correlation and dissipation rate at high Reynolds numbers, which are needed for weather prediction and better estimates of the turbulence generated aero-acoustic noise sources.