International Research Fellow Awards Program: An Experimental Study of the Stability and Wake Dynamics of a Reentry Capsule at Low Speed

9600318王国际研究员奖励计划使美国科学家和工程师能够在国外进行三到二十四个月的研究。该计划的奖励为联合研究提供了机会，并利用独特或互补的设施、专业知识和国外的实验条件。该奖项将支持Frank Y. Wang博士与Jean-Marc Charbonnier教授在比利时von Karman流体动力学研究所进行为期12个月的博士后研究访问。本项目通过实验研究了返回舱的动态稳定性特性及其与下游低速尾流的关系。王博士和Charbonnier教授将测量一个囊状体的气动系数，边界层和下游尾流的平均和湍流量，并进行流动可视化。现有的一个专门为研究胶囊状物体的稳定性而设计的支撑系统将用于安装模型和测量其整体气动系数。暗影/纹影可视化将被用作全球尾流特征的初始步骤。然后，流动诊断工作将集中于使用粒子图像测速（PIV）来绘制边界层和尾迹特征。此外，将使用传统的微型五孔探头对流场进行平行研究，以解决PIV技术在这类问题中的适用性。空气动力系数的测量对于提供必要的信息以确保宇航员安全返回至关重要。边界层和尾流场的详细记录将扩大现有的跨音速钝体数据库，有助于计算模型的开发和验证，并提供前所未有的机会来研究胶囊上的流动与其下游尾流之间的动态相互作用。＊＊＊

9600318 Wang The International Research Fellow Awards Program enables U.S. scientists and engineers to conduct three to twenty- four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award will support a twelve-month postdoctoral research visit which will support Dr. Frank Y. Wang to work with Professor Jean-Marc Charbonnier at the von Karman Institute for Fluid Dynamics in Belgium. This project involves investigating experimentally the dynamic stability characteristics of a reentry capsule and their relation to the downstream wake flow at low speed. Dr. Wang and Professor Charbonnier will measure aerodynamic coefficients of a capsule-like body, mean and turbulent quantities of the boundary layer and the downstream wake flows, and do flow visualization. An existing support system specifically designed for the investigation of the stability of capsule-like bodies will be used for both mounting the model and measuring its global aerodynamic coefficients. Shadowgraph/Schlieren visualization will be utilized as an initial step to globally characterize the wake flow. The flow diagnostic effort will then concentrate on the use of particle image velocimetry (PIV) to map out the boundary layer and wake characteristics. In addition, a parallel investigation of the flow fields using conventional miniature five-hole probes will be carried out to address the applicability of the PIV technique in this type of problems. The measurement of aerodynamic coefficients is crucial in providing the necessary information to ensure the safe return of astronauts. The detailed documentation of the boundary layer and wake flow fields will broaden the existing database for transonic blunt bodies, aiding the development and validation of computational models, as well as offering an unprecedented opportunity to examine the dynamic interaction between the flow over the capsule and its downstream wake. ***