内容摘要：

Our research in the experimental and applied fluid dynamics Laboratory at Purdue University will be briefly reviewed first. The recent effort on developing non-invasive field measurement as a flow diagnostics tool for studying multiphase flow will be introduced in detail. Quantitative application of digital in-line holography (DIH) is applied to record sequential holograms of the breakup of an ethanol droplet in an aerodynamic flow field. Various stages of the breakup process are recorded, including deformation, bag growth, bag breakup, and rim breakup. A recently proposed hybrid method is applied to extract the three-dimensional (3D) location and size of secondary droplets as well as the 3D morphology of the rim. Particle matching between sequential frames is used to determine the velocity. Coincidence with the results obtained from phase Doppler anemometry (PDA) measurement demonstrates the accuracy of measurement by DIH and the hybrid method. This tool contributes to characterize the complex multiphase structures and develop accurate models to describe the underlying physics, which represents a key challenge for high-fidelity CFD-based design tools. Also presented is a novel technique for measuring the thickness distribution of a dynamic liquid sheet spanned by two impinging jets and a study of the dynamic process when a liquid drop impacts a liquid film.

    本报告将首先简要回顾近年来非接触场测量方法作为多相流诊断工具的研究进展，并介绍应用数字全息技术对液滴在气流中的破碎过程进行的定量记录。该研究量化记录了单个液滴在气流中破碎的各个阶段，包括液滴变形、袋状破碎和边缘结构的发展，提出了一种改进方法来提取子液滴的三维位置和尺寸以及边缘的三维形貌，并应用粒子匹配来确定各个液滴的三位速度，测量结果比相位多普勒风速测量结果验证，证明了该方法的测量精度。该诊断工具有助于描述复杂的多相流结构，及研发精确的数学模型来描述机理，有助于结果计算流体力学作为设计工具使用时面临的关键挑战。此外，本报告还介绍一种测量射流对撞冲击下动态液膜厚度分布的新技术和液滴撞击液膜时的动态过程研究。

主讲人介绍：

    陈军教授毕业于北京航空航天大学，2005年获美国Johns Hopkins University (约翰-霍普金斯大学)机械工程博士学位。 2005年至2008年在Los Alamos National Laboratory (洛斯-阿拉姆斯国家实验室)从事博士后研究。自2008年起在美国普度大学机械工程学院任教，现负责实验流体力学及应用流体力学实验室的科研及教学工作，一直担任普度大学机械工程学院本科生及研究生基础流体力学课程、实验流体力学、边界层理论、湍流理论、工程光学、及各类机械工程课程的授课，其研究方向涉及先进测量技术开发、非定常流体力学及湍流模型实验研究、及应用流体力学研究等，其研究成果曾获颁期刊Measurement Science and Technology的2005优秀流体力学论文奖（OUTSTANDING FLUID MECHANICS PAPER AWARD）和美国机械工程师协会2014年度ROBERT T. KNAPP AWARD。2020年晋升为美国机械工程师协会理事（ASME Fellow）。