Interaction of Separated Gas Flow with Thin Liquid Films

项目编号：CTS-0352135 PRINCIPAL调查员：James A.DRALLMEIERINITTION：密苏里大学研究分离气体流动与薄液膜的相互作用在固体表面上发展并由相邻气体流动驱动的薄液膜的动力学在许多工程问题中都有应用，并且一直是许多研究的主题。然而，由于几何形状的突然膨胀而导致的剪切驱动膜与固体表面的分离以及由此导致的分离气体流场中的雾化，几乎没有引起人们的关注。这种分离流动中液膜和气体之间的复杂相互作用在火花点火发动机的混合气制备中以及在雾化器设计、制冷剂流动和湿表面上的气膜阻力中都会遇到。预测胶片与墙壁分离的情况是模拟这种相互作用的第一个重要步骤，但目前的方法极其有限。本程序的目的是了解耦合气相(分离/再附着流动)和液体之间的动力学，以及主要界面不稳定性的细节，以便能够对这些过程进行建模。特别令人感兴趣的是预测薄膜与固体表面的分离及其雾化作为气相速度和壁角的函数。这项工作的目的是利用流动可视化以及气流场、液膜和液滴场的定量测量来识别、表征和模拟膜分离和破碎过程的性质。提出了一种独特的试验段，用于对驱动液膜表面的剪切力、拐角处的气相分离和拐角处液膜所受的加速力进行明确的控制。将使用多种基于激光的定量诊断技术来表征气体和液体的流场。模拟程序与实验程序并行，将依赖于已建立的气相和剪切驱动液膜模型，以及膜不稳定机制和经验关联式的独特组合。为了扩大研究项目的范围，主要调查人员包括本科生和研究生的合作。本科生将被包括在研究和发现过程的各个方面。例如，本科生可以负责较低优先级的测量，如压力或温度测量。本科生将与教师和研究生一起确定传感器的规格、购买、安装、数据采集和结果分析。鼓励有兴趣、有能力的本科生继续攻读研究生课程。研究结果将通过科学期刊、技术会议和研讨会等通常方式传播。

ABSTRACTPROPOSAL NO.: CTS-0352135PRINCIPAL INVESTIGATOR: JAMES A. DRALLMEIERINSTITUTION: UNIVERSITY OF MISSOURI ROLLAINTERACTION OF SEPARATED GAS FLOW WITH THIN LIQUID FILMSThe dynamics of thin liquid films that develop on a solid surface and are driven by an adjacent gas flow have applications in many engineering problems and have been the subject of many studies. However, the separation of shear driven films from the solid surface due to a sudden expansion in geometry and the resulting atomization in the separated gas flow field, has received little attention. This complex interaction between the liquid film and the gas in separated flow is encountered in mixture preparation for spark ignition engines, as well as in atomizer design, refrigerant flows, and film drag over wetted surfaces. Prediction of the circumstances under which the film separates from the wall is the first vital step in modeling this interaction but current approaches are extremely limited. It is the objective of this program to develop an understanding of the dynamics between the coupled gas phase (separated/reattached flow) and liquid phase, along with the details of the dominant interfacial instabilities to the point that these processes can be modeled. Of particular interest is the prediction of film separation from the solid surface and its atomization as a function of gas phase velocity and wall angle. The goals of the proposed work are to identify, characterize and model the nature of the film separation and breakup process, using both flow visualization as well as quantitative measures of the gas flow field, liquid film and drop field. A unique test section is proposed which is designed to provide distinct control of the shear force driving the surface of the liquid film, the gas phase separation at the corner and the acceleration forces experienced by the liquid film at the corner. Multiple quantitative laser-based diagnostics will be used to characterize the gas and liquid flow fields. The modeling program, in parallel with the experimental program, will rely on established models for the gas phase and shear driven liquid film as well as a unique combination of film instability mechanisms and empirical correlations. To broaden the reach of the research programs, the principle investigators include teaming of undergraduates with graduate students. The undergraduates will be included in all aspects of the research and discovery process. For example, undergraduate students may be put in charge of a lower priority measurement such as a pressure or temperature measurement. Undergraduates will work with the faculty and graduate students in determining sensor specifications, purchasing, installation, data acquisition and analysis of results. Interested and capable undergraduate student will be encouraged to pursue graduate studies. The results of the research will be disseminated through the usual means of scientific journals, technical meetings, and seminars.