Investigation of Acoustic and Hydrodynamic Modes in a Two/three-dimensional Incompressible Cavity Flow Using Wall-microphone Arrays

建议没有。项目编号：ct -0425374主要研究者：AHMED NAGUIBINSTITUTION: MICHIGAN STATE university这项资助支持二维和三维低马赫数空腔流动的壁压和流动模式研究。自持续振荡发生在各种各样的实际配置中，包括飞机和海军舰艇，汽车开口（例如天窗），甚至在水力学和土木工程领域。该研究的一个独特之处在于，通过在战略选择的位置采用大型传感器阵列，可以分辨出壁压模式的频率和波数。阵列测量将与同时使用粒子图像测速仪（PIV）进行的流场测量相结合，通过基于多点壁面压力的随机估计获得伪瞬时流结构的时间分辨估计。在这些实验中强调了两个关键的流动特性：(1)腔底壁面压力的波数-频率谱及其相关的频散关系（对流速度-频率）；(2)碰撞唇附近流动结构的三维化。第一年将研究不同腔体几何参数对这些特性的影响。在第二年，将研究分离边界层性质的影响，而第三年将致力于研究平均流三维的意义。该项目利用了几个现有的资源，这些资源已经由以前授予的NSF项目启用。本项目的实施将培养1名博士生。PI打算让一名本科生参与这项研究，希望能让他/她被研究生院录取。此外，将利用密歇根州立大学现有的项目，在夏季将一名高中生纳入团队，向他/她展示研究和发现过程的兴奋。

PROPOSAL NO.: CTS-0425374PRINCIPAL INVESTIGATOR: AHMED NAGUIBINSTITUTION: MICHIGAN STATE UNIVERSITYThis grant supports a study of the wall-pressure and flow modes in a two- and three-dimensional low-Mach-number cavity flows. Self-sustained oscillations occur in a wide variety of practical configurations, including aircraft and naval vessels, openings in automobiles (e.g. sunroofs), and even in the field of hydraulics and civil engineering. A unique feature of the investigation is the resolution of both the frequency and wave number of the wall-pressure modes by employing large sensor arrays at strategically chosen locations. The array measurements will be coupled with simultaneous flow-field measurements using Particle Image Velocimetery (PIV) to obtain time-resolved estimation of the pseudo-instantaneous flow structure via multi-point wall-pressure-based stochastic estimation. Two key flow characteristics are emphasized in these experiments: (1) wave number-frequency spectra of the wall-pressure on the cavity bottom and associated dispersion relation (convection velocity versus frequency); (2) three-dimensionality of the flow structure in the vicinity of the impingement lip. The influence of various cavity geometrical parameters on these characteristics will be investigated during the first year. In the second year, effects of the separating boundary layer properties will be examined, while the third year will be dedicated to examining the significance of mean-flow three-dimensionality. The project capitalizes on several existing resources that have been enabled by a previously awarded NSF project. Execution of this project will result in the training of one Ph.D. student. The PI intends to involve an undergraduate student in the research, hopefully leading to her/his recruitment to graduate school. Moreover, existing programs at Michigan State University will be utilized to include a high-school student in the team during the summer, demonstrating to him/her the excitement of the process of research and discovery.