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

Michigan State University, East Lansing MI

Investigators

Abstract

PROPOSAL NO.: CTS-0425374 PRINCIPAL INVESTIGATOR: AHMED NAGUIB INSTITUTION: MICHIGAN STATE UNIVERSITY This 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.