A facility has been constructed at the David W. Taylor Naval Ship R & D Center for the measurement of bubble splitting noise. The facility is patterned after the bubble splitting apparatus of Sevik and Park of Pennsylvania State University [M. Sevik and S. H. Park, J. Basic Eng. Trans. ASME, Paper No. 72-WA/FE-32, 1–8 (1972)]. The difference in the new facility is the provision for measurement of bubble splitting noise. In addition to the measurement of sound pressure levels associated with controlled bubble splitting the acoustic capabilities of the facility provide a means for measuring the bubble size distribution under different flow conditions. Flow characteristics of the facility, background noise spectra and bubble noise data are presented.

One of the main hydroacoustic noise sources from fully submerged lifting surfaces is the unsteady separated turbulent flow near the surface’s trailing edge that produces pressure fluctuations on the surface and induces vibratory motions of the lifting surface itself. However, the hydrodynamic forcing and subsequent structural response of lifting surfaces are largely undocumented at the high Reynolds numbers typical of many marine propulsion applications. This talk describes a new experimental effort to identify and experimentally document the turbulent flow, induced surface pressures, structural response, and radiated noise of a hydrofoil at chord-based Reynolds numbers up to 60 million. The experiments are conducted at the US Navy’s Large Cavitation Channel with a two-dimensional test-section-spanning hydrofoil (2.1-m chord, 3.0-m span) at flow speeds from 0.5 to 18 m/s. The foil section is a modified NACA 16 with a flat pressure side. At a zero angle of attack, the lift load on the foil approaches 700 kn. The results presented here cover the first phase of the experiments and illustrate flow-structure coupling phenomena that will be investigated in greater detail in the second phase of experiments planned for later this year. [Work sponsored by ONR, Code 333.]

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