Unsteady Pressures on the Surface of a Ship Hull

The unsteady surface pressures caused by turbulent boundary layer flow are a source of sound and vibration. Unsteady surface pressure measurements at locations distributed on the surface of a ship model hull were carried out in order to characterize this source. The pressure measurement locations were distributed over the hull surface from 15% to 70% of the model length. There were several additional pressure measurement locations on the hull surface adjacent to the bow wave. The measurements were performed in the David Taylor Model Basin. The surface pressure spectra collapse to a single curve when scaled by canonical boundary layer variables at measurement locations aft of the bow wave. Additionally, measurements at several of these locations indicate that the pressure sources are convected at 50% to 80% of the free-stream velocity. Both of these observations are similar to equilibrium turbulent boundary layers. The measured surface pressure spectra compare well to predictions done using an empirical model that is based on historical, equilibrium, surface pressure spectra. At low frequencies, the measured surface pressure spectra also compare well to prediction done at lower Reynolds number using a Reynolds-Averged Navier-Stokes Statistical Model.