Full-Scale Investigation of Viscous Roll Damping with Particle Image Velocimetry

摘要

In 2002 the Italian and U.S. Navies initiated a cooperative research program for the development, verification, and validation of a six degree of freedom motion Reynolds Averaged Navier Stokes (6DOF RANS) prediction program. Within the context of this initiative, both model tests and a full scale trial were planned to explore the viscous flow field in the region of the bilge keel of a surface vessel. Over the first few years of this program a systematic series of model tests on the DTMB model 5415 hull form were conducted. Results from these tests allowed researchers a means to validate their theories within a controlled test environment. However, these validation efforts could only be performed at the appropriate model-scale Reynolds number. Left unclear is whether the overall RANS formulation is correct for simulations at the full- scale Reynolds number. In an effort to address this issue, a full-scale calm-water roll-decay trial was performed on the Italian vessel, Nave Bettica. The main thrust of the trial was an examination of the viscous flow field through the collection of particle- image velocimetry (PIV) data. To help in the understanding of the overall flow field and associated forces, strain gage measurements of the bilge keel lateral force were also made. Other data collected includes measurement of the local environment (wave and wind), ship motions and ship speed through water. This paper describes the overall effort and initial findings from this full-scale trial. Among the issues discussed are the technical challenges related to the application of a PIV system in support of full scale measurements, including the overall system configuration, imaging optics, calibration and particle injection methods.