BILGE KEEL LOADS AND HULL INDUCED PRESSURES: EXPERIMENTAL RESULTS AND CFD VALIDATION

摘要

This paper present results obtained in an experiment with a rotating cylinder to which a single bilge keel was fitted. Forced oscillations were performed leading to a KC range between I and 16. The loads acting on the bilge keel were measured as well as the vortex induced hull pressures in the vicinity of the bilge keel. Computational Fluid Dynamic simulations were conducted with a 2D representation of the experiment. Good correlation in the bilge keel loads and vortex induced pressures is obtained. Using Fourier analysis the first and first two higher harmonic (3(0 and 5(0) drag and inertia coefficients of the bilge keel load were calculated. It is shown that the higher harmonic drag and inertia terms are essential to obtain a good load representation. The vortex induced pressure in front of the moving bilge keel is found to be KC independent. The pressure jump over the bilge keel can be correlated to the instantaneous normal force on the bilge keel. In the wake of the moving bilge keel the pressure depend on KC. These findings are in agreement with the observations reported by Ikeda et al.