This paper shows added mass and inertia can be acquired from the pure heaving motion and pure pitching motion respectively. A VPMM (Vertical Planar Motion Mechanism) test for the spheroid-type UUV (Unmanned Underwater Vehicle) was compared with a theoretical calculation and CFD (Computational Fluid Dynamics) analysis in this paper. The VPMM test has been carried out at a towing tank with a specially manufactured equipment. The linear equations of motion on the vertical plane were considered for theoretical calculation, and CFD results were obtained by commercial CFD package. The VPMM test results show good agreement with theoretical calculations and the CFD results, so that the applicability of the VPMM equipment for an underwater vehicle can be verified with a sufficient accuracy.
Recently, UUVs are increasingly used, among in scientific, industrial and military applications. Before designing an UUV, the numerical simulations with a mathematical model are needed to test its performance. The mathematical model contains a number of hydrodynamic derivatives including added mass and damping coefficients. For the precise design of UUVs, therefore, the accurate values of the derivatives are required. The hydrodynamic derivatives can be obtained by several experimental techniques which involve a planar motion mechanism (PMM) test, a rotating arm test and a circular motion test (CMT). Among the above, the most popular is a PMM test, which has the advantage that can acquire both added masses and damping forces simultaneously. In this study, to verify the VPMM equipment for an underwater vehicle, the PMM test for a spheroid-type UUV is performed in a towing tank. The experimental results are compared with the theoretical values (Lamb and Sir Horace, 1945) and the results from CFD analysis.
