Distribution of damping and added mass along the length of a shipmodel¹²

Article type: Research Article

Authors: Gerritsma, J. | Beukelman, W.

Note: [1] Publication of the Netherlands Research Centre T.N.O. for Shipbuilding and Navigation.

Note: [2] Publication No. 21, Shipbuilding Laboratory, Delft.

Abstract: Forced heaving experiments were carried out with a seven-section model in still water, to investigate the distribution of damping and added mass along the length of a shipmodel. The components of the vertical forces in phase with the heave displacement and the quadrature components on each of the seven sections were measured as a function of the frequency and the forward speed of the model. This allowed the determination of the sectional damping coefficients and the sectional added masses, and their distribution along the length of the model. The results show a fairly large influence of frequency and forward speed on the distribution of damping. There is some influence of frequency on the distribution of added mass, but the influence of forward speed is small. In some conditions negative sectional damping and added mass was observed. The distribution of damping results in coefficients of the heave velocity coupling terms, which depend on the forward speed. In the practical range of frequencies the coefficients of the heave acceleration coupling terms are very small. The experimental results are compared with Grim’s theoretical values for damping and added mass at zero speed.

DOI: 10.3233/ISP-1963-1010301

Journal: International Shipbuilding Progress, vol. 10, no. 103, pp. 73-84, 1963