Hydrodynamic Analysis of Interceptors with CFD Methods

Despite the wide use and market proposal of interceptor as modern device to control vertical and horizontal motions of fast ships, few article can be found in the literature about their hydrodynamic design. The effective design of interceptor must not disregard the knowledge of the hydrodynamic action that the blade protruding off the transom edge has on the flow over the hull. For this reason a first fundamental study on the main parameters that influence the phenomena has been programmed and the main outcome is presented in the paper. The general hydrodynamic problem imply the solution of a free surface flow in which viscous effects cannot be neglected. For this purpose a series of systematic analysis on simplified 2D model has been performed with a modern CFD free surface RANSE code. By the analysis of the results, interesting conclusions are drawn and a simple method for the prediction of full scale interceptor forces, based on CFD calculations, is presented in the paper. Example of CFD results are presented in the paper in terms of distributed parameters, such as velocity and pressure distributions, and in terms of global forces and loads. The total force obtained by two full scale installations are finally compared with the predictions and a very good agreement is found.