A hydrodynamic design methodology for large SES based on the integrated use of theory and experiments was developed.
The complex physics of SES was theoretically approached with particular care of the complex interaction effects between lift-system and flexible seals. This led to the development of theoretical prediction tools for SES powering (3D Rankine-source BEM method for linear steady free-surface potential flow, total resistance and steady-running equilibrium), seakeeping (BEM method for linear unsteady free-surface potential flow, time-domain simulation method for the wave-induced motions accounting for the non-linear interaction between lift-system and flexible seals motions, seakeeping post-processor for the evaluation of the local forces induced by wet-deck slamming, seakeeping post-processor for the short/long-term statistical analysis of time-series) and manoeuvering (time-domain procedure for the simulation of standard manoeuvers in the horizontal plane).
Extensive experimental tests were performed using different facilities (resistance and self-propulsion tests in towing-tank, wind-tunnel tests, PMM test, test-rig laboratory tests, forced-oscillation tests in depressurised towing-tank, captive and free-running tests in rectilinear and seakeeping tank) and models of different sizes, in the scope of a better insight into the aero/hydro-dynamics behaviour of SES (including scale effects) and of providing suitable data for correlation and calibration of the physical/mathematical models.
Powering, seakeeping and manoeuvering sea-trials were performed varying systematically the main relevant design parameters on a purposely hired existing SES, in the scope of a better insight into the overall behaviour of SES at sea and of providing suitable data for further correlation and calibration of the physical/mathematical models.
A critical evaluation of the overall theoretical and experimental knowledge gained within the project was finally carried out leading to the formulation of general design criteria and guidelines on the use of the developed experimental/theoretical tools.
Fast vessels for commercial sea transport are the industrial challenge that market evolution poses to shipping world, as it is evidenced by the large amount of money which extra-European countries are investing in this type of crafts. To this regard large SES crafts are well placed to win this challenge leading ship transport to a technological level comparable with aeronautical transport. Existing SES crafts are of very limited size (maximum length of about 30 meters) and are in use only as fast passenger ferries in coastal waters. On the other hand the present design procedures suffer from several simplificative assumptions, neglecting the non-linearities or assuming very coarse treatment of sidehulls/air-cushion/incident-wave interaction in the seakeeping behaviour. For this reasons they are likely to fail in the case of large SES crafts. As a matter of fact shipyards and shipowners are very afraid on the extrapolation from the existing small vessels to the large SES required for fast commercial sea transport.
As a result of the proposed project a better understanding of SES aero-hydrodynamic is expected, taking into account the non-linear effects related to large-size configurations and their impact on ship structures and machineries design. The final goal will be to formulate reliable guidelines on the integrated use of advanced theoretical/experimental methodologies for large SES design.
Funding SchemeCSC - Cost-sharing contracts
6708 PH Wageningen