Slamming

For slamming tests, a hydraulic slamming simulator was developed in the SVA. With the help of this system, the model is made to heave and pitch and produce coupled motions using two longitudinally arranged, vertically movable, hydraulic pistons. Depending on the model size, amplitudes up to 0.1m are reached at frequencies up to 2Hz. Thus slamming loads can be simulated, in which the critical immersion speeds are significantly exceeded. Both hull slamming of planing boats and bow flare slamming on all types of vessels with significant bulkhead failure are examined primarily in the bow area. The system allows the simulation of regular and irregular movements. The advantages over slamming measurements in a conventional sea state tests of the targeted replication of slamming scenarios is that defined immersion conditions can be assigned, and also in the exact reproducibility of the experimental conditions.

The equiping of models with miniature pressure sensors of different sizes allows the measurement of slamming pressures on vulnerable positions of the hull in the model test under extreme sea conditions, both when driving and when stationary. Moreover, slamming pressures can also be measured with regular seakeeping tests.

Slamming phenomena are also simulated with existing CFD tools. The UTHLANDE program serves to determine slamming prevalence. For a quick estimate of slamming pressures the SVA has developed a simplified procedure. It is based on results of systematic model tests and allows the determination of slamming pressure for any hull shape, for a given speed and location on the vessel. An important parameter is the velocity normal to the hull and the fluid at the point of interest of the hull surface. Areas with air entrapment (hull slamming) can therefore not be detected.

As a result, the processing of various R &  D projects [1], [2], the [3] SVA has a wealth of experience in investigating slamming phenomena.