Computer simulations and numerical calculations are valuable tools to study fluid mechanics problems today. Still, model tests are finally essential to obtain quantitatively reliable results.
In the context of ship development resistance and propulsion tests are most relevant to determine propulsion characteristics and thus ultimately the propulsion power needed. At the DST these tests are usually run in the large shallow water tank with a length of 200 m and a breadth of 10 m. The influence of the restricted water depth is considered exactly by adjusting the water depth to scale. The stopping behaviour according to the Rhine Vessel Inspection Regulation is investigated with the help of stopping trials.
A second towing tank with a water depth up to 3 m permits to carry out towing tests for ships in mid to deep water.
The large shallow water tank has a wave generator installed at its end, which is capable of generating any type of one-dimensional wave spectra. The maximum water depth and wave amplitude are continuously adjustable to 1.20 m.
Furthermore, there is a large underwater observation tunnel beneath the large towing tank. This tunnel allows optically observations of the flow around the ship’s bottom. In the easiest case woolen tufts are used to visualize the flow during the video recording. High-speed videos with frame rates up to 1000 Hz are feasible. A modern PIV system allows more detailed measurements of the flow around vessels.
The PMM system (Planar Motion Mechanism) can also be used to investigate the manoeuvring behaviour or the models can be driven freely.
A special feature in the large towing container of the DST is a second high-speed towing system that can be operated independently of the large towing vehicle. While the large towing carriage achieves speeds of up to 6 m/s, the high-speed towing system achieves speeds of up to 15 m/sec. Since both cars are independent of each other, it is possible to carry out encounter and overtaking manoeuvres.
However, the DST does not only examine ships in the test facilities. Depending on the requirements of our customers, various further tests are carried out (e. g. with ground effect vehicles, flow or wave energy systems).