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Hull resistance is determined by doing towing tests at increasing speeds in order to develop a resistance curve for the vessel at the specific condition. The tests are done at one or several displacements or trim angles.
Seakeeping tests are done to evaluate the behaviour of the vessel in waves. Most often head sea tests are done. In the special case were stationary seakeeping capabilities are required, this can be conducted in all headings by rotating the model relative to the incoming waves. The model can be self propelled or spring tethered.
By fitting propulsion units on the model and doing self-propulsion test, an exact prediction of power requirements for the full-scale ship is determined. (The propeller will be working in the correct wake of the hull and hence a more correct prediction is made compared to the resistance test. Resistance test results are necessary for doing the propulsion tests)
For determining the flow pattern along the hull various flow visualization techniques are available. Paint flow tests, tuft tests, die test.
Highly specialized test are needed to determine the abilities of an offshore wind service vessel. Stationary seakeeping tests in all directions, windmill approach tests, bollard push tests towards windmill in sea. By rotating the model relative to the incoming sea all wave headings can be tested.
For ocean structures the goal is normally to reduce motion, but the when it comes to wave energy system the goal is to increase the motions in order to capture as much as possible of the energy. Examples of renewable energy systems tested and analyzed at STT is floating point absorbers, oscillating water column (OWC) and vertical tidal turbines.
The power take off system (PTO) for renewable energy concepts is important to consider as energy converted from the system will affect and alter the hydrodynamic behavior of the structure being tested.
Fishery, fish farming and seismiq equipment tests
Equipment for the fishing industry, seismic industry and fish farming industry has been tested in the towing tank. Both current and waves can be simulated by using the carriage forward speed combined with waves. Drag of various rope designs can be compared, solutions for reducing drag on ropes can be verified and new concepts for closed fish farms can be evaluated. In the case of rope testing, the tests are performed in full scale, but for larger structures models are built.
In the initial phase of a design project, it is often cost effective to evaluate conceptual designs numerically by using CFD as a design-support tool.
CFD analysis has several complementary features that goes well with physical model testing, and is often used for a more detailed analysis of flows and pressure fields. Used together with scale model testing this approach can give a more detailed analysis of the design, provide a clear diagnosis of problems, give insight in scale effects and predict full-scale forces.
Stadt Towing Tank has developed several products during the build-up of the test facility. This is equipment and systems that combine mechanical solutions, sensor systems and computer hardware and software.
Typical is small test facilities for schools and universities with towing carriage, sensors/equipment and software for operating a hydrodynamic laboratory.