Technical Specifications |
|
Nd:YAG double pulse laser | 190 mJ, max. Frequency 15 Hz |
Resolution CCD cameras | 2 Megapixel (1600×1200) |
Colour depth/grey levels | 12 bit |
Max. recording frequency | 14.5 Hz |
Field of view | 100×100 up to 800×1000 mm |
Number of stereoskopic recordings per measurement run at 14.5 Hz | 1200 |
Max. submersion depth of PIV probe | 0.7 m |
Max. submersion depth of single system components | 4.5 m |
Author: pa
Wave Generator
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Towing Tank
At the front of the tank there is a wave generator which can produce regular and irregular waves and also wave packets up to a wave height of 0.30 m. At the back, the towing tank ends in a beach as a wave absorber.
In the towing tank, free running tests are carried out with propellers and propulsion systems as well as resistance and propulsion tests, wake field measurements and paint flow tests. Additional elements of the testing spectrum include maneuvering, seakeeping tests and experiments with submersibles.
The towing carriage is provided with a flexible carrier system that can accommodate all equipment and experiments. The support at the rear of the towing vehicle is hydraulically adjustable in height. For example, the open water dynamometer and the submarine planar motion system (SUBPMM) or the PIV system can be installed there.
The equipment of the towing carriage is completed with cameras for the QualiSys optical tracking system and video cameras as well as cameras for recording experiments and images of wave systems.
Technical Specifications |
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Towing Tank | ||
Length | [m] | 280 |
Width | [m] | 9 |
Depth | [m] | 4.5 |
Towing Carriage | ||
Max. Towing Velocity | [m/s] | 7.5 |
Precision Carriage Velocity | [mm/s] | 0.6 |
Wave Generator | ||
Max. Wave Height | [m] | 0.3 |
Types of Waves | regular, irregular, wave trains |
Sea Trial Evaluation
Prior to delivery and acceptance of new ships, the achievable speed for a given power and the power consumption for a given speed is determined in a trial (measured mile) with the full-scale version. Primarily, it is checked as to whether the contractual parameters have been achieved and, secondarily, whether the required EEDI is fulfilled.
To determine the delivered power, the torque and rotational velocity of the propeller for a given speed can be measured. This measurement can be carried out by the SVA onboard the ship with own measurement equipment.
Unlike model tests, the conditions in a measured mile are only in the rarest cases ideal. It can hardly be avoided that measured miles must be carried out in wind and waves, with shallow water effects, in areas of current, etc. To convert the environmental influences on the contract or experimental conditions, the measured mile results must be evaluated. The SVA Potsdam offers such calculations which are performed in accordance to the current standards of IMO and ITTC.
Power Measurement at Full-Scale
Performance measurements on the propeller shaft are performed during measured miles, acceptance of new ships and, in case of problems, in the area of propeller/engine tuning to determine the power consumption of the propeller at full-scale. For this, the torque and speed of the propeller shaft or gear coupling shafts and intermediate shafts are measured. The torque measurement is carried out with strain gauges and the speed measurement with a magnet-hall sensor system. With a Bluetooth measurement module, the signals are processed and transmitted digitally to a measuring computer. Additional metrics like speed, heading, rudder angle and trim of the vessel may be time equidistantly recorded. For this purpose, GPS / DGPS systems, gyroscopes and other instrumentation are available.
Manoeuvering
Numerical simulations allow to:
- Simulate manoeuvring behaviour in model and full-scale
- Simulation of static and dynamic tests
- Visualisation of flow, detection of separating flow
- Design of control elements such as rudders, thrusters, etc.
The rudder is by far the most frequently used control element; it operates in the wash of the propeller. Below, the pressure distribution on the rudder for a rudder angle of δR = 20° with a rotating propeller is shown.
Context Related References / Research Projects
[1] Lübke, L.: Investigation of a Semi-Balanced Rudder, 10th Numerical Towing Tank Symposium, Hamburg, 24.09.2007
[2] Lübke, L.: Investigation of a Semi-Balanced Rudder, 14. SVA Forum, Potsdam, 07.11.2007
[3] Lübke, L.: Investigation of a Semi-Balanced Rudder, ANSYS Conference & 25th CADFEM Users Meeting 2007, Dresden, 21. – 23.11.2007
[4] Lübke, L.: Numerische und experimentelle Untersuchungen an einem Halbschweberuder, STG-Sprechtag, Verbesserung der Propulsions- und Manövriereigenschaften von Schiffen, Papenburg, 18.09.2008
[5] Lübke, L.: Numerische PMM-Tests für Unterwasserfahrzeuge, ANSYS Seminar, Simulationswerkzeuge für die Marine und Offshore Industrie, Hamburg, 05.11.2008
[6] El Moctar, O., Brehm, A., Lübke, L.: Hydrodynamische und strukturmechanische Untersuchung von Rudern großer, schneller Schiffe (XXL-Ruder), PTJ Statustagung, Warnemünde, 11.12.2008
[7] Lübke, L.: Numerische und experimentelle Untersuchungen der effektiven Ruderzuströmung beim Manövrieren, 2. SVA Forschungsforum „Theoria cum praxi“, Potsdam, 29.01.2009
[8] Lübke, L.: Manoeuvering Simulations of Underwater Vehicles, 12th Numerical Towing Tank Symposium, Cortona Italy, 04.-06.10.2009
[9] Lübke, L.: Investigation of a Semi-balanced Rudder, Ship Technology Research, Vol. 56, No. 2, 2009