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The pressure of the Depressurised Towing Tank (240 x 18 x 8 m) can be reduced to an ambient pressure of 25 millibar. The tank is suitable for models up to 14 m long, which are free to trim and sink, thus accurately modelling the wake field. The tank is used to optimise the erosion and vibration characteristics. To avoid erosive cavitation and vibration hindrance on the propellers, rudders or struts, cavitation is observed using regular and high-speed cameras coupled to pressure pulse measurements.
The pressure of the Depressurised Towing Tank (240 x 18 x 8 m) can be reduced to an ambient pressure of 25 millibar. The tank is suitable for models up to 14 m long, which are free to trim and sink, thus accurately modelling the wake field. The tank is used to optimise the erosion and vibration characteristics. To avoid erosive cavitation and vibration hindrance on the propellers, rudders or struts, cavitation is observed using regular and high-speed cameras coupled to pressure pulse measurements.
Technical data
Tank dimensions are 240 x 18 x 8 m. The harbour (preparation) area is 26 m long and 4.2 m wide. The instrumentation allows for measuring 40 channels at 5 kHz. The noise measurement system is able to test frequencies of 2 – 80 kHz.
Tank dimensions are 240 x 18 x 8 m. The harbour (preparation) area is 26 m long and 4.2 m wide. The instrumentation allows for measuring 40 channels at 5 kHz. The noise measurement system is able to test frequencies of 2 – 80 kHz.
Carriage, main frame
The towing carriage with a maximum speed of 8 m/s consists of a main frame spanning the full width of the tank. The carriage includes an atmospheric pressure cabin for special test equipment and personnel, a visitors platform (only to be used under atmospheric conditions) and a subframe.
The towing carriage with a maximum speed of 8 m/s consists of a main frame spanning the full width of the tank. The carriage includes an atmospheric pressure cabin for special test equipment and personnel, a visitors platform (only to be used under atmospheric conditions) and a subframe.
Carriage, subframe
The subframe consists of a test frame and an observation module, and can be disconnected from the carriage. The test frame holds all measurement and testing equipment, the observation module carries all equipment related to cavitation observations (camera, stroboscopes and remote controlled positioning frame). The subframe can be transferred to the harbour area for preparation through an air lock system and is finally connected to the towing carriage, where it is ready for testing.
The subframe consists of a test frame and an observation module, and can be disconnected from the carriage. The test frame holds all measurement and testing equipment, the observation module carries all equipment related to cavitation observations (camera, stroboscopes and remote controlled positioning frame). The subframe can be transferred to the harbour area for preparation through an air lock system and is finally connected to the towing carriage, where it is ready for testing.
Air lock system
The newly designed and relocated air lock system allows a fast transfer of the subframe to and from the harbour area. This way the complete test set-up (subframe, observation module, ship model and instrumentation) can be prepared and tested outside the tank under atmospheric conditions.
The newly designed and relocated air lock system allows a fast transfer of the subframe to and from the harbour area. This way the complete test set-up (subframe, observation module, ship model and instrumentation) can be prepared and tested outside the tank under atmospheric conditions.
Ambient air pressure
According to the laws of similarity which apply to cavitation, the ambient air pressure in the tank must be reduced to the inverse of model scale. Through three vacuum pumps it can be lowered to a minimum of 2500-4000 Pa.
According to the laws of similarity which apply to cavitation, the ambient air pressure in the tank must be reduced to the inverse of model scale. Through three vacuum pumps it can be lowered to a minimum of 2500-4000 Pa.
Observation systems
The observation systems (both inside and outside the model) offers more operational flexibility through the remote control of camera position, camera settings (zoom and focus), stroboscope positions and intensity. The camera and stroboscope housings allow for testing at a reduced cavitation number of σv 0.4.s
The observation systems (both inside and outside the model) offers more operational flexibility through the remote control of camera position, camera settings (zoom and focus), stroboscope positions and intensity. The camera and stroboscope housings allow for testing at a reduced cavitation number of σv 0.4.s
Model size range
Models range from 2 – 12 m in length, up to 4 m beam and a maximum draught of 10 m. Maximum propeller diameter is 0.4 m.
Models range from 2 – 12 m in length, up to 4 m beam and a maximum draught of 10 m. Maximum propeller diameter is 0.4 m.
Test capabilities
- Cavitation observation and inception
- Pressure fluctuation measurements
- Radiated noise measurements
- Wakefield measurements
- Resistance and propulsion tests
Contact
For more information on the Depressurised Towing Tank, please contact the Ships Powering department.
For more information on the Depressurised Towing Tank, please contact the Ships Powering department.