Post by jeff on Feb 16, 2016 1:01:00 GMT
Oscillating Water Columns (OCWs) have been in use since the 1940s, even to produce some energy, with air-driven turbines, such as for lighted marker buoys. Generally, they have been vertical cylinders open at top and bottom.
Some active systems for motion damping use such tanks, open at the bottom, but with pumps, either moving water, or air, in order to control the water level, in direct response to vessel motion. However, it may be possible to design and tune a passive system, in order to not need an active system, and to remove the power requirement.
As an initial introduction to the design and development of such a system, the following brief paper should suffice...
Reduction of Pitch Motion of FPSO Vessels by Innovative OWC Passive Control
João Seixas de Medeiros
COPPE, UFRJ
Rio de Janeiro, RJ, Brazil
Helio Bailly Guimarães
COPPE, UFRJ
Rio de Janeiro, RJ, Brazil
Antonio Carlos Fernandes
COPPE, UFRJ
Rio de Janeiro, RJ, Brazil
www.academia.edu/10989371/OMAE2014-23686_Reduction_of_Pitch_Motion_of_FPSO_Vessels_by_Innovative_OWC_Passive_Control
ABSTRACT
The improvement of the seakeeping capabilities of Floating, Production, Storage and Offloading (FPSO) vessels increases safety and allows its operation on severe weather conditions. It also increases the fatigue life of the risers. Hence, any improvement on the FPSO motion is mostly welcome. Guimarães [1], following similar efforts by Silva [2], studied the reduction of pitch motions of FPSO vessels with the use of the OWCs (Oscillating Water Columns) passive system. However, both experimental and numerical results were inconclusive due to green water effects during experiments and panel issues with the panel code WAMIT [3], respectively. The objective of the present work is to report a series of new tests that prove the feasibility of an “L-shaped”moon pool concept and estimates and tests the ideal length of such concept that maximizes the restoring moment and minimizes pitch the most. The tests were conducted in the Laboratório de Ondas e Correntes (Laboratory of Waves and Currents) of the Federal University of Rio de Janeiro (COPPE/UFRJ)
Some active systems for motion damping use such tanks, open at the bottom, but with pumps, either moving water, or air, in order to control the water level, in direct response to vessel motion. However, it may be possible to design and tune a passive system, in order to not need an active system, and to remove the power requirement.
As an initial introduction to the design and development of such a system, the following brief paper should suffice...
Reduction of Pitch Motion of FPSO Vessels by Innovative OWC Passive Control
João Seixas de Medeiros
COPPE, UFRJ
Rio de Janeiro, RJ, Brazil
Helio Bailly Guimarães
COPPE, UFRJ
Rio de Janeiro, RJ, Brazil
Antonio Carlos Fernandes
COPPE, UFRJ
Rio de Janeiro, RJ, Brazil
www.academia.edu/10989371/OMAE2014-23686_Reduction_of_Pitch_Motion_of_FPSO_Vessels_by_Innovative_OWC_Passive_Control
ABSTRACT
The improvement of the seakeeping capabilities of Floating, Production, Storage and Offloading (FPSO) vessels increases safety and allows its operation on severe weather conditions. It also increases the fatigue life of the risers. Hence, any improvement on the FPSO motion is mostly welcome. Guimarães [1], following similar efforts by Silva [2], studied the reduction of pitch motions of FPSO vessels with the use of the OWCs (Oscillating Water Columns) passive system. However, both experimental and numerical results were inconclusive due to green water effects during experiments and panel issues with the panel code WAMIT [3], respectively. The objective of the present work is to report a series of new tests that prove the feasibility of an “L-shaped”moon pool concept and estimates and tests the ideal length of such concept that maximizes the restoring moment and minimizes pitch the most. The tests were conducted in the Laboratório de Ondas e Correntes (Laboratory of Waves and Currents) of the Federal University of Rio de Janeiro (COPPE/UFRJ)