Trans RINA, Vol 152, Part A4, Intl J Maritime Eng, Oct-Dec 2010
Figure 5: Openings between the flooded rooms: a) valve between the SB side tank and the equipment room, b) open door between the equipment and pump rooms at frame #22, c) the hole in the bulkhead at frame #25 and d) manhole from the equipment room to the PS side tank
2.2 TEST CONDITIONS
The flooding tests were performed in the covered dry dock of STX Europe Helsinki Shipyard in Finland between August 31st and September 3rd 2009. The water level in the dock was calm and there was practically no wind at all. The ship was located a few meters from the side of the dock. The gangway was lifted and the mooring ropes were kept loose in order to avoid any external forces. Thus the environmental conditions were excluded.
During the tests a couple of persons stayed onboard, watching for possible uncontrolled flooding and taking care of the measurement system. In calculations, these additional (moving) masses were considered to be ignorable.
After each test, the damage hole (i.e. the valve) was closed and the flooded water was pumped out (Figure. 6). This arrangement proved to be very successful and only minimal amount of water was left in the bilge. Therefore, each test started from almost identical intact condition. The very small changes in the initial heeling angle were taken into account in the simulations. The powerful pumping equipment allowed fast emptying of the flooded compartments, thus making it possible to do several tests within a short time.
2.3 MEASUREMENTS
In order to follow the progress of floodwater in different rooms with local stiffeners and brackets, the floodwater level had to be measured in several
locations. The
hydrostatic pressure was measured from the bottom of the rooms with 16 differential pressure sensors (Figure. 7). The measured hydrostatic pressure values were used to determine the water levels. In addition air pressure was measured from the top of every flooded room.
The local flow velocities at the damage hole and in the end of the smaller air pipe were also recorded. After the valve (Figure. 2), the flow velocity close to the pipe surface was measured by using a paddle wheel transducer. The airflow velocity was measured with a pitot tube in the centre of the small air pipe from the SB side tank.
The heel and trim angles were measured with MRU 6 motion sensor, which used three axes gyros and linear accelerometers. In addition, the draft marks of the vessel were monitored during the experiments. Environmental conditions, the density of the water and the atmospheric pressure inside the covered dock, were also measured. Furthermore,
all flooded rooms were equipped with
video cameras in order to allow visual observations of the flooding process.
C1
B3 D2 B10 A1 V1
water level sensor velocity measurement web frame
Figure 6: Pumping after a flooding test ©2010: The Royal Institution of Naval Architects Figure 7: Measurement points
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