541
Figure11. Correction factor kdp for different location and
heightofconsideredtanks
It ought to be emphasized that the considered
dynamiccoefficientcomprisesonlytheeffectsof the
MffandMstatcomponentsoftheheelingmomentdue
to liquid motion. The value
kdP =1 indicates the
dynamic effect of liquid sloshing equal to the static
oneintermsofshiptransversestability.Thevalue
kdP
=0 denotes a lack of the dynamic effect of liquid
sloshinginapartlyfilledtankwhichispossibledue
tothewavecharacterofsloshingflowandanoticed
phase shift. Such a phenomenon is utilized in anti
rolling devices (flume tanks) and it is also
encounteredduringliquefiedcargo
carriage[10].
6
CONCLUSION
The study presented in the paper is focused on the
dynamic effects of liquid sloshing taking place in
partly filled ship tanks. The decomposition of the
dynamicheelingmomentduetoliquidsloshingwas
applied.Thenthefurtherprocessingofafreefloating
component enabled implementation of a novel
variablenamed
adynamiccoefficient.Thecoefficient
correspondswiththeenergybalancemethodofship
dynamicstabilitycalculationsandthankstothisitis
compatiblewith theweathercriterionrecommended
bytheIMOIntactStabilityCode.
A set of sample calculation of the dynamic
coefficient was carried out. The results reveal the
possibility of greater impact of sloshing liquid in a
tankthenitisexpectedonthebasisofcontemporary
quasi‐static calculations.However,inmostanalyzed
casestheimpactofliquidsloshingwasfoundsmaller
then it is supposed on the basis of quasi‐static
approach.
Such a conclusion may be
important from the
economical point of view. Ship stability standards
quiteoftenrestrictthecapabilityofavesseltocarryas
much cargo as may be physically loaded. The so
called safety margin is maintained. The common
applicationoftheproposeddynamiccoefficientcould
make the stability requirements less severe
then
nowadays.Itmaybeespeciallyimportantintheage
ofeconomicalcrisisandaworldwidetendencytocost
optimization.Anyextracargocarriedoverthecurrent
restrictionscontributestotheshipoperator’srevenue.
It could be accepted when without any significant
decayofsafetystandardonboard.Thus,arousingofa
discussiononIMOforumseemstobejustified.
ACKNOWLEDGMENT
The research project was funded by the Polish
NationalScienceCentre.
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