Trans RINA, Vol 154, Part A2, Intl J Maritime Eng, Apr-Jun 2012


THE FLOODING AFTER DAMAGE OF A WARSHIP WITH COMPLEX INTERNAL COMPARTMENTS – EXPERIMENTS ON A FULLY CONSTRAINED MODEL IN CALM


WATER AND REGULAR BEAM SEAS (DOI No: 10.3940/rina.ijme.2012.a2.212)


G J Macfarlane and M R Renilson, Australian Maritime College, University of Tasmania, Australia T Turner, Defence Science & Technology Organisation, Australia SUMMARY


In order to provide data to assist in developing and validating a numerical code to simulate the flooding immediately following damage scale model experiments were conducted on a fully constrained model to investigate the progressive flooding through a complex series of internal compartments within a generic destroyer type hull form.


A 3.268 metre long model of a generic destroyer hull form with a simplified, typical internal arrangement was constructed to cover the configuration of greatest interest. A very rapid damage opening scenario was simulated by rupturing a taut membrane covering an opening. The model was instrumented to measure the levels of water and the air pressures in various compartments. In addition, video footage was obtained of the flooding process from both internally and externally of the model.


Previous work presented by Macfarlane et al. (2010) showed the results for the unconstrained model. This paper reports on the outcomes from the experimental program where the model was fully constrained in all six degrees of freedom. Firstly, tests were conducted in calm water with damage opening extents ranging from 50% to 100%. When the damage opening was only 50% the rate of rise of water in each of the compartments was only marginally slower than for the 100% damage extent case.


Secondly, the test results in calm water were compared against results from tests in regular beam seas. A ‘set-up’ of water inside each of the compartments on the 2nd Deck was found during the wave tests. The result of this is that the mean equilibrium water level in each compartment in the regular beam sea cases is noticeably higher than the equivalent calm water case, particularly for the two compartments on the port side, away from the damage. Finally, analysis of the data from further calm water and beam sea tests suggests that a similar result also occurs when the model is fixed at various non-zero heel angles.


1. INTRODUCTION


The motions, and consequent safety, of a ship after it has been damaged are highly dependent on the way flood water passes


following the damage event. A lot of work has been done to investigate the behaviour


between compartments immediately of


flood water


following damage for simplified internal geometries (for example, de Kat et al. 2000; de Kat and Peters 2002; Vassalos et al. 2004), however less has been done for the more complex arrangements common to warships.


In order to investigate this behaviour and generate data to assist in ongoing validation of the flooding model used in a non-linear time domain code, FREDYN, developed by MARIN for the Cooperative Research Navies group (CRN), model


experiments were conducted using a


model of a generic destroyer hull form with an internal arrangement representative of a typical warship. The experiments were conducted in the 35m x 12m basin at the Australian Maritime College (Macfarlane and Renilson, 2010).


Macfarlane et al. (2010) and Turner et al. (2010) have previously reported on outcomes from this experimental study


with a focus on the model being ©2012: The Royal Institution of Naval Architects fully A-53


unconstrained. The work presented in the current paper concentrates on the experimental results for the model constrained in all six degrees of freedom in both calm water and regular beam seas. FREDYN comprises a ship motion model and a progressive flooding model and the uncertainty in each model can be solved by separating the validation process into several phases, as described by Ypma and Turner (2010). The validation phase of specific interest in the present work requires that the ship model be fully constrained at a prescribed heel, trim and draught which allows for a check of the flooding model without any additional complexities due to the dynamics of the vessel. In addition, the geometry of the numerical model can be verified in this phase.


For consistency, all results given in this paper are at model scale.


2. MODEL DETAILS


A 3.268 metre long model of a generic destroyer was constructed of carbon fibre composite and timber to a scale of 1:45. A removable module containing a simplified arrangement of the internal compartments was


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