An Experimental Study on Progressive and Dynamic Damage Stability Scenarios

Abstract

Current damage stability rules for ships are based on the evaluation of a ship’s residual stability in the final flooding stage. The consideration of the dynamic propagation of water within the inner subdivision as well as intermediate flooding stages and their influence on the resulting stability is very limited in the current damage stability regulations. The investigation of accidents like the one of the Estonia or the European Gateway reveals that intermediate stages of flooding and the dynamic flooding sequence result in significant fluid shifting moments which have a major influence on the time-dependent stability of damaged ships. Consequently, the critical intermediate stages should be considered when evaluating designs with large cargo decks like RoRo vessels, RoPax vessels and car carriers. Also the safety of large passenger ships with respect to damage stability is affected by the aforementioned effects. In this context a new numerical flooding simulation tool has been developed which allows an evaluation of a ship’s time-dependent damage stability including all intermediate stages of flooding. The simulation model is based on a quasi-static approach in the time domain with a hydraulic model for the fluxes to ease the computation and allow for fast and efficient evaluation within the early design stage of the vessel. This allows studying multiple damage scenarios within a short period. For the further validation of this numerical simulation method a series of model tests has been particularly set up to analyse the time-dependent damage stability of a floating body. The test-body has been designed specifically to reflect the most typical internal subdivision layouts of ships affected by the effects mentioned above. The experimental study covers a static model test series as well a dynamic one. The static model test series has been set up with the aim to analyse the progressive flooding of selected compartments in calm water. Within the dynamic model test series, the model is excited by a roll motion oscillator to evaluate the influence of the ship motion on the water propagation and the associated damage stability. The model tests presented in this paper comprise side leaks in typical compartments which are used for a basic validation of the simulation toll and the measurement devices. Particular attention has been drawn on damage scenarios with critical intermediate flooding stages in consequence of restricted water propagation. The presented results enable a further validation of the numerical flooding simulation and give an insight view on the chosen experimental setup.

A simulation model for ship response in flooding scenario

“…The method does not include shallow water equations. 23,24 In this article, the main focus is on improving the results by applying the developed technique, against a quasi-static method. For this reason, viscous effect corrections are disregarded; anyway they would improve the simulation results, as already shown in Manderbacka.…”

Stability Assessment of Drill Ship Using Probabilistic Damage Stability Analysis

“…It was confirmed that Boyle's law can qualitatively predict multiphase dynamic effect between air and water during flooding. A new numerical flood simulation tool which allows evaluation of a ship's time dependent damage stability including all stages of flooding was developed by Lorkowski et al (2014). Lee et al (2015) performed a set of model tests in intact and damaged ship considering six degrees of freedom in beam seas.…”

A Fast Simulation Method for Damaged Ship Dynamics

“…Developing fast numerical simulation tools, capable of modelling water dynamics inside a compartment, is a state of the art challenge. Some of them are based on the lumped mass approach [14]; some of them are based on shallow water equations [15,16]. In [17,18], the so-called quasi-static approach was introduced as the coupling of the equations of motions of a flooded ship in waves with the floodwater, characterized by a flat free surface, moving in phase with the ship.…”