| It is obvious that ship fire is one of the most difficult fires to control. Ship fires occurred frequently and there might be dangerous disasters. Life safety, property protection, cargoes on the ship, and the ship safety itself are the concerns. Lost of lives, damages to property and environmental pollution might be resulted from the fires.Engine plant room is the power source of a ship, regarded as the main core. Power for driving the ship and operating all other equipments and systems are supplied from there. In addition to the operating machines, equipments and wiring in the engine room, there are liquid fuel and other combustible items. Therefore, a fire is likely to occur in the ship engine room. Once a fire occurs, locating the fire and fighting against it are difficult due to obstructions by so many equipments and pipes. An engine room fire can grow to a very big size and become uncontrollable, causing big damages. Preventing and fighting engine room fires on ship vessels should be studied in more detail.Based on the advanced Computational Fluid Dynamics package Fire Dynamics Simulator released by the National Institute of Standards and Technology in the U.S.A., thermal flow field characteristics induced by a ship engine room fire were studied by the Large Eddy Simulation (LES) method. Key works performed in this thesis are:Firstly, mathematical and physical models commonly applied in fire simulations were developed. Fluid flow driven by a fire is a multi-species, low Mach number buoyant flow. The conservation equations on mass, momentum and energy are simplified and reduced to a form suitable for describing fluid flow driven by a fire. The fire was modeled by the mixture fraction combustion method with chemical reaction mechanisms neglected. Laminar diffusion flame theory with one-step irreversible fast reactions is assumed. Flame and smoke were taken as gray medium in the thermal radiation model. The radiative transport equationwas solved using techniques similar to those for convective transport in Finite Volume Method for fluid flow. The governing equations were discretized by finite difference method with stagger grids. Spatial derivatives were approximated by second-order central differences. The flow variables were updated in time using an explicit second-order predictor-corrector scheme.Secondly, an experimental facility was built to carry out experiments on flashover in a chamber. The minimum heat release rate for flashover under different ventilation factors were measured by the oxygen consumption method. Experimental results were compared with the empirical formula reported in the literature. It is demonstrated that oxygen consumption calorimetry can be used to measure the heat release rate. In fact, the minimum heat release rate for flashover in a room was measured directly.Thirdly, two other experiments with a two-room structure were carried out for studying flashover. In simulating flashover, the results will be affected by different values of a constant Cs in using LES. cs of value 0.2 will be acceptablewhen the filter width is 0.1 m. For the two-room structure, the equation of air mass flow rate induced by the fire through a vertical opening was derived. In simulating fires occurring in a sealed chamber, the change of pressure in the chamber was studied. Simulation results show that the numerical simulation program developed can be applied to study ship engine room fires.Finally, real ship fire scenarios were simulated with the developed numerical simulation program. Fluid flow field was predicted for fires at the same source and same place under different ventilation conditions. The study was repeated for fires occurred at different locations with the same source and ventilation condition.The results achieved and the conclusion drawn in this thesis are of great importance and applicable in fire prevention and fire fighting against ship engine room fires or other similar cabin fires.
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