EXPERIMENTAL STUDY OF THE BURNING RATE AND FLAME LENGTH OF A DIESEL POOL FIRE AT DIFFERENT INITIAL OXYGEN CONCENTRATIONS IN THE ENGINE ROOM OF A SHIP

Ventilation is relatively poor in the engine room of ships, and the oxygen content is typically decreased due to the oxygen consumption by many types of power machinery. If a fire occurs in the engine room, its development mechanism will be impacted by the initial oxygen concentration. The experiments in this study involve a confined space with dimensions of 1.5 m × 1.5 m × 1 m and a circular pool with diameters of 8 cm, 10 cm, 12 cm, and 16 cm. The initial oxygen concentration YO2 in the confined space is taken to be 18%, 18.5%, 19%, 19.5%, 20%, 20.5%, and 21%. By comparatively analyzing the changes in fuel mass, burning rate, and flame length, it is found that a lower initial oxygen concentration corresponds to the additional residual fuel mass. The fire extinction time increases with decreasing initial oxygen concentration. Furthermore, the mass burning rate decreases linearly with decreasing initial oxygen concentration. The stability stage of fuel combustion almost disappears at low oxygen concentrations (18.5-20.5%) and contains only the growth stage and declining stage, in which the growth stage period increases with decreasing initial oxygen concentration. In addition, the flame length is found to be coupled to the initial oxygen concentration, and a nonlinear expression for the flame length based on the mass burning rate and oxygen concentration is established.