Experimental Study of Fire Plume Above a Fire Source with Simple Harmonic Oscillation in Horizontal Direction

Abstract

In recent years, significant progress has been made in the development of maritime facilities such as floating storage and regasification units. In such offshore environments, the change in fire source position owing to temporal oscillation associated with maritime facilities affects fire plume properties. Because the properties of fire plumes in maritime facilities are important when dealing with problems related to fire detection, smoke filling, etc., we have focused attention on fire plume properties above a reciprocating fire source in an unconfined space as a first step. In particular, we experimentally investigated the characteristics of temperature rise and upward velocity along the fire plume axis formed above a 0.1 m square diffusion burner, which harmonically oscillates so as to simulate ship rolling motion under the condition of a small rolling angle. To clarify the time-averaged properties of such fire plumes, the temperature rise and upward velocity up to 5.8 m from the burner surface have been measured by varying the amplitude in three steps (0.1 m, 0.2 m, and 0.3 m) and the period in four steps (6 s, 8 s, 12 s, and 18 s). The results show that the time-averaged temperature rise and upward velocity changes from a two-dimensional plume to an axisymmetric plume. Such transition heights were determined from a simple theoretical model for predicting plume properties above a harmonically oscillating fire source. In addition, empirical correlations for effective heat release rates were also developed. These correlations allowed the existing engineering relationships for temperature rise and upward velocity along the plume axis formed above a fixed-point fire source to be utilised in order to estimate the characteristic properties of a plume formed over a harmonically oscillating fire source. This engineering knowledge can be useful for developing elemental models for the development of a two-layer zone model for ship fires.