Abstract
In order to obtain the fundamental physical hazard informations of the alternative fuel gases, a series of labo- scale combustion experiments was carried out. In this work, we focused on the behaviour of the flame propagation and the overpressure rise under various conditions of the equivalent ratio, the initial temperature and the initial moisture.
In the present experiment, we used a cylindrical combustion chamber (volume: 1.36 L) made by SUS316. The ignition was initiated by the electric spark generated by a neon transformer. The overpressure was measured by the pressure transmitter, and the flame propagation was taken by the high-speed schlieren camera.
First, we confirmed that the overpressure and the KG value showed peak value in the case of f = 0.99. The measured peak overpressure was slightly smaller than the theoretical peak overpressure whole range of the equivalent ratios.
Secondary, the peak overpressure decreased with the increase of the initial temperature. But the KG value, which is the deflagration index of gas cloud, was hardly decreased with the increase of the initial temperature. In other words, gradient of overpressure rise due to the combustion of LPG was hardly affected by the initial temperature.
Thirdly, the reduction effect by the moisture on the rise of overpressure due to the burnt LPG-air mixture was hardly observed under the fuel-lean condition. But in the case of the stoichiometric and fuel-rich conditions, the overpressure after the peak value apparently decreased by the influence of moisture. This is mainly because a part of combustion heat was spent as the sensible heat. The reduction effect by moisture on the overpressure rise depends on the flame propagation rate and the chamber size.
