EXPERIMENTAL INVESTIGATION OF PROPANE IGNITION BY A HOT WIRE: INITIAL FLAME LOCALIZATION

We studied the features of hot wire gas ignition in a laboratory setup. Propane-air mixture flows around the nichrome coil heated by electrical current, and the ignition moment and flame propagation are registered using a high-speed camera and thermocouples. The influence of flow rate and gas composition on combustion development is investigated. It is found that the flame appears not at the wire surface, but in the gas phase at a distance of several wire diameters above. The distance of the flame initiation weakly depends on the flow rate in the studied range. Flame oscillations at the early stage of combustion process development are observed, which are related to the interaction between the flame sphere and the coil. The heat balance of the coil is estimated, and the contribution of different heat transfer mechanisms is discussed.