Flame detection by electrostatic double probe with parallel detection and reference electrodes

The flame detection characteristics of an electrostatic probe with parallel detection and reference electrodes were investigated on a simple two-dimensional laminar premixed flame. For the large distance between two electrodes, ion current records showed the dependence on the angle of the plane including those two electrodes from the flame surface, that is, the large angle induced double peaks on the ion current record and the decline of maximum peak. On the other hand, for the small distance between two electrodes, in particular less than the thickness of high ion-electron concentration zone, ion current records were independent and constant with respect to the angle. Those features were caused whether both electrodes could be in the flame simultaneously. For the small distance, furthermore, the variation of current peak as functions of passing velocity of the probe through the flale and equivalence ratio was qualitatively same as that for the conventional single electrostatic probe. Consequently, the present probe with small distance between detection and reference electrodes can be applicable to the flame detection.