Effects of DC Electric Fields on Flickering and Acoustic Oscillations of an M-shape Premixed Flame

This paper reports on the effect of DC electric fields on the dynamics of a premixed methane-air laminar flame, in a buoyant environment. DC electric fields can be capable of affecting both the buoyancy-driven flickering oscillation of the flame and the response of the flame to acoustic modulation of the flow. We conduct fast visualization of the emission of excited methylidyne radicals (CH^*), representing the heat release rate of the flame. Such visualizations are also synchronized with electric current and voltage measurements. We notice that the suppression of buoyancy-driven flickering oscillations can be obtained by applying sub-critical negative DC voltages. Moreover, the current measured in the inter-electrodes area is analyzed for positive and negative DC applied voltages and we find that this quantity cannot be used as a tracer of heat release rate in a configuration where the flame location in the inter-electrodes gap varies with sub-critical electric fields. In addition, the effect of DC electric fields on the flame transfer function for acoustic modulation of the flow is reported and discussed.