Electric Field Modified Bunsen Flame with Variable Anode Placement

Abstract

A methane-air Bunsen flame was tested under dc electric field forcing with different ring anode sizes and locations. The anodes were placed within the flame to far outside the flame, both axially and radially. The focus of the work is to understand the limit of electrode placement and its effect on the flame under a dc field. A stoichiometric flame with voltages up to 9.1 kV was tested. The electrical current and flame height were measured as a function of the bias voltage and anode location. Plasma density measurements of the unmodified flame at various axial locations were used to corroborate that anode placement at regions of high electron density caused the largest reductions in flame height. The results showed the anodes closest to the burner at 35 mm caused the largest reduction (24%) in flame height. The effect of the electric field on flame height decreased as the anode moved farther downstream of the flame or radially outward. For the same voltage, larger currents were also observed for anodes close to the burner, whereas anodes placed far outside of the flame had minimal effects on current and, consequently, on the flame height. These differences are due to the variable electron density at the anode, which limits the net current collected and the strength of the field.

Ion current and carbon monoxide release from an impinging methane/air coflow flame in an electric field

“…The results show that the overall OH fluorescence intensity decreases as the plate approaches the burner. This decrease of strength is a combined effect from the decreasing mole fraction of OH, the temperature dependence of the transition Q1 (7), the density changes due to temperature variation, vignetting as the plate height changes, and collisional quenching. With all of these effects, the results provide primarily comparative information, but the integrated use of fluorescence and tomographically reconstructed chemiluminescence can identify the heat release (HR) zone [31] and at the same time track the primary combustion location [32].…”

“…Studies into the electrical aspects of combustion have a long and rich history that show how proper application of electric fields can act on the charge carriers in flames and modify combustion behavior including the effects of different orientation of electrode to the flow field geometries [1][2][3][4][5][6][7][8][9]. As a foundation, particularly in flame studies, the fundamentals of electrical aspects of combustion have been integrated and published by Lawton and Weinberg in 1969 [10].…”

Propulsion Research and Academic Programs at the University of Alabama in Huntsville - 2018

“…Recent papers published in PAIC have demonstrated, for the first time, the suppression of thermoacoustic instabilities in a Rijke tube using solely electric fields. 69,70 Publications in microplasma have focused on diagnostic development to study these small scale plasmas using physical and optical technique. 71,72 A new project in microplasma for diode pumped rare gas lasers is beginning at the PRC supported by the Army Space Missile Defense Command.…”