Effects of Electric Fields on Stabilized Lifted Propane Flames

Abstract

The effects that various charged electrodes, and associated eiectric fields, have on lifted propane flames have been investigated. Two electrodes were used to provide an electric field with potentials ranging from 0 to 11,000 V. The primaiy electrode was around the flame and the secondary electrode was the fuel nozzle. Electrode polarity and primary electrode location with various flame field locations (near, mid, far) were varied, resulting in a variety of flame behavior. Results show that the body force resultant from the bulk flow of formed ions, from a positively charged fuel nozzle, and grounded ring electrode, will increase flame liftoff height and, eventually, cause blowout. However, for the opposite polarity (positively charged ring electrode and grounded fuel nozzle), the flame progresses toward reattachment with increasing potentiais. Observing the narrow window of flame blowout or reattachment (varying with polarity), it was observed that the lifted flame height fluctuations were increased with the presence of the grounded ring electrode, but reduced when the polarity was shifted to positive configuration (positively charged primary electrode). Flame hysteresis was obsen'ed when the ring electrode was positively charged and it was found that the hysteresis regime increased when the potential of the ring electrode was increased to 1500 V but had little changes at lower potentials. While the ring electrode was positively charged, a distinct hole was observed in the center of the flame. Several images are presented that show these flame holes that are present when the electrodes are charged.

Direct numerical simulation of a turbulent methane/air flame impinged by a sub-breakdown electric field

“…Volkov et al [6] demonstrated the ability of DC electric fields to control thermoacoustic instabilities, at least in a specific range of frequencies. Moreover, applying electric fields has enabled a significant reduction in the liftoff height of lifted flames [7,8]. Similarly, augmentation of the flame propagation speed has been observed for premixed flames subjected to DC [9] and AC [10] electric fields.…”

2-D numerical modeling of flame behavior under electric field effect

“…The effect of electric field on the stability of lean methaneoxygen air was investigated by Tomcik, et al [8], while the lift-off of propane flame under the effect of the electric field was discussed by Hutchins, et al [9]. The polarity and electrode location effects on lift-off were also discussed in their work.…”

An efficient flamelet progress-variable method for modeling non-premixed flames in weak electric fields

“…Flow control is a crucial issue to enhance the performance of modern internal combustion engines. In particular, experimental tests have demonstrated that the extinction limit of both premixed and diffusive flames can be controlled by the application of an external electric field [1][2][3][4]. The effectiveness of this method comes from the action of the imposed electric field on the charged particles produced by the combustion process.…”