Electric Field Damping of Rijke Tube Combustion Instabilities

Abstract

A direct-current electric field was investigated as a damping method for thermoacoustic instabilities generated in a horizontal Rijke tube driven by a premixed propane torch. Electrode lengths of 2.54, 5.08, and 15.24 cm were used with electrode locations relative to the burner tip of −4.60, −2.06, and 0.458 cm and voltages up to 4.68 kV being tested. Electrodes downstream of the burner tip, rather than surrounding the burner, and longer electrodes were most effective at damping instabilities. Damping also increased with applied voltage. These findings held true for both laminar and turbulent flames and were in agreement with theoretical predictions made based on two-dimensional static electric field models. Sound pressure level reductions up to 21 dB for the laminar flame, which completely damped the instability, and 4.4 dB for the turbulent flame were seen using the 15.24 cm electrode at 4.68 kV. When the entire Rijke tube acted as the electrode, a reduction of 19 dB was seen for the turbulent flame at 9 kV, which suppressed the instability. The damping effect was attributed to stabilization of the oscillating flame and its unsteady heat release, driven by the combustion instability pressure fluctuations, via the ionic wind.

Suppression of Thermoacoustic Instabilities Using an Electric Field and Feedback Control

“…In Henderson and Xu [35] , the effect of a DC field on a Bunsen style flame inside of a Rijke tube was studied. The authors found the application of a DC voltage suppressed the instability amplitude, reaching a maximum suppression of 21 dBA.…”

“…The ionization mechanism is primarily through chemical ionization and thus dependent on the fuel type and the fuel to air ratio. While this work only explored methane for the fuel, other fuels known to contain sizeable charge densities and be affected by electric fields include butane [30] , propane [30,35] , and acetylene. Application to other fuel types would require further study.…”

Characterizing hydrogen-fuelled pulsating combustion on thermodynamic properties of a combustor

“…For example, Jocher et al 25 experimentally confirm that combustion instability could be controlled in open-loop configuration by applying a magnetic field via reducing the growth rate of flame perturbations. Henderson and Xu 26 experimentally study the effect of applying direct-current electric field on damping thermoacoustic instability in a horizontal Rijke tube. Approximately 20 dB SPL reduction is achieved.…”