Detailed characterization of DC electric field effects on small non-premixed flames

Karnani, Sunny; Dunn‐Rankin, Derek

doi:10.1016/j.combustflame.2015.03.019

Cited by 48 publications

(19 citation statements)

References 38 publications

(43 reference statements)

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“…Typically, when an external DC field is applied, an electric current from a flame increases with the DC field [21,22]; it becomes saturated with an excessive DC field exceeding a certain critical field intensity [23][24][25][26]. In the sub-saturated regime, space charges redistribute to minimize their potential, shielding the electric field and limiting the current, but in the saturated regime, no further space charges remain in the flame zone-all generated ions and electrons migrate toward their corresponding electrode.…”

Section: Introductionmentioning

confidence: 99%

DC field response of one-dimensional flames using an ionized layer model

Xiong

Park

Lee

et al. 2016

Combustion and Flame

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Abstract:We develop a simplified model to better explain electric current response when direct current (DC) is applied to a flame. In particular, different current responses have been observed by changing the polarity of the DC in a sub-saturated current regime that results from the presence of ions and electrons in the flame zone. A flame zone was modeled as a thin, ionized layer located in one-dimensional DC electric fields. We derived simplified model-governing equations from species equations by implementing mobility differences dependent on the type of charged particle, particularly between ions and electrons; we performed experiments to substantiate the model. Results showed that the sub-saturated current and local field intensity were significantly influenced by the polarity of the DC because of the combined effect of unequal mobility of charged particles and the position of the ionized layer in the gap relative to two electrodes. When an energized electrode is close to the ionized layer, applying a negative DC causes a more rapid increase in current than by applying a positive DC to the same electrode.Results from our experimental measurement of current using counterflow diffusion flames agreed qualitatively well with the model predictions. A sensitivity analysis using dimensional and non-dimensional parameters also supported the importance of the mobility difference and the relative location of the ionized layer on the electric current response.

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Section: Introductionmentioning

confidence: 99%

DC field response of one-dimensional flames using an ionized layer model

Xiong

Park

Lee

et al. 2016

Combustion and Flame

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“…Valuable information on the ionic structure of a flame can be obtained from a detailed understanding of i -V curves [1]. i -V curves have been investigated in the combustion literature with the aim of characterizing the production rates and densities of charged species [2,3] and analyzing electric fields effect on flames [4,5]. An example of the i -V curve is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

The i−V curve characteristics of burner-stabilized premixed flames: detailed and reduced models

Han

Belhi

Casey

et al. 2017

Proceedings of the Combustion Institute

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The i -V curve describes the current drawn from a flame as a function of the voltage difference applied across the reaction zone. Since combustion diagnostics and flame control strategies based on electric fields depend on the amount of current drawn from flames, there is significant interest in modeling and understanding i -V curves. We implement and apply a detailed model for the simulation of the production and transport of ions and electrons in one-dimensional premixed flames. An analytical reduced model is developed based on the detailed one, and analytical expressions are used to gain insight into the characteristics of the i -V curve for various flame configurations. In order for the reduced model to capture the spatial distribution of the electric field accurately, the concept of a dead zone region, where voltage is constant, is introduced, and a suitable closure for the spatial extent of the dead zone is proposed and validated. The results from the reduced modeling framework are found to be in good agreement with those from the detailed simulations. The saturation voltage is found to depend significantly on the flame location relative to the electrodes, and on the sign of the voltage difference applied. Furthermore, at sub-saturation conditions, the current is shown to increase * Corresponding author Email address: fbisetti@utexas.edu (Fabrizio Bisetti)Preprint submitted to Proceedings of the Combustion Institute July 17, 2016linearly or quadratically with the applied voltage, depending on the flame location. These limiting behaviors exhibited by the reduced model elucidate the features of i -V curves observed experimentally. The reduced model relies on the existence of a thin layer where charges are produced, corresponding to the reaction zone of a flame. Consequently, the analytical model we propose is not limited to the study of premixed flames, and may be applied easily to others configurations, e.g. nonpremixed counterflow flames.

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“…Because the application of an electric body force to a volume containing ions (reaction zone) is expected to cause dynamic responses of a flame, carbon flux of each mixture to a reacting volume was used to estimate the ion number density, which is known to be proportional to the carbon flux regardless of fuel [19,20] . However, the carbon flux of the CH 4 /O 2 /CO 2 and C 3 H 8 /O 2 /N 2 mixtures were 60% and 26% higher than the baseline, respectively, suggesting that although the electric body force contributes to the dynamics of the flame, it may not be the sole determining factor.…”

Section: Flame Morphology With Ac Electric Fieldsmentioning

confidence: 99%