Effect of an external electric field on the propagation velocity of premixed flames Mario Sa ´nchez-Sanz a , Daniel C. Murphy b,⇑ , C. Fernandez-Pello b a Dept. Ingenierı ´a Te ´rmica y de Fluidos, Universidad Carlos III de Madrid, 28911 Legane ´s, Spain b Department of Mechanical Engineering, University of California, Berkeley, United States Available online 25 June 2014 Abstract There have been many experimental investigations into the ability of electric fields to enhance combus- tion by acting upon ion species present in flames [1]. In this work, we examine this phenomenon using a one-dimensional model of a lean premixed flame under the influence of a longitudinal electric field. We expand upon prior two-step chain-branching reaction laminar models with reactions to model the creation and consumption of both a positively-charged radical species and free electrons. Also included are the elec- tromotive force in the conservation equation for ion species and the electrostatic form of the Maxwell equations in order to resolve ion transport by externally applied and internally induced electric fields. The numerical solution of these equations allows us to compute changes in flame speed due to electric fields. Further, the variation of key kinetic and transport parameters modifies the electrical sensitivity of the flame. From changes in flame speed and reactant profiles we are able to gain novel, valuable insight into how and why combustion can be controlled by electric fields. Ó 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved. Keywords: Premixed flame; Electric field; Laminar flame speed; Charged species; Chain-branching reaction 1. Introduction In order to study the effect of the electric field on a premixed flame, this paper will consider a one-dimensional model of a lean premixed flame under the influence of a longitudinal electric field. The electric field is oriented in the direction of the gas flow and can have positive or negative signs, indicating different electric field polarities. The model is defined by the set of conservation equa- tions and chemical reactions which should reflect the behavior of a lean premixed flame subjected to an electric field. To model the interaction between the flame and the electric field, we need to include in the chemistry model a radical that can be ionized at high temperatures to give a pro- tons and electrons that can be affected by the elec- tric field. A good candidate is the the two-step, chain- branching chemistry model developed originally by [2,3] and further developed later by [4] using http://dx.doi.org/10.1016/j.proci.2014.05.075 1540-7489/Ó 2014 The Combustion Institute. Published by Elsevier Inc. All rights reserved. ⇑ Corresponding author. Address: 60 Hesse Hall, Department of Mechanical Engineering, University of California, Berkeley, United States. Fax: +1 (510) 642 1850. E-mail addresses: mssanz@ing.uc3m.es (M. Sa ´nchez- Sanz), dmurphy0516@gmail.com (D.C. Murphy), ferpello@me.berkeley.edu (C. Fernandez-Pello). Available online at www.sciencedirect.com ScienceDirect Proceedings of the Combustion Institute 35 (2015) 3463–3470 www.elsevier.com/locate/proci Proceedings of the Combustion Institute