Effects of electric field intensity and frequency of AC electric field on the small-scale ethanol diffusion flame behaviors

Abstract

The Alternating Current (AC) electric field was applied on the small-scale flame in order to promote the characteristics or control the combustion. The effect of AC electric field on the small-scale ethanol diffusion flame behaviors was studied experimentally and numerically. The inner diameter of the burner nozzle was 0.9mm and the flame was established at room temperature and atmospheric pressure. Different electric field intensities and frequencies of AC electric field were generated by two parallel plate electrodes which were respectively placed above and below the flame. Numerical results combined with experimental observations were used to analyze the small ethanol diffusion flame characteristics under the electric field. The results show that flame behaviors are significantly influenced by the applied AC electric field. The body forces acting on charged particles in the electric field are considered under the AC electric field. The charged particles are accelerated in the applied electric field and transfer the momentum to the neutral particles. At a certain flow rate of ethanol, the flame temperature and flow velocity increase with the increasing of electric field intensity and AC frequency. The diffusion effect is strengthened by the electric field and the mass fraction distribution of the component has a tendency of inward contraction, which is consistent with the tendency of flame becoming shorter. It also can be concluded that the applied AC electric field promotes the mixing of fuel and oxidizer, thus enhances the combustion process. The reaction rate in the flame becomes faster and reaction position is closer to the fuel side. The combined effects of diffusion and reaction enhancements affect the flame behaviors.