Simulation of the ignition of a methane-air mixture by a high-voltage nanosecond discharge

Abstract

International audienceThe ignition dynamics of a CH4: O2: N2: Ar = 1: 4: 15: 80 mixture by a high-voltage nanosecond discharge is simulated numerically with allowance for experimental data on the dynamics of the discharge current and discharge electric field. The calculated induction time agrees well with experimental data. It is shown that active particles produced in the discharge at a relatively low deposited energy can reduce the induction time by two orders of magnitude. Comparison of simulation results for mixtures with and without nitrogen shows that addition of nitrogen to the mixture leads to a decrease in the average electron energy in the discharge and gives rise to new mechanisms for accumulation of oxygen atoms due to the excitation of nitrogen electronic states and their subsequent quenching in collisions with oxygen molecules. Acceleration of the discharge-initiated ignition is caused by a faster initiation of chain reactions due to the production of active particles, first of all oxygen atoms, in the discharge

Cross Sections for Electron Collisions with Methane

“…To derive the rotational cross section of CH 4 , Müller et al 52 Theoretically, there are two classes of calculations: closecoupling method and variational calculation, see Itikawa and Mason 56 for details. Three papers [57][58][59] have been published based on close-coupling calculation for CH 4 . Among them, Abusalbi et al 57 reported the cross section only at one energy (10 eV).…”

“…Fits to the recommended total and partial ionization cross section using the formula of Janev and Reiter, 11 Eq. 4 , independent of the method applied, are to be considered as gross total ionization cross section, which is the total ion current collected, i.e., the charge-weighted sum of partial cross sections,…”

“…Studies of plasma-enhanced combustion have also focused extensively on methane plasmas. 4,5 Methane is a major component of the atmospheres of the outer planets and satellites. In particular, atomic processes involving methane play a crucial role in the upper-atmosphere of Titan.…”

Dynamic and hydrodynamic response of premixed methane-air flame to nanosecond pulsed discharges

“…While the discharge energy is transferred into the excitation of internal degrees of freedom in the gas, a portion of the discharges energy is rapidly converted to the energy of translational degrees of freedom. The fraction of transmitted energy varies from 10% to 60% at different electric field [17]. The process of energy transfer and relaxation occurs in tens or hundreds of nanoseconds, which is less than the typical gas-dynamic time.…”

Experimental Study of the Transient Response of Bunsen Flame to Nanosecond Pulsed Discharges

“…While the discharges energy is transferred into the excitation of internal degrees of freedom in the gas (like the electronic excitation of N 2 molecules et al), a portion of the discharges energy is rapidly converted to the energy of translational degrees of freedom. The fraction of transmitted energy varies from 10 to 60 % at different electric field [21]. The process of energy transfer and relaxation occurs in a very short space of time, like the rotational-translational (RT) relaxation process requires only a few collisions.…”