MULTIPHYSICS SIMULATION OF RICH VS. LEAN CHARGE MIXTURES IGNITED BY NANOSECOND PULSED TRANSIENT PLASMA IGNITION SYSTEMS

This paper presents an ANSYS FORTE model comparison between a single point ignition discharge system typical of traditional automotive ignition systems, to a multi-streamer output system with a high discharge efficiency that runs along the center of a combustion chamber, and the same multi-streamer output system with the addition of atomic oxygen to simulate the effect of gaseous radicals produced during the plasma discharge. The atomic oxygen used as a radical chemical greatly enhances the combustion simulation at levels close to what is found in archived laboratory research. The paper outlines key parameters such as discharge efficiency, ignition duration, and output energy and the CHEMKIN kinetic mechanism needed to simulate the proper plasma discharge environment. Simulations for various initial conditions for the combustible mixtures, including the mass fraction of fuel and the constituents of air (oxygen and nitrogen) are presented. For rich fuel mixtures, the peak temperature (K)/temperature rise delay time (msec)/temperature rise time (msec)/peak combustion pressure (atm)/pressure delay time (msec)/pressure rise time (msec)/laminar flame speed (cm/sec) were: 2105/20/31/7.62/20/310/35.8, 2002/24/56/7.46/35/560/33.9, and 1952/47.5/71/7.25/48/720/33.1, for ignition with multiple streamers with atomic oxygen, the multiple streamer model without atomic oxygen, and traditional ignition, respectively. For lean fuel mixtures, the peak temperature (K)/temperature rise delay time (msec)/temperature rise time ( msec)/peak combustion pressure (atm)/pressure delay time (msec)/pressure rise time (msec)/laminar flame speed (cm/sec) were: 2300/0/20/7.35/0/120/1380, 2095/10/20/7.57/10/120/1400, 2295/15/310/7.78/20/180/1400, for ignition with multiple streamers with atomic oxygen, the multiple streamer model without atomic oxygen, and traditional ignition, respectively.