Study of the effect of nitrogen monoxide on the ignition delay using tabulation of dynamic adaptive chemistry

In the context of energy efficient engines, downsizing and turbocharging is increasingly used for spark ignition engines. Irregular combustion phenomena such as knock and pre-ignition currently limit further downsizing. Many parameters influence these phenomena. Among them, the kinetic effect of the nitric monoxide (NO) present in the exhaust gas might not be overruled. This effect has not yet been investigated for pure iso-octane in engine conditions. Moreover, a comprehensive computational fluid dynamics (CFD) methodology is required to investigate these effects numerically. In this paper, we first present a detailed analysis of the impact of NO on the iso-octane ignition delay. After interpreting the chemical kinetics of this effect, we include a very detailed mechanism in CFD simulations using a new version of the tabulation of dynamic adaptive chemistry (TDAC) method [1]. The presence of NO has a significant impact on the ignition delay of iso-octane in HCCI engines for the whole range of concentration tested (from 0 ppmv to 500 ppmv). This impact is well predicted by the TDAC method with a speed-up factor compared to direct integration around 1500. Accordingly, the TDAC method represents a very efficient tool to include detailed chemical mechanism in CFD simulations and to investigate the effect of trace amount of key species.

References
[1] F.Contino,H.Jeanmart,T.Lucchini,G.D'Errico,Proceedings of the Combustion Institute33(2011)3057-3064.