Computational investigation of the chemical dynamics in detonation development at SI engine conditions*

This study employs algorithmic tools from the computational singular perturbation (CSP) approach and statistics to investigate detonation development in SI engines using 2D simulations at different intensity levels – strong and mild detonations. The setups are based on the Zel’dovich theory and Bradley diagram to predict detonability using two non-dimensional parameters ε, ξ. Several 1D cut lines extracted from 2D contours are used to track the detonation propagation and all related dynamics. The evaluation of the chemical dynamics of both detonation events with the use of the CSP tools highlights that the strong detonation case exhibits a more pronounced explosive character. The comparative analysis using the CSP tools also reveals that the action of strong dissipative modes which tends to cancel the explosive ones. The chemical dynamics are further evaluated using the tangential stretching rate (TSR) metric. The statistical analysis of TSR in a temperature-based progress variable space largely displays the dominance of the strong detonation TSR values over the ones of the mild detonation. The PDF’s of TSR identify a trend favoring the high intensity detonation event.