Numerical Modeling of SparkIgnition in Internal Combustion Engines

Rafał Pyszczek , Jooyoung Han , P. Priesching , Andrzej Teodorczyk

Abstract

In this paper, we aim to develop a comprehensive ignition model for three-dimensional (3D)computationalfluid dynamics (CFD) combustion modeling in spark-ignited (SI) engines. Inthe proposed model, we consider the following aspects separately to model the spark igni-tion process comprehensively. An electrical circuit is solved for calculation of the energytransferred to the spark plasma channel. The spark itself is represented by computationalparticles for monitoring its motion and ignitability. Heat diffusion from the spark towardthe surrounding mixture is calculated with a one-dimensional (1D) model, resulting inthe temperature obtained at the surface of the spark channel. Based on the calculated tem-perature and interpolated pressure and local mixture composition, an instantaneous igni-tion delay time is read from tabulated values for every particle representing the sparkchannel. Thefinal ignitability criterion is defined by a precursor calculated with a zero-dimensional (0D) model, which accounts for the history of changes in spark surface temper-ature and local mixture properties. As soon as the precursor reaches a threshold value for agiven spark channel particle, aflame kernel is introduced at a position of the particle.Flame propagation is generally treated by the G-equation combustion model. Validationis performed by measurements of the spark discharge process in high-velocityflowfieldand single-cylinder AVL research engine. We demonstrate that the proposed model can cor-rectly reproduce the electrical circuit, spark channel dynamics, and overall engine perfor-mance