Numerical Modeling of Spark Ignition in Internal Combustion Engines

Abstract

In this paper, we aim to develop a comprehensive ignition model for three-dimensional (3D) computational fluid dynamics (CFD) combustion modeling in spark-ignited (SI) engines. In the proposed model, we consider the following aspects separately to model the spark ignition process comprehensively. An electrical circuit is solved for calculation of the energy transferred to the spark plasma channel. The spark itself is represented by computational particles for monitoring its motion and ignitability. Heat diffusion from the spark toward the surrounding mixture is calculated with a one-dimensional (1D) model, resulting in the temperature obtained at the surface of the spark channel. Based on the calculated temperature and interpolated pressure and local mixture composition, an instantaneous ignition delay time is read from tabulated values for every particle representing the spark channel. The final ignitability criterion is defined by a precursor calculated with a zero-dimensional (0D) model, which accounts for the history of changes in spark surface temperature and local mixture properties. As soon as the precursor reaches a threshold value for a given spark channel particle, a flame kernel is introduced at a position of the particle. Flame propagation is generally treated by the G-equation combustion model. Validation is performed by measurements of the spark discharge process in high-velocity flow field and single-cylinder AVL research engine. We demonstrate that the proposed model can correctly reproduce the electrical circuit, spark channel dynamics, and overall engine performance.

Evaluation of Nitrogen Oxide (NO) and Particulate Matter (PM) Emissions from Waste Biodiesel Combustion

“…Subsequently, nitrogen oxide in the exhaust system and later in the atmosphere quickly transforms into nitrogen dioxide (NO 2 ). NO and NO 2 are found in motor exhausts in the greatest quantity and determine negative impacts on humans and the environment, while NOx further includes other oxides such as N 2 O, N 2 O 3 , N 2 O 4 , and N 2 O 5 [9][10][11]. Nitrogen oxides affect the nervous system, lungs, and respiratory tract.…”

Numerical investigation of the spark discharge process in a crossflow

“…In the past few decades, many SI models [10][11][12][13][14][15][16][17][18][19][20][21] have been developed for engine CFD simulations, and the level of modeling detail varies between the models. Spark channel is an electrically conductive path that deposits electrical energy into surrounding gas via Joule heating.…”

“…Sforza et al [21] also introduced velocity perturbation using a simplified stochastic model to reproduce the cycle-tocycle variability of spark channel evolution. On the other hand, Pyszczek et al [18] employed a numerical model that calculates the motion of a three-dimensional (3D) curve to confine the shape of the overall spark channel to be smooth while keeping constant distances between particles. Although these particle tracking methods based on flow velocity are the best available measures in the given CFD framework, the effect of discharge characteristics on the spark channel evolution would not be resolved explicitly because the solver only takes fluid dynamics into account.…”

“…By solving an electrical circuit model, Duclos and Colin [10] monitored the voltage between the electrodes and determined a restrike when it exceeds the breakdown voltage. Other models [14,15,18,21] adopted the same modeling approach. Without a circuit model, Dahms et al [13] imposed a limit on the channel length by elongation and invoked restrike when it exceeded 10 mm.…”