Comparison between conventional spark ignition and laser ignition of an internal combustion engine using numerical simulations

Abstract

Improving engine performance and reducing emissions are of great importance nowadays. Thus, innovative engine technologies are needed. Laser ignition of internal combustion engines is one of the promising solutions to the problems facing conventional ignition especially in lean-burn engines. First, the available literature related to laser ignition was reviewed. To the authors knowledge, no previous studies have shown the effect of laser ignition on engine its emissions and performance parameters (ηc, ηth, power, gisfc, etc.). In this research work laser ignition was compared to conventional electric spark using CFD simulations in the commercial package ANSYS Forte. The studied cases covered two equivalence ratios (φ=0.8 and φ=1) and a range of laser energies (10, 25 and 40 m J) in addition to 4 different location configurations of laser ignition. Results showed that conventional ignition performed better than laser ignition at stoichiometric conditions. However, when φ=0.8 was used the differences were minimized. The ability of changing ignition location is one of the advantages of using laser ignition. This proved to be right by locating the ignition point halfway between the center and the wall of the cylinder. Such configuration performed in some cases better than a centrally located ignition in terms of combustion efficiency, power output and emissions. Additional research needs to be done in term of covering a wider range of location configurations and laser energies. Moreover, validating simulation results against measurement in a real engine is a must.