Diagnostics of Electrical Phenomena in Gases for the Monitoring of Spark-Ignited Combustion
Abstract
The goal of this work is to demonstrate how diagnostics of electrical phenomena in combustible gases can be employed to increase the understanding of the spark ignition process as well as to monitor the subsequent combustion. Both aspects are considered important for the further optimization of spark ignition engines with respect to fuel consumption and emissions.
The energy release of a spark discharge has been studied by means of calorimetry. The contribution of breakdown and glow has been separated, and the dependency of the effectiveness of energy conversion on the gas density could be explained using a simple model. Time-resolved studies of the energy deposition during the glow yielded information considered valuable as input for spark ignition modeling.
The increased conductivity of the burning gases can be used to monitor the combustion by applying a voltage over the spark plug gap and measuring the current after ignition. In this work, relations between the local equivalence ratio and the current signal have been studied, as well as the effects of electrode geometry. The findings motivate further experiments, especially the investigation of the role of gas flow for the reliability of the current signal. An improvement of currently available models for simulation of the current is encouraged. The results obtained motivate an extension of the models with respect to electrode geometry.
