Investigation of Multiple-Ion-Probe Measurement and Data Analysis Method for Flame Propagation in SI Engines

In the multiple-ion probe method, multiple ion probes are installed on the combustion chamber wall, and each individual ion probe detects flame contact and records the time of flame arrival. From the recorded data, it is possible to reconstruct the dynamic behavior of the flame surface and, for example, indirectly visualize the inside of the combustion chamber as a moving image. In this study, 32 ion probes were used to record flames propagating in a 2-stroke SI engine, and various analysis and evaluation methods other than indirect visualization was investigated and evaluated. Although it is possible to extract local flame propagation velocity, direction of propagation, etc. from the reconstructed flame propagation in the engine, an analysis method that aims to find the characteristics of the overall combustion in the actual combustion during a single cycle from a single feature, rather than local data, was investigated. Five types of features were extracted from the flame detection time data interpolated between ion probes by cubic splines. These features were used to investigate the characteristics of the data obtained from the multiple-ion probe measurement. It is expected that multiple-ion probe measurement can be used in combination with pressure measurement and visualization measurement to obtain more detailed information on combustion in the engine.