Flow dynamics near the gap of a spark plug and their effect on the behavior of spark discharge and the development of the initial flame kernel have become important in promoting more stable lean/dilute combustion in internal combustion engines. One of the experimental techniques for measuring instantaneous gas flow near solid objects such as spark plugs is fluorescent particle image velocimetry (f-PIV). However, many of the available fluorescent particles are expensive and/or combustible because they are organic materials. We have therefore previously proposed the mass production of inexpensive inorganic-based fluorescent particles (f-particles). Such f-particles have also been used in f-PIV measurements of the air flow around a spark-plug gap in automotive applications, where they even enabled the flow through the plug gap to be detected under atmospheric conditions. In the present study, we investigated the possibility of simultaneously measuring the spark channel and the flow behind it using f-PIV in conjunction with the proposed f-particles. The results can potentially be used in the future to validate the corresponding numerical models, such as the behavior of a spark channel. Under atmospheric conditions, fluorescence images of particles were obtained, separate from the spectrum of the spark discharge even between the gap of the spark plug during the actual spark, using combinations of the proposed f-particles and adequate optical band-pass filters; the flow behind the spark channel was then analyzed. With the development of a method for the simultaneous measurement of gas temperature, the proposed measurement technique might enable the validation of models related to the development and extinction of the initial flame through investigations using f-particles that emit multi-color fluorescence.
