Electrical waveform analysis of spark discharge for monitoring conditions inside prototype prechambers

Using renewable fuels like hydrogen in internal combustion engines requires new combustion strategies and ignition systems like pre-chamber sparkplugs. This necessitates novel measurement and monitoring techniques to gain insights into the phenomena arising from the use of new fuels and components. For understanding the phenomenon of pre-chamber ignition, it is important to observe how sparks behave inside them. The spark-elongation under certain conditions inside a particular pre-chamber, its location at a given time during discharge, and the flow conditions during spark discharge are all significant factors in gaining insight into this phenomenon. However, such information is difficult to obtain from inside a pre-chamber due to the difficulty of gaining optical access. In such cases, the electrical waveform analysis could prove useful. During this study, the electrical parameters are used to calculate the spark length, providing information about the igniting volume inside a pre-chamber during the spark discharge. Information regarding the flow conditions inside the pre-chamber could also be derived from this since the spark elongation is influenced by the surrounding flow. This was achieved by modifying the Kim and Anderson equation to meet the specific requirements of the study, which involved correlating it to the optical spark length obtained in a spark wind tunnel test bed under conditions similar to those in an engine. This modified equation was then used to calculate the spark length inside different prototype pre-chambers and sparkplug to compare and contrast the conditions. This additional information could provide a better understanding of the development process and help to explain what makes a pre-chamber design effective for a particular fuel and set of conditions, and why it is less effective in other situations. This proves to be a key monitoring tool for understanding the performance of prototype pre-chambers designed for renewable fuels such as hydrogen.