Study on the Deformation of Spark Discharge Paths in the Flow Using a Small Wind Tunnel

Improving thermal efficiency is a critical goal for internal combustion engines which act as energy conversion systems. Within this context, lean-burn combustion is considered a promising approach for spark-ignition engines. To shorten the combustion duration in lean-burn operations, it is essential to intensify the fluid flow and increase the turbulent combustion velocity. However, during this process, the ignition and subsequent flame propagation are significantly influenced by the flow, leading to substantial deformation of the discharge path. This research aims at the correlation between discharge path deformation and fluid flow. This report focuses particularly on the flow field and investigates the analogy between the flow field measured in experiments and that by Computational Fluid Dynamics (CFD). Calculations were carried out using LES in a configuration similar to the small wind tunnel used in the experiments. As a results, the velocity fluctuations behind the spark plug were very large and it is strongly suggested that this velocity fluctuation field is influencing the shape change of the discharge path. On the other hand, the velocity fluctuations measured in the experiment were not as large. Similarities and differences between the calculations and experiments is to be discussed.