Impact of Plasma Stretch on Spark Energy Release Rate and Ignition Capability under Lean Burn Conditions
2022-01-0526
03/29/2022
- Event
- Content
- Performance of the ignition system becomes more important than ever, because of the extensively used EGR in modern spark ignition engines. Future lean burn SI and SACI combustion modes demands even stronger ignition capability for robust ignition control. For spark based ignition systems, extensive research has been carried out to investigate the discharge characteristics on ignition process, including discharge current amplitude, discharge duration, spark energy and plasma stretching. The individual contribution of the parameters on flame kernel formation process is hard to distinguish from each other, especially under flow conditions, but is of importance to the development of future ignition systems. For example, it is a known fact that ignition capability can be improved by increase discharge current amplitude. However, it is not clear whether this enhancement is contributed by a longer plasma stretch or by increase in total ignition energy. A longer plasma stretch can be enhanced by the design of sparkplug electrode geometry, but discharge energy profile can only be modified via ignition strategy changes. In this paper, a constant volume combustion vessel is used to study the impact of plasma stretch on spark energy release process under pressurized conditions with cross flow speed from 0m/s up to 60 m/s. Research results show that cross flow speed can significantly enhance total discharge energy, especially under pressurized conditions. The longer plasma stretch contributes to the increase in total spark energy, because the resistance of the plasma channel per unit length remains stable, regardless of the change in background conditions. Ignition capability enhancement is correlated with various discharge parameters, including total discharge energy, discharge duration, discharge power, and accumulative plasma length.
- Citation
- Yu, X., Wang, L., Yang, Z., and Zheng, M., "Impact of Plasma Stretch on Spark Energy Release Rate and Ignition Capability under Lean Burn Conditions," SAE Technical Paper 2022-01-0526, 2022, .