Optimizing High-Energy Tunable Ignition Technology: Preventing Electrode Damage While Extending The Lean Flammability Limit Of Gas Engines
The use of the High-Energy Tunable Ignition Technology has successfully demonstrated the potential for extending the lean flammability limit and the spark plug life. This advantage is fundamental in reducing the gas engine emissions and fuel consumption. Furthermore, and especially with high brake mean effective pressure (BMEP) gas engines, the advantage of extending plug life is a key enabler in achieving acceptable operating costs. However, the realization of these advantages is subordinate to the correct use of the high energy spark produced by the High-Energy Tunable Ignition Technology. In situations where the high energy spark is not precisely matched to the flow fields that exist between the electrodes and the in-cylinder thermodynamic conditions, then damage to the spark plug electrode surface and/or insufficient extension of the flammability limit can be experienced. To remedy this situation, extensive computational flow dynamic (CFD) analysis and engine validation has been undertaken to optimize the primary spark waveform parameters. A thermodynamic model describing the interaction between the spark discharge and the electrode surface has been developed to determine the heat flux and required arc travel to minimize electrode damage and maximize ignitability. The results from the CFD model are validated by microscopic analysis of the electrode surface and by engine combustion performance data. Experimental and analytical results are then used to develop spark waveform application guidelines for the most common engine applications. An overview of how these guidelines can assist engine users is also provided.