Abstract:

The effects of electric fields on the natural gas laminar premixed flame were investigated under
lean combustion condition to promote the flame propagation and improve the flame combustion speed and
stability. Experiments were conducted in a constant volume combustion bomb under the room temperature
and atmospheric pressure conditions to analyze the effects of DC and AC electric fields on the flame shape,
combustion pressure, the pressure rise rate, and flame combustion duration. The results show that the peak
combustion pressure increased by 6.96%, 8.84%, 10.50%, 13.78%, and 14.40% and peak pressure arrival time
were shortened by 14.67%, 13.58%, 18.93%, 25.41%, and 27.97% when the DC electric fields of -5 kV and
AC electric fields with the voltage virtual value of -5 kV and frequencies of 5, 10, 15, and 25 kHz were applied
at the excess air ratio of 1.6, the flame was stretched with the applied voltage. Initial duration was shortened
significantly with the applied voltage. Therefore, AC and DC electric field have a promoting effect on the flame,
and the high frequency AC electric fields for the promotion of flame are better than that of DC electric fields.
These results will be helpful to the theory research of alternative fuel vehicles engine combustion process.

Key words: alternative fuel vehicles, natural gas, lean combustion, combustion pressure, flame combustion duration, negative DC electric fields, high-frequency AC electric fields