Impact of the Dielectric Surface on the Electric Field in a 10-ns Transient Plasma in Methane-Air Mixture
Document Type
Abstract
Publication Date
11-7-2024
DOI
10.25776/pfcj-7221
Abstract
Transient plasma ignition (TPI) initiated by nanosecond high-voltage pulses was shown to improve combustion efficiency and reduce the NOx production due to its lean burn capability and the volumetric ignition effect [1]. Having a sufficiently large ignition kernel is important to reliably achieve successful combustion in extremely lean-fuel mixtures. A recent study showed that a repetitive nanosecond pulsed surface discharge could initiate sufficiently large ignition kernel without requiring an impractically high peak voltage and hence bear good economy in the ignition technology for internal combustion engines [1]. This study examines the transient electric field prior to the discharge breakdown or development of ignition kernel, and during the streamer mode of the discharge. We compare the field strength and distribution with and without the presence of a dielectric surface using a pin-to-pin electrode configuration in a CH4/air mixture at the atmospheric pressure, obtained with the spatiotemporally resolved, electric field-induced second harmonic generation (EFISH) method. The maximum electric field, observed at approximately 90% of the FWHM of the applied voltage, ranged between 15–30 kV/cm in the electrode gap with a lean fuel-air mixture (ϕ=0.4) for a high-impedance streamer discharge excited at ~6.3 kV, while a minimum peak electric field of 45 kV/cm was required to initiate the mode transition from streamer to prior-to-transient spark exciting with 10.3 kV. Effects of the discharge modes and the time interval between pulses on the electric field in the surface discharge are also discussed.
[1] Ryan J. Umstattd and Chunqi Jiang, “Repetitive Multi-pulses Enabling Lean CH4-Air Combustion Using Surface Discharges”, SAE International Journal of Engines, 16.03-16-08-0061 (2023)
Repository Citation
Rahman, Md Ziaur; Kliewer, Christopher J.; and Jiang, Chunqi, "Impact of the Dielectric Surface on the Electric Field in a 10-ns Transient Plasma in Methane-Air Mixture" (2024). 2024 Frank Reidy Research Center for Bioelectrics Retreat. 3.
https://digitalcommons.odu.edu/bioelectrics-2024retreat/3
Comments
* This material is based upon work supported by the Air Force Office of Scientific Research of the United States of America (AFOSR) under award number FA9550-22-1-0428 and by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, under award number DE-SC0024623 and DE-NA0003525. This research used resources of the Low Temperature Plasma Research Facility at Sandia National Laboratories, which is a collaborative research facility supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences.