Speaker
Description
Combustion efficiency and rate of ignition were shown to be improved when fuel-air ignition was initiated with highly non-equilibrium plasmas generated by high-voltage, nanosecond pulses, also known as transient plasma ignition (TPI). In order to optimize the pulse power parameters for plasma ignition for combustion, detailed experimental investigations of the effect of rise time and pulse repetition frequency (PRF) were conducted for atmospheric pressure static methane/air ignitions. Plasmas driven by 10 ns, 12 kV pulses at a range of PRF from 1 kHz to 10 kHz were generated for combustion ignition with a pin-to-plate electrode configuration. Experiments revealed that a different mode in the plasma was initiated when the fuel/air mixture was ignited. At constant pulse duration and PRF, this plasma mode change occurred earlier for the faster rise time (e.g. 4 ns) compared to (e.g. 8 ns) [1]. In addition, faster PRF favored the earlier plasma mode change or earlier ignition. In this study, the kinetics of reactive plasma species that generated during the transient plasma ignition and combustion were investigated using optical emission spectroscopy (OES). Gated and filtered imaging in combination with electrical diagnostic techniques are to help understand the plasma chemistry related to combustion that is initiated with different pulse rise times and PRFs at a constant pulse width of 10 ns. Gas temperature of the PRF plasma ignition for combustion is discussed by measuring the rotational temperature of the second positive systems of nitrogen N2 (C-B).
*The work was supported in part by the Department of Energy (Phase I STTR, DE-SC001788) and the Air Force Office of Scientific Research (Award No. FA9550-17-1-0257).
[1] D. Alderman, C. Tremble, J. Sanders, D. Singleton, and C. Jiang, "Initial Evaluation of Pulse Risetime on Transient Plasma Ignition for Combustion," in IEEE International Power Modulator and High Voltage Conference, 2018.
