<p class="western" style="margin-bottom: 0in; line-height: 100%">Recent interest in non-equilibrium plasma discharges as sources of ignition for the automotive industry has not yet been accompanied by the availability of dedicated models to perform this task in Computational Fluid Dynamics (CFD) engine simulations. The need for a low-temperature plasma (LTP) ignition model has spurned much work in simulating these discharges from first principles. Most ignition models assume that an equilibrium plasma comprises the bulk of discharge kernels. LTP discharges, however, exhibit highly non-equilibrium behavior. This difference manifests in the inhomogeneous variation of temperature and key radical species in the kernel, which are brought about nanosecond timescale de-excitation reactions. In this work, a method to determine a consistent initialization of LTP discharge kernels for use in engine CFD codes like CONVERGE is proposed. The method utilizes first principles discharge simulations. Such an LTP kernel is introduced in a flammable mixture of air and fuel, and the subsequent plasma expansion and ignition simulation is carried out using 3D Large Eddy Simulations (LES) with detailed chemistry. The proposed numerical approach is shown to produce results that agree with experimental observations regarding the ignitability of methane-air and ethylene-air mixtures by LTP discharges. It is found that the ignition delay times of these mixtures serve as a key indicator of successful ignition.</p>

CFD Modeling of Low Temperature Ignition Processes From a Nanosecond Pulsed Discharge at Quiescent Conditions

Paper Proceedings: https://asmedigitalcollection.asme.org/ICEF/ICEF2021/volume/85512

ASME 2021 Internal Combustion Engine Division Fall Technical Conference (ICEF2021)

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