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DEVELOPMENT OF A SWIRL-STABILIZED PLASMA-ASSISTED BURNER WITH A RING-PIN ELECTRODE CONFIGURATIONNadia M. Numa (5930774) 15 May 2019 (has links)
<p>A small
plasma generation system was first developed using a ring-pin electrode
configuration with the goal of producing a plasma disk at the burner outlet. Two
distinct plasma regimes were identified: diffused and filamentary. Diffuse
discharges were generated at low frequencies while filamentary discharges were
generated at moderate to high frequencies. The induced flow fields generated by
both diffuse and filamentary plasma discharges were investigated using
high-speed schlieren visualization and particle image velocimetry. The rise in
gas temperature was measured using optical emission spectroscopy. Lastly, the
electrical properties for both types of plasma discharges was measured. The
measurements provided a set of pulse parameters for the investigation of the
plasma-flame interaction on the atmospheric pressure burner. </p>
An
atmospheric pressure plasma-assisted burner with a ring-pin electrode geometry
was designed and fabricated to investigate the effect of nanosecond
repetitively pulsed discharges on methane-air flames. The burner can produce
both Bunsen-type and swirl-stabilized flames (helical vane swirlers, swirl
number of 0.62) with a modular design to allow for a removable block swirler
component. Flame chemiluminescence and direct imaging of flame structure and
dynamics was done to understand the burner’s operating limits. The burner can
operate 6 – 13 kW flames, with flames stabilizing at approximately 2 inches
above the burner exit. The effect of air flow rate on plasma formation was
investigated and it was found that the high velocity of the incoming gas
changes the plasma regime and electrical properties. Finally, the plasma
discharge was applied on lifted, swirled flames and used for plasma-assisted
ignition. For lifted swirled flames, we found that a minimum of 100 pulses is
required to generate a filamentary discharge in the air stream. Higher number
of pulses at high frequencies appeared to extinguish the primary flame. A
minimum of 6000 was used for ignition. The plasma-assisted burner will allow
for future studies to investigate the plasma flame coupling for various
conditions using a wide variety of diagnostics. <br>
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