Abstract
Based on an experimental system involving a pulsating airflow burner and gliding arc generator, the characteristics of gliding arc plasma at different flow rates and its control effect on the static instability of the swirl flame have been studied. The current, voltage, and power wave forms, as well as the simultaneous evolution of plasma topology, were measured to reveal the discharge characteristics of the gliding arc. A bandpass filter was used to capture the chemiluminescence of CH in the flame, and pressure at the burner outlet was acquired to investigate the static instability. Experimental results showed that there were two different discharge types in gliding arc plasma. With the low flow rate, the glow type discharge was sustained and the current was nearly a sine wave with hundreds of milliamperes of amplitude. With the high flow rate, the spark type discharge appeared and spikes which approached almost 1 ampere in 1 μs were found in the current waveform. The lean blowout limits increased when the flame mode changed from stable to pulsating, and decreased significantly after applying the gliding arc plasma. In pulsating flow mode, the measured pressure indicated that static instability was generated at the frequency of 10 Hz, and the images of flame with plasma showed that the plasma may have acted as the ignition source which injected the heat into the flame.
Highlights
With the development of the aviation industry and the improvement of environmental awareness, exhaust emission standards for NOx, CO, and other contaminants are becoming stricter.lean premixed combustion technology has been widely adopted in aircraft engine combustion chambers to reduce NOx [1]
Many studies have confirmed that the air flow rates have a great influence on gliding arc plasma [26,27]
The supply of CH4 was cut off, and the pulsating air flow generator was in stable flow mode, which meant the combustor operated in stable cold flow conditions
Summary
With the development of the aviation industry and the improvement of environmental awareness, exhaust emission standards for NOx, CO, and other contaminants are becoming stricter. Controlling flame instability and reducing the lean blowout limits was another issue that researchers focused on. Some researchers applied plasma to supersonic combustion [10,11], turbulent premixed flames [12], and counterflow diffusion flames [13,14,15], and found that plasma had a good effect in ignition and controlling instability. The characteristics of gliding arc plasma and its applications have been investigated by many researchers, but there are few reports applying it in flame instability control. The characteristics of the gliding arc, as well as its control effect on the static instability of premixed swirl flame, were investigated experimentally in the research, and an extension of lean blowout limits for the methane–air flame was observed. The relationships between pressure and heat release rate of the pulsating flame were measured to explore the mechanism of the static instability
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