Characterization of transient plasma ignition flame kernel growth for varying inlet conditions

Abstract

Pulse detonation engines (PDEs) have the potential to significantly improve the efficiency of a variety of internal combustion engine designs. This efficiency improvement hinges on the ability of the engine to detonate fuel/air mixture through deflagration-to-detonation transitions at 60 to 100 times a second. A major breakthrough in reducing the cycle time of a pulse detonation device is through the use of a Transient Plasma Ignition (TPI) system vice the normal Capacitive Discharge Ignition (CDI) system. The TPI system deposits an equivalent amount of energy as the CDI system but in a fraction of the time and over a larger combustor volume. The TPI also creates high quantities of OH due to the high density of energetic electrons produced by the TPI event. The combination of decreased energy deposition time, larger ignition volume, and a high density of free radicals reduces the flame kernel growth time, which in turn creates a choked flame condition more rapidly. This thesis characterized the flame kernel growth following a transient plasma ignition event for various combustor inlet configurations so as to better understand the flame patterns within the combustion chamber. High-speed images of the combustor were taken from a side profile and end view to observe the flame growth. Time from ignition event until initial flame kernel observation and from ignition event until fully developed flame were gathered from the images and plotted to find the most favorable inlet condition.