BEGIN:VCALENDAR VERSION:2.0 PRODID:-//wp-events-plugin.com//6.6.4.4//EN TZID:Asia/Jerusalem X-WR-TIMEZONE:Asia/Jerusalem BEGIN:VEVENT UID:0-236@aerospace.technion.ac.il DTSTART;TZID=Asia/Jerusalem:20210804T133000 DTEND;TZID=Asia/Jerusalem:20210804T143000 DTSTAMP:20230417T063626Z URL:https://aerospace.technion.ac.il/events/theoretical-study-of-flame-ini tiation-by-electrical-discharge/ SUMMARY:Theoretical study of flame initiation by electrical discharge DESCRIPTION:Lecturer:Nir Druker\n Faculty:Department of Aerospace Engineeri ng\n Institute:Technion – Israel Institute of Technology\n Location:http s://technion.zoom.us/j/94376262264\n Zoom: \n Abstract: \n Details: \n In Internal Combustion Engines (ICE’s)\, the combustible mixture is ignited at each cycle by a time-controlled spark discharge. The success of the fl ame initiation depends to a large extent on the operating conditions (engi ne speed\, engine load\, ambient conditions\, and spark characteristics). It was found that with traditional ignition systems\, the nature of the ig nition process induces very significant cycle-to-cycle variations\, and as compared to theoretical cycles\, these are believed to be the main reason for lower engine torque\, high fuel consumption and surplus engine emissi on. In order to improve the success level of the ignition process\, quite a number of different ignition systems have been proposed. Higher discharg e energies\, longer discharge durations and multi-spark systems have been developed. During the last decade\, cold-plasma multi-pulse assisted ignit ion systems have been proposed. In practice\, these systems have shown muc h better results\, though our understanding of how the energy evolves in t his complex ignition process is still deficient. Such an understanding is valuable not only for widening and deepening our scientific knowledge\, bu t also to optimize the systems in practical settings.\nIn this research\, we conducted a preliminary\, theoretical/numerical investigation into the possibility of use of on-board control of electrically-based cold plasma-a ssisted ignition and combustion The focus was on diagnostics and enhanceme nt of energy deposition in specific modes\, by application of bi-polar sho rt duration voltage pulses in low-pressure air. The physical model couples the electric field\, potential and current\, with the relevant conservati on equations for 24 species via 168 kinetic reactions\, including molecule s’ rotation\, vibration\, electronic excitation\, dissociation\, and ion ization inside the electrodes gap. Evaluation using various pulse repetiti on frequencies and different pulse shapes was conducted. Special attention was given to the overall coupled energy\, deposited during the discharge\ , and to energy channeled to known ignition supportive modes such as nitro gen electronic excitation and oxygen radicals generation.\nThe results of the analysis show that for the considered conditions\, energy deposition c an be divided into two main stages\, characterized by high and low voltage magnitudes\, respectively. It was found for the first time\, that the (lo w voltage) second stage’s energy deposition can be higher than that of t he first (high voltage) stage. At the second stage\, the deposition of ene rgy into specific modes can be tuned by setting appropriate voltage magnit udes. In addition\, the energy deposited in modes important for ignition\, exhibits a simple linear relation to the overall energy deposition. Furth ermore\, based on these findings\, we demonstrate how a new sequence of vo ltage pulses can further increase enhancement of ignition and combustion s upportive processes.\nlink to Zoom CATEGORIES:Seminars LOCATION:https://technion.zoom.us/j/94376262264 END:VEVENT BEGIN:VTIMEZONE TZID:Asia/Jerusalem X-LIC-LOCATION:Asia/Jerusalem BEGIN:DAYLIGHT DTSTART:20210326T030000 TZOFFSETFROM:+0200 TZOFFSETTO:+0300 TZNAME:IDT END:DAYLIGHT END:VTIMEZONE END:VCALENDAR