Numerical simulation of nanosecond repetitively pulsed discharges in air at atmospheric pressure : Application to plasma-assisted combustion
In this Ph.D. thesis, we have carried out numerical simulations to study nanosecond repetitively pulsed discharges (NRPD) in a point-to-point geometry at atmospheric pressure in air and in H2-air mixtures. Experimentally, three discharge regimes have been observed for NRPD in air at atmospheric pres...
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Ecole Centrale Paris
2012
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ndltd-CCSD-oai-tel.archives-ouvertes.fr-tel-008798562013-11-06T03:20:52Z http://tel.archives-ouvertes.fr/tel-00879856 2012ECAP0055 http://tel.archives-ouvertes.fr/docs/00/87/98/56/PDF/these_version_jury1.pdf Numerical simulation of nanosecond repetitively pulsed discharges in air at atmospheric pressure : Application to plasma-assisted combustion Tholin, Fabien [SPI:OTHER] Engineering Sciences/Other Nanosecond repetitively pulsed discharges Ignition In this Ph.D. thesis, we have carried out numerical simulations to study nanosecond repetitively pulsed discharges (NRPD) in a point-to-point geometry at atmospheric pressure in air and in H2-air mixtures. Experimentally, three discharge regimes have been observed for NRPD in air at atmospheric pressure for the temperature range Tg = 300 to 1000 K: corona, glow and spark. To study these regimes, first, we have considered a discharge occurring during one of the nanosecond voltage pulses. We have shown that a key parameter for the transition between the discharge regimes is the ratio between the connection-time of positive and negative discharges initiated at point electrodes and the pulse duration. In a second step, we have studied the dynamics of charged species during the interpulse at Tg = 300 and 1000 K and we have shown that the discharge characteristics during a given voltage pulse remain rather close whatever the preionization level (in the range 109-1011 cm��3) left by previous discharges. Then, we have simulated several consecutive nanosecond voltage pulses at Tg = 1000 K at a repetition frequency of 10 kHz. We have shown that in a few voltage pulses, the discharge reaches a stable quasi-periodic glow regime observed in the experiments. We have studied the nanosecond spark discharge regime. We have shown that the fraction of the discharge energy going to fast heating is in the range 20%- 30%. Due to this fast heating, we have observed the propagation of a cylindrical shockwave followed by the formation of a hot channel in the path of the discharge that expands radially on short timescales (t < 1 _s), as observed in experiments. Then we have taken into account an external circuit model to limit the current and then, we have simulated several consecutive pulses to study the transition from multipulse nanosecond glow to spark discharges. Finally the results of this Ph.D. have been used to find conditions to obtain a stable glow regime in air at 300 K and atmospheric pressure. Second we have studied on short time-scales (t_ 100_s) the ignition by a nanosecond spark discharge of a lean H2-air mixture at 1000 K and atmospheric pressure with an equivalence ratio of _ = 0:3. We have compared the relative importance for ignition of the fast-heating of the discharge and of the production of atomic oxygen. We have shown that the ignition with atomic oxygen seems to be slightly more efficient and has a completely different dynamics. 2012-12-20 ENG PhD thesis Ecole Centrale Paris |
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[SPI:OTHER] Engineering Sciences/Other Nanosecond repetitively pulsed discharges Ignition |
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[SPI:OTHER] Engineering Sciences/Other Nanosecond repetitively pulsed discharges Ignition Tholin, Fabien Numerical simulation of nanosecond repetitively pulsed discharges in air at atmospheric pressure : Application to plasma-assisted combustion |
description |
In this Ph.D. thesis, we have carried out numerical simulations to study nanosecond repetitively pulsed discharges (NRPD) in a point-to-point geometry at atmospheric pressure in air and in H2-air mixtures. Experimentally, three discharge regimes have been observed for NRPD in air at atmospheric pressure for the temperature range Tg = 300 to 1000 K: corona, glow and spark. To study these regimes, first, we have considered a discharge occurring during one of the nanosecond voltage pulses. We have shown that a key parameter for the transition between the discharge regimes is the ratio between the connection-time of positive and negative discharges initiated at point electrodes and the pulse duration. In a second step, we have studied the dynamics of charged species during the interpulse at Tg = 300 and 1000 K and we have shown that the discharge characteristics during a given voltage pulse remain rather close whatever the preionization level (in the range 109-1011 cm��3) left by previous discharges. Then, we have simulated several consecutive nanosecond voltage pulses at Tg = 1000 K at a repetition frequency of 10 kHz. We have shown that in a few voltage pulses, the discharge reaches a stable quasi-periodic glow regime observed in the experiments. We have studied the nanosecond spark discharge regime. We have shown that the fraction of the discharge energy going to fast heating is in the range 20%- 30%. Due to this fast heating, we have observed the propagation of a cylindrical shockwave followed by the formation of a hot channel in the path of the discharge that expands radially on short timescales (t < 1 _s), as observed in experiments. Then we have taken into account an external circuit model to limit the current and then, we have simulated several consecutive pulses to study the transition from multipulse nanosecond glow to spark discharges. Finally the results of this Ph.D. have been used to find conditions to obtain a stable glow regime in air at 300 K and atmospheric pressure. Second we have studied on short time-scales (t_ 100_s) the ignition by a nanosecond spark discharge of a lean H2-air mixture at 1000 K and atmospheric pressure with an equivalence ratio of _ = 0:3. We have compared the relative importance for ignition of the fast-heating of the discharge and of the production of atomic oxygen. We have shown that the ignition with atomic oxygen seems to be slightly more efficient and has a completely different dynamics. |
author |
Tholin, Fabien |
author_facet |
Tholin, Fabien |
author_sort |
Tholin, Fabien |
title |
Numerical simulation of nanosecond repetitively pulsed discharges in air at atmospheric pressure : Application to plasma-assisted combustion |
title_short |
Numerical simulation of nanosecond repetitively pulsed discharges in air at atmospheric pressure : Application to plasma-assisted combustion |
title_full |
Numerical simulation of nanosecond repetitively pulsed discharges in air at atmospheric pressure : Application to plasma-assisted combustion |
title_fullStr |
Numerical simulation of nanosecond repetitively pulsed discharges in air at atmospheric pressure : Application to plasma-assisted combustion |
title_full_unstemmed |
Numerical simulation of nanosecond repetitively pulsed discharges in air at atmospheric pressure : Application to plasma-assisted combustion |
title_sort |
numerical simulation of nanosecond repetitively pulsed discharges in air at atmospheric pressure : application to plasma-assisted combustion |
publisher |
Ecole Centrale Paris |
publishDate |
2012 |
url |
http://tel.archives-ouvertes.fr/tel-00879856 http://tel.archives-ouvertes.fr/docs/00/87/98/56/PDF/these_version_jury1.pdf |
work_keys_str_mv |
AT tholinfabien numericalsimulationofnanosecondrepetitivelypulseddischargesinairatatmosphericpressureapplicationtoplasmaassistedcombustion |
_version_ |
1716612802855043072 |