摘要 :
This work presents a computational model of a ID laminar premixed flame acted on by a nanosecond repetitively pulsed dielectric barrier discharge (NRP DBD). The model allows for incorporation of arbitrarily complex combustion and ...
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This work presents a computational model of a ID laminar premixed flame acted on by a nanosecond repetitively pulsed dielectric barrier discharge (NRP DBD). The model allows for incorporation of arbitrarily complex combustion and discharge chemical kinetic models and builds on existing open source tools for 0D simulations. Laminar flame speed is used as a metric of performance due to the ease of measuring it, both in experiments and simulation, and as a fundamental parameter that captures information of the burning rate in a combustor and can inform more complex combustion phenomena (including turbulent combustion, exhaust emissions, or combustion efficiency). The model is able to handle both in-situ plasma deposition (overlapping plasma with the reaction front), as well as plasma deposition on the reactant stream (plasma ahead of the reaction front). It is shown in simulation that the discharge can have both a negative and a positive effect on the flame speed relative to the fresh gas. The former is due to disruptions at the reaction front caused by small amplitude pressure waves caused by exothermic reactions in the unburnt mixture; and the latter results in flame speed enhancement by radicals seeded by the discharge. Both the positive and the negative effects of the discharge have been observed in experiments, and further work is underway to confirm the mechanisms of action. The model allows many different parameters to be varied and going forward will be used as an engineering tool to design experiments to achieve the maximum benefit from the discharge.
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摘要 :
This work presents a computational model of a ID laminar premixed flame acted on by a nanosecond repetitively pulsed dielectric barrier discharge (NRP DBD). The model allows for incorporation of arbitrarily complex combustion and ...
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This work presents a computational model of a ID laminar premixed flame acted on by a nanosecond repetitively pulsed dielectric barrier discharge (NRP DBD). The model allows for incorporation of arbitrarily complex combustion and discharge chemical kinetic models and builds on existing open source tools for OD simulations. Laminar flame speed is used as a metric of performance due to the ease of measuring it, both in experiments and simulation, and as a fundamental parameter that captures information of the burning rate in a combustor and can inform more complex combustion phenomena (including turbulent combustion, exhaust emissions, or combustion efficiency). The model is able to handle both in-situ plasma deposition (overlapping plasma with the reaction front), as well as plasma deposition on the reactant stream (plasma ahead of the reaction front). It is shown in simulation that the discharge can have both a negative and a positive effect on the flame speed relative to the fresh gas. The former is due to disruptions at the reaction front caused by small amplitude pressure waves caused by exothermic reactions in the unburnt mixture; and the latter results in flame speed enhancement by radicals seeded by the discharge. Both the positive and the negative effects of the discharge have been observed in experiments, and further work is underway to confirm the mechanisms of action. The model allows many different parameters to be varied and going forward will be used as an engineering tool to design experiments to achieve the maximum benefit from the discharge.
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摘要 :
This work presents the development of a model for a ID flame propagating in a rectangular cross section channel of finite height, with a nanosecond repetitively pulsed dielectric barrier discharge (NRP DBD) acting on the premixed ...
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This work presents the development of a model for a ID flame propagating in a rectangular cross section channel of finite height, with a nanosecond repetitively pulsed dielectric barrier discharge (NRP DBD) acting on the premixed reactant stream. The work proposes a strategy for accounting for the three timescales present in the problem (discharge kinetics, combustion chemistry and fluid motion) using the operator splitting method to separate timescales and tracking different particle species in different regions of the domain based on their lifetimes. A simplified version of the model is constructed and demonstrated to be able to capture the different processes. Preliminary results indicate that a NRP DBD acting in the premixed reactant stream can accelerate the flame by a purely kinetic mechanism, with a velocity increase of up to 10% seen for both adiabatic flames and flames in finite height channels with heat loss. The model presented is a work in progress, and the ongoing improvements being made are discussed. It is proposed that models such as this would be useful engineering design tools to develop practical systems based on plasma assisted combustion technology.
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摘要 :
This work presents the development of a model for a 1D flame propagating in a rectangular cross section channel of finite height, with a nanosecond repetitively pulsed dielectric barrier discharge (NRP DBD) acting on the premixed ...
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This work presents the development of a model for a 1D flame propagating in a rectangular cross section channel of finite height, with a nanosecond repetitively pulsed dielectric barrier discharge (NRP DBD) acting on the premixed reactant stream. The work proposes a strategy for accounting for the three timescales present in the problem (discharge kinetics, combustion chemistry and fluid motion) using the operator splitting method to separate timescales and tracking different particle species in different regions of the domain based on their lifetimes. A simplified version of the model is constructed and demonstrated to be able to capture the different processes. Preliminary results indicate that a NRP DBD acting in the premixed reactant stream can accelerate the flame by a purely kinetic mechanism, with a velocity increase of up to 10% seen for both adiabatic flames and flames in finite height channels with heat loss. The model presented is a work in progress, and the ongoing improvements being made are discussed. It is proposed that models such as this would be useful engineering design tools to develop practical systems based on plasma assisted combustion technology.
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摘要 :
This work experimentally investigates the interaction between a mesoscale flame and a pulsed nanosecond dielectric barrier discharge, which has applications to plasma-assisted microcombustion. This interaction is interesting due ...
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This work experimentally investigates the interaction between a mesoscale flame and a pulsed nanosecond dielectric barrier discharge, which has applications to plasma-assisted microcombustion. This interaction is interesting due to the comparable length scales of the flame and discharge at atmospheric pressure (on the order of a few millimeters); in this work we investigate how a transient flame will change the discharge properties. We observed that the temperature rise caused by the passing flame front can change the structure of the discharge from filamentary, to a uniform discharge in the burned gas volume, and back to filamentary as the burned gas cools against the walls of the combustion chamber. This transition was observed visually using high-speed videography. Energy measurements were also taken for many pulses within a pulse train, and it was found that the energy deposited by the discharge was strongly related to the discharge structure and relative flame front location. The energy of individual pulses was mostly dependent on the applied voltage, but the discharge structure and impact on the global flame properties had a notable dependency with the pulsation frequency. While many past works have shown the effect of plasma to modify a flame, this work shows that the reverse effect (flame modifying discharge) must also be considered especially in cases involving transient combustion phenomena and in-situ plasma generation.
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