Multiscale modeling and general theory of non-equilibrium plasma-assisted ignition and combustion

Suo Yang, Sharath Nagaraja, Wenting Sun, Vigor Yang

Research output: Contribution to journalReview articlepeer-review

34 Scopus citations

Abstract

A self-consistent framework for modeling and simulations of plasma-assisted ignition and combustion is established. In this framework, a 'frozen electric field' modeling approach is applied to take advantage of the quasi-periodic behaviors of the electrical characteristics to avoid the re-calculation of electric field for each pulse. The correlated dynamic adaptive chemistry (CO-DAC) method is employed to accelerate the calculation of large and stiff chemical mechanisms. The time-step is dynamically updated during the simulation through a three-stage multi-time scale modeling strategy, which utilizes the large separation of time scales in nanosecond pulsed plasma discharges. A general theory of plasma-assisted ignition and combustion is then proposed. Nanosecond pulsed plasma discharges for ignition and combustion can be divided into four stages. Stage I is the discharge pulse, with time scales of O (1-10 ns). In this stage, input energy is coupled into electron impact excitation and dissociation reactions to generate charged/excited species and radicals. Stage II is the afterglow during the gap between two adjacent pulses, with time scales of O (1 0 0 ns). In this stage, quenching of excited species dissociates O2 and fuel molecules, and provides fast gas heating. Stage III is the remaining gap between pulses, with time scales of O (1-100 μs). The radicals generated during Stages I and II significantly enhance exothermic reactions in this stage. The cumulative effects of multiple pulses is seen in Stage IV, with time scales of O (1-1000 ms), which include preheated gas temperatures and a large pool of radicals and fuel fragments to trigger ignition. For flames, plasma could significantly enhance the radical generation and gas heating in the pre-heat zone, thereby enhancing the flame establishment.

Original languageEnglish (US)
Article number433001
JournalJournal of Physics D: Applied Physics
Volume50
Issue number43
DOIs
StatePublished - Sep 26 2017

Bibliographical note

Funding Information:
This work was supported partly by the William RT Oakes Endowment of the Georgia Institute of Technology, and partly by MURI research grant FA9550-09-0602 from the Air Force Office of Scientific Research, with Dr. Chiping Li as technical monitor. Wenting Sun acknowledges the AFOSR award FA-9550-16-1-0441.

Keywords

  • ignition
  • low-temperature chemistry
  • nanosecond plasma discharge
  • plasma fluid modeling
  • plasma-assisted combustion

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