Plasma assisted cavity flame ignition in supersonic flows

Abstract A nanosecond pulsed plasma discharge located within a wall cavity is used to ignite jet flames (hydrogen and ethylene) in supersonic crossflows. The nonequilibrium plasma is produced by repetitive pulses of 15 kV peak voltage, 20 ns pulse width and 50 kHz repetition rate. Sonic fuel jets are injected into free stream air of Mach numbers Ma = 1.7 to Ma = 3.0. The flow pattern and shockwaves induced by the fuel jets and cavity are characterized by Schlieren imaging and planar laser induced fluorescence is used to image the distribution of OH radicals. Combustion is found to be enhanced by the plasma discharge, with the time evolution of the flame suggesting that enhancement is caused by the reduction in ignition delay time. Similar trends are observed with both hydrogen and ethylene fuel injection. The experimental results for hydrogen combustion are interpreted using a simple model in which the pulsed plasma serves as a repetitive source of reactive radicals. The reaction kinetics following radical production is evolved numerically, confirming a reduction in ignition delay comparable to that seen in the experiments. The model description allows us to predict how a broader range of plasma operation conditions will affect combustion.

[1]  S. Corrigan.  Dissociation of Molecular Hydrogen by Electron Impact , 1965 .

[2]  Jin Zhou,et al.  Supersonic flows over cavities , 2008 .

[3]  A. Kuthi,et al.  Nanosecond Plasma Ignition for Improved Performance of an Internal Combustion Engine , 2007, IEEE Transactions on Plasma Science.

[4]  D. Van Wie,et al.  Propane–Air Mixture Combustion Assisted by MW Discharge in a Speedy Airflow , 2006, IEEE Transactions on Plasma Science.

[5]  G. Zissis,et al.  Modeling the Voltage Drop Across the Cathode Sheath in HPS , 2007, IEEE Transactions on Plasma Science.

[6]  G. Settles.  Schlieren and shadowgraph techniques , 2001 .

[7]  D. Vroom,et al.  Production of Excited Atoms by Impact of Fast Electrons on Molecular Hydrogen and Deuterium , 1969 .

[8]  Joseph A. Schetz,et al.  Liquid-fuel aeroramp injector for scramjets , 2005 .

[9]  Ronald K. Hanson,et al.  Cavity Flame-Holders for Ignition and Flame Stabilization in Scramjets: An Overview , 2001 .

[10]  Walter R. Lempert,et al.  Plasma assisted ignition and high-speed flow control: non-thermal and thermal effects , 2009 .

[11]  Andrew G. Glen,et al.  APPL , 2001 .

[12]  P. H. Wallman,et al.  Pulsed corona and dielectric‐barrier discharge processing of NO in N2 , 1996 .

[13]  Z. Wroński.  Dissociation of nitrogen in the plasma-cathode interface of glow discharges , 2005 .

[14]  A. Napartovich,et al.  Plasma-Assisted Combustion of Gaseous Fuel in Supersonic Duct , 2006, IEEE Transactions on Plasma Science.

[15]  S. Starikovskaia,et al.  Nanosecond gas discharge ignition of H2− and CH4− containing mixtures , 2003 .

[16]  Campbell D. Carter,et al.  Mixing and combustion studies using cavity-based flameholders in a supersonic flow , 2004 .

[17]  S. Baek,et al.  Numerical study on supersonic combustion with cavity-based fuel injection , 2004 .

[18]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[19]  Campbell D. Carter,et al.  Characteristics of Cavity-Stabilized Flames in a Supersonic Flow , 2005 .

[20]  Zhenwei Zhao,et al.  An updated comprehensive kinetic model of hydrogen combustion , 2004 .

[21]  M. Cappelli,et al.  Formation and role of cool flames in plasma-assisted premixed combustion , 2008 .