Plasma and Photoionization Approaches for Combustion Initiation

"The proposed research will analyze the effect of radical production by non-equilibrium plasmas on the ignition characteristics of methane-air flows. We will develop a plasma ignition module using transverse radio frequency (RF) discharge. Previously,unique stable non-equilibrium RF plasmas have been generated in cold steady-state air and methane flows. Non-intrusive diagnostics including a Fourier transform infrared (FTIR) spectroscopy, microwave resonance lamp and tunable diode laser absorptionspectroscopy (TDLAS) will be employed to characterize the discharge through measurements of OH, H2O, NO concentrations, and temperature. These results will validate a RF discharge kinetic model, and help develop a predictive and development tool forignition module design.Direct measurements of the ignition delay and energy will be obtained, using an ignition module including RF generator, flameholder, and a spark ignition source located behind the flameholder. Measurements with and without the presence of the plasma willdemonstrate the effect of the RF discharge on ignition delay time and energy. Ignition delay measurements will be obtained by measuring the blow-off velocity using a rod-stabilized flameholder. Additionally, the spark energy measurements with and withoutthe RF discharge will quantify the effect of radical production on the minimum ignition energy. This research will yield four important benefits. First is the development of a plasma ignition module which will be applicable to phase II experimentation. This module will be developed using the experimental and modeling information derived from thisprogram with the advantage of advisement from General Electric corporation. They have offered to assist this research effort to help align the development of the plasma igniter with the interest of the customer. Additionally, the experimental data willprovide code validation for the development of a predictive numerical tool to be used in further igniter and diagnostic development in Phase II. The successful development of a plasma