Plasma-Assisted Combustion for Flame Stabilization and Enhanced Operability of Gas Turbine Engines

The control of ignition and combustion in fast gas flows is important because of applications to aircraft jet engines. Issues such as lengthened ignition delay time, problematic high-altitude flame holding and the extension of flame blow-off limits are critical for combustor operation in aircraft engines. Many of these issues are related to the wide range of conditions that an aircraft engine must operate over.  The application of plasma to ignition and combustion stabilization seems a promising way to improve combustor operation for the entire flight envelope.  Plasma-assisted combustion (PAC) has the potential to assist in several areas, including ignition and flame stabilization.  Non-equilibrium plasma can be used to stabilize ignition at high altitudes with cold fuel at low dynamic pressures. One of the approaches to enhance ignition and stabilizing depleted ?ame is the use of combined plasma nozzles, also called plasmatrons.  Combustion Science & Engineering, Inc in partnership with Princeton University and Thermofluid Modeling & Computational Solutions propose to develop a PAC system for a gas turbine main combustor utilized in small aerial vehicles.  The plasma generated excitations, thermalization, and active radicals in combination with gas-dynamic flame stabilization in a fuel-air mixture in plasma allows for reliable cold engine start, high-altitude restart, and stabilization of the combustion chamber in low-power mode at low fuel concentration. Though other techniques are feasible and will be reviewed, one of the most effective methods of plasma generation for such plasma nozzles is nanosecond pulse-periodic discharge.  The key parameter of plasma injectors is power consumption and the possibility of stable operation in a wide range of power, fuel-air mixture parameters, pressure, and flow temperature. The practical application of this technology for Navy aircraft will require the ability to ignite and stabilize liquid fuel streams, i.e., streams with significant droplet components. The technical objective of the project will focus on improving the ignition / relight and stabilization capability of the engine, especially at parts of the flight envelope where temperatures (of both air and fuel) inhibit vaporization and mixing.