SBIR-STTR Award

An innovative method for ignition and flame front sustenance of jet engine aircraft propulsion systems is proposed. This method utilizes the interaction of controlled and concentrated microwave energy with the fuel-air mixture in the combustion chamber or afterburner. The highly efficient microwave sources are located external to the combustion chamber and coupled through ceramic windows. Igniter components are not required within the combustion chamber, and flame holders may-be minimized or eliminated by developing distributed microwave centers of energy concentration using standing wave and focusing techniques coupled with multiple radiating sources. The microwave interactions can rapidly and repeatedly develop electron populations in preselected zones of interest in the fuel-air mixture with the deposited energy density limited only by the microwave source energy over the altitude range for which free start combustible mixtures are obtainable. Thus, improved start capability and minimization of flameout probabilities should be achievable at all these altitudes. Microwave igniter concepts and operating parameters will be defined, and ignition and ignition sustenance scenerios will be devised. A demonstration test will be devised and proposed for phase II performance.

In Phase I, Aero-Plasma Technologies (APT) has demonstrated the ability of an advanced ignition system to relight air/fuel mixtures equivalent to altitudes up to about 50,000 ft with windmilling combustor pressures representative of relight conditions at mach 0.5. A variety of combustor compatible igniter configurations induced large volume discharges and repeatable ignition with energies estimated at less than 1/10 joule. The Phase II program will emphasize experimental demonstrations of ignition and flame stabilization without use of drag inducing bluff bodies in flowing systems representative of jet engine afterburners, and large ignition kernel altitude relight in representative conventional combustors. The flowing tests in conventional combustors will demonstrate that the advanced ignition system can develop large volume ignition kernels significantly increasing the magnitude of the time parameter necessary for high altitude relight. A laboratory scale blowdown test bed capable of simulating operational ignition conditions will be used for both afterburner test types and combustor testing.