Advanced Instrumentation for Real-Time Detection and Control of Ramjet/Scramjet Combustion Dynamics

An advanced instrumentation system is proposed for the real-time detection and control of combustion dynamics for use in the harsh environments of direct connect and free jet facilities for ramjets and scramjets and for on-line combustor applications. The selected system components can obtain accurate point or field measurements of pressures and heat release rates in a combusting flowfield without disturbing the flow. The proposed system consists of three major components: sensor, system identification and controller, and actuator. Micro-opto-mechanical pressure sensors and silicon carbide photodiode sensors can detect instantaneous chamber pressure and heat release even in the presence of droplets and soot particles in high-temperature environments. The signals are then processed by a congtroller for engine health monitoring and system identification. In addition to conventional fuel injectors, a novel hydrodynamic pulsing injector capable of producing high-frequency pulsing liquid sprays is proposed to generate secondary fuel injection and alleviate undesired unsteady motions. The proposed system has high spatial resolution and rapid frequency response, and requires minimal pre- and post-calibration. This approach to the detection and control of combustion dynamics is generic and can be applied to ramjets and scramjets, as well as other propulsion systems.