Active Control of a Scramjet Engine

ABSTRACT: The hydrocarbon-fueled scramjet is capable of providing hypersonic air-breathing propulsion for high-speed applications. The effective operation of high-speed air-breathing engines (ram- and scram-jets) over a wide range of flow parameters (velocity and altitude) is one of the most technically difficult challenges in the design of hypersonic vehicles. The most promising approach to overcome these difficulties is a scramjet having flexible gasdynamic configurations that meet a number of extremely challenging technical issues such as mitigation of unsteady separation, peaks of thermal loads, material durability, etc. Combustion Science & Engineering, Inc. and the University of Notre Dame propose to use a plasma-based combustion actuator, several types of sensors, and robust algorithm of feedback control built on predictive scenarios to permit stable operation of the combustion process during scramjet operation. The main advantage of plasma application for control of fuel ignition/combustion is due to the non-equilibrium, non-uniform, and transient nature of electrical discharges, which deliver a synergy with thermal effects (heating). The work proposed will focus on the use of passive sensors, due to the robustness of these devices and relatively low complexity of implementation in actual flight hardware.; BENEFIT: The tangible result of this project will be an apparatus for controlling combustion in high-speed flows. This apparatus will use passive sensor(s) and a plasma-actuator to allow vehicles, such as ramjets and scramjets, to operate across the entire flight envelope and through flight transitions where flameholding and flame instabilities can be difficult. The products developed in this work will be useful technologies in the aircraft industry to allow for improved operation for all high-speed vehicles. An obvious market for the technology is the United States military, which have been developing high-speed vehicles such as the ramjet and scramjet for nearly 50 years. Safe and stable operation of these vehicles has proven difficult due to the wide variably in engine conditions during flight, especially during transitions between flight modes. Therefore, there is a substantial need for this technology for the military to maximize the operability of these aircraft. The technology, however, is not just applicable to the military. Non-military aircraft also can benefit from technology to identify and mitigate combustion stability issues, especially as an additional safety measure for passenger planes.