Plasma-assisted Combustion for Improved Performance in Gas Turbines and Jet Engines

Controlling combustion dynamics in industrial gas turbines (IGTs) continues to be a major challenge and is expected to be exacerbated as pressure and air/fuel ratios continue to increase to meet stringent fuel efficiency and emissions targets. Conventional passive dynamic control methods are not appropriate for wide-range combustion instability tones. While various mechanical active instability suppression schemes have been developed, bandwidth and lifetime limitations have not led to wide-spread commercial use. Plasma-assisted actuators for active combustion control (PAAs) are proposed here as a method of actively controlling combustion dynamics in existing and future low emission IGT designs. Plasma actuators are solid-state, providing nanosecond-scale energy deposition to impact the flames interaction with the acoustic field. The proposers have identified PAAs not only for their capability to actively control combustion instabilities, but to further enable 1) extended sub-idle engine operation, 2) expanded fuel flexibility, 3) reduce emissions, and 4) high-altitude and high loading relight for aviation turbines. These varied benefits makes PAAs an attractive technology for commercial infusion in both current and future engine designs. The current Phase II effort has focused on development of a functional actuator/controller pair for demonstration of broad actuator instability suppression authority in an industrially relevant IGT injector. The proposers demonstrated 6dB sound-pressure-level and 90% suppression of an instability of significantly greater magnitude (2500Pa) than previously demonstrated in the literature. To maximize the commercialization potential of the proposed technology, the proposers have conducted extensive customer exploration interviews with IGT and jet engine OEMs and end users. The key technical objectives identified in this proposal represent the key questions and objectives identified by customers as critical to integration and commercialization of plasma-assisted actuators for active combustion control. The proposed Phase IIB effort will focus on 1) robust mechanical design of the actuators, 2) robust actuator design via fundamental mechanistic studies of plasma/flame interaction in plasma-assisted actuators, and 3) robust controller design to implement advanced controller techniques developed for active combustion control systems. The Phase IIB effort will further focus expanding the capabilities of the developed actuator/controller pair for 4) liquid fueled systems such as aviation turbines, and 5) standard annular combustor geometries and resulting multi-modal combustion instabilities. The Phase IIB effort will finish with a customer demo at an OEM testing facility. Customer explorational interviews conducted in preparation for this Phase IIB submission indicate successful fulfillment of the work plan and technical objectives below will de-risk the technology, lead to significant buy-in from customers and enable privately- and Phase III-funded commercial transition.