Reduced Order Augmentor Static Stability Modeling

Augmentor static stability is critical to the operational performance of numerous military jet engines. Current predictive tools for augmentor performance and static stability (i.e., lean blowout) are based on decades old empirical correlations that do not provide reliable estimates for advanced augmentor designs. Recent advances in computational fluid dynamics (CFD) and advanced combustion diagnostics have provided new insight into the fundamental processes that occur in these flows. Reacting flow CFD has yet to mature to a level where it can be practically applied as a design tool for this problem. In this project, we will develop reduced order models to provide designers with a significantly improved near term predictive capability for these flows. Our modeling approach involves using low order CFD calculations of the nonreacting flow or simplified calculations of the reacting flow to characterize the flow timescales, and reactor models to characterize the important chemical timescales in the system. Timescales that determine blowout are identified and used to form a Damköhler number for predicting blowout. This methodology will be extended to the use of networks of reactors to fully model augmentor flows. Fully coupled reacting flow CFD and experimental data will be used to support model development and validation.