Physical Sub-Model Development for Turbulence Combustion Closure

ABSTRACT: Ramjets and scramjets are the preferred propulsion platforms for flight in the supersonic (3<M<5) and hypersonic (5<M<15) regimes, respectively. Combustion phenomena in ramjets and scramjets are highly unsteady and susceptible to compressibility effects. Also, this flow can have regions that are premixed and within the thin-reaction-zones (TRZ) regime or in the broken-reaction-zones (BRZ) regime of premixed combustion. These characteristics make the use of current turbulent combustion models questionable. Therefore, Combustion Science & Engineering, Inc. (CSE) and the Computational Combustion Lab at Georgia Tech (CCL) propose to analyze the underlying physical assumptions of current models for their use in simulations of ramjet and scramjet combustion. This analysis will pay particular attention to whether or not current turbulent combustion models can capture compressibility effects and, if not, how to modify them to capture such effects. Based on this analysis, new physics-based models will be initiated in Phase I, and then will be further developed and validated in Phase II. Preliminary simulations for this validation study will be conducted in Phase I. BENEFIT: The product developed in this work will be a useful tool for supersonic and hypersonic vehicle design applications for the U. S. Air Force. Discussions with engine design teams indicate that the capabilities of this project will greatly enhance current design tools in use by equipment manufacturers. Also the market for this product will include gas turbine designers and manufacturers for both military and civilian aircraft. The use of this tool will significantly reduce development costs by eliminating some design iterations and hardware testing, which is quite expensive and time-consuming. Because of the broad range of applicability of the model, it will be useful for other flight vehicle systems, such as interturbine burners, new concepts for high speed aircrafts. It will also be useful to predict blowout and ignition. Therefore, the potential market for this tool is fairly large and ranges over a number of different industries.