Improved Two-Phase Model for JP-8 and Alternative Fuels

Augmentor stability is a major issue for the design of reliable engines over a broad range of operating conditions.  The stability of the combustion process in augmentors is a result of the interaction between the unsteady fluid mechanics around the flameholder, finite-rate chemistry, and the physics of fuel spray formation, transport, and evaporation.  In order to accurately model spray combustion of liquid fuels in combustion devices such as aircraft gas turbine combustors and augmentors, improved sub-models for spray formation and multicomponent evaporation are needed.  Recently developed evaporation models use continuous thermodynamics (CT) to accurately describe the behavior of multicomponent fuels through the use of distribution functions that require only a few additional variables to describe real multicomponent fuels rather than the n variables (n is the number of fuel components) needed using a discrete approach, and thus have the potential for inclusion in commercial CFD at reasonable computational expense. Combustion Science & Engineering, Inc. (CSE) proposes to develop and demonstrate a methodology to unite a state-of-the-art CT sub-model for multicomponent evaporation with an accurate chemical kinetic model for real fuel combustion, and to implement this methodology in a commercial CFD code for use in solving practical combustor design issues. BENEFIT: An important product from this project will be a sub-model package for CFD codes that couples a multicomponent evaporation model with reduced kinetics for the simulation of reacting sprays.  This product will make simulation of multicomponent liquid fueled combustion practical, and as such will be an important design tool for most propulsion systems, including gas turbine applications, for predicting flame location, ignition and flameholding phenomena, and emissions.  This product will give the design engineer much more freedom to test new combustor designs operating at wider range of pressures, temperature and fuel / air mixtures, and fuels. CSE will market and commercialize this technology as a sub-model package that will offered as an add-on to existing CFD codes.  CSE anticipates making a strategic alliance with one or more CFD code developer, where this technology will add value to the existing code and aid in opening new markets and uses of the CFD package.  Furthermore, licensing the technology to a CFD code developer will remove the need to develop a sales force or customer service capability.  However, a number of gas turbine OEMs use CFD codes that were developed in-house.  CSE will work with these customers directly to incorporate and license the package into their own CFD codes.  Hence, CSE will use a two-prong commercialization approach, through incorporation into general-purpose CFD codes (e.g. STAR*CD, CFX, Fluent) and into gas turbine manufacturers in-house codes (e.g. Allstar (Pratt & Whitney), Concert (GE)).