An Efficient Methodology for Chemical Reactions of JP-8

The proposed project will leverage REI’s experience creating and applying reduced chemical kinetic mechanisms for JP-8 with source-term speed-up techniques such as in-situ adaptive tabulation (ISAT) and artificial neural networks (ANN) to develop techniques for speeding evaluation of JP-8 kinetics in gas turbine combustor simulations. During Phase I, pre-trained ANN models using reduced chemical kinetic mechanisms will be combined with an existing ISAT code. The ANN models will be trained using a Linear Eddy Model (LEM) code to generate a range of thermochemical states similar to those found in combustion simulations. The combined ANN-ISAT model will be benchmarked against direct integration, again using an LEM code and a Partially-Stirred Reactor (PaSR) code. Efforts will initially focus on simple fuels such as hydrogen and methane, then advance to JP-8 reduced mechanisms created from previous R&D projects. Phase I work will also investigate the benefits of combining multiple reduced mechanisms into a single source term subroutine with the sub-mechanisms carefully selected for high accuracy and low stiffness over a specified range of conditions. Phase II work will focus on implementation/demonstration of the Phase I techniques into the FLUENT CFD code to simulate gas turbine combustors. BENEFIT: Requirements for high performance gas turbine engines have continued to push the state-of-the-art in combustion technology. CFD tools have the potential for assessing performance, stability, and durability in gas turbine engine combustors because simulations can model conditions that can’t be easily duplicated experimentally and can provide information on quantities that are difficult to measure. CFD simulations can thus reduce the length and cost of the design cycle and test innovative concepts quickly and inexpensively compared to building and testing prototypes. However, useful CFD simulations of gas turbine combustors and augmentors require accurate and efficient models of hydrocarbon chemistry and turbulence interaction of the reacting flows. This project will provide the DoD and contractor personnel with a robust, accurate, validated, computationally efficient modeling capability for JP-8 that can be integrated into chemical kinetic solvers and CFD packages used for gas turbine combustor modeling. The models will be based on the best available reaction kinetics descriptions. The combustion modeling capability provided by this project will allow engineers and scientists to more accurately assess gas turbine engine designs and provide better guidance for ground and flight tests. While this software will focus initially on Air Force gas turbine applications, other areas will benefit from the technology as well. These include: (1) Support of U.S. government gas turbine development programs such as VAATE (Versatile, Affordable, Advanced Turbine Engine) and military programs that support VAATE, such as ADVENT (Adaptive Versatile Engine Technology); (2) Support of commercial companies that work in gas turbine engine production and R&D such as General Electric, Honeywell, Rolls-Royce North America, UTRC / Pratt & Whitney, Williams International and Teledyne Continental Motors and to companies that provide computational tools to these companies, such as ANSYS/Fluent, CD-ADAPCO, Metacomp Technologies, CFD Research Corporation and Reaction Design; (3) Use of numerical and chemistry modeling techniques in other software applications. Accurate, verified models of combustion chemistry that can be efficiently run in CFD simulations are in critical demand in all areas of reacting flow simulation including simulations of gas turbine and internal combustion engines, mineral and chemical processing furnaces, as well as in the areas of energy production, incineration, rocket/SCRAMJET propulsion, and fire and explosion research. REI provides CFD consulting services in many of these areas and expects that the type of models developed here would find application in a wide variety of industries outside the target application of gas turbine combustion.