Improved Kinetic Models for High Speed Combustion Simulation

Scramjet propulsion has the potential to power high Mach number flight without the need to carry its own oxidizer like a rocket, thus significantly reducing vehicle flight weight. Numerical simulations will play an increasingly important role in the development of scramjet engines. Hydrocarbon fuels are advantageous for scramjet propulsion because of their higher energy density and ease of transport. CPU and memory limitations prohibit implementation of full detailed chemistry of hydrocarbon fuels into 3-D CFD simulations, even using the latest massively parallel computers. The proposed project will develop a hydrocarbon chemical kinetics modeling capability suitable for scramjet design applications by: (1) Improving existing chemical kinetic mechanisms for ethylene, JP-7 and JP-8 focusing on the low pressures and high temperatures found in a scramjet combustor using density functional and ab initio calculations of thermochemical properties and chemical kinetic rates; (2) Performing counterflow diffusion flames at subatmospheric pressures to fill gaps in existing data; (3) Automatically optimizing reduced mechanisms using a genetic algorithm; and (4) Implementing an advanced chemical source term tabulation technique (ISAT) that works efficiently in a parallel-processing environment. The parallel ISAT and reduced mechanisms based on improved kinetics will be implemented into the VULCAN and CFD++ CFD codes.