Sensitivity of Hydrocarbon Combustion Modeling for Hypersonic Missile Design

Aspects relating to the aerodynamic and propulsive design and analysis of missile-class, waverider-based hypersonic vehicles are explored in this paper. A quasi-one-dimensional engine model, including the effects of fuel injection, mixing, chemical production rates, heat transfer, and viscous losses, is developed and utilized to assess the effects of finite rate, hydrocarbon chemistry on optimized missile configurations. Resultant optimized single-and double-engine missile designs are shown for changes in fuel mixing length, fuel mixing efficiency, fuel-injector location, and assumed fuel mass fraction. The effects of these different design conditions on the cruise range are explored, as well as perturbations around these design points for optimized vehicles. Missiles are optimized for steady-state trim conditions at the beginning of cruise flight using parallelized genetic algorithm optimization software developed for this study. All missile designs are assumed to reach cruising altitude and velocity through the use of an external rocket booster. The missile is geometrically constrained to fit within the 0.61 x 0.61 × 4.27 m box limits for a naval vertical launch tube and has a desired cruise range of 750 km at Mach 8. Results show that the optimized combustor designs were extremely sensitive to small design perturbations. Two engine configurations are shown to be more robust than single-engine models for engine design perturbations.