CFD Analysis of Scramjet Fuel Injectors

Stable combustion in scramjet engines is strongly dependent on the mixing characteristics supplied from the fuel injection scheme. Because of the low residence time of fuel in a supersonic combustor, free stream penetration and air-fuel mixing need to happen efficiently. Although there are a number of ways to optimize mixing properties, ramp injectors were the main focus of study due to the non-intrusive nature of their geometry. Star-CCM+ (SCCM) was used to create a 2D simulation of Mach 3 flow with conditions set to replicate air at an altitude of 5km. Different ramp geometries were then tested in an 80mm tall cross section combustor. The parameters modified between tests include ramp angle, height, and streamwise injector placement. The effects of these changes on mixing and free-stream penetration were then analyzed and recorded.