Simulation of a Combined Cycle for High Speed Propulsion

The programming environment EcosimPro together with the European Space Propulsion Simulation System has been used to model a high speed propulsion system. The selected engine is the Synergistic AirBreathing Rocket Engine (SABRE), which is the power plant of the Skylon space plane. The particularities of this engine comprise the use of a pre-cooler in the accelerating air-breathing phase. By contrast, in the anaerobic phase the engine behaves as a staged combustion rocket. New models for the turbomachinery components based in experimental performance maps have been developed. This ad hoc compressor, turbine and circulator components are evaluated at off-design conditions. A full simulation has been done to compute the SABRE performance during its air-breathing trajectory from take-off to Mach 5 at 25 km altitude. This analysis yields the variation of specific impulse and thrust necessary to design high speed vehicles. This model is being coupled by an optimizer to allow the definition of the optimal operating conditions for a given trajectory.