Analysis of combined cycle Air Breathing-Cryogenic rocket engine for single stage to orbit vehicle

Abstract Single Stage to Orbit (SSTO) and hypersonic flights are very demanding and challenging technologies in which a significant amount of studies are being conducted worldwide. One of the major challenges in this technology is the development of the propulsion system of the spacecraft or aircraft. It is found that combined cycle engines have huge potential in this area and when properly used, can be utilized for SSTO as well as hypersonic travel. Towards this, a comprehensive study is being done on the available combined Cycle Engines in aerospace technology: Turbine Based Combined Cycle (TBCC) & Rocket Based Combined Cycle (RBCC). Later, a prospective combined cycle engine technology under development was recognised, with the proposed capability of achieving single-stage-to-orbit (SSTO) travel. The air-breathing mode of this technology under development was modified and redesigned to incorporate the simultaneous use of intake air and onboard cryogenic oxygen, and along with this, the Cryogenic pure rocket mode design of this engine at an altitude of 40 km was developed. The design proposed here in this study incorporates the regenerative cooling of the nozzle in either mode. The complex multifluid thermodynamic loop of this new design was analysed by dividing it into different fluid lines having multiple stations. The properties of these stations were calculated with the help of fundamental governing equations, reasonable assumptions, and support from the literature. For each developed mode, the thrust produced was calculated and obtained as 3. 26 MN and 3.10 MN for air breathing and pure rocket mode respectively. The combustion analysis of preburner and the main combustion chamber of this system was carried out using the NASACEARUN program. This study proposes an analysis methodology for understanding a complex multifluid system and puts forward a design for the Air breathing and Cryogenic rocket mode of a Combined Cycle Air Breathing Rocket Engine at specified conditions.