Thermodynamic analysis of key parameters on the performance of air breathing pre-cooled engine

Abstract Synergetic Air-Breathing Rocket Engine is a revolutionary air breathing pre-cooled engine with complex circuits and multiple components. The performance of Synergetic Air-Breathing Rocket Engine depends on the key design parameters among subsystems, i.e. air cycle, helium cycle and propellant system, and for which the performance of key design parameters on engine and the design criteria have not been well established. On account of this purpose, a component-level model was proposed as the basis for thermodynamic analysis. The calculation of engine performance was adopted by the method of combination of solving equations of a component-level model and numerical calculation for precooler, in which several constraint equations were considered. The results show that the helium flowrate and distribution ratio in branch have little impact on the thrust and thermal efficiency of the engine, but the enlargement of total hydrogen consumption and distribution ratio significantly increases total hydrogen consumption. Moreover, with helium inlet temperature increasing by 140 K, the specific thrust decreases by 3.6%, and the total efficiency decreases by 5.6%. Besides, with combustion chamber pressure increasing by 1 MPa, the specific thrust increases by 5.9%, and total engine efficiency decreases by only 2%. Some suggestions are also proposed for engine design and operation. The helium flowrate, distribution ratio and helium inlet temperature should be designed as small as possible, within the range of parameters considered. A compromised design is needed for combustion chamber pressure to balance its impacts to structural design.