Thermodynamic assessment on performance extremes of the fuel indirect precooled cycle for hypersonic airbreathing propulsion

Abstract

Abstract Fuel indirect precooled cycles (IPC) are attractive candidate to enable next generation reusable launch vehicle. Thermodynamic analysis was carried out to bound the performance of this innovative propulsion concept. A unified model which can represent the core working principle of the whole engine family was proposed to make the analysis possible, with which the conditions in determining the performance boundaries of the family were derived, and new efficiency figure (i.e., EoP) for the precooling-compression sub-cycle (PCS) was defined. Numerical method for the model was developed also to perform the parametric analysis. The results show that the cycle performance is bounded by two extremes, with the upper and lower of which are defined by the EoP of 100% and 0 respectively. For real engines, the state of the art design practice gives an EoP level of 10∼30%. Moreover, it indicates that fuel properties possess remarkable effects on the PCS, whereas hydrogen shows the best application potential. From the standpoint of system overall design, optimum choice for the EoP and fuel equivalence ratio are proposed, with the performance superiority of the IPC over the Brayton cycles is revealed, and the impacts of the intake and combustor performance on the extremes are clarified.