Author: Jiafan Guo (Beihang University) - The adaptive cycle engines are typically designed with elevated turbine inlet temperatures, which leads to increased fuel consumption and NOx emissions. Adjustment of the pre-swirl nozzle angle in the modulated pre-swirl system enables a reduction in bleed air flow, thereby facilitating further improvements in fuel consumption and NOx emission performance of the adaptive cycle engine under subsonic cruising conditions. In this study, a coupled model was developed that integrates the modulated pre-swirl system with the overall engine performance, incorporating the energy coupling between the mainstream and secondary air system. The influence of secondary air system power consumption on overall engine matching performance was evaluated. Based on the coupled model, the effects of pre-swirl modulation on key secondary air system functionalities were analyzed. Furthermore, the advantages of employing a modulated pre-swirl system for reducing fuel consumption and NOx emissions during subsonic cruising were assessed. The results indicate that a 7.3° reduction in the pre-swirl angle leads to a 4.42% decrease in the pre-swirl bleed ratio (δ), resulting in approximately a 10.09% reduction in NOx emissions and a 1.89% decrease in fuel consumption during subsonic cruising.
