Regulation Scheme of Turbofan Engine Nozzle for Infrared Signature Management

To enhance the comprehensive performance of a low-infrared turbofan engine with CCFCS in throttling state, a rapid calculation method for infrared signature integrating with the component-level model was established. Based on the results analyzed by this method, two distinct nozzle regulation schemes were devised for diverse flight missions. Nozzle regulation scheme 1 is tailored for subsonic cruising, with the primary objective of minimizing fuel consumption, while concurrently mitigating the infrared signature of the tail jet. In this scheme, the nozzle throat area is closed-loop controlled through LP rotor speed, facilitating bypass flow at the mixer inlet nearing choke conditions. On the other hand, regulation scheme 2maintains the nozzle throat area equivalent to the central cone's cross-sectional area, emphasizing infrared stealth in the rearward direction of the fighter, making it suitable for penetration or combat missions. During the subsonic cruise, scheme 1exhibits an average fuel consumption rate 6.15% lower than scheme 2, accompanied by a 32.66% reduction in jet flow infrared radiation intensity. In the supersonic penetration state, scheme 2 shows an average decrease of 19.45% in the exhaust system infrared radiation intensity when compared to scheme 1. Ultimately, the application of performance-seeking control technology enhances infrared stealth performance by integrating optimal scheduling of multiple adjustable components, resulting in further reduction of infrared signature while maintaining constant thrust. These findings contribute to the advancement of infrared signature management and have important implications for the development of more efficient and stealthy engine designs.