Superiority analysis of the cooled cooling air technology for low bypass ratio aero-engine under typical flight mission

Abstract

The cooled cooling air technology (CCA technology) is beneficial to increase the aero-engine operating pressure ratio and turbine inlet temperature, while its influence mechanism during the full flight envelope is still ambiguous. A comparative analysis has been completed in this study to assess the flight performance of an aircraft engine with or without CCA technology. Based on the aircraft and aero-engine integrated technique, a novel analytical model is developed by combining the propulsion requirement analysis model with the engine design/off-design point analysis model. The precise submodules of the heat exchanger and the turbine blade in engine model improve the -practicability of analysis, which considers the influence of the flight mission on the heat transfer performance. This literature suggests that CCA technology could enhance the fuel weight at take-off phase, the weight-specific surplus power, the load factors, and the supersonic cruising Mach number by approximately 3–4.85% with re-optimizing the cycle parameters. The inlet temperature of turbine Tt4 rises by around 3% without the turbine blade temperature exceeding the limitation. This work further analyzes the most influential structural factor of the total engine performance and the transverse tube pitch is discovered as a noteworthy feature. Additionally, it is well known that the heat transfer and pressure drop of the CCA heat exchanger (CCA-HEX) change dramatically during the whole flight mission. Our findings provide valuable insights into a better understanding of the mechanisms of CCA-HEX characteristic change, in which poor heat transfer occurs at low altitudes and high Mach numbers, whereas the largest flow resistance appears in the high-altitude and low-Mach-number regionsin theopposite manner. In conclusion, CCA technology is a cost-effective method to improve the propulsion performance of the aircraft engine for flight mission.