Abstract
High-performance geared turbofan engines generate significant heat within the planetary power gearbox. This study presents the thermal design of an integrated fan guide vane heat exchanger aimed at recovering gearbox heat losses with minimal pressure loss and converting them into useful propulsive energy via the Junkers–Meredith Effect. Hot gearbox oil is routed through hollow fan static guide vanes, enabling heat transfer to the bypass airflow while simultaneously reducing oil temperature and augmenting thrust. A comprehensive analytical framework is applied, incorporating heat transfer modeling, guide vane geometry reconstruction, lubrication flow sizing, and propulsion performance evaluation for both take-off and cruise flight conditions, using the PW1127G-JM geared turbofan as the reference engine. The results indicate that the proposed system can achieve a thrust increase of up to 6.4% at the end of take-off and deliver a thrust-specific fuel consumption reduction of up to 5.6% during take-off and approximately 2% during cruise. While sufficient heat dissipation is achieved under cruise conditions, take-off operation requires a higher transient oil temperature. Overall, this study demonstrates that integrating heat recovery into existing engine structures offers a promising pathway to enhance propulsion efficiency, reduce fuel consumption, and support more sustainable aircraft engine designs.