Thermodynamic Optimization of F35 XA100 Architecture

This paper investigates thermodynamic optimization strategies for the GE XA100 adaptive cycle engine, focusing on reducing dominant sources of irreversibility that limit efficiency and off-design performance. Two complementary modifications are analyzed using first principles thermodynamics, chemical kinetics, and compressible flow theory. The first is an endothermic catalytic fuel pre-reformer integrated upstream of the combustor, which converts waste thermal energy from compressor discharge and turbine cooling flows into chemical potential energy, thereby reducing combustor entropy generation and cooling air requirements. The second is an adaptive micro nozzle array for the third stream, which enables near-optimal expansion across a wide range of flight conditions and minimizes kinetic and pressure losses associated with fixed geometry nozzles. Control volume analysis, entropy and exergy balances, reaction rate considerations, and area Mach relations are used to quantify performance impacts. Calculated results indicate reductions in combustor exergy destruction, decreased turbine cooling mass flow, improved propulsive efficiency, and lower thrust specific fuel consumption under off-design conditions. The combined architecture demonstrates how targeted entropy minimization and adaptive flow control can extend the thermodynamic limits of next-generation variable-cycle propulsion systems.