Hierarchical optimal control of a coupled hydrogen-fueled engine and its hydrogen supply system

Liquid hydrogen enables aviation decarbonization, but hydrogen-fueled engines require an integrated supply system for heat exchange and flow regulation, whose thermal–flow coupling shifts safety boundaries. This paper proposes a two-layer hierarchical optimal-control architecture based on a coupled steady-state model of a hydrogen-fueled turbojet and its supply system, with a semi-empirical thermal- NO x model. The upper layer performs offline thrust planning for eco-mode (minimum fuel burn) and NOxmin-mode (minimum NO x ), while the lower layer employs an adaptive model predictive controller (AMPC) with feed-forward constraint tightening for icing protection. Closed-loop simulations show that the icing and NO x constraints narrow the feasible thrust-optimization region. Both modes remain below an ICAO-derived comparative benchmark for D p / F o o ; NOxmin-mode is predicted to reduce NO x by 24.2 % at a 4.47 % fuel penalty. Compared with three benchmark controllers, only the AMPC maintains all constraints during the transients. The controller also exhibits robustness under the tested conditions.