Design Space Exploration of Geared Turbofans Using Alternative Fuels

Abstract This paper explores the design space of UHBPR geared turbofan engines for the short-to-medium range market, focusing on the comparative performance of engines powered by conventional Jet A-1, Hydroprocessed Esters and Fatty Acids (HEFA), and liquid hydrogen accounting for the thermal management effect of the cryogenic fuel. Utilizing a multi-point design approach, the research aims to optimize engine configurations for each fuel type, considering the anticipated entry into service in 2035 (EIS2035). The study investigates key parameters such as engine performance, size and weight. The findings reveal that HEFA-optimised engines show a moderate 0.16% improvement in energy-specific fuel consumption (ESFC) and exhibit minimal changes in engine performance, size, and weight compared to the Jet-A baseline, confirming its feasibility as a retrofitted fuel in existing Jet-A engines. This positions HEFA as a practical short-term solution. In contrast, hydrogen-optimised engines that utilise fuel preheating, demonstrate an increase in specific energy consumption by nearly 5.6% mainly attributed to the fuel conditioning, but can enable more compact designs with a reduction of 1.9% in bare engine weight. Furthermore, a retrofitting analysis indicates that Jet A-1-optimised design can adequately accommodate both HEFA and H2 but with decreasing ESFC differences of −0.1% and 6.9% for HEFA and Hydrogen.