Session: 03-04 Advancements in Turboprop and Turboshaft Engine Technologies

Paper Number: 153997

Design Space Exploration of Geared Turbofans Using Alternative Fuels 

The aviation industry faces increasing pressure to reduce its environmental impact, particularly
in terms of carbon emissions and fuel consumption. In response, the development of alterna-
tive fuels, such as Sustainable Aviation Fuel (SAF) and hydrogen, has become critical in the
pursuit of greener aviation technologies. Ultra-High Bypass Ratio (UHGBPR) geared turbofan
engines are at the forefront of this innovation, offering potential improvements in efficiency
and reductions in emissions when paired with these alternative fuels.
This paper explores the design space of UHGBPR geared turbofan engines for the short-to-
medium range market, focusing on the comparative performance of engines powered by con-
ventional Jet-A, Hydroprocessed Esters and Fatty Acids (HEFA), and hydrogen. 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, weight, and shaft inertia.
The findings reveal that HEFA engines show a moderate 2.8% improvement in specific fuel
consumption (SFC) and exhibit minimal changes in engine performance, size, and weight com-
pared to the Jet-A baseline, confirming its feasibility as a retrofitted fuel in existing Jet-A en-
gines. This positions HEFA as a practical short-term solution. In contrast, hydrogen-fuelled
engines demonstrate a significant reduction in SFC by nearly 65% and roughly 2.5% in Energy
Specific Fuel Consumption (ESFC), leading to more compact designs with reductions of 4.5%
in length and 3.2% in weight. Furthermore, the inertia analysis indicates a considerable mis-
match between the high-pressure and low-pressure shafts, which becomes more pronounced
in hydrogen-fueled engines. This mismatch influences engine operability, necessitating careful
consideration in the design of UHGBPR geared turbofan engines.

Presenting Author: Pavlos Rompokos Cranfield University

Presenting Author Biography: Pavlos Rompokos is a research fellow in the power and propulsion centre of Cranfield University School of Aerospace, Transport and Manufacture. He received an integrated master’s degree in mechanical engineering from National Technical University of Athens and an MSc and PhD in aerospace propulsion from Cranfield University. His current field of research is the implementation of hydrogen on propulsion systems for civil aviation and is contributing to the tasks of EU and ATI funded projects.

Authors:

Nabila Cava Zamorano CRANFIELD UNIVERSITY
Pavlos Rompokos Cranfield University
Christos Mourouzidis Cranfield University
Ioannis Roumeliotis Cranfield University