Session: 01-11 Electrified Propulsion and Novel Cycles I

Paper Number: 151605

On the Performance Potential of Ducted Fans With Integrated Heat Exchangers 

Fuel-cell-powered aircraft propulsion is a key hydrogen-based technology that could enable zero in-flight carbon emissions.  However, managing the heat rejection associated with such systems poses significant design and operational challenges, but at the same time provides potential for additional thrust generation coming from the waste heat. Integrating ducted heat exchangers within the flowpath of an electrically-driven propulsor could present a promising solution, which this study refers to as the “Heat Propulsor.” 
A virtual propulsion system framework is deployed to develop a dedicated cycle design and 2D sizing model for the Heat Propulsor. The fan is sized at cruise while the heat exchanger at take-off, to accommodate the high heat load demands during this phase of operation. An analytical heat exchanger model is integrated within the Heat Propulsor simulation framework. A linear diffuser model is used to achieve the necessary flow diffusion before the heat exchanger inlet, with its length adjusted to prevent flow separation. 
The analysis reveals a trade-off based on the selected Mach number at the heat exchanger inlet. While heat transfer is more efficient at lower Mach numbers, this leads to configurations with excessively long linear diffusers and increased duct losses. It is shown that designing the fan for lower fan-face Mach numbers and shifting part of the required diffusion to the intake duct can revitalize the integration of heat exchangers within the fan flowpath. The study concludes that fuel-cell propulsion systems with high efficiency, and thereby low levels of heat dissipation, makes integrated ducted heat exchangers with linear diffusers an unsuitable solution. 

Presenting Author: Mavroudis Kavvalos German Aerospace Center (DLR)

Presenting Author Biography: Mavroudis is a Research Scientist on novel fan and compressor technologies at the German Aerospace Center (DLR) and the Institute of Propulsion Technology. In parallel, he is a PhD Researcher on robust design of electrified aero-engine architectures at Mälardalen University (MDU), Sweden. He holds a Diploma in Mechanical Engineering from the Aristotle University of Thessaloniki in Greece and an MSc in Thermal Power from Cranfield University in the UK. Currently, he is serving as the Primary Point of Contact for the ASME IGTI Aircraft Engines Committee, while has a long-time involvement in the leadership of the ASME IGTI Student Advisory Committee for the past 5 years (Vice-Chair, Chair and Past-Chair).

Authors:

Mavroudis Kavvalos German Aerospace Center (DLR)
Susanna Bunse German Aerospace Center (DLR)
Maximilian Mennicken German Aerospace Center (DLR)
Rainer Schnell German Aerospace Center (DLR)
Niccolo Ferrari Technical University Vienna
Christopher Gross Advanced Drivetrain Technologies GmbH