Conceptual Design of Propulsion Systems for Boundary Layer Ingestion
Doktorsavhandling, 2019

To reduce the climate impact of aviation new aircraft and engine concepts as well as improved design methods are needed. In this thesis, two fronts are explored. The first concerns improved methods for the conceptual design of the engine. A consistent conceptual design approach is presented, where calculated parameters such as stage loadings are used to update the component efficiency assumptions within the cycle optimization loop. The result is that the design space is fully explored, and that pressure ratio is optimally distributed between the components. A coupled analysis of a low pressure turbine and turbine rear structure has also been conducted, showing the importance of considering their coupled interaction when these components are designed.

On the second front, concerning the application of the developed methods to new propulsion applications, a conceptual design of a propulsion system for a turbo-electric boundary layer ingesting aircraft concept is presented. The aircraft features and aft-mounted fuselage fan for boundary layer ingestion. Earlier studies have shown a theoretical potential of 10% in power savings compared to a conventional aircraft configuration. The fuselage fan is electrically powered and fed by power offtake from two under-wing mounted geared turbofan engines. To this end, a 5 MW-class generator is integrated into the geared turbofans. The generator is connected to a free power turbine that is introduced to facilitate an optimal generator design and to mechanically decouple the generator from the low pressure shaft. A system-level analysis of the designed propulsion system, including the effects of the boundary layer ingesting fuselage fan shows a fuel burn reduction of 0.6%-3.6%, depending on electric machinery technology, compared to a conventional aircraft in the 2050 time frame. The modest reduction, compared to the theoretical potential, is caused by the difficulty of obtaining a benefit from ingesting the outer part of the boundary layer. This benefit is more than offset by electric machinery losses and the reduced efficiency of the fuselage fan compared to the main engine fan.

turbo-electric aircraft

performance modeling


boundary layer ingestion

aircraft engine

conceptual design

propulsion integration

Opponent: Dr. Wilfried Visser, TU Delft, Nederländerna


Sebastian Samuelsson

Chalmers, Mekanik och maritima vetenskaper, Strömningslära

Consistent Conceptual Design and Performance Modeling of Aero Engines

ASME Turbo Expo 2015: Turbine Technical Conference and Exposition, GT 2015; Montreal; Canada; 15 June 2015 through 19 June 2015,; (2015)

Paper i proceeding

Exploring Influence of Static Engine Component Design Variables on System Level Performance

22nd International Symposium on Air Breathing Engines, ISABE2015,; (2015)

Övrigt konferensbidrag

Concept validation study for fuselage wake-filling propulsion integration

31st Congress of the International Council of the Aeronautical Sciences, ICAS 2018,; (2018)

Paper i proceeding

Integration Aspects for Large Generators into Turbofan Engines for a Turbo-electric Propulsive Fuselage Concept

24th International Symposium on Air Breathing Engines (ISABE 2019),; (2019)p. 536-552

Paper i proceeding

Samuelsson, S., Grönstedt, T. Performance Analysis of Turbo-electric Propulsion System with Boundary Layer Ingestion


Hållbar utveckling





Rymd- och flygteknik



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4660


Chalmers tekniska högskola


Opponent: Dr. Wilfried Visser, TU Delft, Nederländerna

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