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@PHDTHESIS{Khler:854403,
author = {Köhler, Jo Alexander},
othercontributors = {Jeschke, Peter and Stumpf, Eike},
title = {{E}ntwurfsmethode für elektrische und hybride
{K}leinflugzeugantriebe},
school = {Rheinisch-Westfälische Technische Hochschule Aachen},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2022-09519},
pages = {1 Online-Ressource : Illustrationen, Diagramme},
year = {2022},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, Rheinisch-Westfälische Technische
Hochschule Aachen, 2022},
abstract = {The objective of the present work is the development and
application of a conceptual design method for electric and
hybrid propulsion systems in small aircraft. The method is
applied to design propulsion systems for a motorized glider
with a maximum take-off mass of 1000 kg. Four propulsion
systems are investigated: the conventional internal
combustion engine, the fully electric, the parallel, and
series hybrid propulsion system. Key physical relationships,
trade-offs, and design decisions are discussed and a
comparison between the propulsion systems is made. On this
basis, the suitability of the propulsion systems is
evaluated with respect to different thrust requirements. The
design method can be used to evaluate the influence of
design parameters and operating strategies of hybrid
propulsion systems on key targets such as system mass and
cruise efficiency. Detailed component models are used to
capture all interrelationships and operational limitations
essential to the conceptual design. The design method is
applied to study the suitability of the propulsion systems
for different thrust requirements. The four propulsion
systems considered are each designed for two different sets
of thrust requirements. All propulsion systems are capable
of the same flight mission, which allows for a meaningful
comparison between the propulsion systems. Due to the high
gravimetric power density of electric components and high
efficiencies over a wide operating range, the electric
propulsion system is suitable for high peak power combined
with low cruise power. However, cruise range is limited due
to the high battery mass. At a range of 300 km, the electric
propulsion system is 2.6 times heavier than the conventional
propulsion system. Within the study, the electric power of
the hybrid propulsion systems is used for a boost during
take-off. With this control strategy and the current
technology level, the parallel hybrid propulsion system is
able to achieve a lower total mass than the conventional
propulsion system if the propeller power ratio between
take-off and cruise is bigger than three. The downsizing of
the internal combustion engine results in cruise efficiency
advantages if the ratio is bigger than two. In this study,
with a power ratio of 4.4, the parallel hybrid propulsion
system can achieve a cruise efficiency that is 12 $\%$
higher and a total mass that is 8 $\%$ lower than the
conventional propulsion system. The series hybrid propulsion
system has significant disadvantages compared to
conventional and parallel hybrid propulsion systems and
should only be used if the aircraft design requires it. This
study demonstrates that system considerations are necessary
for concept evaluations and designs of electric and hybrid
propulsion systems in small aircraft. The developed method
is able to model all interrelationships between propulsion
components relevant to the conceptual design and to
determine system optima.},
cin = {413510},
ddc = {620},
cid = {$I:(DE-82)413510_20180101$},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2022-09519},
url = {https://publications.rwth-aachen.de/record/854403},
}
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