Abstract:
This thesis describes
an
Engineering Doctorate
project
in Distributed Propulsion
carried
out
from 2004 to 2007
at
Cranfield University. Distributed
propulsion
is
a propulsion
system arrangement that consists
in
spreading the engine thrust along the aircraft span.
This
can
be
accomplished
by distributing
a series of
driven fans
or the engines
themselves. The
aim of this project
is to determine the feasibility
of
distributed
propulsion
for
civil aviation
in the medium term (with
small gas turbines) and
long term
(with driven fans) from
a technical and economic perspective.
The
effect of
distributed
propulsion was assessed
by
creating a
long-range
subsonic
airliner
baseline
with conventional technology for the small gas turbines study, and an
equivalent
blended
wing
body baseline for the driven fans
study.
Different distributed
propulsion effects were modelled and
integrated together to produce optimised
baselines
with
different technological parameters.
The feasibility
of small gas turbine distributed
propulsion was
found to be limited by the
excessive
fuel
consumption associated with small gas turbines. Although
advanced
heat
exchanger technology could
improve their performance, the resulting cost advantage
might not
be large
enough to justify the development
costs.
The feasibility
of
distributed driven fans depends on the availability of superconductive
elements, as electrical power transmission seems to be the only promising transmission
method
in the long
run.
If
superconductive elements are applied,
distributed driven fans
could afford
fuel burn
reductions of more than 50%
relative to current technology.
As both distributed
propulsion concepts rely on small propulsive units, their enabling
technologies coincide with those required to develop future
unmanned aerial vehicles.
UAVs therefore represent the most appropriate technological avenue to develop
technologies with
the potential to become distributed
propulsion enablers.
Future
work
should therefore concentrate on
improving
engine performance and cost
for
unmanned
aerial vehicles.
