The effects of high shaft power offtake (POT) in a direct drive, a geared drive, and a novel turbofan configuration are investigated. A design and off-design performance analysis shows the configuration specific limitations and advantages. The more electric aircraft (MEA) concept promises to offer advantages with respect to aircraft performance, maintenance, and operating costs. The engines for the MEA concept are based on conventional turbofan architectures. These engines are designed for significantly increased shaft POT that is required by the airframe, and the shaft power is usually taken off the high-pressure (HP) spool. This can impair the off-design performance of the engine and lead to compromises during engine design and to operability limitations. Taking the power off the low-pressure (LP) spool mitigates some of the problems but has other limitations. In this work, an alternative novel turbofan architecture is investigated for its potential to avoid the problems related to high shaft POTs. This architecture is called the dual drive booster because it uses a summation gearbox to drive the booster from both the LP and HP spool. The shaft power, if taken off the booster spool, is effectively provided by both the LP and HP spools, which allows the provision of very high power levels. This new concept is benchmarked against a two-spool direct drive and a geared drive turbofan (GTF). Furthermore, it is described, how the new architecture can incorporate an embedded motor generator. The presented concept mitigates some of the problems, which are encountered during high POT in conventional configurations. In particular, the core compressors are less affected by a change in shaft POT. This allows higher POTs and gives more flexibility during engine design and operation. Additionally, the potential to use the new configuration as a gas turbine-electric hybrid engine is assessed, where electrical power boost is applied during critical flight phases. The ability to convert additional shaft power is compared with conventional configurations. Here, the new configuration also shows superior behavior because the core compressors are significantly less affected by power input than in conventional configurations. The spool speed and its variation are more suitable for electrical machines than in conventional configuration with LP spool power transfer. The dual drive booster concept is particularly suited for applications with high shaft POTs and inputs, and should be considered for propulsion of MEAs.

References

References
1.
Lupelli
,
L.
, and
Geis
,
T.
,
2012
, “
A Study Integration IP Power Offtake System within Trent 1000 Turbofan Engine
,” Rolls-Royce plc, London, accessed July 12, 2017, https://core.ac.uk/download/pdf/14703878.pdf
2.
Oyori
,
H.
,
Morioka
,
N.
, and
Fukuda
,
T.
,
2015
, “
Conceptual Study of Low-Pressure Spool-Generating Architecture for More Electric Aircraft
,”
SAE
Paper No. 2015-01-2408.
3.
Mitcham
,
A. J.
, and
Grum
,
N.
,
1998
, “
An Integrated LP Shaft Generator for the More Electric Aircraft
,”
IEE Colloquium on All Electric Aircraft
, London, June 17, p.
8
.
4.
Pluijms
,
A.
,
Schmidt
,
K.-J.
,
Stastny
,
K.
, and
Chibisov
,
B.
,
2008
, “
Performance Comparison of More Electric Engine Configurations
,”
ASME
Paper No. GT2008-50758.
5.
Newman
,
R.
,
2004
, “
The More Electric Engine Concept
,”
SAE
Paper No. 2004-01-3128.
6.
Bradley
,
M. K.
, and
Droney
,
C. K.
,
2011
, “
Subsonic Ultra Green Aircraft Research: Phase I Final Report
,” National Aeronautics and Space Administration, Washington, DC, Report No.
NASA/CR-2011-216847
.https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110011321.pdf
7.
Speak
,
T. H.
,
Sellick
,
R. J.
,
Kloos
,
V.
, and
Jeschke
,
P.
,
2016
, “
Dual Drive Booster for a Two-Spool Turbofan: Performance Effects and Mechanical Feasibility
,”
ASME J. Eng. Gas Turbines Power
,
138
(
2
), p. 0
22603
.
8.
Speak, T.
, and
Sellick, R.
, 2014, “
Compressor System
,” UK Patent No. WO 2014/177836 A1.
9.
Lents
,
C. E.
,
Hardin
,
L. W.
,
Rheaume
,
J.
, and
Kohlman
,
L.
,
2016
, “
Parallel Hybrid Gas-Electric Geared Turbofan Engine Conceptual Design and Benefits Analysis
,”
AIAA
Paper No. AIAA 2016-4610.
10.
Stewart
,
J. D.
,
1986
, “
Operation of the CT7 Turboprop Engine as an Auxiliary Power Unit (APU)
,”
ASME
Paper No. 86-GT-28.
11.
GasTurb GmbH, 2017, “
GasTurb 13 Manual: Design and Off-Design Performance of Gas Turbines
,” GasTurb GmbH, Aachen, Germany, accessed July 12, 2017, http://www.gasturb.de/manual.html
12.
SAE
,
2009
, “
Aircraft Propulsion System Performance Station Designation and Nomenclature
,” SAE International, Warrendale, PA.
13.
Kurzke
,
J.
,
2011
, “
Correlations Hidden in Compressor Maps
,”
Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels
, Vol.
1
,
Wind Turbine Technology
,
Vancouver, BC, Canada
, pp.
161
170
.
14.
Walsh
,
P. P.
, and
Fletcher
,
P.
,
2008
,
Gas Turbine Performance
,
2nd ed.
,
Blackwell Science
,
Oxford, UK
.
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