Research Papers: Gas Turbines: Aircraft Engine

Dual Drive Booster for a Two-Spool Turbofan: High Shaft Power Offtake Capability for More Electric Aircraft and Hybrid Aircraft Concepts

[+] Author and Article Information
Vadim Kloos

Institute of Jet Propulsion and Turbomachinery,
RWTH Aachen University,
Templergraben 55,
Aachen 52062, Germany
e-mail: kloos@ist.rwth-aachen.de

Trevor H. Speak

Derwent Aviation Consulting Ltd,
58-60 Wetmore Road,
Burton on Trent DE14 1SN, UK
e-mail: trevor.speak@hotmail.com

Robert J. Sellick

Derwent Aviation Consulting Ltd,
58-60 Wetmore Road,
Burton on Trent DE14 1SN, UK
e-mail: robertsellick@msn.com

Peter Jeschke

Institute of Jet Propulsion and Turbomachinery,
RWTH Aachen University,
Templergraben 55,
Aachen 52062, Germany
e-mail: jeschke@ist.rwth-aachen.de

Contributed by the Aircraft Engine Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received June 24, 2018; final manuscript received July 1, 2018; published online November 29, 2018. Editor: Jerzy T. Sawicki.

J. Eng. Gas Turbines Power 140(12), 121201 (Nov 29, 2018) (9 pages) Paper No: GTP-18-1327; doi: 10.1115/1.4040822 History: Received June 24, 2018; Revised July 01, 2018

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.

Copyright © 2018 by ASME
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DDBTF configuration and station numbering

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Fig. 3

Arrangement with starter/generator and fan brake

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Fig. 4

HPC operating line in DDTF

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Fig. 5

HPC operating line in GTF

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Fig. 6

HPC operating line in DDBTF

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Fig. 7

Effects of LP and HP spool POT on HPC operation at constant thrust in DDTF

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Fig. 8

Booster OL in DDTF

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Fig. 10

Booster OL in DDBTF

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Fig. 11

Gear ratio effect on booster SM in DDBTF

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Fig. 12

Maximum DDTF and DDBTF POT in Cruise

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Fig. 13

Booster OL, HP and LP power input in DDTF

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Fig. 14

HPC OL, HP and LP power input in DDTF

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Fig. 15

Booster OL, booster spool power input in DDBTF

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Fig. 16

HPC OL, booster spool power input in DDBTF

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Fig. 17

Speed range, cruise

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Fig. 19

VGV settings for booster at 500 kW POT



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