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Research Papers: Gas Turbines: Aircraft Engine

Installed Performance Assessment of an Array of Distributed Propulsors Ingesting Boundary Layer Flow

[+] Author and Article Information
Chana Goldberg

Hybrid Electric Propulsion Group,
Propulsion Engineering Centre,
Cranfield University,
Cranfield MK43 0AL, UK
e-mail: c.goldberg@cranfield.ac.uk

Devaiah Nalianda, Panagiotis Laskaridis

Hybrid Electric Propulsion Group,
Propulsion Engineering Centre,
Cranfield University,
Cranfield MK43 0AL, UK

Pericles Pilidis

Propulsion Engineering Centre,
Cranfield University,
Cranfield MK43 0AL, UK

1Corresponding author.

Contributed by the Aircraft Engine Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received October 30, 2017; final manuscript received November 7, 2017; published online April 24, 2018. Editor: David Wisler.

J. Eng. Gas Turbines Power 140(7), 071203 (Apr 24, 2018) (10 pages) Paper No: GTP-17-1588; doi: 10.1115/1.4038837 History: Received October 30, 2017; Revised November 07, 2017

Conventional propulsion systems are typically represented as uninstalled systems to suit the simple separation between airframe and engine in a podded configuration. However, boundary layer ingesting systems are inherently integrated, and require a different perspective for performance analysis. Simulations of boundary layer ingesting propulsions systems must represent the change in inlet flow characteristics, which result from different local flow conditions. In addition, a suitable accounting system is required to split the airframe forces from the propulsion system forces. The research assesses the performance of a conceptual vehicle, which applies a boundary layer ingesting propulsion system—NASA's N3-X blended wing body aircraft—as a case study. The performance of the aircraft's distributed propulsor array is assessed using a performance method, which accounts for installation terms resulting from the boundary layer ingesting nature of the system. A “thrust split” option is considered, which splits the source of thrust between the aircraft's main turbojet engines and the distributed propulsor array. An optimum thrust split (TS) for a specific fuel consumption at design point (DP) is found to occur for a TS value of 94.1%. In comparison, the optimum TS with respect to fuel consumption for the design 7500 nmi mission is found to be 93.6%, leading to a 1.5% fuel saving for the configuration considered.

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Figures

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Fig. 1

Sketch of NASA's N3-X aircraft

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Fig. 2

Assumed Mach number distribution over the N3-X airframe [15]

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Fig. 3

Station definition for a BLI propulsion system [13]

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Fig. 4

Simulation method for the off-design performance of a BLI propulsion system

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Fig. 5

Inlet flow characteristics validation (model —, Ref. [15] - - -)

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Fig. 6

Propulsor inlet height validation (model △, Ref. [21] ×)

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Fig. 7

Map of N3-X propulsion system NPF (DP power setting)

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Fig. 8

Influence of TS on SFC at DP (—) and RTO (- - -)

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Fig. 9

Influence of TS and transmission efficiency on SFC at DP, 99.8% (—), 95% (- - -)

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Fig. 10

Influence of TS on propulsion system weight

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Fig. 11

Payload range chart for the baseline N3-X configuration

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Fig. 12

Influence of TS on aircraft fuel burn for a 7500 nmi mission

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