Research Papers: Gas Turbines: Turbomachinery

An Automated Approach to Nacelle Parameterization Using Intuitive Class Shape Transformation Curves

[+] Author and Article Information
Robert Christie

Propulsion Engineering Centre,
School of Aerospace, Transport,
and Manufacturing,
Cranfield University,
Bedfordshire MK43 0AL, UK
e-mail: r.christie@cranfield.ac.uk

Alexander Heidebrecht, David MacManus

Propulsion Engineering Centre,
School of Aerospace, Transport,
and Manufacturing,
Cranfield University,
Bedfordshire, MK43 0AL, UK

1Corresponding author.

Contributed by the Turbomachinery Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received June 18, 2016; final manuscript received October 10, 2016; published online January 18, 2017. Editor: David Wisler.

J. Eng. Gas Turbines Power 139(6), 062601 (Jan 18, 2017) (9 pages) Paper No: GTP-16-1227; doi: 10.1115/1.4035283 History: Received June 18, 2016; Revised October 10, 2016

A tool to create parametric aerodynamic shapes using intuitive design variables based on class shape transformation (CST) curves is presented. To enable this, a system has been developed which accepts arbitrary constraints and automatically derives the analytical expressions which describe the corresponding class shape transformation curves. Parametric geometry definitions for fan cowl and intake aero-lines were developed using the generalized method. Computational fluid dynamics (CFD) analysis of the fan cowl shows that despite the simple geometry definition, its performance characteristics are close to what would be expected of a finished design. The intake geometry was generated in a similar way and met the typical performance metrics for conventional intakes. This demonstrates the usefulness of the tool to quickly and robustly produce parametric aero-lines with good aerodynamic properties, using relatively simple intuitive design variables.

Copyright © 2017 by ASME
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Fig. 1

Perturbation of the shape function by variation of the Bernstein polynomial weighting coefficients

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Fig. 2

Geometry formed using a unit shape function and a shape function perturbed by Bernstein polynomial weighting coefficients (Fig. 1)

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Fig. 3

Fan cowl and intake CST curves, their first and second derivatives, and their constraints

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Fig. 4

Comparison of the original geometry of the CRM through-flow nacelle and the fan cowl line constructed using the parametric geometry

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Fig. 5

View of one of the two-dimensional axisymmetric meshes used in this study, representing fan cowl and intake, including spinner

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Fig. 8

Comparison of drag rise curves for the original and the reconstructed parametric shape, at midcruise mass-flow capture ratio of 0.75, and spillage curve at cruise Mach number (0.85)

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Fig. 9

Variation of DC60, maximum MISEN and IPR with changes in α, M = 0.25, Alt. = 16,600 ft, MFCR = 1.4: (a) α = 22 deg and (b) α = 28 deg

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Fig. 10

Mach number distributions around the lower lip (180 deg from top dead center (TDC)) of the parametrically defined intake at different angle of attack, M = 0.25, Alt. = 16,600 ft, MFCR = 1.4

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Fig. 11

Variation of isentropic Mach number around the bottom lip with changes in α, M = 0.25, Alt. = 14,000 ft, MFCR = 1.62

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Fig. 12

Variation of total pressure ratio on the nominal fan face with changes in α, M = 0.25, Alt. = 16,600 ft, MFCR = 1.4. Iso-surfaces of zero axial velocity are shown in white to illustrate areas of separation.

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Fig. 13

Variation of total pressure ratio on the nominal fan face for short intakes A, B, and C. M = 0.25, Alt. = 16,600 ft, α = 22 deg, Qfan equal to that of the conventional length intake. Iso-surfaces of zero axial velocity are shown in white to illustrate areas of separation.

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Fig. 14

The extent and initial cause of intake separations for short intakes A, B, and C. M = 0.25, alt. = 16,600 ft, α = 22 deg, Qfan equal to that of the conventional length intake.



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