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Reproducing Existing Nacelle Geometries with the Free-Form Deformation Parametrization

Rusch, Thorben Konstantin and Siggel, Martin and Becker, Richard-Gregor (2017) Reproducing Existing Nacelle Geometries with the Free-Form Deformation Parametrization. In: Proceedings of ASME 2018 Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers. ASME 2018 Turbomachinery Technical Conference and Exposition, 11.-15. Jun. 2018, Lillestrøm (Oslo), Norwegen. DOI: 10.1115/GT2018-76445 ISBN 978-0-7918-5102-9

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Official URL: https://proceedings.asmedigitalcollection.asme.org/proceeding.aspx?articleID=2700767

Abstract

In the conceptual and preliminary aircraft design phase the Free-Form Deformation (FFD) is one of various parametrization schemes to define the geometry of an engine's nacelle. In this paper we present a method that is able to create a G2 continuous approximation of existing reference nacelles with the B-spline based FFD, which is a generalization of the classical FFD. The basic principle of our method is to start with a rotational symmetric B-spline approximation of the reference nacelle, which is subsequently deformed with a FFD grid that is placed around the initial geometry. We derive a method that computes the displacement of the FFD grid points, such that the deformed nacelle approximates the reference nacelle with minimal deviations. As this turns out to be a linear inverse problem, it can be solved with a linear least squares fit. To avoid overfitting effects - like degenerative FFD grids which imply excessive local deformations - we regularize the inverse problem with the Tikhonov approach. For the reference geometries we selected the NASA CRM model and the IAE V2500 engine. Both resemble nacelles that are typically found on common aircraft models and both deviate sufficiently from the rotational symmetry. We demonstrate that the mean error of our approximation decreases with an increase of the number of FFD grid points and how the regularization affects these results. Finally, we compare the B-spline based FFD with the classical Bernstein based FFD for both models.

Item URL in elib:https://elib.dlr.de/117494/
Document Type:Conference or Workshop Item (Speech)
Title:Reproducing Existing Nacelle Geometries with the Free-Form Deformation Parametrization
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Rusch, Thorben Konstantinkonstantin.rusch (at) dlr.deUNSPECIFIED
Siggel, Martinmartin.siggel (at) dlr.deUNSPECIFIED
Becker, Richard-GregorRichard.Becker (at) dlr.deUNSPECIFIED
Date:30 October 2017
Journal or Publication Title:Proceedings of ASME 2018 Turbomachinery Technical Conference and Exposition
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
DOI :10.1115/GT2018-76445
Publisher:American Society of Mechanical Engineers
Series Name:ASME Turbo Expo 2018 Proceedings
ISBN:978-0-7918-5102-9
Status:Published
Keywords:Nacelle, FFD, B-splines, Fit, Regularization
Event Title:ASME 2018 Turbomachinery Technical Conference and Exposition
Event Location:Lillestrøm (Oslo), Norwegen
Event Type:international Conference
Event Dates:11.-15. Jun. 2018
Organizer:ASME International Gas Turbine Institute
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:fixed-wing aircraft
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - VicToria, R - Vorhaben SISTEC
Location: Köln-Porz
Institutes and Institutions:Institut of Simulation and Software Technology > High Performance Computing
Institute of Propulsion Technology > Engine
Deposited By: Siggel, Dr. Martin
Deposited On:10 Jan 2018 15:16
Last Modified:05 Dec 2018 15:12

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