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Multi-fidelity Kriging-assisted structural optimization of whole engine models employing medial meshes

Multi-fidelity Kriging-assisted structural optimization of whole engine models employing medial meshes
Multi-fidelity Kriging-assisted structural optimization of whole engine models employing medial meshes
Finite element models of whole gas turbine engines, also known as Whole Engine Models (WEM), which consist of three-dimensional solid elements are not commonly used in design optimization studies due to the high computational cost of solving them for many designs. WEMs consisting of two-dimensional shell elements can be a suitable replacement for high-fidelity solid WEMs as they approximate the responses well while being significantly quicker to solve. However, in a surrogate-assisted optimization study, the accumulation of errors in the shell WEM evaluations can result in the construction of a surrogate model that can be somewhat misleading compared to the solid WEM response surface. Such a surrogate model could return promising designs that, when validated using solid WEMs, turn out to be sub-optimal or infeasible. A novel approach which combines medial meshing and multi-fidelity surrogate modelling techniques is proposed to increase the feasibility of conducting whole engine optimization studies. We demonstrate the workflow for generating medial meshes on an engine intercasing geometry. The accuracy of medial mesh simulations with respect to solid mesh simulations are evaluated and discussed in the context of their suitability as a source of low-fidelity structural information for multi-fidelity surrogate models. The impact of this combination of techniques is subsequently illustrated using two case studies. The first case study is the optimization of an intermediate compressor casing for minimum mass with constraints on the casing stiffness. The results show that the multi-fidelity approach is able to find optimum designs that are equivalent to the expensive single-fidelity approach of using only solid mesh evaluations but at a significantly lower computational cost. The second case study is the optimization of a whole engine geometry. This case study serves to demonstrate the effectiveness of the multi-fidelity approach for solving realistic design problems.
Surrogate modelling, multi-fidelity, kriging, whole engine models, medial mesh
1615-147X
1-18
Yong, Hau Kit
47dace32-a052-46b8-a720-05cee3bd7c8b
Wang, Leran
91d2f4ca-ed47-4e47-adff-70fef3874564
Toal, David J.J.
dc67543d-69d2-4f27-a469-42195fa31a68
Keane, Andy J.
26d7fa33-5415-4910-89d8-fb3620413def
Stanley, Felix
1132f965-08d3-4c98-8b6d-2b82a64e92f5
Yong, Hau Kit
47dace32-a052-46b8-a720-05cee3bd7c8b
Wang, Leran
91d2f4ca-ed47-4e47-adff-70fef3874564
Toal, David J.J.
dc67543d-69d2-4f27-a469-42195fa31a68
Keane, Andy J.
26d7fa33-5415-4910-89d8-fb3620413def
Stanley, Felix
1132f965-08d3-4c98-8b6d-2b82a64e92f5

Yong, Hau Kit, Wang, Leran, Toal, David J.J., Keane, Andy J. and Stanley, Felix (2019) Multi-fidelity Kriging-assisted structural optimization of whole engine models employing medial meshes. Structural and Multidisciplinary Optimization, 1-18. (doi:10.1007/s00158-019-02242-6).

Record type: Article

Abstract

Finite element models of whole gas turbine engines, also known as Whole Engine Models (WEM), which consist of three-dimensional solid elements are not commonly used in design optimization studies due to the high computational cost of solving them for many designs. WEMs consisting of two-dimensional shell elements can be a suitable replacement for high-fidelity solid WEMs as they approximate the responses well while being significantly quicker to solve. However, in a surrogate-assisted optimization study, the accumulation of errors in the shell WEM evaluations can result in the construction of a surrogate model that can be somewhat misleading compared to the solid WEM response surface. Such a surrogate model could return promising designs that, when validated using solid WEMs, turn out to be sub-optimal or infeasible. A novel approach which combines medial meshing and multi-fidelity surrogate modelling techniques is proposed to increase the feasibility of conducting whole engine optimization studies. We demonstrate the workflow for generating medial meshes on an engine intercasing geometry. The accuracy of medial mesh simulations with respect to solid mesh simulations are evaluated and discussed in the context of their suitability as a source of low-fidelity structural information for multi-fidelity surrogate models. The impact of this combination of techniques is subsequently illustrated using two case studies. The first case study is the optimization of an intermediate compressor casing for minimum mass with constraints on the casing stiffness. The results show that the multi-fidelity approach is able to find optimum designs that are equivalent to the expensive single-fidelity approach of using only solid mesh evaluations but at a significantly lower computational cost. The second case study is the optimization of a whole engine geometry. This case study serves to demonstrate the effectiveness of the multi-fidelity approach for solving realistic design problems.

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More information

Accepted/In Press date: 19 February 2019
e-pub ahead of print date: 11 May 2019
Keywords: Surrogate modelling, multi-fidelity, kriging, whole engine models, medial mesh

Identifiers

Local EPrints ID: 431570
URI: https://eprints.soton.ac.uk/id/eprint/431570
ISSN: 1615-147X
PURE UUID: 0ce42c27-afaf-4868-846b-af184cbdc4b3
ORCID for David J.J. Toal: ORCID iD orcid.org/0000-0002-2203-0302

Catalogue record

Date deposited: 07 Jun 2019 16:30
Last modified: 20 Jul 2019 00:51

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