High-fidelity aero-structural optimization framework for transonic aircraft design

Ranjan, Prateek

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https://hdl.handle.net/2142/117728 Copy

Description

Title

High-fidelity aero-structural optimization framework for transonic aircraft design

Author(s)

Ranjan, Prateek

Issue Date

2022-10-14

Director of Research (if dissertation) or Advisor (if thesis)

Ansell, Phillip J

Doctoral Committee Chair(s)

James, Kai A

Committee Member(s)

• Geubelle, Philippe H
• Panesi, Marco
• Magalhaes, Jose

Department of Study

Aerospace Engineering

Discipline

Aerospace Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

MDO, Aero-elasticity, Optimization, Topology Optimization

Abstract

Aircraft design is challenging endeavor. From a computational design perspective, this is partly due to the synergy between sub-systems such as aerodynamics, structure, control and navigation, and partly due to the modeling fidelity required to resolve such inter-dependencies. This dissertation presents a novel high-fidelity aero-elastic topology optimization framework for aircraft design that focuses on the synergy between the aerodynamic shape and the underlying wing structure, at transonic flight speeds. A high fidelity aero-elasticity framework is developed to resolve non-linear effects such as shock-induced boundary layer separation, aero-elastic bend-twist coupling, etc, using large distributed and shared memory architectures. This framework is based on a network-based data-transfer paradigm which yields ∼ 5% higher efficiency when compared to the conventional disk-based POSIX I/O data sharing protocol. The accuracy of the non-linear aero-elasticity solver is studied with the help of an extensive validation campaign at Mach number ranging from 0.55 to 0.88, and Reynolds numbers from 7 to 50 Million. The error in predicted aero-elastic displacements ranges from ∼ 0.02% in the linear regime to ∼ 12% in the non-linear regime. Qualitative Mach and internal stress field visualizations obtained during this test campaign also help identify primary and secondary load-carrying members for a high aspect ratio cantilevered wing. The aero-elasticity design problem is extended to solve topology optimization problems by parameterizing the elastic stiffness at the finite element level. A lift-constrained elastic compliance minimization problem is solved for a RAE 2822 wing section as well as the NASA Common Research Model, resulting in novel unconventional material distributions that sustain aerodynamic loads up to transonic Mach numbers. The aero-elastic topology optimization problems presented herein include the outer skin to serve as the primary load-carrying member of the wing box. For the quasi-two-dimensional RAE 2822 wing-section, the optimization yields internal structural layouts with a smooth seamless distribution in the entire domain. Optimal material layouts obtained from a low-fidelity coupled two-dimensional topology optimization problem for a NACA 0012 wing-section are also presented. For the NASA CRM configuration, the optimal structural design is dominated by non-linear bend-twist coupling effects and the optimization results in compliance reduction by ∼ 74%. High-fidelity aerodynamic shape optimization is also studied to better understand its implementation in the large-scale MDA/O framework. A two dimensional RAE 2822 airfoil is optimized for drag and multiple novel airfoil configurations are obtained due to varying design space dimension and size of the feasible region. The NASA CRM wing is optimized at design conditions with varying degrees of parameterization, resulting in four optimal configurations with drag savings ranging from 6.9% to 25.8%.

Graduation Semester

2022-12

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Prateek Ranjan

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