Recent Advances in High-Fidelity Multidisciplinary Adjoint-Based Optimization with the NSU3D Flow Solver Framework

2022

Struct Multidisc Optim

Efficient optimization of an aeroelastic wing is presented through multi-disciplinary analysis using low-dimensional modal design variables. Much work in wing optimization has concentrated on high-fidelity surface control, therefore utilising often hundreds of design variables. However, whilst fine surface control can be useful, problems can arise such as large disparities in design variable values when planform variables are introduced, slow convergence speeds, and lack of compatibility with global algorithms. Therefore, the focus of this paper is to filter the design space of this problem to reduce the dimensionality and complexity of the problem. Orthogonal geometric design variables are derived in the geometric space via singular value decomposition. Orthogonality of design variables leads to a well-conditioned design space and ensures effective optimizer convergence. These variables are applied in a sectional fashion for fixed planform drag minimization of a flexible transonic wing, using a gradient-based optimizer. Shock-free solutions are demonstrated when optimizing a rigid wing, indicating suitability of the aerofoil modes for sectional-based wing optimization. However, it is shown that these wings have poor performance when subsequently deformed under flight loads, hence optimisation including full aeroelastic performance is performed. Encouragingly, shock-free solutions are again computed. Loading is shifted outboard, leading to increased tip deflection. Monotonic improvement in the objective function (drag) with increase in dimensionality is also proven. Furthermore, applying these sectional deformation modes globally across the wing with only 10 design variable leads to a 28% drag reduction, which is within 7 drag counts of when the modes are applied locally through 82 design variables. This therefore opens the possibility of introducing global optimization algorithms to high-fidelity aeroelastic wing optimization.

Section: Introductionmentioning

confidence: 99%

Efficient aeroelastic wing optimization through a compact aerofoil decomposition approach

2022

Struct Multidisc Optim

“…17,18 Furthermore, recent developments include the ongoing work to couple more disciplines into the process, including coupling aerodynamics, structures and acoustics in a fully coupled unsteady optimization of rotorcraft. 19 Large numbers of design variables permit detailed small-scale optimization. However, the quantity of design variables has a significant effect on the convergence of the optimizer.…”

Section: Introductionmentioning

confidence: 99%

Efficient Modal Design Variables for Optimization of Aero-Elastic Wing

AIAA Scitech 2020 Forum

2020

Efficient multidisciplinary optimization is presented for aero-structural wing optimization using efficient low-dimensional modal design variables. Orthogonal aerofoil design variables are derived in the geometric space via singular value decomposition. Orthogonality of design variables leads to a well-conditioned design space and encourages positive optimizer convergence. These are applied in a sectional fashion for fixed planform drag minimization of a flexible transonic wing. Shock-free solutions are demonstrated for the rigid wing, indicating suitability of the aerofoil modes for sectional-based wing optimization. However, these wings have poor performance when deformed under flight loads, hence full aeroelastic performance is taken into account. Encouragingly, shock-free solutions are again found. Loading is shifted outboard, leading to increased tip-deflection. Monotonic improvement in objective with increase in dimensionality is also observed.

“…Using this, coupled aero-structural adjoint methods have been presented [19][20][21], which has permitted high-fidelity, large-scale aero-structural optimization [22]. Furthermore, recent developments include the ongoing work to couple more disciplines into the process, including coupling aerodynamics, structures and acoustics in a fully coupled unsteady optimization of rotorcraft [23].…”

Section: Introductionmentioning

confidence: 99%

Efficient Aero-Structural Wing Optimization Using Compact Aerofoil Decomposition

AIAA Scitech 2019 Forum

2019

Aerodynamic shape optimization of an aero-structural transonic wing is presented using a compact set of design variables. Modal decomposition (via singular value decomposition) of a training library of aerofoils to extract a compact set of aerofoil design variables has previously been shown to be highly effective. These have been used for high-fidelity global optimization of aerofoils. Hence, this work applies these design variables to optimization of an aero-structural wing. A representative transonic aircraft wing with defined structural modes is optimized as a rigid and aeroelastic shape. For fixed planform optimization, using as few as nine variables at ten spanwise sections is enough permit shock-free solutions when using a gradient-based optimizer for both the rigid and aeroelastic shapes. A drag reduction of 21.7% of the rigid wing is obtained. However, the aero-structural solution of the optimised rigid wing shows a shocked solution, demonstrating the need to consider the optimization of the aeroelastic shape. As such, optimization of the aeroelastic wing is considered, where a drag reduction of and 29.7% is obtained against the aeroelastic baseline wing.