Aerodynamic Redesign Using Discrete Adjoint Approach on Overset Mesh System

Lee, Byung Joon; Kim, Chongam

doi:10.2514/1.34112

Cited by 16 publications

(7 citation statements)

References 24 publications

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“…Most previous design works were conducted focusing on uniform sinusoidal plunging and pitching motions, where the number of design parameters is small (limited to two or three), because of a prohibitive computational cost in unsteady optimization problems-even with an efficient gradient-based method. In a realistic aerodynamic shape optimization, the number of design D parameters needed to adequately describe an airfoil shape in transonic flow can vary from O (10) to O(100), even for a two-dimensional airfoil application [8][9][10]. As a result, the design cost of optimization based on CFD is expensive, even with today's computation power; hence a judicious choice of optimization approach for the current problem is warranted.…”

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confidence: 99%

“…As a result, the design cost of optimization based on CFD is expensive, even with today's computation power; hence a judicious choice of optimization approach for the current problem is warranted. In our study, we adopt the approach of using adjoint sensitivity analyses [8][9][10] in our aerodynamic shape and trajectory optimizations for flapping airfoils.…”

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confidence: 99%

“…The adjoint approach has been regarded as a very efficient sensitivity analysis method for aerodynamic shape optimization because the computational time cost is almost independent of the number of design variables [8][9][10]. To apply this method to an unsteady aerodynamic application, two different ways of accounting for physical time can be taken.…”

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Unsteady Adjoint Approach for Design Optimization of Flapping Airfoils

Lee

Liou

2012

AIAA Journal

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confidence: 99%

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confidence: 99%

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Unsteady Adjoint Approach for Design Optimization of Flapping Airfoils

Lee

Liou

2012

AIAA Journal

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“…The adjoint method enables the computation of all shape sensitivities for a given problem at the cost of only one flow solution and one adjoint solution [22]. As a result of its efficiency, the adjoint method has become widely used for aircraft design, evolving to the design optimisation of full wing-body configurations [23]. The adjoint method has also been considered an enabling technology for MDO of complex configurations [24], recent examples include aerostructural design optimisation [25] and sonic boom mitigation [26].…”

Section: Modern Cfd-based Design Optimisationmentioning

confidence: 99%

“…As a result of its efficiency, the adjoint method has become widely used for aircraft design, evolving to the design optimisation of full wing-body configurations [23,26]. This section will provide a brief review of adjoint studies that have focused on the design of hypersonic aircraft.…”

Section: Hypersonic Applicationsmentioning

confidence: 99%

Adjoint-based aerodynamic design optimisation in hypersonic flow

Damm¹

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The drive for improved flexibility and reusability in satellite launch systems has brought a resurgence in the popularity of scramjet-powered access-to-space launch vehicle concepts. A challenge in scramjet-powered accelerator vehicles is achieving positive thrust margins at the high-speed end of their flight envelopes. As a consequence, scramjet-powered vehicles typically rely on highly integrated airframe-engine configurations. However, due to the tight integration, the geometries and the flow physics are complex. An automated optimisation method seems an excellent candidate approach to explore the complex design space of hypersonic vehicles. This thesis focuses on the development and application of a particular optimisation method, adjoint-based optimisation, to aid in efficient aerodynamic design in hypersonic flows. Shape optimisation of scramjet-powered vehicles requires many design parameters to capture the geometric detail, and, since the flow physics is complex, the fidelity of Reynolds-Averaged Navier-Stokes (RANS) analyses is desirable. The combination of many design parameters and an expensive objective function evaluation drives the need for gradient evaluation methods that scale well with the number of design variables. An advantage of the adjoint method is that all shape sensitivities for an objective function are evaluated at the cost of only one flow solution and one adjoint solution. As a result of its efficiency, the adjoint method has become widely used for aircraft design, evolving to the design optimisation of full configurations. Despite the wide use of adjoint methods in aircraft optimisation, there has been very little application to hypersonic vehicle design. Several high-speed adjoint solvers have been reported in the literature, however, a majority of these works have only verified the adjoint sensitivities, few have followed on to demonstrate the method for use in design optimisation. The contribution of this work is the description and application of a discrete adjoint solver in high-speed compressible flow optimisation. What is unique in this work is a demonstration that complex-step differentiation works well to linearise a second-order spatially accurate unstructured RANS solver. In particular, the approach presented in this work utilises the k − ω turbulence model in high-speed ducted flow configurations. As part of this work, to provide flow analysis with a rapid turnaround , an unstructured steadystate RANS solver driven by a Jacobian-Free Newton-Krylov method was developed. Turbulence is modelled using the two-equation k − ω turbulence model. The Newton method is globalised by using the pseudo-transient approach. A restarted GMRES method is used to solve the system of linear equations arising when solving for the Newton steps. Evaluation of the matrix-vector products required in the GMRES algorithm is accomplished by Fréchet derivatives using imaginary perturbations in the complex plane. This is necessary to achieve robust convergence of the types of turbulent hypersonic flows...

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Robust aerodynamic shape optimization using a novel multi-objective evolutionary algorithm coupled with surrogate model

Tian

2020

Struct Multidisc Optim

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Aerodynamic Redesign Using Discrete Adjoint Approach on Overset Mesh System

Cited by 16 publications

References 24 publications

Unsteady Adjoint Approach for Design Optimization of Flapping Airfoils

Unsteady Adjoint Approach for Design Optimization of Flapping Airfoils

Adjoint-based aerodynamic design optimisation in hypersonic flow

Robust aerodynamic shape optimization using a novel multi-objective evolutionary algorithm coupled with surrogate model

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