Metamodel Assisted Multi-Objective Global Optimisation of Natural Laminar Flow Aerofoils

Cameron, Lee; Early, Juliana; McRoberts, Richard

doi:10.2514/6.2011-3001

“…But not much literature can be found on this topic thus far. The work of Cameron et al [25] and our previous work [26] have demonstrated the capability of SBO for the optimization of 2-D NLF airfoils. However, the extension to a 3-D swept wing would be a challenge because the optimization can be very complicated and expensive.…”

mentioning

confidence: 87%

“…Besides the gradient-based optimizations, gradient-free methods capable of global optimization were also employed in recent years. In 2011, Cameron et al [25] developed a metamodel (or surrogate model) assisted multi-objective global optimization method for NLF airfoils. In 2012, Han et al [26] developed an efficient surrogate-based global optimization for design optimization of supercritical NLF airfoils.…”

mentioning

confidence: 99%

Aerodynamic Shape Optimization of Natural-Laminar-Flow Wing Using Surrogate-Based Approach

Han

¹

,

Chen

²

,

Zhang

³

et al. 2018

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Aerodynamic shape optimization of a swept natural-laminar-flow wing in the transonic regime is still challenging. The difficulty is associated with reliable prediction of laminar-turbulence transition and reasonable compromise of viscous and wave drags. This paper proposes to use efficient global optimization based on surrogate models to address this problem. The Reynolds-averaged Navier-Stokes flow solver features automatic transition prediction via a full e N method, in which dual N factors are used for Tollmien-Schlichting and crossflow instabilities, respectively. The optimizer is based on the kriging surrogate model and parallel infill-sampling method. The baseline natural-laminarflow wing for short-and medium-range transport aircraft is designed at a cruise Mach number 0.75. Then, drag minimization with up to 42 design variables is carried out, and significant drag reduction (8.79%) has been achieved. A close examination of the optimal wing shows that the drag reduction mainly comes from shock-wave weakening on the upper surface and laminar flow extending via suppression of crossflow instability on the lower surface. Robustness of the optimal wing is investigated, and multipoint optimization is further exercised to improve the robustness to the Mach number variation. It is demonstrated that surrogate-based optimization is feasible and effective for aerodynamic shape optimization of transonic natural-laminar-flow wings.

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“…The majority of research in this field employs inviscid-viscous coupling strategies, making use of boundary-layer codes for the viscous formulation and either a panel method or the Euler equations for the inviscid formulation. 30,31,32,33,34,35,36,37 Although the inviscid/viscous coupling strategies can be computationally cheaper than the higher-fidelity RANS solvers, the industry's trend toward the use of RANS solvers strongly suggests that NLF design tools should follow suit. Recent research making use of RANS solvers to optimize with transition prediction has shown promising results.…”

Section: Iib Rans-based Aerodynamic Shape Optimization For Nlfmentioning

confidence: 98%

Aerodynamic Shape Optimization for Natural Laminar Flow Using a Discrete-Adjoint Approach

Rashad

¹

,

Zingg

²

2015

22nd AIAA Computational Fluid Dynamics Conference

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The design of natural-laminar-flow airfoils is demonstrated by high-fidelity, multipoint, aerodynamic shape optimization capable of efficiently incorporating and exploiting laminarturbulent transition. First, a two-dimensional Reynolds-averaged Navier-Stokes (RANS) flow solver has been extended to incorporate an iterative laminar-turbulent transition prediction methodology. The natural transition locations due to Tollmien-Schlichting instabilities are predicted using the simplified e N envelope method of Drela and Giles or alternatively, the compressible form of the Arnal-Habiballah-Delcourt criterion. The boundarylayer properties are obtained directly from the Navier-Stokes flow solution, and the transition to turbulent flow is modeled using an intermittency function in conjunction with the Spalart-Allmaras turbulence model. The RANS solver is subsequently employed in a gradient-based sequential quadratic programming shape optimization framework. The laminar-turbulent transition criteria are tightly coupled into the objective and gradient evaluations. The gradients are obtained using a new augmented discrete-adjoint formulation for non-local transition criteria. The aerodynamic design requirements are cast into a multipoint design optimization problem. A composite objective is defined using a weighted integral of the operating points. A Pareto front is also formed to study and quantify off-design performance. The proposed framework is applied to the single and multipoint optimization of subsonic and transonic airfoils, leading to robust natural-laminar-flow designs.

show abstract

“…The majority of research in this field employs inviscid-viscous coupling strategies, making use of boundary-layer codes for the viscous formulation and either a panel method or the Euler equations for the inviscid formulation. 30,31,32,33,34,35,36,37 Although the inviscid/viscous coupling strategies can be computationally cheaper than the higher-fidelity RANS solvers, the industry's trend toward the use of RANS solvers strongly suggests that NLF design tools should follow suit. Recent research making use of RANS solvers to optimize with transition prediction has shown promising results.…”

Section: Iib Rans-based Aerodynamic Shape Optimization For Nlfmentioning

confidence: 99%

Aerodynamic Shape Optimization for Natural Laminar Flow Using a Discrete-Adjoint Approach

Rashad

¹

,

Zingg

²

2016

View full text Add to dashboard Cite

The design of natural-laminar-flow airfoils is demonstrated by high-fidelity, multipoint, aerodynamic shape optimization capable of efficiently incorporating and exploiting laminarturbulent transition. First, a two-dimensional Reynolds-averaged Navier-Stokes (RANS) flow solver has been extended to incorporate an iterative laminar-turbulent transition prediction methodology. The natural transition locations due to Tollmien-Schlichting instabilities are predicted using the simplified e N envelope method of Drela and Giles or alternatively, the compressible form of the Arnal-Habiballah-Delcourt criterion. The boundarylayer properties are obtained directly from the Navier-Stokes flow solution, and the transition to turbulent flow is modeled using an intermittency function in conjunction with the Spalart-Allmaras turbulence model. The RANS solver is subsequently employed in a gradient-based sequential quadratic programming shape optimization framework. The laminar-turbulent transition criteria are tightly coupled into the objective and gradient evaluations. The gradients are obtained using a new augmented discrete-adjoint formulation for non-local transition criteria. The aerodynamic design requirements are cast into a multipoint design optimization problem. A composite objective is defined using a weighted integral of the operating points. A Pareto front is also formed to study and quantify off-design performance. The proposed framework is applied to the single and multipoint optimization of subsonic and transonic airfoils, leading to robust natural-laminar-flow designs.

show abstract

Metamodel Assisted Multi-Objective Global Optimisation of Natural Laminar Flow Aerofoils

Cited by 13 publications

References 16 publications

Aerodynamic Shape Optimization of Natural-Laminar-Flow Wing Using Surrogate-Based Approach

Aerodynamic Shape Optimization of Natural-Laminar-Flow Wing Using Surrogate-Based Approach

Aerodynamic Shape Optimization for Natural Laminar Flow Using a Discrete-Adjoint Approach

Aerodynamic Shape Optimization for Natural Laminar Flow Using a Discrete-Adjoint Approach

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