Aerodynamic Shape Optimization of Natural Laminar Flow (NLF) Airfoils

Khayatzadeh, Peyman; Nadarajah, Siva

doi:10.2514/6.2012-61

Cited by 17 publications

(11 citation statements)

References 20 publications

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“…The gradient calculations in their work did not include the transition prediction, and their optimizations focused on the elimination of shock-waves for reduced wave drag. Khayatzadeh and Nadarajah 39,40 successfully extended the Langtry-Menter transport equation approach to an adjoint-based optimization framework in two dimensions, and applied the framework to the design of low Reynolds number NLF airfoils with separation bubbles. Design objectives investigated included the minimization of turbulent kinetic energy and the maximization of the lift-to-drag ratio.…”

Section: Iib Rans-based Aerodynamic Shape Optimization For Nlfmentioning

confidence: 99%

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

Rashad

Zingg

2016

AIAA Journal

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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.

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Section: Iib Rans-based Aerodynamic Shape Optimization For Nlfmentioning

confidence: 99%

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

Rashad

Zingg

2016

AIAA Journal

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“…Currently, existing optimization studies which incorporate laminarturbulent transition are mainly concentrated on subsonic cases, especially on the natural laminar airfoils. [3][4][5] The only related work found in hypersonic flow was performed by Johnson et al, 6 who adopted the parabolized stability equations (PSE) for analysis of properties in the boundary layer. Axisymmetric cone and 3D surface shape were optimized in their study and how changes of the geometries enhanced or suppressed the transition was illustrated.…”

Section: Introductionmentioning

confidence: 99%

Multiobjective shape optimization of a hypersonic lifting body using a correlation-based transition model

Xia

Tao

Chen

2016

Proceedings of the Institution of Mechanical Engineers, Part G:

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Although substantial numbers of aerodynamic shape optimization works have been carried out in the past few decades, the effects of boundary layer transition are not considered in the overwhelmingly majority of those previous studies. For more accurate prediction of the flow field, and for exploration of relations between aerodynamic heating and geometrical features, the commonly used local correlation-based transition model [Formula: see text] is implemented into a computational fluid dynamics (CFD) solver. A CFD-based multiobjective shape optimization method is then described and applied to a hypersonic lifting body in this paper. For parametric modeling and grid deformation, the flexible free form deformation and robust transfinite interpolation techniques are used respectively. The response surface model is adopted as the approximation model for the reduction of computational cost, and the multiobjective genetic algorithm is employed for the exploration of optimal solutions. Optimization processes have been conducted by the optimization toolkit DAKOTA and two Pareto fronts are obtained. Besides, typical solutions on the Pareto fronts are compared and analyzed. The results obtained from the case considered in this study indicate that the lift-to-drag ratio and transition onset position are closely related with the volume of the vehicle, and trade-off can be made for aerodynamic and aerothermodynamic performance from the optimal solutions. Moreover, the design problem of lifting body demonstrates the robustness and practicality of the new optimization procedures, which incorporates the transition phenomenon for hypersonic flow.

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“…A equação (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19) é chamada a equação de Orr-Sommerfeld e é a equação fundamental para a teoria de estabilidade incompressível. As soluções da equação (2-19) correspondem às ondas de pequenas perturbações e são denominadas as ondas de Tollmien-Schlichting.…”

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“…Através da teoria de amplicação espacial, soluções da equação(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19) serão determinadas, visto que a amplitude da perturbação em um ponto é independente no tempo, mudando apenas com a distância. Os autovalores da equação de Orr-Sommerfeld são apresentados em diagramas (α,Re) que descrevem os três estados de uma perturbação a um dado número de Reynolds: amortecido, neutro ou amplicado.…”

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“…Os autovalores da equação de Orr-Sommerfeld são apresentados em diagramas (α,Re) que descrevem os três estados de uma perturbação a um dado número de Reynolds: amortecido, neutro ou amplicado. Assim, cada solução da equação(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19) fornecerá uma autofunção φ(y) e um autovalor complexo c = c r + i · c i , para cada par de α e Re. O termo c i possui um mesmo indicador de estabilidade que ω i , onde c i = 0 indica os casos neutros para as perturbações.…”

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Estudo Da Melhoria De Performance Aerodinâmica De Um Perfil Aplicado a Veículos Aéreos Não Tripulados

CALDAS¹

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AgradecimentosAgradeço às minhas famílias. Primeiro, agradeço aos meus queridos pais, Gabriela Geminiani e José Filipe Pereira Caldas, pelo eterno apoio, amor e carinho ao longo de toda a minha vida, meus companheiros que sempre me souberam guiar e mais do que tudo perseguir meus sonhos. Agradeço à minha irmã e meu irmão, Agustina Caldas e Gonzalo Caldas, vocês trouxeram felicidade e coragem para ganhar responsabilidades que fui ganhando ao longo dos anos. Agradeço a minha avó, Mercedes Geminiani, minha madrinha, Marina Geminiani, pelo apoio e carinho que recebi e que, assim como minha mãe e irmã, são mulheres das quais tenho como referência, de pessoas fortes e com atitude sem igual. Agradeço à Escola Parque e todo seu corpo docente, que me permitiu obter uma formação mais crítica do mundo que gira em torno de todos nós, obrigado em especial aos professores Marco Silami, Renato Cardoso, Frederico Montanari e Daniel Bahiense pelo apoio e mais do que tudo por acreditarem em mim. Agradeço à PUC-Rio e todo o corpo docente do Departamento de Engenharia Mecânica por todos os conhecimentos adquiridos. Agradeço aos meus colegas Thiago Costa, Petrus Arruda, Daniel Rotolo, João Nassif, Matheus Peres e Raphael Mastrangelo pelo grande grupo que formamos ao longo da faculdade e são amigos que guardo com muita felicidade pelas experiências e aprendizados que tivemos juntos. Agradeço à equipe AeroRio UAV Design, obrigado pela minha transformação pessoal, acadêmica e prossional e permitir alcançar meu sonho de estar mais próximo do mundo da aeronáutica. Agradeço a todos os membros e ex-membros pela conança e amizade, que me trouxe coragem a perseguir meus sonhos. Todo este trabalho e outros que passaram foram elaborados buscando gerar frutos para o desenvolvimento e sucesso futuro dessa equipe. Por m, gostaria de agradecer meu orientador Prof. Igor Braga por todo o apoio e conança que me deu ao longo dos projetos que construímos ao longo dos últimos anos. Todas as críticas e ensinamentos foram essenciais e permitiram o desenvolvimento deste projeto e também as minhas escolhas e perspectivas para a minha vida prossional. Palavraschave Veículos Aéreos Não-Tripulados; aerofólio; Natural Laminar Flow; camada limite; redução de arrasto; previsão da transição. Abstract Study of aerodynamic performance improvement of an airfoil applied to autonomous air vehicles Autonomous aerial systems have a growing range of applications in various areas such as agriculture and logistics. Within this branch, stand out the xed and rotary wing Unmanned Aerial Vehicles (UAVs), because they have particular advantage over multirotor vehicles for their versatility, autonomy and eciency. These aircraft generally operate at low speeds, hencein Reynolds number ranges around 200,000 to 400,000. In this range the ow can still be kept laminar over the pressure recovery region in the wing upper surface of these vehicles. Thus, the presence of laminar separation bubbles caused by the unfavorable pressure gradient may occur. These bubbles cause loss of lift and d...

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Aerodynamic Shape Optimization of Natural Laminar Flow (NLF) Airfoils

Cited by 17 publications

References 20 publications

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

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

Multiobjective shape optimization of a hypersonic lifting body using a correlation-based transition model

Estudo Da Melhoria De Performance Aerodinâmica De Um Perfil Aplicado a Veículos Aéreos Não Tripulados

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