Natural laminar flow wing optimization using a discrete adjoint approach

Shi, Yayun; Mader, Charles A.; Martins, Joaquim R. R. A.

doi:10.1007/s00158-021-02936-w

Cited by 13 publications

(7 citation statements)

References 65 publications

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“…Nevertheless, the DMD modes presented here are exclusively located within the high shear stress regions, indicating their inflectional nature. Similarly tilted modes are observed with skewed (oblique) roughness elements in Groskopf & Kloker (2016), with distributed surface roughness in Di Giovanni & Stemmer (2018) and more intensively with cross-flow instability in Malik, Li & Chang (1994); Wassermann & Kloker (2002) and Shi, Mader & Martins (2021). As for case , the mean flow has already been distorted by the interaction of its leading modes, which are identified in figure 18.…”

Section: Controlled Transitionmentioning

confidence: 74%

“…It is to be noted that the amplitude of the leading mode in Ω u = 1.25 is several orders of magnitude lower than the DMD modes of other cases. Further increase of the rotation speed to Ω u = 1.31 leads to the occurrence of two leading DMD modes (2002) and Shi, Mader & Martins (2021). As for case Ω u = 1.31, the mean flow has already been distorted by the interaction of its leading modes, which are identified in figure 18.…”

Section: Dmd Analysismentioning

confidence: 86%

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Transition mechanisms in a boundary layer controlled by rotating wall-normal cylindrical roughness elements

Römer²,

Axtmann³

et al. 2022

J. Fluid Mech.

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The transition to turbulence induced by counter-rotating wall-normal rotating cylindrical roughness pairs immersed within a laminar boundary layer on a flat plate is investigated with direct numerical simulations, dynamic mode decomposition (DMD) and perturbation kinetic energy (PKE) analysis. As long as the cylinder stub is rotating, the wake contains a steady dominating inner vortex (DIV) surrounded by a secondary inner vortex. Its circumferential velocity accelerates the fluid on one side of the cylinder and decelerates it on the other side. With low rotation speed, the perturbation is initiated by a combination of elliptical and centrifugal instabilities in the near wake. At medium rotation speeds, Taylor–Couette-like streamwise vortices are generated on the decelerated side, resulting in a protruding reverse-flow zone. Results from DMD analysis and corresponding PKE analysis reveal the unstable nature of the deceleration region and the wake. At the largest rotation speed investigated, the onset of perturbations is directly located on the decelerated side of the cylinder stubs, where a deceleration mechanism feeds the instability. In the near wake, the mechanism gradually changes to a pure centrifugal instability when the rotation speed increases. In the far wake, both elliptical and centrifugal instabilities fade away, and the streaky flow featuring a vigorous DIV is then only subject to inviscid inflectional instability.

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Section: Controlled Transitionmentioning

confidence: 74%

Section: Dmd Analysismentioning

confidence: 86%

Transition mechanisms in a boundary layer controlled by rotating wall-normal cylindrical roughness elements

Römer²,

Axtmann³

et al. 2022

J. Fluid Mech.

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“…where K i is the state feedback gain, derived from (56), and δ i > 0 is the scalar variable. Tis ensures that the m poles of each rule consequence subsystem with PDC controller are precisely situated at λ [48][49][50].…”

Section: Multichannel-h 2 State-feedback Gain Designmentioning

confidence: 99%

Adaptive Optimal Terminal Sliding Mode Control for T-S Fuzzy-Based Nonlinear Systems

Soltanian,

Valadbeigi,

Tavoosi

et al. 2024

Complexity

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This study utilizes the Takagi–Sugeno fuzzy model to represent a subset of nonlinear systems and presents an innovative adaptive approach for optimal dynamic terminal sliding mode control (TSMC). The systems under consideration encompass bounded uncertainties in parameters and actuators, as well as susceptibility to external disturbances. Performance evaluation entails the design of an adaptive terminal sliding surface through a two-step process. Initially, a state feedback gain and controller are developed using Linear Matrix Inequality (LMI) techniques, grounded on H2-performance and partial eigenstructure assignment. Dynamic sliding gain is subsequently attained via convex optimization, leveraging the derived state feedback gain and the designed terminal sliding mode (TSM) controller. This approach diverges from conventional methods by incorporating control effort and estimating actuator uncertainty bounds, while also addressing sliding surface and TSM controller design intricacies. The TSM controller is redefined into a strict feedback form, rendering it suitable for addressing output-tracking challenges in nonlinear systems. Comparative simulations validate the effectiveness of the proposed TSM controller, emphasizing its practical applicability.

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“…For the laminar techniques, the NLF and HLFC techniques are widely used in maintaining laminar flow [6][7][8][9][10]. The NLF achieves laminar flow on wings via a suitable profile, whereas the HLFC utilizes the suction before the front spar in combination with a suitable shape of the wing box.…”

Section: Introductionmentioning

confidence: 99%

“…The sweep angle of the leading edge is 19 °, and the MAC (Mean Aerodynamic Chord) is 3.75 m. After optimization, a considerable laminar region, almost more than 60%, is obtained on the upper surface. Shi et al [8] opti-mized an infinite swept wing with a 25 °sweep angle using an adjoint-based optimization approach. The Mach number is 0.78, and the Reynolds number is 10 × 10 °.…”

Section: Introductionmentioning

confidence: 99%

Hybrid Laminar Flow Control Optimizations for Infinite Swept Wings

Shi

Lan

Yang

2023

International Journal of Aerospace Engineering

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Maintaining the laminar flow on surfaces through active control is a significantly promising technique for reducing fuel burn and alleviating environmental concerns in commercial aviation. However, there is a lack of systematic parameter studies for the hybrid laminar flow control (HLFC) together with natural laminar flow (NLF). To address this need, we optimize the infinite swept wings with different sweep angles and at various conditions, including different Mach numbers, Reynolds numbers, and lift coefficients. The Reynolds-averaged Navier-Stokes (RANS) solver coupled with the linear stability theory is applied for the laminar-turbulent transition prediction, and the traditional optimization method based on evolutionary algorithms is applied for laminar flow wing optimization. The optimization results found that HLFC is required when the NLF fails at a larger sweep angle (35°) and Reynolds number ( 20 × 10 6 ). The lower pressure peak with boundary-layer suction is found to delay the transition of the regional aviation condition. Besides, the pressure distribution of HLFC is similar to NLF results at the lower Reynolds number ( 10 × 10 6 ) or sweep angle (25°), i.e., a gentle negative pressure gradient near the leading edge and a small favorable pressure gradient behind it. Clarifying the characteristics of laminar flow wings will advance the application of the laminar flow technique within its field.

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Natural laminar flow wing optimization using a discrete adjoint approach

Cited by 13 publications

References 65 publications

Transition mechanisms in a boundary layer controlled by rotating wall-normal cylindrical roughness elements

Transition mechanisms in a boundary layer controlled by rotating wall-normal cylindrical roughness elements

Adaptive Optimal Terminal Sliding Mode Control for T-S Fuzzy-Based Nonlinear Systems

Hybrid Laminar Flow Control Optimizations for Infinite Swept Wings

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