Analysis of Novel Morphing Trailing Edge Flap Actuated by Multistable Laminates

Haldar, A.; Jansen, Eelco; Hofmeister, Benedikt; Bruns, Marlene; Rolfes, Raimund

doi:10.2514/1.j058870

Cited by 28 publications

(13 citation statements)

References 35 publications

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“…The amplitude of spike in the drag coefficient was also found to be proportional to the morphing frequency, with higher frequencies causing larger overshoots. The results obtained for the range of frequencies investigated at a Reynolds number of 0.62 ×10 6 show the potential of rapid downward deflections for obtaining instantaneous lift increments. However, the frequencies studied did not seem to produce a recovery from the stall, and instead at the higher AoA of 12 • the morphing even drove the airfoil into a dynamic stall.…”

Section: Discussionmentioning

confidence: 88%

“…The promising bio-inspired concept of morphing structures is used on wings not only to optimize their shape during flight, but also to actively interact with the surrounding flow field in order to mitigate possible aerodynamic performance degradation, reduce the profile drag, delay onset of stall, or achieve early recovery from flow separation. However, there are many technical challenges in the integration of morphing configurations with an existing 'rigid' wing; one in particular is the difficulty of simulating and resolving the complex flow physics around morphing structures [4][5][6][7]. In addition, one would imagine the difficulty of finding the optimal morphing arrangements (e.g., frequency, amplitude, angle) whilst solving such numerically intensive simulations.…”

Section: Introductionmentioning

confidence: 99%

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Near Stall Unsteady Flow Responses to Morphing Flap Deflections

Abdessemed

Yao

Bouferrouk

2021

Fluids

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The unsteady flow characteristics and responses of an NACA 0012 airfoil fitted with a bio-inspired morphing trailing edge flap (TEF) at near-stall angles of attack (AoA) undergoing downward deflections are investigated at a Reynolds number of 0.62 × 106 near stall. An unsteady geometric parametrization and a dynamic meshing scheme are used to drive the morphing motion. The objective is to determine the susceptibility of near-stall flow to a morphing actuation and the viability of rapid downward flap deflection as a control mechanism, including its effect on transient forces and flow field unsteadiness. The dynamic flow responses to downward deflections are studied for a range of morphing frequencies (at a fixed large amplitude), using a high-fidelity, hybrid RANS-LES model. The time histories of the lift and drag coefficient responses exhibit a proportional relationship between the morphing frequency and the slope of response at which these quantities evolve. Interestingly, an overshoot in the drag coefficient is captured, even in quasi-static conditions, however this is not seen in the lift coefficient. Qualitative analysis confirms that an airfoil in near stall conditions is receptive to morphing TEF deflections, and that some similarities triggering the stall exist between downward morphing TEFs and rapid ramp-up type pitching motions.

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Section: Discussionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Near Stall Unsteady Flow Responses to Morphing Flap Deflections

Abdessemed

Yao

Bouferrouk

2021

Fluids

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“…We refer to compliance selectivity as the capacity for structures to alter their stiffness as a function of time, in contrast to structures with spatially distributed reinforcements that show time‐invariant, spatially varying modulus 19 . The type of selective compliance we explore in this paper can be achieved, for example, using mechanistic approaches, 20,21 by pressurized composites, 22,23 or bistable beam‐like elements inside truss‐like compliant systems 24‐28 . Structures displaying such selectively compliant behavior leverage geometric effects that are independent of the constitutive material used 29 .…”

Section: Introductionmentioning

confidence: 99%

“…19 The type of selective compliance we explore in this paper can be achieved, for example, using mechanistic approaches, 20,21 by pressurized composites, 22,23 or bistable beam-like elements inside truss-like compliant systems. [24][25][26][27][28] Structures displaying such selectively compliant behavior leverage geometric effects that are independent of the constitutive material used. 29 Phase transitions found in shape memory alloys 30,31 or thermoplastic polymers 32,33 have been used to achieve variable stiffness; however, the use of specific constitutive compounds restricts the choice of materials from which the desired stiffness adaptation can be attained.…”

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confidence: 99%

Passive load alleviation on wind turbine blades from aeroelastically driven selectively compliant morphing

Cavens¹,

Chopra

Arrieta

2020

Wind Energy

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Load alleviation control is highly desirable to reduce penalties associated with the added structural mass required to withstand rare load scenarios. This is particularly true for wind turbine designs incorporating long-span blades. Implementation of compliance-based morphing structures to modify the lift distribution passively has the potential to mitigate the impact of rare, but integrally threatening, loads on wind turbine blades while limiting the addition of actuation and sensing systems. We present a novel passive load alleviation concept based on a morphing flap exhibiting selective compliance from an embedded bistable element. A multifidelity, aeroelastic tool is used to study the shape adaptability of a morphing flap indicating that passive changes from high lift generation to load alleviation configurations can be achieved by exploiting the energy of the flow. This mechanism offers a method to reduce catastrophic peak loads potentially, thus offering the possibility to lower the overall structural weight of wind turbine blades.

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“…Due to the difficulties in applying mechanical loads to trigger the snap-through from one stable state to another, the actuators consisting of shape memory alloy (SMA) and piezoelectric composites [29][30][31][32] have been widely employed. Dano explored the concept of using SMA wires to trigger the snap-through of unsymmetric composite laminates [32].…”

Section: Introductionmentioning

confidence: 99%