Approximate Aeroelastic Modeling of Flapping Wings in Hover

Gogulapati, Abhijit; Friedmann, Peretz P.; Kheng, Eugene; Shyy, Wei

doi:10.2514/1.j051801

Cited by 38 publications

(57 citation statements)

References 30 publications

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“…The geometrical and mechanical properties of these wings are obtained from Ref. [12] are reported in Table 1. For each considered wing, a high-fidelity, nonlinear, multi-body dynamics finite element (FE) model is built using rigid and flexible shell elements that has roughly 13, 000 degrees of freedom (see Figure 11 Table 1.…”

Section: Application To Flapping Wingmentioning

confidence: 99%

“…For each considered wing, a high-fidelity, nonlinear, multi-body dynamics finite element (FE) model is built using rigid and flexible shell elements that has roughly 13, 000 degrees of freedom (see Figure 11 Table 1. Material properties of the composite skeleton and wing membrane [12].…”

Section: Application To Flapping Wingmentioning

confidence: 99%

“…Even though these studies help understand some of the flow physics, they do not provide a complete knowledge of the problem. Most of the aeroelastic computational efforts in the literature make use of low-order aerodynamic models [10,11,12], and these models do not necessarily provide a good approximation of the unsteady flowfield. Recently, there have been limited number of studies performing coupled CFD-CSD aeroelastic analysis of flexible flapping wings [13,14,15].…”

Section: Introductionmentioning

confidence: 99%

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Nonlinear Aeroelastic Analysis of Highly Flexible Flapping Wings Using an ALE Formulation of Embedded Boundary Method

Lakshminarayan

Farhat

2014

52nd Aerospace Sciences Meeting

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Bio-inspired flapping wings have garnered a large amount of attention in achieving the goal of developing energy efficient highly maneuverable hover-capable Micro Air Vehicles (MAVs). Flapping wings are typically very flexible undergoing large deformations, leading to complex nonlinear interactions between aerodynamics and structure. Computational studies are critical to understanding this highly coupled non-linear Fluid Structure Interaction (FSI) problem and to explore the wide design parameter space for developing efficient and robust flapping wing MAVs. Arbitrary Lagrangian-Eulerian (ALE) methods for Computational Fluid Dynamics (CFD) are unfeasible to handle large structural motions and deformations that are seen in flapping wings. Eulerian Embedded Boundary Methods (EBMs) are particularly attractive in this situation. However, EBMs become expensive in viscous FSI problems, since they do not track the boundary layers around bodies because of their Eulerian nature. Recently, the current authors developed an ALE-embedded framework, in which the underlying non body-fitted mesh tracks structure and therefore providing significant computational savings. The focus of the current work is to apply this framework to study highly flexible flapping wings; the initial step being to carefully validate the methodology with an available experimental data. Three different wings of varying flexibility are simulated for a range of flapping frequencies. The calculations show good qualitative agreement with the experimental measurements in predicting the structural deformations as well as the generated thrust. The quantitative differences are primarily attributed to the uncertainties in the structural model. The results indicate that wing flexibility is beneficial for flapping wing aerodynamics, however excessive flexibility can be counter-productive. Flow visualization show the presence of stable leading edge vortex on moderately flexible wings; whereas no stable vortex is evident on highly flexible wing.

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Section: Application To Flapping Wingmentioning

confidence: 99%

Section: Application To Flapping Wingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Nonlinear Aeroelastic Analysis of Highly Flexible Flapping Wings Using an ALE Formulation of Embedded Boundary Method

Lakshminarayan

Farhat

2014

52nd Aerospace Sciences Meeting

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“…Accurate prediction of unsteady induced-drag is of great importance in flexible aircraft flight dynamics and flapping flight applications 26,27 in which all components of the aerodynamic forces play an important role.…”

Section: B Evaluation Of Forcesmentioning

confidence: 99%

Numerical aspects of nonlinear flexible aircraft flight dynamics modeling

Simpson

Palacios

2013

54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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A critical review of the numerical approximations made in flexible aircraft dynamics modeling is presented. The baseline model is a geometricallyexact composite beam model describing the flexible-body dynamics which are subject to aerodynamic forces predicted using the unsteady vortexlattice method (UVLM). The objectivity of the beam formulation is first investigated for static problems with large nodal rotations. It is found that errors associated with non-objectivity of the formulation are minimized to negligible levels using quadratic (3-noded) elements. In addition to this, two force calculation methods are presented and compared for the UVLM.They show subtle but important differences when applied to unsteady aerodynamic problems with large displacements. Nonlinear static aeroelastic analysis of a very flexible high-altitude long-endurance (HALE) wing is also carried out, and time-marching analysis is applied to the Goland wing in order to predict to the response at, and around, the flutter velocity. Conclusions drawn from the studies in this work work are directly applicable in the identification of appropriate modeling strategies in nonlinear flexible aircraft flight dynamics simulations.

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“…The aeroelastic model 11,12 is obtained by coupling a nonlinear finite element model of the wing with an approximate aerodynamic model that incorporates LEV's and a free wake. The ingredients of the model are concisely described next.…”

Section: Nonlinear Aeroelastic Modelmentioning

confidence: 99%

Optimization of the Kinematics of a Flapping Wing MAV in Hover for Enhanced Performance

Gogulapati

Friedmann

Martins

2013

54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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The kinematics of a rigid and flexible flapping wing micro air vehicle (MAV) in hover are optimized for enhanced performance using surrogate based approximation of the unsteady aerodynamic loads. The surrogates are generated using kriging interpolation of the time averaged thrust generated and power consumed by the wings. The fitting data is obtained using a nonlinear approximate aeroelastic model that combines a nonlinear finite element based structural dynamic model with an approximate unsteady aerodynamic model. The parameter space for the rigid wings consists of seven kinematic parameters. For the flexible wing case, six structural parameters are used to augment the kinematic parameters, resulting in a total of 13 design variables. The surrogates are combined with a hybrid search algorithm to identify feasible designs that produce the desired combination of thrust and power. The best rigid and flexible configurations predicted using the surrogates are superior to the best designs available in the corresponding sets of sample points used to create the surrogates. Thrust and power are found to be competing design objectives. The phase angle between flap and pitch motions has a significant impact on the wing performance for fixed stroke amplitudes and frequency. The peak performance of flexible wings occurs for smaller amounts of pitch actuation compared to the rigid wings due to elastic wing twist. Rigid wings performed better than flexible wings in several regions of the parameter space, leading to the conclusion that the choice between rigid or flexible wings is not straightforward.

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Approximate Aeroelastic Modeling of Flapping Wings in Hover

Cited by 38 publications

References 30 publications

Nonlinear Aeroelastic Analysis of Highly Flexible Flapping Wings Using an ALE Formulation of Embedded Boundary Method

Nonlinear Aeroelastic Analysis of Highly Flexible Flapping Wings Using an ALE Formulation of Embedded Boundary Method

Numerical aspects of nonlinear flexible aircraft flight dynamics modeling

Optimization of the Kinematics of a Flapping Wing MAV in Hover for Enhanced Performance

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