scholarly journals Geometrically Nonlinear Aeroelastic Stability Analysis and Wind Tunnel Test Validation of a Very Flexible Wing

2016 ◽  
Vol 2016 ◽  
pp. 1-17 ◽  
Author(s):  
Changchuan Xie ◽  
Yi Liu ◽  
Chao Yang ◽  
J. E. Cooper
Keyword(s):  
Stability Analysis ◽  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Geometrically Nonlinear ◽  
Analysis Model ◽  
Aeroelastic Stability ◽  
Lattice Method ◽  
Flexible Wings ◽  
Structural Dynamic ◽  
Flutter Boundary

VFAs (very flexible aircraft) have begun to attract significant attention because of their good flight performances and significant application potentials; however, they also bring some challenges to researchers due to their unusual lightweight designs and large elastic deformations. A framework for the geometrically nonlinear aeroelastic stability analysis of very flexible wings is constructed in this paper to illustrate the unique aeroelastic characteristics and convenient use of these designs in engineering analysis. The nonlinear aeroelastic analysis model includes the geometrically nonlinear structure finite elements and steady and unsteady nonplanar aerodynamic computations (i.e., the nonplanar vortex lattice method and nonplanar doublet-lattice method). Fully nonlinear methods are used to analyse static aeroelastic features, and linearized structural dynamic equations are established at the structural nonlinear equilibrium state to estimate the stability of the system through the quasimode of the stressed and deformed structure. The exact flutter boundary is searched via an iterative procedure. A wind tunnel test is conducted to validate this theoretical analysis framework, and reasonable agreement is obtained. Both the analysis and test results indicate that the geometric nonlinearity of very flexible wings presents significantly different aeroelastic characteristics under different load cases with large deformations.

scholarly journals The Effect of Rigging Angle on Longitudinal Direction Motion of Parafoil-Type Vehicle: Basic Stability Analysis and Wind Tunnel Test

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Takahiro Moriyoshi ◽  
Kazuhiko Yamada ◽  
Hiroyuki Nishida
Keyword(s):  
Stability Analysis ◽  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Leading Edge ◽  
Longitudinal Direction ◽  
Aerodynamic Characteristics ◽  
Vehicle Stability ◽  
Flexible Wings ◽  
Allowable Range ◽  
Analytical Approaches

The paraglider, a flexible flying vehicle, consists of a parafoil with flexible wings, suspension lines, and a suspended payload. At this time, the suspension lines have several parameters to be designed. Above all, a parameter called Rigging Angle (RA) is sensitive to the aerodynamic characteristics of a paraglider during flight. In this study, the effect of RA is clarified using the two-dimensional stability analysis and a wind tunnel test. The mechanisms about the parafoil-type vehicle stability are clarified through the experimental and analytical approaches as follows. The RA has an allowable range for a stable flight. When the RA is set out of the range, the parafoil cannot fly stably. Furthermore, the behavior of the parafoil wing in the case of lower RA than the allowable range is different from the case of higher RA. The parafoil collapses from the leading edge of the canopy and cannot glide in the case of lower RA.

scholarly journals Full-Span Flying Wing Wind Tunnel Test: A Body Freedom Flutter Study

Fluids ◽  
2020 ◽  
Vol 5 (1) ◽  
pp. 34
Author(s):  
Pengtao Shi ◽  
Jihai Liu ◽  
Yingsong Gu ◽  
Zhichun Yang ◽  
Pier Marzocca
Keyword(s):  
Wind Tunnel ◽  
Theoretical Analysis ◽  
Mass Balance ◽  
Degrees Of Freedom ◽  
Wind Tunnel Test ◽  
Suspension System ◽  
The Body ◽  
Structural Dynamic ◽  
Flutter Speed ◽  
Theoretical Results

Aiming at the experimental test of the body freedom flutter for modern high aspect ratio flexible flying wing, this paper conducts a body freedom flutter wind tunnel test on a full-span flying wing flutter model. The research content is summarized as follows: (1) The full-span finite element model and aeroelastic model of an unmanned aerial vehicle for body freedom flutter wind tunnel test are established, and the structural dynamics and flutter characteristics of this vehicle are obtained through theoretical analysis. (2) Based on the preliminary theoretical analysis results, the design and manufacturing of this vehicle are completed, and the structural dynamic characteristics of the vehicle are identified through ground vibration test. Finally, the theoretical analysis model is updated and the corresponding flutter characteristics are obtained. (3) A novel quasi-free flying suspension system capable of releasing pitch, plunge and yaw degrees of freedom is designed and implemented in the wind tunnel flutter test. The influence of the nose mass balance on the flutter results is explored. The study shows that: (1) The test vehicle can exhibit body freedom flutter at low airspeeds, and the obtained flutter speed and damping characteristics are favorable for conducting the body freedom flutter wind tunnel test. (2) The designed suspension system can effectively release the degrees of freedom of pitch, plunge, and yaw. The flutter speed measured in the wind tunnel test is 9.72 m/s, and the flutter frequency is 2.18 Hz, which agree well with the theoretical results (with flutter speed of 9.49 m/s and flutter frequency of 2.03 Hz). (3) With the increasing of the mass balance at the nose, critical speed of body freedom flutter rises up and the flutter frequency gradually decreases, which also agree well with corresponding theoretical results.

scholarly journals Experimental and Numerical Studies on Static Aeroelastic Behaviours of a Forward-Swept Wing Model

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yan Ouyang ◽  
Kaichun Zeng ◽  
Xiping Kou ◽  
Yingsong Gu ◽  
Zhichun Yang
Keyword(s):  
Wind Tunnel ◽  
Dynamic Pressure ◽  
Wind Tunnel Test ◽  
Swept Wing ◽  
Lattice Method ◽  
Model Calculations ◽  
Wind Tunnel Tests ◽  
Model Based ◽  
Wing Model ◽  
Fidelity Model

The static aeroelastic behaviours of a flat-plate forward-swept wing model in the vicinity of static divergence are investigated by numerical simulations and wind tunnel tests. A medium fidelity model based on the vortex lattice method (VLM) and nonlinear structural analysis is proposed to calculate the displacements of the wing structure with large deformation. Follower forces effect and geometric nonlinearity are considered to calculate the deformation of the wing by finite element method (FEM). In the wind tunnel tests, the divergence dynamic pressure is predicted by the Southwell method, and the static aeroelastic displacement is measured by a photogrammetric method. The results obtained by the medium fidelity model calculations show reasonable agreement with wind tunnel test results. A high fidelity model based on coupled computational fluid dynamics (CFD) and computational structural dynamics (CSD) predicts better results of the wing tip displacement when the freestream dynamic pressure is approaching the divergence dynamic pressure.

Aeroelastic Stability Analysis of a Wind Tunnel Wing Model Equipped with a True Scale Morphing Aileron

2017 ◽  
Vol 6 (6) ◽  
pp. 440-450
Author(s):  
Francesco Rea ◽  
Rosario Pecora ◽  
Francesco Amoroso ◽  
Maurizio Arena ◽  
Maria Chiara Noviello ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Wind Tunnel ◽  
Aeroelastic Stability ◽  
Wing Model

Aeroelastic Stability Analysis of a Wind Tunnel Wing Model Equipped with a True Scale Morphing Aileron

2018 ◽  
Vol 7 (4) ◽  
pp. 440-450
Author(s):  
Francesco Rea ◽  
Rosario Pecora ◽  
Francesco Amoroso ◽  
Maurizio Arena ◽  
Maria Chiara Noviello ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Wind Tunnel ◽  
Aeroelastic Stability ◽  
Wing Model

scholarly journals Nonlinear Aeroelastic Simulations and Stability Analysis of the Pazy Wing Aeroelastic Benchmark

Aerospace ◽  
2021 ◽  
Vol 8 (10) ◽  
pp. 308
Author(s):  
Jonathan Hilger ◽  
Markus Raimund Ritter
Keyword(s):  
Stability Analysis ◽  
Wind Tunnel ◽  
Vortex Lattice ◽  
Structural Model ◽  
State Space Model ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Aeroelastic Simulations ◽  
The Stability ◽  
German Aerospace

The Pazy wing aeroelastic benchmark is a highly flexible wind tunnel model investigated in the Large Deflection Working Group as part of the Third Aeroelastic Prediction Workshop. Due to the design of the model, very large elastic deformations in the order of 50% span are generated at highest dynamic pressures and angles of attack in the wind tunnel. This paper presents static coupling simulations and stability analyses for selected onflow velocities and angles of attack. Therefore, an aeroelastic solver developed at the German Aerospace Center (DLR) is used for static coupling simulations, which couples a vortex lattice method with the commercial finite element solver MSC Nastran. For the stability analysis, a linearised aerodynamic model is derived analytically from the unsteady vortex lattice method and integrated with a modal structural model into a monolithic aeroelastic discrete-time state-space model. The aeroelastic stability is then determined by calculating the eigenvalues of the system’s dynamics matrix. It is shown that the stability of the wing in terms of flutter changes significantly with increasing deflection and is heavily influenced by the change in modal properties, i.e., structural eigenvalues and eigenvectors.

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