scholarly journals Flexible wings take the effort out of swimming for diving penguins

2021 ◽  
Vol 224 (21) ◽  
Author(s):  
Kathryn Knight
Keyword(s):  
Flexible Wings

scholarly journals Monitoring of a Highly Flexible Aircraft Model Wing Using Time-Expanded Phase-Sensitive OTDR

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3766
Author(s):  
Miguel Soriano-Amat ◽  
David Fragas-Sánchez ◽  
Hugo F. Martins ◽  
David Vallespín-Fontcuberta ◽  
Javier Preciado-Garbayo ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Fuel Efficiency ◽  
Optical Fiber Sensor ◽  
High Sensitivity ◽  
Time Domain Reflectometry ◽  
Structural Deformation ◽  
Flexible Wings ◽  
Sensing Technology ◽  
Distributed Optical Fiber Sensor ◽  
Phase Sensitive

In recent years, the use of highly flexible wings in aerial vehicles (e.g., aircraft or drones) has been attracting increasing interest, as they are lightweight, which can improve fuel-efficiency and distinct flight performances. Continuous wing monitoring can provide valuable information to prevent fatal failures and optimize aircraft control. In this paper, we demonstrate the capabilities of a distributed optical fiber sensor based on time-expanded phase-sensitive optical time-domain reflectometry (TE-ΦOTDR) technology for structural health monitoring of highly flexible wings, including static (i.e., bend and torsion), and dynamic (e.g., vibration) structural deformation. This distributed sensing technology provides a remarkable spatial resolution of 2 cm, with detection and processing bandwidths well under the MHz, arising as a novel, highly efficient monitoring methodology for this kind of structure. Conventional optical fibers were embedded in two highly flexible specimens that represented an aircraft wing, and different bending and twisting movements were detected and quantified with high sensitivity and minimal intrusiveness.

Experimental analysis of fluid-structure interaction in flexible wings at low Reynolds number flows

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mustafa Serdar Genç ◽  
Hacımurat Demir ◽  
Mustafa Özden ◽  
Tuna Murat Bodur
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Fluid Structure Interaction ◽  
Leading Edge ◽  
Flexible Wings ◽  
Flexible Membrane ◽  
Fluid Structure ◽  
Content Type ◽  
Structure Interaction ◽  
Membrane Deformations

Purpose The purpose of this exhaustive experimental study is to investigate the fluid-structure interaction in the flexible membrane wings over a range of angles of attack for various Reynolds numbers. Design/methodology/approach In this paper, an experimental study on fluid-structure interaction of flexible membrane wings was presented at Reynolds numbers of 2.5 × 104, 5 × 104 and 7.5 × 104. In the experimental studies, flow visualization, velocity and deformation measurements for flexible membrane wings were performed by the smoke-wire technique, multichannel constant temperature anemometer and digital image correlation system, respectively. All experimental results were combined and fluid-structure interaction was discussed. Findings In the flexible wings with the higher aspect ratio, higher vibration modes were noticed because the leading-edge separation was dominant at lower angles of attack. As both Reynolds number and the aspect ratio increased, the maximum membrane deformations increased and the vibrations became visible, secondary vibration modes were observed with growing the leading-edge vortices at moderate angles of attack. Moreover, in the graphs of the spectral analysis of the membrane displacement and the velocity; the dominant frequencies coincided because of the interaction of the flow over the wings and the membrane deformations. Originality/value Unlike available literature, obtained results were presented comparatively using the sketches of the smoke-wire photographs with deformation measurement or turbulence statistics from the velocity measurements. In this study, fluid-structure interaction and leading-edge vortices of membrane wings were investigated in detail with increasing both Reynolds number and the aspect ratio.

Recent progress in flapping wings for micro aerial vehicle applications

2020 ◽  
pp. 095440622091742
Author(s):  
Naeem Haider ◽  
Aamer Shahzad ◽  
Muhammad Nafees Mumtaz Qadri ◽  
Syed Irtiza Ali Shah
Keyword(s):  
Leading Edge ◽  
Flapping Wing ◽  
Flapping Wings ◽  
Structural Flexibility ◽  
Micro Aerial Vehicles ◽  
Flexible Wings ◽  
Performance Variables ◽  
Aerial Vehicles ◽  
Wide Range ◽  
Wing Geometry

Micro aerial vehicles using flapping wings are under investigation, as an alternative to fixed-wing and rotary-wing micro aerial vehicles. Such flapping-wing vehicles promise key potential advantages of high thrust, agility, and maneuverability, and have a wide range of applications. These applications include both military and commercial domains such as communication relay, search and rescue, visual reconnaissance, and field search. With the advancement in the computational sciences, developments in flapping-wing micro aerial vehicles have progressed exponentially. Such developments require a careful aerodynamic and aeroelastic design of the flapping wing. Therefore, aerodynamic tools are required to study such designs and configurations. In this paper, the role of several parameters is investigated, including the types of flapping wings, the effect of the kinematics and wing geometry (shape, configuration, and structural flexibility) on performance variables such as lift, drag, thrust, and efficiency in various modes of flight. Kinematic variables have a significant effect on the performance of the flapping wing. For instance, a high flap amplitude and pitch rotation, which supports the generation of the strong leading-edge vortex, generates higher thrust. Likewise, wing shape, configuration, and structural flexibility are shown to have a large impact on the performance of the flapping wing. The wing with optimum flexibility maximizes thrust where highly flexible wings lead to performance degradation due to change in the effective angle of attack. This study shows that the development of the flexible flapping wing with performance capabilities similar to those of natural fliers has not yet been achieved. Finally, opportunities for additional research in this field are recommended.

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