{"id":3063,"date":"2024-11-02T13:42:44","date_gmt":"2024-11-02T04:42:44","guid":{"rendered":"https:\/\/www.kikulab.it-chiba.ac.jp\/Eng\/?page_id=3063"},"modified":"2025-03-08T14:32:06","modified_gmt":"2025-03-08T05:32:06","slug":"kubo-works","status":"publish","type":"page","link":"https:\/\/www.kikulab.chibatech.ac.jp\/Eng\/research\/flapping-robot\/hamming-bird\/kubo-works\/","title":{"rendered":"Kubo Works"},"content":{"rendered":"
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Aerodynamic Characteristics based on the Wing Tip Trajectory of a Humming Bird (by Kubo, 2023)<\/h6>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n
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Wing attitude definition:<\/p>\r\n

Each wing has three degrees of freedom, flapping, feathering, and lead-lag, which generates the various tip trajectories such as concave, figure-zero, and figure-eight shapes. <\/p>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n

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 Fluid-structure (multi-body) Interaction simulation model:<\/p>\r\n

The model consists of the body scanned from a biological specimen and the flat plate wings, which are connected by spring and damper. The CFD is conducted under the condition: incompressible, unsteady, turbulent, and overset mesh,\r\n using openFOAM.<\/p>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n

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Simulation cases:<\/p>\r\n

Case 1 is the humming bird trajectory.<\/p>\r\n

Case 2 is the figure-zero-shaped trajectory.<\/p>\r\n

Case 3 is the figure-eight-shaped trajectory. <\/p>\r\n

Note that red show the stroke plane, blue is the upper side of the wing, and orange is the lower side. <\/p>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n

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The average lift per stroke in Case 1 was the most, i.e., 4.29 gf (74% of the hummingbird weight of 5.8g). The analysis of both the deformation of the elastic membrane wing and the motion of the feathering will be needed. <\/p>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n <\/div>\r\n

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Pressure Contour Surface (Blue and red show negative and positive pressures, respectively):<\/p>\r\n

The strong leading edge vortex (LEV) and wing tip vortex (WTV) were generated during the flap reversal phase from the upstroke to downstroke.<\/p>\r\n

The fastest motion position of the wing tip depended on the combination among the feathering, lead-lag, and stroke plane and the angular velocity of Case 1 was the largest.  <\/p>\r\n

When the leading edge tilted in the direction of the stroke, the lift increased in case of valley-shaped wingtip trajectory and decreased in case of mountain-shaped one. <\/p>\r\n <\/div>\r\n <\/div>\r\n

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