著者

中 尚義 五十里 啓司 成澤 海舟 橋本 巨

出版者

The Visualization Society of Japan

雑誌

可視化情報学会論文集 (ISSN:13465260)

巻号頁・発行日

vol.36, no.12, pp.71-81, 2016 (Released:2016-12-31)

参考文献数

22

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トンボは飛翔のための空気力を得るために三次元的な流れを生成している.しかしながら,トンボの自由飛翔時の三次元流れは実験的には未だ明らかでない.本研究では実験的に三次元流れを明らかとするため,断層撮影を用いた可視化実験およびPIV解析を行った.断層撮影では測定の再現性が重要となることから,可視化実験にはトンボの羽ばたき運動を模擬した羽ばたきシミュレータを使用した.流れの可視化は前方および側面方向の2方向から行った.その結果,直線飛翔時のトンボは翅の中央部において後方に向かって強い流れを生成していることが確認された.また,翅の基部方向に向かって流れが引き寄せられていることが明らかとなった.これは後方に向かう強い流れによって横方向から流れが引っ張られていると考えられる.このことから,直線飛翔時のトンボは翼幅方向の余分な流れを作らず,後方への強い流れのみを生成しているといえる.

著者

中 尚義 橋本 巨

出版者

公益社団法人 日本設計工学会

雑誌

設計工学 (ISSN:09192948)

巻号頁・発行日

vol.51, no.11, pp.788-801, 2016 (Released:2016-11-05)

参考文献数

24

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Dragonflies have high flight performance in spite of small size. Therefore, the research of clarifying the flight mechanisms of dragonflies, and then applying it to Micro Air Vehicles (MAVs) is proceeding. Dragonfly's flight mainly consist of a flapping motion and a feathering motion. To control the MAV like dragonflies, clarifying the effect of the flapping motion and the feathering motion on generating aerodynamic force is necessary. In this study, lift and thrust force generated by flapping were measured using flap simulator adjusted the flapping and feathering angle. As a result, lift and thrust force were increased with increase in the flapping angle. Thrust force was particularly increased with increase from 30° to 40° in the flapping angle. When the feathering angle is 45°, downforce was very small, and a lift fluctuation was small. Therefore, the feathering angle of 45° are suitable for the straight flight. When the feathering angle is 60°, momentary lift force was very high. Therefore, the feathering angle of 60° are suitable for a climbing flight such as the take-off. In fact, it was confirmed by the motion analysis that the feathering angle of a dragonfly in the take-off is 60° or more.

著者

中 尚義 橋本 巨

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.82, no.833, pp.15-00209-15-00209, 2016 (Released:2016-01-25)

参考文献数

11

被引用文献数

1 1

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Dragonflies can perform both of gliding and flapping flight and have high maneuverability in spite of small-size. The aim of this study is to develop Micro Air Vehicle (MAV) based on the flight of dragonfly. The characteristics of wings are very important for development of MAV. Dragonfly wing is easy to be passively deformed in the tip side from the nodus in flapping flight, and thereby, aerodynamic force is generated effectively. In this study, the effect of passive deformation of wing on aerodynamic force was investigated using fluid-structure interaction analysis to develop the artificial wing suitable for dragonfly-like MAV. In this study, aerodynamic characteristics of wings in the gliding flight and aerodynamic force generated in flapping flight are numerically analyzed. In this analysis, nodus wing models, which can deform passively, and rigid wing model, which cannot deform, are used. Nodus wing model imitates the nodus structure; the tip side of this model is free to rotate around leading edge. As a result of gliding flight, the lift coefficient of the nodus wing was lower in low-angle of attack and was higher in high-angle of attack, compared to rigid wing. Moreover, the more flexible wings are, the more change. The gliding flight is low-angle of attack usually. Therefore, flexible wing is less suitable for the gliding flight than inflexible wing. As a result of flapping flight, the nodus wing made drag force generated during down stroke lower compared with the rigid wing. However, thrust forces generated during up stroke in both wings were the same. Therefore, flexible wing is more suitable for the flapping flight than inflexible wing. The wings of dragonfly-like MAV need to appropriate level of flexibility to upgrade the performance in both case of gliding and flapping flight.

著者

橋本 巨 石本 早霧

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 C編 (ISSN:03875024)

巻号頁・発行日

vol.63, no.607, pp.723-731, 1997-03-25 (Released:2008-02-26)

参考文献数

20

被引用文献数

1 1

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Elucidation of the vibration mechanism of winged insect from the viewpoint of bionic design might aid in development and design of the driving systems for small- or micro-size actuators, because some flying insects easily overcome scale effects through use of wing vibration and achieve flight with high robustness and speed under conditions of large air viscosity. The aim of this report is to describe a theoretical model of the dynamics of relatively large-size insect wings powered by the direct-flight-muscle and of the dynamics of small-size insect wings powered by the indirect-flight-muscle. Based on morphological consideration of these two types of insect wing dynamics, the equations of motion for the wings are formulated. In the model, the dry friction-type and van der Pol-type forces are employed to power the wings of direct-flight-muscle-type insects, and the periodic impulsive force is assumed to power the wings of indirect-flight-muscle-type insects. Applying the equations of motion to the wings of insects such as dragonflies and flies, the wing vibration is analyzed under various conditions. From the numerical results, the vibration mechanism of two types of flying insects' wings is clarified.

著者

茨木 博 橋本 巨

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. C編 (ISSN:03875024)

巻号頁・発行日

vol.75, no.757, pp.2596-2603, 2009-09-25

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This study is concerning the optimum design of a water nozzle for firefighting equipment used to protect large indoor spaces and high-rise buildings. Water nozzles for such use are required to have a long range of reach and/or a wide coverage. Such performance can be obtained by simply increasing the flow rate, but that is caused substantial pressure loss by the fluid friction within the nozzle and the pipe. The objective of this study is to obtain a water nozzle with minimum fluid friction by optimum design, as a result the size of piping, pump and water reservoir for firefighting equipment can be minimized. The conventional water nozzle used in firefighting is called the smooth bore nozzle, which have a wedge-shape profile whose diameter decreasing toward the exit. However, whether or not this shape is optimum have not been known. In this study, a method is presented to obtain a friction-minimum nozzle profile, while setting the inlet-and outlet-diameters and the length of the nozzle as fixed parameters. It was found that the half-spindle-type nozzle, whose diameter is almost constant along the length but quickly decreases at the exit, shows the smallest friction than the other profiles (i.e. smooth-bore, straight and concaved), therefore showing maximum arrival distance.