著者

林 裕介 渡辺 昌宏 原 謙介

出版者

一般社団法人 日本機械学会

雑誌

Dynamics & Design Conference 2010 (ISSN:24242993)

巻号頁・発行日

pp._260-1_-_260-6_, 2010-09-14 (Released:2017-06-19)

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This paper deals with theoretical stability analysis of an active feedback control of web flutter which occurs to the web with both ends fixed and tensioned. In this paper, a non-contact active feedback control method of web flutter by using movable plates set at inlet or outlet of the passage are developed and its analytical model is constructed. The equations of motion of the flexible sheet coupled with the fluid flow controlled by the movable plates are obtained. The characteristic equation of the system is derived as a function of the flow velocity in the narrow gap. As a result, it is shown that the web flutter occurs to the web with increasing the flow velocity, and is effectively suppressed by the proposed non-contact flow control devices and active feedback control method. Furthermore, calculation results are verified by the experiments.

著者

廣明 慶一 渡辺 昌宏

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.84, no.858, pp.17-00416-17-00416, 2018 (Released:2018-02-25)

参考文献数

23

被引用文献数

1

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An instability mechanism of flutter generated on a rectangular flexible sheet in an axial fluid flow is investigated through the energy-transfer quantifications. The work done by unsteady fluid force acting on the fluttering sheet surface is calculated based on a three dimensional flutter analysis utilized the Doublet-point method and finite element method. Then the work done by fluid force is divided to three terms caused by fluid added mass, damping and stiffness by applying Roger's approximation, and influence of each term on stability is clarified. As a result, it is clarified that the work caused by fluid added stiffness is dominant for excitation of flutter. Lastly, the influence of the work caused by interaction of natural vibration modes of the sheet which are dominant for flutter on stability is investigated, and the instability mechanism of flutter is discussed.

著者

武田 真和 渡辺 昌宏

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.84, no.858, pp.17-00415-17-00415, 2018 (Released:2018-02-25)

参考文献数

16

被引用文献数

3

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This paper presents experiments and an analysis of the self-excited vibration of a plate supported by air pressure. In the analysis, the unsteady fluid force acting on the plate is calculated based on the basic equation of a two-dimensional gap flow between the plate and a chamber surface. The basic equation considers the effect of air compressibility in the chamber. The characteristic equation of the system is derived from the plate motion coupled with the unsteady fluid force acting on the plate. The instability condition and vibration frequency are predicted through the root locus of the system with changing air flow rate supplied to the chamber. The experiment consists of a plate supported by the air pressure supplied from a slit on the upper surface of the chamber, where the vibration characteristics are examined. The influence of the slit width and chamber volume on the instability condition of the self-excited vibration is clarified comparing the analytical result with experiments. Moreover, the local work done by the unsteady fluid force acting on the plate (bottom surface) is shown in this paper, and the instability mechanism is discussed. Lastly, the influence of slit width on the unsteady fluid force is addressed by the block diagram showing the phase relationship of pressure fluctuation and plate displacement.

著者

廣明 慶一 河合 伸人 渡辺 昌宏

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.83, no.852, pp.17-00025-17-00025, 2017 (Released:2017-08-25)

参考文献数

20

被引用文献数

2

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This paper presents a three dimensional flutter analysis of slender webs under tension in cross flow. In the flutter analysis, Doublet-point method based on the unsteady lifting surface theory is used to calculate unsteady fluid force acting on the web surface. The equation of motion of the web under tension is derived by using the finite element method. Flutter velocity, frequency and mode are predicted through the root locus of the flutter determinant of the system with changing flow velocity. The theoretical results are compared to experimental results to confirm validity. Moreover, the local work done by the fluid force acting on the web surface is calculated, and instability mechanism is discussed. Lastly, unified empirical equation of flutter velocities for several parameters of webs is proposed.

著者

小林 信之 渡辺 昌宏 張 亜軍

出版者

青山学院大学

雑誌

基盤研究(C)

巻号頁・発行日

2003

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船舶などで推進器として使用されているスクリューは,推進効率と運動性能の向上に限界がある.一方,進化の過程で最適化された水棲生物の泳動方法を見てみると,高い運動性能と高推進効率を有する泳動を行っていることが分かる.このことから,高効率で運動性能の高い船舶を開発する上で,水棲生物の泳動を模倣した研究は有益な知見をもたらすと考えられる.このため,本研究は柔軟なヒレの波動運動における波の数と振動数を変えられる水中推進機構の開発とその波動運動を滑らかに制御するための制御手法を構築した。水中推進機構の開発では、カムとフォロワーから構成されるスコッチヨーク機構を用いて柔軟なヒレに波動運動を発生させる水中推進機構を開発し,その機構を水槽内で泳動させることにより,柔らかいヒレの波の数と振動数の推進力と泳動速度への影響を調べた.また、波動運動を滑らかに制御する目的のために、水中推進機構の運動をマルチボディ・ダイナミクスの手法を用いて定式化した。運動方程式は幾何学的な拘束により非線形な微分代数方程式により表される。そして、運動制御のための制御系設計するための効率的な線形化手法を開発した。また、出力を用いたスライディングモード制御系の設計において、PD制御を併用する方法を提案し、より高い制御性能を得られる超平面設計を可能にした。実験から得られた以下の結果をいかに示す.(1)製作した水中推進機構は波の移動方向を変えることで前進と後進が可能である.(2)波の数が多くなると推力と泳動速度の変動が小さくなりスムーズな泳動が可能である.しかしながら,平均推力は小さい.(3)振動数が大きくなると平均推力と推力の変動は増大する.また,泳動速度は増大する.(4)波の数n=1程度の時,大きな平均泳動速度を得られる.(5)無次元振動数が大きくなると推進力と平均泳動速度は減少し,無次元振動数の値にかかわらず泳動速度の変動はほぼ一定である.