著者

土井 康明 茂里 一紘 堀田 多喜男

出版者

The Japan Society of Naval Architects and Ocean Engineers

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

vol.1991, no.170, pp.55-63, 1991 (Released:2009-09-04)

参考文献数

10

被引用文献数

1

---

A drag reduction for 3-dimensional body is attempted by microbubble injection. Two models with different lengths are used for experiments to distinguish the resistance due to on microbubble injection itself and the skin friction affected by microbubble covering. A reformed Wigley model is used to investigate the effect of microbubble injection on wave making. Measurements of the resistance and the longitudinal wave profiles are performed. The covering by microbubbles is realized by injected air through a porous pipe with pore size of 15 μm. The flow of microbubbles is obsered and the bubble sizes are estimated based on the rising velocity of a bubble in still water.The results show that it is possible to reduce the resistance of a 3-dimensional body by use of microbubbles if the body is well covered by microbubbles. Although the resistance increases where microbubbles are injected, the local frictional resistance is reduced more than 20 % where microbubbles cover the body. The total resistance is reduced more than 5 %. Based on a wave analysis, it is found that injecting microbubbles into water does not affect on wave making resistance.

著者

茂里 一紘 土井 康明 伊藤 昌広 岸本 由豆流

出版者

The Japan Society of Naval Architects and Ocean Engineers

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

vol.1991, no.169, pp.143-149, 1991 (Released:2009-09-04)

参考文献数

4

---

A semi-submersible displacement-type high-speed ship with wings is studied on its stability control by flaps.The vehicle, called HSV (High-speed Semi-submersible Vehicle with wings) here, is consisting of a main hull, main and tail wings with flaps, and a strut to support the super-structure. The HSV floats at a certain draft like a conventional ship while it is still, and it submerges when it moves forward due to a downward lift force induced by the main wings. HSV cannot have enough upright moment as conventional ships because of its small waterplane area. HSV is expected to be stable by an active control of flaps.Experiments are carried out to study about the possibility of the stability control by the flaps of the main and tail wings. An automatic control system is developed under which HSV is towed with the heaving, rolling, pitching and yawing motions free. The angles of attack of flaps are controlled after the measured ship motion in order to stabilize the motion.It is concluded that, although the control is not perfect due to the mechanical limitation of the used system, HSV can run stably by the active control of the flaps. The experiments among regular waves made clear that waves could not be a serious factor for the stability of HSV.

著者

肥後 靖 土井 康明 茂里 一紘 岩下 英嗣

出版者

広島大学

雑誌

基盤研究(A)

巻号頁・発行日

1999

---

本研究は,海上浮体が受ける海震による衝撃荷重を合理的に求めるプログラムの開発を第一の目的と実施した。開発にあたっては,模擬的な海震を発生させられる水槽を製作し,海震実験法を確立すると共に,当該海震実験の結果と開発したプログラムによる計算とを対比し,開発プログラムの妥当性を検証しながら海震のメカニズムについて検討した。その結果,まず海震実験によって,圧力波が水面と水底で共振していることが確認できた。また,本研究で開発した数値計算プログラム(時間領域,周波数領域双方)の妥当性を検証するために,実験によって得られた結果と計算との比較を行い,その結果,理論上第一共振に対応する周波数で,実験においては大きな圧力分布を示さず,第二共振に対応する周波数付近で大きな圧力変動が見られた。この実験の傾向と計算の結果の不一致の原因は,圧力波の伝播速度が水温に依存しており,実際と計算で異なっていること,また,水槽の側壁が振動装置からの隔離が完全ではなく,二次的な振動源となっていることが考えられるが,詳細にはさらなる検討が必要である。さらに,当該水槽を使用して海震荷重計測試験も行ったが,これも側壁の振動が原因と思われる雑音が存在し,理想的な実験結果を得られるにいたらなかった。いずれにしても,未だ実施されたことのない実験のために,色々と解決すべき問題はあるが,今後それらを一つ一つ解消し,目的である海震のメカニズム解明に役立てられるという目処は立った。特に,数値計算の検証という意味で本模擬海震発生水槽はこれから威力を発揮すると期待される。

著者

土井 康明 上田 隆浩 茂里 一紘 二宮 伸治

出版者

公益社団法人日本船舶海洋工学会

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

no.186, pp.89-96, 1999-12

被引用文献数

3 2

---

A numerical simulation method of the motion of a rowing race boat is developed in order to evaluate the performance of oar size and rowing pattern. The driving force of blade is measured experimentally. The resistance of the boat is referred to the experimental result carried out in a towing tank. The motion of crew, which is most important in the simulation, is evaluated from the equation of a boat motion where the other terms are experimentally measured. These measured external forces are modeled by Fourier series or polynominal expressions. The equation of a boat motion is numerically solved by use of Runge-Kutta method. The Simulated boat velocity and force acting on blade are compared with the measured ones. The experiment was carried out in cooperation with the crew at Hiroshima University. Good agreement with the simulated results and measured ones shows that the present simulation method has merit to evaluate the rowing performance. Through the present simulation method, outboard length, blade area, stroke rage and phase of catch are evaluated.