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

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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

新井 洋 土井 康明 中島 卓司 陸田 秀実 三好 潤

出版者

社団法人 日本船舶海洋工学会

雑誌

日本船舶海洋工学会論文集 (ISSN:18803717)

巻号頁・発行日

vol.9, pp.55-62, 2009 (Released:2009-10-08)

参考文献数

9

被引用文献数

7

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The objective of the present study is to elucidate the ow mechanism of delaying stall by use of wavy leading edges. Experiments were carried out to examine the effects of variant wavy leading edges attached on NACA0018 section wing of aspect ratio 1.6. The Reynolds number based on the chord length is Rec = 1:38 × 105 for the experiments. For these tests, lift, drag, and moment of wings with and without wavy leading edges were measured in a circular water channel. Flow visualization on the surface of wings was also conducted in order to clarify the eects of the wavy leading edges on the delaying stall. It is found that the wavy leading edges can control ow separation and delay stall, which in turn is good for producing large lift force at poststall angles of attack. Under the same height condition, the short width of wavy protuberance shows good performance of the wings compared with that of the long width. The wavy protuberance located near the wing tip does not enhance hydrodynamic performance.

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

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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

川島 敏彦 西本 仁 土井 康明 陸田 秀実 松田 英揮

出版者

公益社団法人 日本船舶海洋工学会

雑誌

日本船舶海洋工学会論文集 (ISSN:18803717)

巻号頁・発行日

vol.31, pp.1-14, 2020 (Released:2020-09-17)

参考文献数

13

被引用文献数

1 1

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A small saury fishing vessel (19GT-type) is newly developed and evaluated the total performance in order to increase profits and to attract the younger generation of fishermen. On the basis of inquiring surveys to fisheries unions, ship-owners and shipbuilders, problems and needs of saury fishing vessels are analyzed. Then, the performance of conventional fishing vessels is evaluated through model resistance tests in a circulating water channel. The hull form design for the fore-body is improved by the use of wave-making resistance theory. The aft-body is improved by the use of the Eulerian scheme with the Lagrangian particles. The general arrangement of the hull form improved vessel is developed to upgrade the habitability and fishing performance. The newly developed and advanced small saury fishing vessel can reduce the fuel consumption by half compared to the conventional vessels. An actual 19 GT saury fishing vessel, constructed based on the results of this study by using the present design method, demonstrates the superiority of performance.

著者

陸田 秀実 村上 一樹 土井 康明 山本 民次 川口 修

出版者

公益社団法人 土木学会

雑誌

土木学会論文集B3(海洋開発) (ISSN:21854688)

巻号頁・発行日

vol.67, no.2, pp.I_364-I_369, 2011 (Released:2011-12-08)

参考文献数

5

被引用文献数

3

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To evaluate impacts of oyster raft placement on tidal current and seawater exchange in Etajima Bay, northern part of Hiroshima Bay, we have developed a coastal circulation model incorporating the drag force of the oyster raft in Etajima Bay. We found that the number of oyster rafts in summer season is twice as large as that in winter season. In Etajima Bay, the seawater exchange is relatively large in the northwest part, whereas the term of the seawater exchange is about one year in the southern part. Moreover, we computed some scenarios which the oyster rafts are reduced at each zone, and then it could be desirable to reduce 40% of the total number of oyster rafts in order to make a plane for reducing organic matter load from the oyster culture.

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

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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

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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.

著者

中島 卓司 坪倉 誠 岡田 義浩 農沢 隆秀 溝兼 通矢 土井 康明

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.80, no.818, pp.FE0301-FE0301, 2014 (Released:2014-10-25)

参考文献数

13

被引用文献数

2

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The objective of this study is to investigate aerodynamics and its generating mechanism of a road vehicle in steady-state cornering, which is the most basic cornering condition. The vehicle motion in the steady-state cornering was defined on a frame of reference fixed on the vehicle and it was divided into a rotation around a vertical axis and a sideslip. Then, aerodynamic force generated by each motion and its generating mechanism was discussed. In order to reproduce an effect of the rotational motion, a towing tank experiment was conducted to measure the fluid-dynamic force acting on a one-fifth-scale model of a sedan-type road vehicle. Assuming that the fluid-dynamic forces are expressible as a linear superposition of effects of the rotation and sideslip, first derivatives of the side force and yaw moment with respect to the yaw rate and the lateral velocity were analyzed by a multiple linear regression analysis. From the results of measurement and analysis, it was clarified that the assumption can provide good approximations of the force and the moment within a range of measurement conditions in this study. Regarding the fluid-dynamic side force, the rotation generates a centripetal force of the circular motion and the sideslip generates a force suppressing the slip motion. Regarding the fluid-dynamic yaw moment, the rotation generates a moment suppressing the rotation, and the sideslip generates a moment enhancing the vehicle's slip angle. Aerodynamics of a sedan-type road vehicle was estimated quasi-steadily by multiple regression equations with measured vehicle motion in an on-road test. From this estimation, the effects of both the rotation and the sideslip had the same order of magnitude. This result indicates that the effects of the vehicle's rotational motion have the same level of importance as the effects of the sideslip in vehicle aerodynamics in steady-state cornering.

著者

福地 信義 木原 和之 土井 康明 豊貞 雅宏 若菜 啓孝 篠田 岳思 小川原 陽一

出版者

九州大学

雑誌

試験研究(B)

巻号頁・発行日

1992

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軽量構造船は構造材がアルミ合金であるため、火災時には溶融・発熱燃焼が起こる危険性があり、軽量構造船特有の防火対策が不可欠である。このため、アルミ合金の船における火災伝播現象のシミュレーションと防火対策の等価性評価のための評価法の提案を行った。主な研究成果は次の通りである。(1)火災伝播現象シミュレーションのための数学モデル軽量構造船を対象に、火災時に破損孔を生じる可能性のある場合について火災伝播の様相を調べるために、火災現象の状態方程式と船内区画をリニアグラフで結合によりモデル化し、可燃物の燃焼特性、ガスの発生、熱および気流に関する状態方程式により火災現象の数学モデルを構築した。これにより火災伝播現象の数値シミュレーションのための計算法を確立した。(2)軽量構造船の火災伝播状態形状を簡易化した3層甲板客船モデルおよび単胴型高速船の延焼状態について計算を行い、壁体の破損温度、防熱材厚さおよび火災荷重と火災拡大の関係を明らかにした。また、壁体に破損が起こる場合の火災の拡大要因は、破損孔による酸素補給の有無と熱移流であり、防火構造の防熱性能と耐熱強度が問題であること、特に発火区画での火災減退期までの熱封鎖の可否が火災拡大の分岐条件となることを示した。(3)防火対策の等価性評価のための手法評価対象を評価する際に、代替項目により優れた特徴のみを問題視する代替的評価と欠点のないものを選好する補完的評価がある。このような多面性問題に対して、評価選好基準にBelief測度あるいはPlausibi-lity測度のようなFuzzy測度を用いた多基準分析法による代替性・補完性評価の手法を提案した。

著者

平山 次清 高山 武彦 平川 嘉昭 庄司 るり 上野 道雄 塚田 吉昭 岩下 英嗣 土井 康明

出版者

横浜国立大学

雑誌

基盤研究(B)

巻号頁・発行日

2008

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海上が荒れた場合はバラストタンクと主翼および尾翼を制御することによって浅く潜航し波浪影響を避けるという新コンセプト船を提案し、その実現可能性について主として流体力学・運動制御工学の観点から実験・数値計算を実施して検討した結果、船長の半分程度まで潜水すれば波浪影響は数%以下に抑制可能であることやウェザールーチングの観点からは10%程度の燃費低減が可能といった結果を得た。