著者

乾 崇夫 菊池 義男 岩田 達三

出版者

The Japan Society of Naval Architects and Ocean Engineers

雑誌

造船協會論文集 (ISSN:18842062)

巻号頁・発行日

vol.1956, no.100, pp.35-45, 1956 (Released:2009-09-16)

参考文献数

27

被引用文献数

2

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Since 1944, when one of the present Authors (INUI) and his collaborator calculated mathematically the wave-making resistance of ships in a shallow sea, necessity has long been recognized for making further quantitative investigations regarding to the practical adaptability of the theory. The following notes are aimed for clarifying the still remained question to what extent such a linearized wave-making theory can be safely applied in cases of a restricted water (b=h=finite) as well as a shallow water (h=finite, b=infinitive), where h denotes the depth of a water, b the width.A 1.750 m mathematical model S-201, whose equivalent source distribution is known, is towed in the Tokyo University Tank at the depth of water h/L=1.371, 0.400, 0.300 and 0.200.Comparatively good coincidence has been obtained between the calculated and measured wavemaking resistance, excluding the narrow critical range of Fh=0.820.95 where the KREITNER'S non-linear restricted water effect is clearly observed especially at the shoalest depth h/L=0.200.

著者

乾 崇夫 菊池 義男 岩田 達三

出版者

The Japan Society of Naval Architects and Ocean Engineers

雑誌

造船協會論文集 (ISSN:18842062)

巻号頁・発行日

vol.1956, no.100, pp.47-67, 1956 (Released:2010-01-25)

参考文献数

12

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The wave profile measurements are made with two wall-sided, deep-drafted mathematical models (S-103, S-203) by applying the chemical film method, where the Benzoic Acid is effectively used for the first time, and found as pre-eminently suited to contrasting the flow phenomena on ship models such as wave profiles, initial still water lines, stream lines, and laminar flow area.Comparisons are also made between the calculated and the observed wave profiles.Coincidence is good along the models, but is unsatisfactory in the rear.The principal cause might be safely ascribed to the fact that the wake intesity is always extinguishedly strong just on the narrow band in the vertical symmetrical plane (y=0).Conclusions are then drawn that the present field of the mentioned comparisons between the theory and the observation must be extended from one dimension (on the line y=0, exclusively) to two dimensions, to which the photographic measurements by stereograph might be expected as essential.

著者

乾 崇夫 高幣 哲夫 熊野 道雄

出版者

The Japan Society of Naval Architects and Ocean Engineers

雑誌

造船協會論文集 (ISSN:18842062)

巻号頁・発行日

vol.1960, no.108, pp.39-51, 1960 (Released:2009-09-16)

参考文献数

29

被引用文献数

3

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As to the wave-interference phenomena connected with the bulb there have been presented two kinds of explanations : one being theoretical, and the other practical.Following the theoretical explanation, which is largely indebted to Havelock and Wigley, we may assume that the wave-making characterististics of the bulbous bow can be safely represented by an isolated point doublet. If admitted, this goes at once to the conclusion that the free wave patterns due to the fitted bulb can be intentionally put just in inverse phase or with strictly half wave-length difference against the main hull waves. This is nothing but the most desirable situation for us in view of promoting the maximum interfering merits of the bulb.On the contrary, the other explanation enforces, rather practically, too much importance of the virtual increment in the wave-making length of the hull which is caused by the bulb waves. In this way, it has long been believed that the reduced wave-making resistance accompanying the bulbous bow has much to do with its increased “effective wave-making length”. From this standpoint of view, it is suggested that, when any amount of bulb merit observed, the bulb waves must proceed by some intermediate fraction between 1/41/2 of ship wave length against the main hull waves. This means that from the bulbous bow we can expect only an incomplete interfering merit at the best.This report is aimed for the experimental determination of the existing conflict, mentioned above, with regard to the 'actual' phase-difference between the bulb waves and the hull waves. The wave analysis procedure is applied for the first time. The conclusion is that the theoretical treatment of the bulb which is introduced by Havelock and Wigley can be practically approved. A few remarks are also made on the two different phases of the hydrodynamical characteristics of the bulbous bow. Its corresponding system of singularities is represented by the combination of an isolated doublet with a continuous source distribution.The former has a positive and therefore the same sense with the latter in hull form characteristics, but has a negative and therefore the reverse sense in wave-making characteristics. This is the true reason why the wavemaking resistance is sometimes reduced remarkably with the bulbous form whose displacement is larger by its bulb than the original form.

著者

元良 誠三

出版者

The Japan Society of Naval Architects and Ocean Engineers

雑誌

造船協會論文集 (ISSN:18842062)

巻号頁・発行日

vol.1960, no.107, pp.83-89, 1960 (Released:2009-09-16)

参考文献数

4

被引用文献数

3

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In this paper, the author states about the results of measurement of added moment of inertia and damping coefficieut about y axis, i. e. for pitching motion.A forced oscillation method same as was used by Golovato was employed for measuring device, and 14 series models varying Cb and L/B are used.As the added moment of inertia and the damping of pitching motion vary with the frequency of the motion, values of them corresponding to the natural pitching frequency are choosen as the typical values when discussing the effect of ship forms.A chart from which additional moment of enertia and damping coefficent of ships having arbitrary Cb, L/B and d/B can be obtained is proposed in this paper.