大形油送船の貨物油管系の抵抗に関する研究
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概要
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Following special features concerned with the resistance of the cargo oil piping system installed on the large tanker are also big problems for the practical design of the shipping. (1) Frictional resistance of the welded steel pipe. (2) Investigation on the resistance of the piping at large Reynolds' number such as 10^6. (3) Shortening of the unloading operation with large cargo pump. Auther analizes the technical data of the experiments having been done on the several large tankers to investigate the above problems and gives the followings as the vital items. (1) Welded steel pipe, which is fabricated at shipyard, can be assumed as an ordinary seamless steel pipe from resistance point of view if its roughness is estimated right. (2) Auther proposes empirical formulas of the coefficient of the frictional resistance λ. (3) It is well known that the critical Reynolds' number in the turbulent flow exists in case of formal resistance of the spherical or cylindrical bodies in the stream. In another word, there is a remarkable hollow on the curve of coefficient of formal resistance C, and Reynolds' number R. {R=(2〜5)×10^5}. Auther points out similar phenomenon occur also in case of the formal resistance of the piping, especially in the pipe bend and branches. (4) Critical Reynolds' number Rc of the pipings is (3〜8)×10^5 and the ratio (ζ_H)/(ζ_L)=1/4〜1/8 where ζ_H (ζ_L) is C at higher (lower) Reynolds' number than Rc. (5) Rc seams to vary according to the shape of the pass of the fluid in the piping similar to bodies in stream, and we can design reasonable and economical size and flow of the piping if R can be put in the zone of Rc. (6) The value of Net positive suction head (NPSH_R) of the large centrifugal pump is very important to save the unloading period of the tanker. Auther describes this matter quantitatively based on the actual data of the ships.
- 社団法人日本船舶海洋工学会の論文
- 1962-03-30