Twenty-Third Symposium on Naval Hydrodynamics (2001) / Chapter Skim
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Hull Design by CAD/CFD Simulation
Hull Design by CAD/CFD Simulation
Pages 181-190
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From page 181... ...
Since then a number of codes have been developed and inhoduced to floe de ign office b it e past 10 years such CFD ted immR have been e Fended to it e pianffy mohon and mohon in waves The use has been made of it e time-marching solution procedure such as that of the MAC method anc the technique of c mbimng floe CFD solution wifl floe solution of the equations of mohon The technic i fifficulties con i t mo fly in it e heatmnt of the moving boundaries, flat is floe fiee-suface and floe body-bounda y of a ship in motion The den ity fl notion method is often employed for the trongly interachng free-smface motion :d it e mo ing bounda y techmq r is well used H wevff it e use of the flved gyid ystem is used to be more vffsahie when the mohon is e Dressed by coordinates h:sformahon and inn i accelerations When the wave spedmm of the sea on which the hip will be expected to s .1 in her life-range is given for the estimation of the tot i resistance and the resultant fuel consmmphon, it e design of hull-fomm is made fl m the total life- ycle viewp int This means that floe hull-form design can be made wifl it e prefiddon of it e OVER il pe formance of it e ship in her life For it e special case of the design of the h 51-fomm of it e Intemation i Amenca's Cup Class IMCCI sailing boat this de igm procedure is very suitably applied Since it e race area is :nommced about 3 years before, it e stahstic i wave data can be collected :d then the CAD uFD de ign moced re above mentioned is successfllly applied though the tatishcal wind data plays more important role in the design procedure In this paper one of it e most advanced design proced re for hull-form is described especi fly for the IACC class s fling boat :d another case of the high-speed forty HULL DESIGN SYSTEM Desigm system for Amn ica's Cup 2flflfl For it e research and devel pment work for it e 30 Amenca's Cup yacht race the technic i team of it e Nippon Challenge made the CAD plan in 1995 The most scientific CAD work was fir t pursued for it e race of 1957 by the syndicate at S: Diego, which is ret owed by Oliver et al This mocedme seams us shll very used I as fw as the boat hardware design is concerned However it e computer techmology has made I rapid progress in it e past 15 years The pe fommance of the computer has bee r ised by 10000 hmes in 15 years The pe formance of the first supercomputer of it e University of it e Tokyo, whi ch was inh oduced in 19 53 and I used for ship wave computation with TUMMAC-IV method for the second worksh p on wave resistance computation, is almo t same wifl that of a PC in 2000 in it e meanwhile the CFD technique also made rapidprogyess For it e development and design j ob of Nippon Challnge Amffica's C p 2000, the proced re described in Fig I was ad pted, see whcle by Miyata et i, 2000 and a book by Miyata, 2000 The de ign is mo fly d ne by the redproc i use of CAD :d CFD simulation More than 200 hulls we desigmed :d thdr pffform:ce is 1
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From page 182... ...
Thc hull ~~ in 3D dots made by the CAD software is used by the grid-gener~or as prc-procossing far CFD simulator. This data is also used ~, Oh America swing process at ~ modal mature ln the 1~1er stage Then some gem hull farms are obisined the race Emulsion ~ pared with the Hind data of 1700 days at Hauraki (Surf of NO Zealand.
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From page 183... ...
Together with the wave spectrum of the race area the prediction of total resistance of candidate hulls is made and the optimum hull of statistically minimum resistance is selected. Thus the advanced hull design method by simulation is composed as shown in the flow chart of Fig.
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From page 184... ...
The reliability of the CFD simulation by PPS (WISDAM-VI) during the design procedure with 210 hull forms is, grossly speaking, 75%, which means that the relative relation between two designed hulls is 75% correct.
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From page 185... ...
The Allowing inert farces arc included in K ~=~xV-~x~x~xr~ ~ Here, the Brat 1crm is Sac Coriolis Cc, the second is the circum~rcrtid farce, the third is the singular ccclcr~ion and the Numb is 1be tr~sl~io~1 accclc~ion, where ~ ~ angular Clock vector ~ is the velocity vector r is the poshion vector and Vs is the voloci~ of the origin of the body-~xed coordinates.
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From page 186... ...
Two-degrees of freedom motion The most useful simulation results will be expected when it is conducted with 6-degrees of Table 1 Condition of computation The tested model is a typical IACC yacht, which is 24.5 meter long and about 4.1 meter wide. The lines are shown in Fig.
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From page 187... ...
Aid.
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From page 188... ...
14 seems to be useful for the understanding of the life-eyele design system for hull forms. motion characteristics ..
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From page 189... ...
For low and middle speed ships the bulbous bulb with sphere-shaped head configuration is no more used but bulbs with long protrusion and sharp entrance are designed mostly based on the understanding of the presence of free-surface shock wave. However for high speed ships, of which draft changes only slightly, an old-fashioned cylindrical bulb or so-called SV-type bulb are efficient to reduce wave resistance.
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From page 190... ...
Since the CPU time for one case of and JPN52 were mostly made by the first version ofPPS computation is several hours and the hull form for the steady sailing. It may be safe to say that the modification is made by CAD process with some hours CAD/CFD system was satisfactorily applied to one of of labor, it may be noted that the hull form optimization the most difficult hull design problem.
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