Grant-in-Aid for Scientific Research (A)
|Allocation Type||Single-year Grants|
|Research Institution||Osaka University|
SUZUKI Toshio Osaka Univ.Fac.Eng., Prof., 工学部, 教授 (80029107)
MORI Kazuhiro Hiroshima Univ.Fac.Eng., Assoc.Prof., 工学部, 教授 (90011171)
OKUNO Taketosi Osaka pref.Univ.Fac.Eng., Assoc.Prof., 工学部, 教授 (60081395)
TODA Yasuyuki Kobe Mercantile Univ.Fac.Nav., Assoc.Prof., 商船学部, 助教授 (20172166)
SUZUKI Hiroyoshi Osaka Univ.Fac.Eng., Res.Assoc., 工学部, 助手 (00252601)
|Project Period (FY)
1994 – 1996
Completed(Fiscal Year 1996)
|Budget Amount *help
¥14,900,000 (Direct Cost : ¥14,900,000)
Fiscal Year 1996 : ¥2,500,000 (Direct Cost : ¥2,500,000)
Fiscal Year 1995 : ¥5,800,000 (Direct Cost : ¥5,800,000)
Fiscal Year 1994 : ¥6,600,000 (Direct Cost : ¥6,600,000)
|Keywords||3-Dimensional Hot Wire / Evaluation of Turbulence Model / Distributions of Reynolds Stresses / 3-Dimensional Separation / Turbulence Data-base around Stern Flow Field / 肥大船船尾流場 / レイノルズ応力 / 乱流モデル / 速度変動の位相差 / 長周期変動 / 熱線流速計の精度確認 / 乱動計測 / 船尾近傍の乱流場 / 伴流内の周波数解析|
Characteristics of the turbulence with longitudinal vortices and deformation of boundary layr, due to the existence of the vortices are investigated.
Obtained results are as follows ;
1. Characteristic of 3-dimensional turbulent flow around a fine ship model (Series 60, CB=0.6) and a full ship form (Ryuko-Maru) were investigated experimentally. The results are,
(1) Accurate data-base for 3-D averaged velocity components, vortices and Reynolds stress distributions are obtained.
(2) Position of the peak value of longitudinal vortices are not correspond to the peak of Reynolds stress and turbulence strength are weak inside of the longitudinal vortices.
(3) Wake distribution is deformed by vortices which was caused by 3-D separation near the stern bilge.
(4) Phase of fluctuation between the velocity inside of the longitudinal vortices and the outer region of the vortices are differ each other. Strong correlation between the fluctuations of the area of longitudinal vortices and fluctuations of x-component of velocity are recognized.
(5) Estimated normal stress components using Boussinesq's hypothesis are well coincident with experimental results but shear stress components are not coincident.
(6) Turbulence model based on the Boussinesq's hypothesis underestimate the shearing stress and the damping method for the kinematic eddy viscosity by helicity underestimate more the shearing stresses.
2. CFD calculations are carried out and the results show qualitative agreement with experimental results, i.e.weak deformation of the wake distribution is calculated.
3. Shearing stress components on the hull surface are measured by image processing technique.
4. Bow wave breaking are calculated with the zero tangential stress conditions on the free surface.