KATAYAMA Toru (Research Associate, College of Engineering, Osaka Prefecture University), 大学院・工学研究科, 助手 (20305650)
大塚 耕司 大阪府立大学, 工学部, 助教授 (90213769)
奥野 武俊 大阪府立大学, 工学部, 教授 (60081395)
岡田 博雄 大阪府立大学, 大学院・工学研究科, 教授 (90081398)
MASAOKA Koji (Associate Professor, College of Engineering, Osaka Prefecture University), 大学院・工学研究科, 助教授 (10244659)
BABA Nobuhiro (Associate Professor, College of Engineering, Osaka Prefecture University), 大学院・工学研究科, 助教授 (10198947)
|Budget Amount *help
¥15,000,000 (Direct Cost : ¥15,000,000)
Fiscal Year 2000 : ¥4,900,000 (Direct Cost : ¥4,900,000)
Fiscal Year 1999 : ¥4,800,000 (Direct Cost : ¥4,800,000)
Fiscal Year 1998 : ¥5,300,000 (Direct Cost : ¥5,300,000)
Very limited numbers of studies on maneuverability of hard-chine planing hulls have been carried out, and any theoretical or experimental procedures to simulate the maneuvering characteristics of them have not been established yet. Although the most important characteristic that is different from that of a conventional displacement vessel seems to be the significant effects of changing of running attitude on maneuvering, measured hydrodynamic forces to use in a motion equations for maneuverability of six-degree-of-freedom for them are almost nonexistent as far as the authors know.
In the first year, in order to clarify the effects, a six components of hydrodynamic forces acting on the scale model of a planing craft in oblique towing condition are measured using a high-speed carriage, maximum speed of which is 15m/s, in the towing tank of Osaka Prefecture University. The model is fully captured by a six-component load cell, and its attitudes, trim, rise and heel angle, are systematical
ly changed. The experimental results show that the hydrodynamic forces are proportional to the square of advanced speed at planing speed, and demonstrate that the effects of attitude on the hydrodynamic forces are significant. The dependency of each hydrodynamic component on the running attitude is identified on the basis of the experimental results.
In the second year, six-component hydrodynamic forces acting on the 1/4 scale model of a planing craft by planar motion mechanism test at high forward speed are measured for various planar motions and running attitudes, rise and trim angle. The measured data show that the first order components with the same frequency as that of forced motion are significantly larger than high order components. This means that the hydrodynamic forces model can be expressed by only the first order components of motion's velocity and acceleration. The effect of running attitudes on the hydrodynamic coefficients is significant and it is necessary for maneuverability of planing craft to take into account this effect.
In the final year, a model test method, a partly captured PMM test, to measure unstable motions of a planing crafl induced by periodic maneuvering motion is developed. The experimental results of a planing craft at Fn=2.0 by the method demonstrates that a violent motion which is large rolling, heaving and pitching coupling motion occurs when the frequency of motion given by PMM coincides with the rolling natural frequency, and with the half of the heaving and pitching natural frequency of the craft. It should be noted that the rolling motion has the same frequency as the forced motion given by PMM, but that the heaving and pitching motions have the twice of the frequency of the forced motion. In order to clarify the cause of the violent motion, the hydrodynamic forces acting on the hull in periodic maneuvering motions are measured by PMM tests for a captured model and obliquely towing tests. The experimental results show that the rolling displacement of the craft generates hydrodynamic heaving force and pitching moment at high speed. A non-linear time-domain simulation of the motions using the measured hydrodynamic forces is carried out. The simulated motions are in fairly good agreement with the experimental ones.