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022192B.ENG
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Country: Japan
From:
Memoirs of the Faculty of Engineering, Kyushu University, Vol. 51,
No. 4., p. 329-354, December 1991
Numerical Calculation of Free Surface Effect on Propulsive
Performance of Ship
by
Kuniharu NAKATAKE*, Jun ANDO**, Katsumi KATAOKA***
and Kohichi ODA****
*Professor, Department of Naval Architecture
**Lecturer, Department of Naval Architecture
***Research Associate, Department of Naval Architecture
**** Technical Official, Department of Naval Architecture
(Received September 9, 1991)
Abstract
In order to elucidate the mechanism of free surface effect on
the propulsive performance of ship. We performed several
experiments and numerical calculations for the Wigley hull model
with a propeller and a rudder. Experiments consist of resistance
test, propeller open test, load varying test and rudder drag
measurement. At first we develop the Kyushu University method to
calculate the wave flow around the ship. Then, through the
theoretical calculations, we attempt to elucidate the mechanism of
propulsive performance of ship under free surface effect by using
the Kyushu Unhersity method, which needs the double model flows
around Wigley hull, the simplified propeller model and the rudder
model. Since we can obtain from the boundary conditions the
singularity distributions which represent the hull, the propeller
and the rudder, we calculate the forces such as the hull
resistance, the thrust and torque of the propeller and the rudder
drag. After several iterations, we obtain the rate of revolutions,
the thrust and torque of the propeller and the rudder drag at the
self-propelled state. Though the viscous effects are only roughly
taken into consideration in our calculations, we show that
experimental results are qualitatively explained by numerical
calculations.
Keywords: Free surface effect. Propulsive performance, Ship
+++++Text, Equations, Illustrations not Transmitted+++++++++
7. Concluding Remarks
We presented a method to calculate the propulsive performance
of a ship under the free surface effect and compared the calculated
results with experimental ones. Though the viscous effects are only
roughly taken into consideration, the main features of mutual
interactions among the hull, the propeller and the rudder seem to
be explained by our method. We should improve this method in many
respects such as considerations of the trim and shrinkage of the
ship, the viscous flows around the ship and the nonlinear effects
around the stem and so on.
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