BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
[0001] The present invention relates to finned rudders provided on ships to change their
course.
2. DESCRIPTION OF RELATED ART
[0002] In the related art, there are known structures for converting a rotational flow from
a propeller to a flow in the propulsion direction in order to improve the propulsion
performance. For example, Japanese Unexamined Patent Application, Publication No.
HEI-6-305487 discloses a structure in which horizontal fins whose inclination angle (twist angle)
is set relative to the inflow angle, which changes according to the distance from
the center of the propeller shaft, are provided on the port and starboard sides of
a center axis position of a rudder bulb. In another known structure, in order to improve
the propulsion performance, a bulb is added to the leading edge of the rudder near
the center of the propeller shaft, and horizontal fins at the same heights on the
left and right are provided integrally with this bulb, see Japanese Unexamined Patent
Application, Publication No.
HEI-11-139395 which constitutes the closest prior art.
[0003] However, as a result of detailed analysis by the present inventors of the flow field
around a rudder behind the ship's propeller that runs clockwise, it was found that
a water flow like that shown in Fig. 12 is generated at the leading edge of the rudder
plate, and a water flow like that shown in Fig. 13 is generated at the center position
of the rudder shaft. As can be understood from Figs. 12 and 13, at the port side of
the ship's rudder R (the right side in Figs. 12 and 13), the upward flow is strong
inside a rotation radius P of the screw propeller above a center position C, and the
downward flow is strong near the rudder R. On the other hand, at the starboard side
of the rudder (the left side in Figs. 12 and 13), the downward flow is strong inside
the rotation radius P of the screw propeller below the center position C, and the
downward flow is strong near the rudder R.
[0004] Accordingly, at the center position of the rudder shaft in the propeller wake, the
flows above and below the center position, as well as the strengths of the flows,
significantly differ at the port and starboard sides where the propeller rotation
directions are different, as described above. Therefore, as described in Japanese
Unexamined Patent Application, Publication No.
HEI-6-305487 and Japanese Unexamined Patent Application, Publication No.
HEI-11-139395, there is a problem in that it is not possible to efficiently improve the propulsion
efficiency in the propeller wake with horizontal fins provided at the same height
on the port and starboard sides at the shaft center position and close to the center.
[0005] Figs. 12 and 13, which show the flow field analysis results obtained at a Reynold's
number of 1,080,000 and a screw propeller rotational speed of 7.8 rps, illustrate
forward motion as viewed from the bow side. The screw propeller, which is not shown
in the figures, rotates clockwise, as viewed from the stern side, during forward motion.
The directions of the arrows in these figures indicate the directions of flows in
the plane thereof, and the lengths of the arrows indicate the magnitudes of the flows.
In particular, the downward flow is strong below the center line of the propeller
on the starboard side of the rudder.
BRIEF SUMMARY OF THE INVENTION
[0006] The present invention as defined by independent claims 1 and 2 has been conceived
in light of the circumstances described above, and an object thereof is to provide
a finned rudder, as well as a ship provided therewith, that can increase the wake
gain by more effectively rectifying the flow of water behind a screw propeller, thereby
improving the propulsion performance (propulsion efficiency).
[0007] In order to solve the problems described above, the present invention employs the
solutions defined in the claims.
[0008] A first aspect of a finned rudder according to the present invention is a finned
rudder, disposed aftward of a screw propeller, for changing the course of a ship and
provided with a first fin in a port-side rudder surface and a second fin in a starboard-side
rudder surface. When the screw propeller rotates clockwise, as viewed from a stern
side, during forward motion, a first end of the first fin is attached at a position
higher than a center position of the screw propeller on a leading edge side of a central
portion of the port-side rudder surface, and a first end of the second fin is attached
at a position lower than the center position of the screw propeller on the leading
edge side of a central portion of the starboard-side rudder surface. When the screw
propeller rotates anticlockwise, as viewed from the stern side, during forward motion,
the first end of the first fin is attached at a position lower than the center position
of the screw propeller on the leading edge side of the central portion of the port-side
rudder surface, and the first end of the second fin is attached at a position higher
than the center position of the screw propeller on the leading edge side of the central
portion of the starboard-side rudder surface. The second end of each fin horizontally
extends to a position inside a rotation radius of the screw propeller where an upward
or downward flow is strong.
[0009] A second aspect of a finned rudder according to the present invention is a finned
rudder, disposed aftward of a screw propeller that rotates clockwise as viewed from
a stern side during forward motion, for changing a course of a ship and provided with
a first fin in a port-side rudder surface and a second fin in a starboard-side rudder
surface. A first end of the first fin is attached at a position higher than a center
position of the screw propeller on a leading edge side of a central portion of the
port-side rudder surface, and a first end of the second fin is attached at a position
lower than the center position of the screw propeller on the leading edge side of
a central portion of the starboard-side rudder surface; a second end of the first
fin extends at an upward inclination to a position inside a rotation radius of the
screw propeller where an upward flow is strong; and a second end of the second fin
extends horizontally to a position inside the rotation radius of the screw propeller
where a downward flow is strong.
[0010] When disposed aftward of a screw propeller that rotates anticlockwise, as viewed
from the stern side, during forward motion, the positional relationship of the first
fin and the second fin is inverted left-right.
[0011] With the finned rudder according to the present invention, because a fin presenting
an appropriate angle relative to the falling, rising, and swirling flows near the
rudder generates thrust, the hull resistance can be reduced, thus decreasing the propulsion
horsepower. By moving the attachment position of the fin up or down, as shown in Fig.
7, or by inclining the attachment angle, as shown in Fig. 8, to be better adapted
to the flow around the rudder, it is possible to achieve a greater reduction in the
propulsion horsepower with the fin.
[0012] As shown in Fig. 13, the flow at the upper port-side of the rudder surface may approach
a swirling flow formed by combining the rising flow and the inward flow. In such a
case, if the attachment angle of the fin is directed at an upward inclination, it
is possible to achieve a greater thrust production effect with the fin.
[0013] In the finned rudder described above, preferably, a rudder bulb formed of a raised
bump is provided at a leading edge portion opposing a propeller boss of the screw
propeller, and a leading edge thereof is twisted in conformance with the inflow direction
of a wake from the screw propeller.
[0014] With the finned rudder having this configuration, the flow generated from the aft
end of the propeller boss is made to flow along the surface of the rudder bulb, thereby
attenuating the boss vortex. Therefore, it is possible to reduce the vortex resistance
and to further improve the propulsion performance (propulsion efficiency).
[0015] The leading edges of the finned rudder are twisted in opposite directions at the
top and bottom in conformance with the inflow direction of the wake from the screw
propeller, and a gap that would normally occur at the height of the propeller shaft
at the leading edges of the rudder, causing cavitation, is eliminated by the rudder
bulb. It is thus possible to inhibit rudder cavitation produced at the leading edge,
which makes it possible to prevent erosion of the rudder surface and paint peeling
off from the rudder surface.
[0016] The second end of the leading edge is connected to the top of the rudder bulb, and
the first end of the leading edge is connected to the bottom of the rudder bulb. In
other words, because the first and second ends of the leading edge are connected via
the rudder bulb, it is possible to simplify processing of the leading edge and to
improve the manufacturability.
[0017] In the finned rudder described above, preferably, the first fin is formed so as to
have a wing shape in cross section and an upward camber, and the second fin is formed
so as to have a wing shape in cross section and a downward camber.
[0018] With the finned rudder having this configuration, cambers that are oriented so as
to increase the dynamic lift are provided in the respective fins. Thus, because the
forward component of this lift acts as a thrust that propels the hull of the ship
in the forward direction, this thrust acts on the hull, and the hull resistance decreases.
[0019] Accordingly, it is possible to further improve the propulsion performance (propulsion
efficiency).
[0020] With the finned rudder according to the present invention, because a fin presenting
an appropriate angle relative to the falling, rising, and swirling flows near the
rudder generates thrust, the hull resistance can be reduced, thus decreasing the propulsion
horsepower.
[0021] The finned rudder according to the present invention affords an advantage in that,
because a fin presenting an appropriate angle relative to the falling, rising, and
swirling flows near the rudder generates thrust, the hull resistance can be reduced
and the fuel efficiency can be improved.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0022]
Fig. 1 is a right side view, taken from the starboard side, of a stern portion of
a ship equipped with a finned rudder according to a first embodiment of the present
invention.
Fig. 2 is a left side view, taken from the port side, of the stern portion of the
ship equipped with the finned rudder according to the first embodiment of the present
invention.
Fig. 3 is an elevational view, taken from the bow side, of the finned rudder according
to the first embodiment of the present invention.
Fig. 4 is a graph showing experimental results obtained by propelling a ship equipped
with the finned rudder according to the first embodiment of the present invention.
Fig. 5 is a right side view, taken from the starboard side, of a stern portion of
a ship equipped with a finned rudder according to a second embodiment of the present
invention.
Fig. 6 is a left side view, taken from the port side, of the stern portion of the
ship equipped with the finned rudder according to the second embodiment of the present
invention.
Fig. 7 is an elevational view, taken from the bow side, of the finned rudder according
to the second embodiment of the present invention.
Fig. 8 is an elevational view, taken from the bow side, of a finned rudder according
to a third embodiment of the present invention.
Fig. 9 is a right side view, taken from the starboard side, of a stern portion of
a ship equipped with a finned rudder according to a fourth embodiment of the present
invention.
Fig. 10 is a left side view, taken from the port side, of the stern portion of the
ship equipped with the finned rudder according to the fourth embodiment of the present
invention.
Fig. 11 is an elevational view, taken from the bow side, of a finned rudder according
to a fourth embodiment of the present invention.
Fig. 12 is a view, taken from the bow side, of water flow at a leading edge of a rudder
plate of a ship equipped with a conventional ship's rudder.
Fig. 13 is a view, taken from the bow side, of water flow at a center position of
a rudder shaft of a ship equipped with a conventional ship's rudder.
DETAILED DESCRIPTION OF THE INVENTION
[0023] A first embodiment of a finned rudder according to the present invention will be
described below with reference to Figs. 1 to 4.
[0024] Fig. 1 is a right side view, taken from the starboard side, of a stern portion of
a ship equipped with a finned rudder according to this embodiment; Fig. 2 is a left
side view, taken from the port side, of the stern portion of the ship equipped with
the finned rudder according to this embodiment; Fig. 3 is an elevational view, taken
from the bow side, of the finned rudder according to this embodiment; and Fig. 4 is
a graph showing experimental results obtained by propelling the ship equipped with
the finned rudder according to this embodiment.
[0025] As shown in Fig. 1 or 2, a finned rudder 10 according to this embodiment is a plate-shaped
member which is attached to a rudder shaft 5 that extends vertically downward from
a stern bottom 4 of a stern portion 3 located aftward (on the stern side) of a screw
propeller 2, and is rotated about a vertical axis together with the rudder shaft 5
to change the course of a ship 1.
[0026] The screw propeller 2 is attached to the aft end (the end at the stern side) of a
propeller shaft 7 that passes through a bossing 6. The screw propeller 2 rotates together
with the propeller shaft 7, clockwise (right) as viewed from the stern side during
forward motion, and anticlockwise (left) as viewed from the stern side during reverse
motion.
[0027] A first fin 12 is provided in (attached to) a port-side rudder surface 11 of the
finned rudder 10 according to this embodiment, and a second fin 14 is provided in
(attached to) a starboard-side rudder surface 13 of the finned rudder 10.
[0028] As shown in Figs. 2 and 3, the first fin 12, a first end (root) of which is towards
the leading edge of a center portion of the rudder surface 11, is a small blade having
a wing shape in cross-section and an upward camber and is attached higher than a center
position C of the screw propeller 2 so as to extend horizontally (outward towards
the port side in Fig. 3). A second end (tip) of the first fin 12 extends to a position
(region) inside the rotation radius P (see Figs. 12 and 13) of the screw propeller
2 where the upward flow is strong.
[0029] As shown in Fig. 1 and 3, the second fin 14, a first end (root) of which is towards
the leading edge of a center portion of the rudder surface 13, is a small blade having
a wing shape in cross-section and a downward camber and is attached lower than the
center position C of the screw propeller 2 so as to extend horizontally (outward towards
the starboard side in Fig. 3). A second end (the tip) of the second fin 14 extends
to a position (region) inside the rotation radius P (see Figs. 12 and 13) of the screw
propeller 2 where the downward flow is strong.
[0030] With the finned rudder 10 according to this embodiment, an upward flow generated
inside the rotation radius P of the screw propeller 2, which is produced close to
the rudder surface 11, and above the center position C of the screw propeller 2 is
attenuated (inhibited) by the first fin 12. Additionally, a downward flow generated
inside the rotation radius P of the screw propeller 2, which is produced close to
the rudder surface 13, and below the center position C of the screw propeller 2 is
attenuated (inhibited) by the second fin 14.
[0031] Thus, it is possible to reduce hull resistance by rectifying the upward and downward
flows near the rudder surfaces. In other words, by utilizing a lift generated by the
fins on the rudder surfaces from the upward and downward flows, it is possible to
improve the propulsion performance (propulsion efficiency).
[0032] Fig. 4 is a graph of experimental results obtained by propelling a ship equipped
with the finned rudder 10 according to this embodiment, showing ship speed (kn: knots)
on the horizontal axis and horsepower (kW) on the vertical axis. The broken line drawn
from the bottom left to the top right in this figure is data obtained from a ship
that is not equipped with the finned rudder 10 according to this embodiment, and the
solid line drawn from the bottom left to the top right is data obtained from the ship
equipped with the finned rudder 10 according to this embodiment.
[0033] As shown in Fig. 4, the ship equipped with the finned rudder 10 according to this
embodiment requires less horsepower to attain the same speed as a ship that is not
equipped with the finned rudder 10 according to this embodiment, and the speed is
higher (increased) when applying the same horsepower as the ship that is not equipped
with the finned rudder 10 according to this embodiment. Accordingly, a reduction in
fuel consumption of about 2% compared with the conventional case can be achieved,
which is an effective experimental result demonstrating the above-described advantages
of the finned rudder 10 according to this embodiment.
[0034] Furthermore, with the finned rudder 10 according to this embodiment, the fin 12 is
given an upward camber by attaching it to the corresponding rudder surface 11 so that
the leading edge thereof is located lower than the trailing edge, and the fin 14 is
given a downward camber by attaching it to the corresponding rudder surface 13 so
that the leading edge thereof is located higher than the trailing edge. Therefore,
it is possible to generate upward and downward lifts at the bow side of the respective
fins 12 and 14. Because the forward component of these lifts serves as thrust propelling
the hull of the ship 1 in the forward direction, this thrust acts on the hull, reducing
the hull resistance.
[0035] Accordingly, the propulsion performance (propulsion efficiency) can be improved.
[0036] A finned rudder according to a second embodiment of the present invention will be
described with reference to Figs. 5 to 7. Fig. 5 is a right side view, taken from
the starboard side, of a stern portion of a ship equipped with a finned rudder according
to this embodiment, Fig. 6 is a left side view, taken from the port side, of the stern
portion of the ship equipped with the finned rudder according to this embodiment,
and Fig. 7 is an elevational view, taken from the bow side, of the finned rudder according
to this embodiment.
[0037] As shown in Figs. 5 to 7, a finned rudder 20 according to this embodiment differs
from that in the first embodiment described above in that it includes a rudder bulb
21, and as shown in Fig. 7, leading edges 22 and 23 thereof are inclined with respect
to the perpendicular axis (vertical axis). The other components are the same as those
in the first embodiment described above, and a description thereof is thus omitted
here.
[0038] The rudder bulb 21 is a raised bump provided at the leading edge of the finned rudder
20 at a position facing the propeller boss 2a (see Fig. 1 or Fig. 2) of the screw
propeller 2 (see Fig. 1 or Fig. 2). As shown in Figs. 5 and 6, it steeply increases
in diameter at the leading edge of the finned rudder 20 from the bow-side end face
opposing the propeller boss 2a, and gently reduces in diameter from the leading edge
of the finned rudder 20 towards the trailing edge. The second fin 14 is provided below
the rudder bulb 21 at the wake side of the leading edge of the finned rudder 20, as
shown in Fig. 5. The first fin 12 is provided above the rudder bulb 21 on the wake
side of the leading edge of the rudder 20, as shown in Fig. 6. Accordingly, in view
of the flow field near the rudder, it is possible to obtain the most effective thrust
by providing the first fin 12 and the second fin 14 in the vicinity of the rudder
bulb 21 at the wake side of the leading edge of the finned rudder 20. As shown in
Fig. 7, the cross-sectional shape of the rudder bulb 21 is substantially circular,
and the cross section thereof has the same shape at all positions from the bow side
to the stern side.
[0039] This rudder bulb 21 inhibits a boss vortex produced from the aft end of the propeller
boss 2a; in other words, it attenuates (collects) the boss vortex by making the flow
produced from the aft end of the propeller boss 2a flow along the surface of the rudder
bulb 21, thus reducing vortex resistance and improving the propulsion performance
(propulsion efficiency).
[0040] Regarding the leading edge 22 which is located above the rudder bulb 21, that is
to say, at the top end of the rudder bulb 21, as shown in Fig. 7, a first end thereof
(the top end) is located at the same position as the center position C of the screw
propeller 2 or on the starboard side of the center position C of the screw propeller
2, and a second end thereof (the bottom end) is located on the port side of the center
position C of the screw propeller 2. Additionally, the leading edge 22 is formed so
as to form a substantially straight line from the first end to the second end thereof.
The second end of the leading edge 22 is connected to the top of the rudder bulb 21.
[0041] On the other hand, regarding the leading edge 23 which is located below the rudder
bulb 21, that is to say, at the bottom end of the rudder bulb 21, a first end thereof
(the top end) is located on the starboard side of the center position C of the screw
propeller 2, and a second end thereof (the bottom end) is located at the same position
as the center position C of the screw propeller 2 or on the starboard side of the
center position C of the screw propeller 2. Additionally, the leading edge 23 is formed
so as to form a substantially straight line from the first end to the second end thereof.
The first end of the leading edge 23 is connected to the bottom of the rudder bulb
21.
[0042] In other words, the leading edges 22 and 23 are twisted in conformance with the inflow
direction of the wake from the screw propeller 2, thereby reducing the inflow directions
at the finned rudder 20 (inflow angle) from the screw propeller 2, and inhibiting
rudder cavitation produced by the leading edges 22 and 23 of the finned rudder 20.
[0043] With the finned rudder 20 according to this embodiment, by means of the rudder bulb
21, the flow produced from the aft end of the propeller boss 2a is made to flow along
the surface of the rudder bulb 21, thereby attenuating boss vortex. Therefore, it
is possible to decrease vortex resistance and to further improve the propulsion performance
(propulsion efficiency).
[0044] Because the leading edges 22 and 23 of the finned rudder 20 are twisted in conformance
with the inflow direction of the wake from the screw propeller 2, thereby reducing
the inflow directions (inflow angle) of the wake from the screw propeller 2 at the
finned rudder 20, it is possible to inhibit rudder cavitation produced by the leading
edges 22 and 23, and to prevent erosion of the rudder surfaces 11 and 13 and peeling
of paint from the rudder surfaces 11 and 13. In particular, with high-speed ships
such as container ships, there is a possibility of erosion and paint peeling due to
rudder cavitation. There is a significant reduction in rudder cavitation when the
present invention is applied to high-speed ships such as container ships.
[0045] The second end of the leading edge 22 is connected to the top of the rudder bulb
21, and the first end of the leading edge 23 is connected to the bottom of the rudder
bulb 21. One problem with this kind of reaction rudder is that, because the twist
direction is reversed at the center of the propeller shaft, a step occurs at the leading
edge of the rudder, causing cavitation at this step portion and making the processing
difficult. With the present invention, however, because the second end of the leading
edge 22 and the first end of the leading edge 23 are connected via the rudder bulb
21, no step occurs at the leading edge of the rudder, thus preventing the occurrence
of cavitation. In addition, processing of the leading edge can be simplified and the
manufacturability improved.
[0046] The other operation and effects are identical to those of the first embodiment described
above, and a description thereof is thus omitted here.
[0047] A finned rudder according to a third embodiment of the present invention will now
be described with reference to Fig. 8. Fig. 8 is an elevational view, taken from the
bow side, of a finned rudder 30 according to this embodiment.
[0048] The finned rudder 30 according to this embodiment differs from that in the first
embodiment described above in that a first fin 31 is provided instead of the first
fin 12. The other components are the same as those in the first embodiment described
above, and therefore, a description thereof will be omitted here.
[0049] As shown in Fig. 8, the first fin 31, a first end (root) of which is towards the
leading edge of a center portion of the rudder surface 11, is a small blade having
a wing shape in cross-section and an upward camber and is attached higher than the
center position C of the screw propeller 2 so as to extend upward at an angle (towards
the upper right in Fig. 8). A second end (tip) of the first fin 31 extends to a position
(region) inside the rotation radius P (see Figs. 12 and 13) of the screw propeller
2 where the upward flow is strongest.
[0050] As shown in Fig. 13, a flow that approaches a swirling flow formed as a combination
of the rising flow and the inward flow may occur at the upper port side of the rudder
surface; in such cases, it is possible to further increase the thrust producing effect
of the fin by directing the attachment angle thereof at an upward inclination, as
with the first fin 31 according to this embodiment.
[0051] The other operation and effects are the same as those in the first embodiment described
above, and a description thereof is thus omitted here.
[0052] A finned rudder according to a fourth embodiment of the present invention will now
be described with reference to Figs. 9 to 11. Fig. 9 is a right side view, taken from
the starboard side, of a stern portion of a ship equipped with a finned rudder according
to this embodiment, Fig. 10 is a left side view, taken from the port side, of the
stern portion of the ship equipped with the finned rudder according to this embodiment,
and Fig. 11 is an elevational view, taken from the bow side, of the finned rudder
according to this embodiment.
[0053] A finned rudder 40 according to this embodiment differs from that in the second embodiment
described above in that a first fin 41 is provided instead of the first fin 12. The
other components are identical to those in the second embodiment described above,
and therefore, a description thereof is omitted here.
[0054] As shown in Fig. 10 and Fig. 11, the first fin 41 according to this embodiment, a
first end (root) of which is towards the trailing edge of the top of the rudder bulb
21, is a small blade having a wing shape in cross-section and an upward camber and
is attached higher than the center position C of the screw propeller 2 so as to extend
at an upward inclination (towards the upper right in Fig. 11). A second end (tip)
of the first fin 41 extends to a position (region) inside the rotation radius P (see
Figs. 12 and 13) of the screw propeller 2 where the upward flow is strongest.
[0055] The operation and effects of the finned rudder 40 according to this embodiment are
the same as those of the third embodiment described above, and therefore, a description
thereof is omitted here.
[0056] Because the flows shown in Figs. 12 and 13 differ from ship to ship, it is preferable
to perform flow field analysis for each ship to identify regions where the first fin
and the second fin are most effective. The present invention is not limited to the
embodiments described above; various modifications are permissible as required, so
long as they do not depart from the technical idea of the present invention.
[0057] In addition, the finned rudder according to the present invention can be applied
to ships and commercial vessels such as gas carriers, tankers, container ships, ferries,
roll-on roll-off (RORO) ships, car carriers, bulk carriers, and passenger ships. It
is possible to thereby reduce the propulsion horsepower and improve fuel efficiency,
thus holding promise for low-energy ships.
1. A finned rudder (20) for changing the course of a ship (1), comprising:
a first fin (12) provided at a port-side rudder surface (11) and a second fin (14)
provided at a starboard-side rudder surface (13),
wherein,
when the finned rudder (20) is intended to be disposed in a vertical orientation aftward
of a screw propeller (2) which is designed to rotate clockwise, as viewed from a stern
side, during forward motion of the ship (1), a first end of the first fin (12) is
attached to the rudder surface at a position higher than a center position (C) of
the screw propeller (2) and toward a leading edge side of a central portion of the
port-side rudder surface (11), and a first end of the second fin (14) is attached
to the rudder surface at a position lower than the center position (C) of the screw
propeller (2) and toward the leading edge side of a central portion of the starboard-side
rudder surface (13) ; or
when the finned rudder (20) is intended to be disposed in a vertical orientation aftward
of a screw propeller (2) which is designed to rotate anticlockwise, as viewed from
the stern side, during forward motion of the ship (1), a first end of the first fin
(12) is attached to the rudder surface at a position lower than a center position
(C) of the screw propeller (2) and toward a leading edge side of a central portion
of the port-side rudder surface (11), and a first end of the second fin (14) is attached
to the rudder surface at a position higher than the center position (C) of the screw
propeller (2) and toward the leading edge side of the central portion of the starboard-side
rudder surface (13); and
a second end of each fin (12,14) extends horizontally to a position inside a rotation
radius (P) of the screw propeller (2) where an upward or downward flow is strong;
and
a rudder bulb (21) formed of a raised bump provided at a leading edge portion of the
finned rudder (20) opposing a propeller boss (2a) of the screw propeller (2);
characterized in that
a leading edge (22,23) of the finned rudder (20) is twisted in conformance with the
inflow direction of a wake from the screw propeller (2); and
the first fin (12) and the second fin (14) are provided in the vicinity of the rudder
bulb (21) at the wake side of the leading edge (22,23) of the finned rudder (20).
2. A finned rudder (30;40) for changing a course of a ship (1), comprising:
a first fin (31;41) provided at a port-side rudder surface (11) and a second fin (14)
provided at a starboard-side rudder surface (13),
wherein, when the finned rudder (30;40) is intended to be disposed in a vertical orientation
aftward of a screw propeller (2) which is designed to rotate clockwise, as viewed
from a stern side, during forward motion of the ship (1), a first end of the first
fin (31;41) is attached to the rudder surface at a position higher than a center position
(C) of the screw propeller (2) and toward a leading edge side of a central portion
of the port-side rudder surface (11), and a first end of the second fin (14) is attached
to the rudder surface at a position lower than the center position (C) of the screw
propeller (2) and toward the leading edge side of a central portion of the starboard-side
rudder surface (13); and
a second end of the second fin (14) extends horizontally to a position inside the
rotation radius (P) of the screw propeller (2) where a downward flow is strong;
characterized in that
a second end of the first fin (31;41) extends at an upward inclination to a position
inside a rotation radius (P) of the screw propeller (2) where an upward flow is strong.
3. The finned rudder according to claim 2, wherein a rudder bulb (21) formed of a raised
bump is provided at a leading edge portion of the finned rudder (40) opposing a propeller
boss (2a) of the screw propeller (2), and a leading edge (22,23) thereof is twisted
in conformance with the inflow direction of a wake from the screw propeller (2).
4. The finned rudder according to claim 1 or 3, wherein
a first end of the leading edge (22) which is located above the rudder bulb (21) is
located at the same position or on the starboard-side of the center position (C) of
the screw propeller (2), and
a second end of the leading edge (22) which is located above the rudder bulb (21)
is located on the port-side of the center position (C) of the screw propeller (2),
and wherein
a first end of the leading edge (23) which is located below the rudder bulb (21) is
located on the starboard-side of the center position (C) of the screw propeller (2),
and
a second end of the leading edge (23) which is located below the rudder bulb (21)
is located at the same position or on the starboard-side of the center position (C)
of the screw propeller (2).
5. The finned rudder according to claim 4, wherein
the leading edge (22) which is located above the rudder bulb (21) is formed so as
to form a substantially straight line from the first end to the second end thereof,
and the second end is connected to the top of the rudder bulb (21), and
the leading edge (23) which is located below the rudder bulb (21) is formed so as
to form a substantially straight line from the first end to the second end thereof,
and the first end is connected to the bottom of the rudder bulb (21).
6. The finned rudder according to claim 5, wherein
the rudder bulb (21) steeply increases in diameter at the leading edge of the finned
rudder (20;40) from the bow-side end face opposing the propeller boss (2a), and gently
reduces in diameter from the leading edge of the finned rudder (20;40) towards the
trailing edge.
7. The finned rudder according to one of claims 1 to 6, wherein the first fin (12;31;41)
is formed so as to have a wing shape in cross section and an upward camber, and the
second fin (14) is formed so as to have a wing shape in cross section and a downward
camber.
8. A ship comprising a finned rudder (20;30:40) according to one of claims 1 to 7.
1. Ein Flossenruder (20) zur Kursänderung eines Schiffs (1) mit:
einer ersten Flosse (12), welche an einer backbordseitigen Ruderfläche (11) vorgesehen
ist und einer zweite Flosse (14), welche an einer steuerbordseitigen Ruderfläche (13)
vorgesehen ist,
wobei,
wenn das Flossenruder (20) in einer vertikalen Orientierung heckwärts eines Schraubenpropellers
(2), welcher, während der Vorwärtsbewegung des Schiffs (1) und von einer Bugseite
aus gesehen, für eine Drehung im Uhrzeigersinn ausgestaltet ist, ein erstes Ende der
ersten Flosse (12) an der Ruderfläche an einer höheren Position als einer Mittenposition
(C) des Schraubenpropellers (2) und zu einer Anströmkantenseite eines Mittelabschnitts
der backbordseitigen Ruderfläche (11) hin angebracht ist, und ein erstes Ende der
zweiten Flosse (14) an der Ruderfläche an einer tieferen Position als der Mittenposition
(C) des Schraubenpropellers (2) und zu der Anströmkantenseite eines Mittelabschnitts
der steuerbordseitigen Ruderfläche (13) hin angebracht ist, oder,
wenn das Flossenruder (20) in einer vertikalen Orientierung heckwärts eines Schraubenpropellers
(2), welcher, während der Vorwärtsbewegung des Schiffs (1) und von der Bugseite aus
gesehen, für eine Drehung im Gegenuhrzeigersinn ausgestaltet ist, ein erstes Ende
der ersten Flosse (12) an der Ruderfläche an einer tieferen Position als der Mittenposition
(C) des Schraubenpropellers (2) und zu einer Anströmkantenseite eines Mittelabschnitts
der backbordseitigen Ruderfläche (11) hin angebracht ist, und ein erstes Ende der
zweiten Flosse (14) an der Ruderfläche an einer höheren Position als der Mittenposition
(C) des Schraubenpropellers (2) und zu der Anströmkantenseite des Mittelabschnitts
der steuerbordseitigen Ruderfläche (13) hin angebracht ist, und
ein zweites Ende jeder Flosse (12,14) sich horizontal zu einer Position innerhalb
eines Rotationsradius (P) des Schraubenpropellers (2) erstreckt, wo eine aufwärts
oder abwärts gerichtete Strömung stark ist, und
einem Ruderwulst (21), welcher aus einem erhabenen Buckel gebildet ist, der an einem
Anströmkantenabschnitt des Flossenruders (20) gegenüberliegend einer Propellernabe
(2a) des Schraubenpropellers (2) vorgesehen ist,
dadurch gekennzeichnet, dass
eine Anströmkante (22,23) des Flossenruders (20) in Übereinstimmung mit der Einströmrichtung
eines Nachstroms von dem Schraubenpropeller (2) verdreht ist, und
die erste Flosse (12) und die zweite Flosse (14) in der Nähe des Ruderwulstes (21)
an der Nachstromseite der Anströmkante (22,23) des Flossenruders (20) vorgesehen sind.
2. Ein Flossenruder (30;40) zur Kursänderung eines Schiffs (1) mit:
einer ersten Flosse (31;41), welche an einer backbordseitigen Ruderfläche (11) vorgesehen
ist und eine zweite Flosse (14), welche an einer steuerbordseitigen Ruderfläche (13)
vorgesehen ist, und
ein erstes Ende der zweiten Flosse (14) an der Ruderfläche an einer tieferen Position
als der Mittenposition (C) des Schraubenpropellers (2) und zu der Anströmkantenseite
eines Mittelabschnitts der steuerbordseitigen Ruderfläche (13) hin angebracht ist,
wobei, wenn das Flossenruder (30;40) in einer vertikalen Orientierung heckwärts eines
Schraubenpropellers (2), welcher, während der Vorwärtsbewegung des Schiffs (1) und
von einer Bugseite aus gesehen, für eine Drehung im Uhrzeigersinn ausgestaltet ist,
ein erstes Ende der ersten Flosse (31;41) an der Ruderfläche an einer höheren Position
als einer Mittenposition (C) des Schraubenpropellers (2) und zu einer Anströmkantenseite
eines Mittelabschnitts der backbordseitigen Ruderfläche (11) hin angebracht ist, und
ein erstes Ende der zweiten Flosse (14) an der Ruderfläche an einer tieferen Position
als der Mittenposition (C) des Schraubenpropellers (2) und zu der Anströmkantenseite
eines Mittelabschnitts der steuerbordseitigen Ruderfläche (13) hin angebracht ist,
und
ein zweites Ende der zweiten Flosse (14) sich horizontal zu einer Position innerhalb
des Rotationsradius (P) des Schraubenpropellers (2) erstreckt, wo eine abwärts gerichtete
Strömung stark ist,
dadurch gekennzeichnet, dass
ein zweites Ende der ersten Flosse (31;41) sich in einer aufwärts gerichteten Neigung
zu einer Position innerhalb eines Rotationsradius (P) des Schraubenpropellers (2)
erstreckt, wo eine aufwärts gerichtete Strömung stark ist.
3. Das Flossenruder gemäß Anspruch 2, wobei ein Ruderwulst (21), welcher aus einem erhabenen
Buckel gebildet ist, an einem Anströmkantenabschnitt des Flossenruders (40) gegenüberliegend
einer Propellernabe (2a) des Schraubenpropellers (2), vorgesehen ist, und eine Anströmkante
(22,23) davon in Übereinstimmung mit der Einströmrichtung eines Nachstroms von dem
Schraubenpropeller (2) verdreht ist.
4. Das Flossenruder gemäß Anspruch 1 oder 3, wobei
ein erstes Ende der Anströmkante (22), welches oberhalb des Ruderwulstes (21) angeordnet
ist, an derselben Position oder auf der Steuerbordseite der Mittenposition (C) des
Schraubenpropellers (2) angeordnet ist, und
ein zweites Ende der Anströmkante (22), welches oberhalb des Ruderwulstes (21) angeordnet
ist, auf der Backbordseite der Mittenposition (C) des Schraubenpropellers (2) angeordnet
ist, und
wobei ein erstes Ende der Anströmkante (23), welches unterhalb des Ruderwulstes (21)
angeordnet ist, auf der Steuerbordseite der Mittenposition (C) des Schraubenpropellers
(2) angeordnet ist, und
ein zweites Ende der Anströmkante (23), welches unterhalb des Ruderwulstes (21) angeordnet
ist, an derselben Position oder auf der Steuerbordseite der Mittenposition (C) des
Schraubenpropellers (2) angeordnet ist.
5. Das Flossenruder gemäß Anspruch 4, wobei
die Anströmkante (22), welche oberhalb des Ruderwulstes (21) angeordnet ist, derart
ausgebildet ist, dass sie eine im Wesentlichen gerade Linie von dem ersten Ende zu
dem zweiten Ende davon ausbildet, und das zweite Ende mit der Oberseite des Ruderwulstes
(21) verbunden ist, und
die Anströmkante (23), welche unterhalb des Ruderwulstes (21) angeordnet ist, derart
ausgebildet ist, dass sie eine im Wesentlichen gerade Linie von dem ersten Ende zu
dem zweiten Ende davon ausbildet, und das erste Ende mit der Unterseite des Ruderwulstes
(21) verbunden ist.
6. Das Flossenruder gemäß Anspruch 5, wobei
der Durchmesser des Ruderwulstes (21) an der Anströmkante des Flossenruders (20;40)
von der wölbungsseitigen Endfläche, welcher der Propellernabe (2a) gegenüberliegt,
stark zunimmt, und der Durchmesser von der Anströmkante des Flossenruders (20;40)
zu der Abströmkante hin sanft abnimmt.
7. Das Flossenruder gemäß einem der Ansprüche 1 bis 6, wobei die erste Flosse (12;31;41)
derart ausgebildet ist, dass sie im Querschnitt eine Flügelform und eine aufwärts
gerichtete Wölbung aufweist, und die zweite Flosse (14) derart ausgebildet ist, dass
sie im Querschnitt eine Flügelform und eine abwärts gerichtete Wölbung aufweist.
8. Ein Schiff mit einem Flossenruder (20;30;40) gemäß einem der Ansprüche 1 bis 7.
1. Gouvernail à ailerons (20) permettant de changer le cap d'un navire (1), comprenant
:
un premier aileron (12) agencé au niveau d'une surface de gouvernail côté bâbord (11)
et un second aileron (14) agencé au niveau d'une surface de gouvernail côté tribord
(13),
dans lequel,
lorsque l'on souhaite disposer le gouvernail à ailerons (20) dans une orientation
verticale vers l'arrière d'une hélice propulsive (2) qui est conçue pour tourner dans
le sens horaire, telle que vue depuis un côté poupe, pendant un mouvement vers l'avant
du navire (1), une première extrémité du premier aileron (12) est arrimée à la surface
de gouvernail en une position plus haute qu'une position centrale (C) de l'hélice
propulsive (2) et vers un côté bord d'attaque d'une portion centrale de la surface
de gouvernail côté bâbord (11), et une première extrémité du second aileron (14) est
arrimée à la surface de gouvernail en une position plus basse que la position centrale
(C) de l'hélice propulsive (2) et vers le côté bord d'attaque d'une portion centrale
de la surface de gouvernail côté tribord (13) ; ou
lorsque l'on souhaite disposer le gouvernail à ailerons (20) dans une orientation
verticale vers l'arrière d'une hélice propulsive (2) qui est conçue pour tourner dans
le sens antihoraire, telle que vue depuis le côté poupe, pendant un mouvement vers
l'avant du navire (1), une première extrémité du premier aileron (12) est arrimée
à la surface de gouvernail en une position plus basse qu'une position centrale (C)
de l'hélice propulsive (2) et vers un côté bord d'attaque d'une portion centrale de
la surface de gouvernail côté bâbord (11), et une première extrémité du second aileron
(14) est arrimée à la surface de gouvernail en une position plus haute que la position
centrale (C) de l'hélice propulsive (2) et vers le côté bord d'attaque de la portion
centrale de la surface de gouvernail côté tribord (13) ; et
une seconde extrémité de chaque aileron (12, 14) s'étend horizontalement vers une
position à l'intérieur d'un rayon de rotation (P) de l'hélice propulsive (2) où un
flux ascendant ou descendant est fort ; et
un bulbe de gouvernail (21) formé d'une bosse en saillie agencée au niveau d'une portion
de bord d'attaque du gouvernail à ailerons (20) s'opposant à un bossage d'hélice (2a)
de l'hélice propulsive (2) ;
caractérisé en ce que
un bord d'attaque (22, 23) du gouvernail à ailerons (20) est torsadé en conformité
avec la direction d'afflux d'un sillage de l'hélice propulsive (2) ; et
le premier aileron (12) et le second aileron (14) sont agencés au voisinage du bulbe
de gouvernail (21) au niveau du côté sillage du bord d'attaque (22, 23) du gouvernail
à ailerons (20).
2. Gouvernail à ailerons (30 ; 40) permettant de changer un cap d'un navire (1), comprenant
:
un premier aileron (31 ; 41) agencé au niveau d'une surface de gouvernail côté bâbord
(11) et un second aileron (14) agencé au niveau d'une surface de gouvernail côté tribord
(13),
dans lequel, lorsque l'on souhaite disposer le gouvernail à ailerons (30 ; 40) dans
une orientation verticale vers l'arrière d'une hélice propulsive (2) qui est conçue
pour tourner dans le sens horaire, telle que vue depuis un côté poupe, pendant un
mouvement vers l'avant du navire (1), une première extrémité du premier aileron (31
; 41) est arrimée à la surface de gouvernail en une position plus haute qu'une position
centrale (C) de l'hélice propulsive (2) et vers un côté bord d'attaque d'une portion
centrale de la surface de gouvernail côté bâbord (11), et une première extrémité du
second aileron (14) est arrimée à la surface de gouvernail en une position plus basse
que la position centrale (C) de l'hélice propulsive (2) et vers le côté bord d'attaque
d'une portion centrale de la surface de gouvernail côté tribord (13) ; et
une seconde extrémité du second aileron (14) s'étend horizontalement vers une position
à l'intérieur du rayon de rotation (P) de l'hélice propulsive (2) où un flux descendant
est fort ;
caractérisé en ce que
une seconde extrémité du premier aileron (31; 41) s'étend au niveau d'une inclinaison
vers le haut vers une position à l'intérieur d'un rayon de rotation (P) de l'hélice
propulsive (2) où un flux ascendant est fort.
3. Gouvernail à ailerons selon la revendication 2, dans lequel un bulbe de gouvernail
(21) formé d'une bosse en saillie est agencé au niveau d'une portion de bord d'attaque
du gouvernail à ailerons (40) s'opposant à un bossage d'hélice (2a) de l'hélice propulsive
(2), et son bord d'attaque (22, 23) est torsadé en conformité avec la direction d'afflux
d'un sillage de l'hélice propulsive (2).
4. Gouvernail à ailerons selon la revendication 1 ou 3, dans lequel
une première extrémité du bord d'attaque (22) qui est situé au-dessus du bulbe de
gouvernail (21) est située à la même position ou sur le côté tribord de la position
centrale (C) de l'hélice propulsive (2), et
une seconde extrémité du bord d'attaque (22) qui est situé au-dessus du bulbe de gouvernail
(21) est située sur le côté bâbord de la position centrale (C) de l'hélice propulsive
(2), et dans lequel
une première extrémité du bord d'attaque (23) qui est situé en dessous du bulbe de
gouvernail (21) est située sur le côté tribord de la position centrale (C) de l'hélice
propulsive (2), et
une seconde extrémité du bord d'attaque (23) qui est situé en dessous du bulbe de
gouvernail (21) est située à la même position ou sur le côté tribord de la position
centrale (C) de l'hélice propulsive (2).
5. Gouvernail à ailerons selon la revendication 4, dans lequel
le bord d'attaque (22) qui est situé au-dessus du bulbe de gouvernail (21) est formé
de façon à former une ligne sensiblement droite de sa première extrémité à sa seconde
extrémité, et la seconde extrémité est raccordée au sommet du bulbe de gouvernail
(21), et
le bord d'attaque (23) qui est situé sous le bulbe de gouvernail (21) est formé de
façon à former une ligne sensiblement droite de sa première extrémité à sa seconde
extrémité, et la première extrémité est raccordée au fond du bulbe de gouvernail (21).
6. Gouvernail à ailerons selon la revendication 5, dans lequel
le diamètre du bulbe de gouvernail (21) augmente fortement au niveau du bord d'attaque
du gouvernail à ailerons (20 ; 40) à partir de la face d'extrémité côté proue s'opposant
au bossage d'hélice (2a), et réduit modérément à partir du bord d'attaque du gouvernail
à ailerons (20, 40) vers le bord de fuite.
7. Gouvernail à ailerons selon l'une des revendications 1 à 6, dans lequel le premier
aileron (12 ; 31 ; 41) est formé de façon à avoir une forme d'aile en section et une
courbure vers le haut, et le second aileron (14) est formé de façon à avoir une forme
d'aile en section et une courbure vers le bas.
8. Navire comprenant un gouvernail à ailerons (20 ; 30 ; 40) selon l'une des revendications
1 à 7.