JPS62137289A - Bilge keel with rear extension part - Google Patents

Abstract

PURPOSE:To smooth velocity of flow distribution of water flow entering a propeller, by a method wherein the extension parts, extended to the rear, of bilge keel formed to the curved part of the bottom part of a ship hull, are disposed in a manner to be extended to a portion in the vicinity of a position above a propeller at the stern. CONSTITUTION:A pair of right and left bilge keels 1 and 1, adapted to relieve rolling of a ship hull 1, are formed to the curved part of the bottom part of the ship hull 4, and an extension part 1a is connected to each bilge keel 1 so that the bilge keel is extended rearward to a position in the vicinity of a position above a propeller 2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a bilge keel provided at the curved bottom of a ship, and particularly to a bilge keel provided with a rear extension portion for rectifying water flow flowing into a propeller (helical propulsion device). Regarding the bilge keel.

[Conventional technology]

Generally, the flow velocity distribution of the water flow at the stern part is as shown in Figure 3, and near the top of propeller 2,
The inflow speed of the water flow is slow, and the inflow speed of the water flow is high near the bottom of the propeller 2.

In addition, in FIG. 3, the reference numeral 6 indicates a stern frame;
7 is the bottoming, 8 is the shoe piece, VX is the longitudinal velocity component of the water flow relative to the hull, ■ is the ship speed, and
The speed distribution line shown as a solid line is the flow velocity distribution state in a light loaded state, and the speed distribution line shown as a broken line is the flow velocity distribution state in a fully loaded state.

When the propeller 2 rotates in such a water flow with an uneven velocity distribution, it is subjected to large fluctuating pressure, which generates vibrations that are propagated to the hull.

In order to reduce this hull vibration, a stern tunnel fin 11 is conventionally attached to the hull 4 from the ship side to above the propeller 2, as shown in FIGS. 1 to 6.

By installing such a stern tunnel fin 11, the water flow from the ship side can be diverted from the stern to the stern tunnel fin 1.
1 above the propeller 2, the water flow becomes faster in areas where the water flow was slow, the speed distribution of the water flow flowing into the propeller 2 is smoothed, and ship vibration due to uneven flow speed distribution can be reduced. .

Note that the propeller 2 is not shown in Figure 54.

[Problem that the invention seeks to solve]

However, as described above, in the conventional means of attaching the stern tunnel fin 11, the stern tunnel fin 11 is large and heavy as a structure, and the stern tunnel fin 11 is attached at a location where the curved surface of the stern section has a large change. Since it is a part, there are problems in that the installation work is difficult and costs are high.

Furthermore, there is also the problem that the stern 1 neck fin 11 itself becomes a major drag on propulsion performance.

By the way, as shown in FIG. 7, conventionally, the hull 4 is sometimes provided with a bilge keel 1' in order to reduce rolling of the hull 4. This bilge keel 1' normally has a length of about one-fourth of the length of the ship's length and is attached to the curved bottom of the ship's hull 4, but it is used for purposes other than reducing the above-mentioned rolling. It has not been.

The present invention aims to solve the above-mentioned problems, and uses a bilge keel to straighten the water flow flowing into the propeller, thereby easily and at low cost without causing an increase in hull resistance. The purpose of the present invention is to provide a bilge keel with an aft extension that can be peeled off to reduce hull vibration.

[Means for solving problems]

For this reason, the bilge keel with one aft part of the present invention is characterized in that the bilge keel is provided at the bottom curved part of the hull, and the rearward extension part of the bilge keel is disposed near above the propeller at the stern. It is said that

[For production]

In the above-mentioned bilge keel with rear extension part of the present invention, the rear extension part of the bilge keel provided at the bottom curved part of the hull is disposed near above the propeller at the stern, so that the front part of the hull is The water flow that is generated under the bottom of the ship is guided above the propeller along the bilge keel, increasing the flow velocity of the water flow above the propeller, and smoothing the flow velocity distribution of the water flow flowing into the propeller.

〔Example〕

Below, a bilge keel with a rear extension part as an embodiment of the present invention will be explained with reference to the drawings: Figure S1 is a perspective view of a ship equipped with the bilge keel, and Figure 2 is an enlarged perspective view of the stern of the ship. It is a diagram.

As shown in Figure 1.2, the curved bottom of the hull 4 has a Q
A pair of left and right bilge keels 1.1 are provided to reduce H3H2O2 shaking, and each bilge keel 1 has a
The extension part 1a is connected so as to go rearward and reach near the upper part f/Y of the propeller 2.

In FIG. 1, reference numeral 3 indicates a rudder, and 5 indicates a water flow, and in FIG. 2, the opening 3 is omitted from illustration.

Since the bilge keel with the rear extension part as an embodiment of the present invention is configured as described above, the water flow 5 from the hull 4 is directed along the bilge keel 1.1 while the ship is running. , 1 is guided to the extension portions La, 1a and flows above the propeller 2. As a result, the flow velocity above the propeller 2, where the flow velocity of the water flow was conventionally slow, can be increased.
Since the flow velocity distribution of the water flow, which was uneven near the propeller 2, is now made uniform, the propeller 2 rotating in the same water flow is no longer subject to large fluctuating pressure, and changes in the generation of thrust F in the circumferential direction of the propeller 2 are reduced. This reduces hull vibration and improves the comfort of the hull 4.

Furthermore, since hull vibration is reduced, vibration-proof reinforcing members are not required.

Furthermore, by extending the bilge keel 1, it becomes possible to more reliably reduce the rolling of the ship body 1 by the original action of the bilge keel 1.

Moreover, the stern tunnel fins (
(See reference numeral 11 in Figs. 4 to 6), in this embodiment, the water flow can be efficiently guided above the propeller 2 by extending the bilge keel 1 to the upper blade of the propeller 2, which is an extremely low-cost and easy operation. In addition, the structure is smaller and lighter, and the flow velocity flowing into the propeller 2 is smoothed, so propulsion efficiency is greatly increased.

〔Effect of the invention〕

As described in detail above, according to the bilge keel with the rear extension part of the present invention, the bilge keel is provided at the bottom curved part of the hull, and the rear extension part of the bilge keel is arranged up to near above the propeller at the stern. With this simple configuration, water flow from the front of the ship can be guided above the propeller along the bilge keel and its extension while the ship is sailing.
This makes it possible to equalize the flow velocity distribution of the water flow near the propeller, so the propeller rotating in the same water flow is no longer subject to large fluctuating pressures, significantly reducing hull vibration and improving the comfort of the hull. Further, by extending the bilge keel, the 'WL shaking of the hull can be more reliably reduced by the original action of the bilge keel.

Furthermore, by extending the bilge keel above the propeller, which is an extremely low-cost and easy process, water flow can be efficiently guided above the propeller, and the flow velocity flowing into the propeller can be smoothed out without increasing hull resistance. 7
``L, so it has the advantage of greatly increasing propulsion efficiency.

[Brief explanation of drawings]

Figure 1.2 shows a bilge keel with a rear extension as an embodiment of the present invention, Figure 1 is a perspective view of a ship equipped with the bilge keel, and Figure 1.2 is an enlarged view of the stern of the ship. Fig. 3 is a flow velocity distribution diagram of the water flow near the propeller of a normal ship during navigation, and Fig. 3 shows a conventional ship vibration prevention means using stern tunnel fins Fig. f54 is a perspective view of the stern of the ship equipped with the stern tunnel fin, Fig. 5 is a side view of the stern, and Fig. 6 is a perspective view of the stern of the ship equipped with the stern tunnel fin.
It is a sectional view taken along the line ■-■ in the figure, and FIG. 7 is a perspective view of a ship swinging a conventional bilge keel. 1...Bilge keel, 1a...Bilge keel extension,
2. Propeller, 3. Rudder, 4. Hull, 5. Water flow. Sub-Agent Patent Attorney Yoshihiko Iinuma Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 ■4 Figure 6 Figure 7

Claims (1)

[Claims] A bilge keel with an aft extension section, characterized in that a bilge keel is provided at the bottom curved part of the hull, and the aft extension part of the bilge keel is arranged up to near above the propeller at the stern.