JPH0579558B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application: The present invention relates to an asymmetrical stern-shaped vessel, and more particularly to an asymmetrical stern-shaped vessel having a stern structure of a single-shaft vessel.

BACKGROUND ART Conventionally, in various large ships, various considerations have been made to improve propulsion efficiency. In particular, in relation to the propeller, various measures have been taken regarding the shape of the stern for the convenience of directly improving propulsion efficiency. In some cases where the stern shape is asymmetrical, it is twisted in an S-shape above and below the propeller shaft when viewed from the rear. Next, a specific example of this asymmetrical stern-shaped ship will be described with reference to FIGS. 4 and 5.

In FIG. 5, the stern end 1 including the propeller shaft 3 located on the hull centerline 6 extending in the vertical direction is twisted left and right in an S-shape around the hull centerline 6 and further around the propeller shaft 3. 1 is partially formed in the stern twist part 7 completely distributed on both sides of the hull centerline 6, forming a so-called S-shaped stern. Such an S-shaped stern with the propeller axis 3 as the point of symmetry produces a counterclockwise rotational flow when viewed from the rear, and this rotational flow also generates a clockwise rotational flow.
The propulsion efficiency is improved by reducing the rotational component in the propeller wake.

Problems to be Solved by the Invention: However, when an asymmetric stern-shaped ship with an S-shaped stern as described above was confirmed in a water tank test,
Although this type of S-shaped stern has been found to have a horsepower reduction effect on thin ships such as container ships with a large master/width ratio, it is not so effective in reducing horsepower on large ships with a small master/width ratio. was not recognized.
Various studies have revealed that the reason why this horsepower reduction effect was not observed is as follows.

In the case of an enlarged ship, as shown in Fig. 6, a pair of inward bilge vortices 11 are generated around the stern when viewed from the rear, and these bilge vortices enter the propeller surface 4, causing the right This is because the formation of a rotating flow in the opposite direction to the direction of rotation of the surrounding propeller is weakened.

The present invention aims to solve such problems, and in the case of a large ship, the formation of a rotational flow in the opposite direction to the rotational direction of the propeller is not weakened, and the horsepower reduction effect is recognized, and the propulsion efficiency is improved. The object of the present invention is to provide a ship with an asymmetric stern shape that can be improved.

Means for Solving the Problems: In order to achieve the above-mentioned object, an asymmetrical stern-shaped ship according to the present invention is an asymmetrical stern-shaped ship with a stern structure of a single-shaft ship, and the stern end extends near the propeller axis. It is biased with a curve in the left-right direction opposite to the propeller rotation direction; the upper and lower ends of the curve at the stern end intersect with the hull centerline above and below the propeller axis. It is characterized by:

Effect: By creating the so-called C-shaped stern, of the pair of inner bilge vortices that are generated around the stern when viewed from the rear, the first bilge vortex, which rotates in the opposite direction to the propeller rotation direction, is inside the plane of the propeller. be led to. On the other hand, since the second bilge vortex in the direction of rotation of the propeller is pushed out of the plane of the propeller, the rotational flow in the direction of rotation of the propeller and in the opposite direction is prevented from being attenuated.

Embodiment: Next, a specific example of the asymmetrical stern-shaped boat according to the present invention will be described with reference to the drawings. Note that the same reference numerals as those used in explaining the conventional example indicate the same contents.

In the stern structure of the single-shaft ship shown in Figure 1, the propeller 2 rotates clockwise when viewed from the rear.
and a propeller shaft 3 which is the rotation axis of this propeller 2.
and further a rudder 5. As shown in FIG. 2, the stern end 1 of the stern of a ship having the stern structure of a single-shaft ship is located in the vicinity of the propeller shaft 3 located at the hull center line 6 extending in the vertical direction, and the stern end 1 extends left and right. When viewed from the rear, it is curved and biased to the left side in the opposite direction to the clockwise rotation direction of the propeller 2, in other words, to the port side. Further, the upper and lower ends of the stern end 1 which are biased in this way intersect with the hull center line 6 above and below the propeller shaft 3.

With this configuration, as shown in Fig. 3, among the inner bilge vortices that occur around the stern when viewed from the rear, the right bilge vortex that rotates in the opposite direction to the rotation direction of the propeller 2 is prevented. Propeller surface 4
The counterclockwise rotational flow is strengthened, and the propulsion efficiency of the propeller 2 in the clockwise rotational direction is improved. Note that the fact that the upper and lower ends of the stern end 1 intersect with the hull centerline 6 has the effect of making unnecessary parts as close to symmetry as possible and minimizing the influence on maneuverability (steer steering when going straight).

In this embodiment, a case is explained in which the propeller 2 rotates clockwise, but in the case of a propeller 2 rotating counterclockwise, the stern end 1 is similarly biased to one side on the starboard side by drawing a curve. It goes without saying that similar effects can be obtained by doing so.

Effects of the Invention: As described above, according to the present invention, the formation of a rotational flow in the opposite direction to the rotational direction of the propeller is not weakened, so the horsepower reduction effect is observed, and the propulsion efficiency can be improved.

[Brief explanation of the drawing]

1 to 3 are drawings for explaining a specific embodiment of the asymmetrical stern-shaped vessel according to the present invention, in which FIG. 1 is a side view, FIG. 2 is a front view, and FIG.
The figure is an explanatory view showing the in-plane flow direction of the propeller, and Figs. 4 to 6 are drawings for explaining the conventional example, in which Fig. 4 is a side view corresponding to Fig. 1, and Fig. 5 is a side view corresponding to Fig. 1. is a front view corresponding to FIG. 2, and FIG. 6 is an explanatory diagram corresponding to FIG. 3. Explanation of symbols: 1...Stern end, 2...Propeller, 3...
Propeller shaft, 4... Propeller surface, 5... Rudder, 6... Hull center line, 7... Stern twist section, 11... Bilge vortex.

Claims (1)

[Claims] 1. An asymmetrical stern-shaped ship with a stern structure of a single-shaft ship, wherein the stern end curves in the left-right direction around the propeller axis in one direction opposite to the rotational direction of the propeller. An asymmetrical stern-shaped ship characterized in that the upper and lower ends of the curve of the stern end of the stern end intersect with the hull centerline above and below the propeller axis.