JPH09254881A - Hull structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve propulsion performance without increase in the hull cost by projecting a fin on the outside surface of the hull stern in front of a propeller in which a rotary flow by a propeller goes upward below the shaft center of the propeller. SOLUTION: A fin 3 is projected on the outside surface where a rotary flow by a propeller 2 goes upward below the shaft center of the propeller 2. The fin is installed along a separating line (a) where a flow is separated from the hull within the range of square station numbers of 1/4-2.0, and the width from the outer end to the inner end of the fin 3 is within the range of 0.2-0.3 times as large as the diameter of the propeller 2. The fin 3 is of a plate-like structure as a whole, and the sectional form is such that the base end part of the hull side is thick and it is gradually decreased in thickness as it goes toward the forward end part. Thus, the flow along the hull flows as it is into the propeller so as to improve the propulsion performance. Just the fin is projected on the outside surface of the stern part so as to facilitate modification works to the utmost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hull structure capable of improving propulsion performance.

[0002]

2. Description of the Related Art Conventionally, various methods have been adopted in ships in order to improve propulsion performance.

[0003] For example, in the case of a single propeller, that is, in order to improve the propulsion performance of a single-axis ship, the rear half of the hull, particularly the shape near the stern, is left and right asymmetric (for example, (S-shaped).

By making the flow into the propeller in the direction opposite to the direction of rotation of the propeller, the asymmetrical shape makes the flow inflow uniform on the left and right sides, and thus the rotational energy of the wake of the propeller. By absorbing the, the propulsion performance is improved.

[0005]

However, as described above, making the shape of the stern of the hull asymmetrical requires construction.
There is a problem that the work becomes troublesome and the hull cost becomes high.

Therefore, it is an object of the present invention to provide a hull structure capable of improving propulsion performance without causing an increase in hull cost.

[0007]

In order to solve the above-mentioned problems, the hull structure of the present invention is provided on the outer surface of the stern of the hull at the forward position of the propeller where the flow of the rotational flow by the propeller is upward and from the propeller axis. The fins are projected at the lower position.

Further, in the above-mentioned hull structure, the mounting positions of the fins are the square station numbers 1/4 to 2.
It is within the range of 0. According to the above configuration, by attaching the fins, the stern flow, which is a flow along the hull, is conventionally guided to the part that was separated by the stern and becomes a vortex and separated from the hull and flowed behind the propeller. Therefore, the propulsion performance of the hull, that is, the hull efficiency and the propeller propulsion efficiency are improved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, reference numeral 1 denotes a stern of the hull, which is located in front of the propeller 2 of the stern of the hull 1 on the outer surface where the flow of the rotational flow by the propeller 2 is upward (when the propeller is rotating clockwise On the left side surface, on the right side surface when the propeller rotates counterclockwise), and at a position below the propeller shaft center, that is, on the port side bilge portion, the fin 3 is projected.

Explaining the mounting range of this fin 3, this fin 3 has a square station number of 1 /
It is attached within the range of 4 to 2.0, and as shown in FIG. 3, the distance L from the outer end to the inner end at the rear end position.
Has a length that is within a range of 0.2 to 0.3 times the diameter of the propeller 2.

The fin 3 is generally plate-shaped, and its cross-sectional shape is such that the base end on the hull side is made thicker and becomes thinner toward the tip.
Further, as shown in FIG. 1, the fins 3 are provided along the separation line a in the stern 1 of the hull where the flow separates from the hull.

Therefore, the flow of water along the hull by the fins 3 is as shown by the arrow in FIG.
It flows to the lower rear side and separates and swirls b as in the conventional case shown in FIG. 4A (when no fin is attached).
Therefore, the flow along the hull flows into the portion where the separated vortex flow was flowing, and then flows into the propeller as it is, so that the propulsion performance is improved.

For example, in the conventional case, as shown in FIG. 4 (b), eddy currents in the same direction are generated on both sides of the hull. Therefore, on the port side, the flow is in the direction opposite to the rotation direction of the propeller. Occurs and the propulsion efficiency decreases.

The flow at the propeller position when the fin 3 is attached and when the fin is not attached is shown in FIG. 5A shows a case where the fin 3 is attached, and FIG. 5B shows a case where the fin 3 is not provided. When the fin 3 is attached,
It can be clearly seen that the flow is generated in the same direction on the propeller surface.

By attaching the fins 3 in this manner, the stern flow, which is a flow along the hull, is conventionally guided to the portion which has separated from the hull and formed a vortex flow away from the hull and flowing to the rear of the propeller. As a result, the directions of the flows flowing into the propeller surface become the same, and therefore, the propulsion performance of the hull, that is, the hull efficiency, the propeller propulsion efficiency, etc. are improved.

Further, since the fins are simply provided on the outer surface of the stern portion of the hull in this manner, when the existing hull is improved, the repair work can be performed very easily. it can.

[0017]

As described above, according to the hull structure of the present invention, since the fins are projectingly provided on the outer surface of the stern of the hull where the flow of the rotary flow by the propeller is upward, the construction cost is almost increased. Without this, it is possible to improve the propulsion performance of the hull, that is, the hull efficiency and the propeller propulsion efficiency.

[Brief description of drawings]

FIG. 1 is a perspective view of a stern portion of a hull structure according to an embodiment of the present invention.

FIG. 2 is a view as viewed in the direction of arrows AA in FIG. 1;

FIG. 3 is a perspective view of fins on the stern of the ship.

FIG. 4 is a perspective view showing a flow when a fin is not attached.

FIG. 5 is a front view showing the flow in the plane of the propeller, (a)
Shows the case where the fin is attached, and (b) shows the case where the fin is not attached.

[Explanation of symbols]

 1 Hull stern 2 Propeller 3 Fin

Claims (2)

[Claims] 1. A hull structure characterized in that fins are projectingly provided on the outer surface of the stern part of the hull at the front position of the propeller where the flow of the rotational flow by the propeller is upward and below the propeller axis. 2. The hull structure according to claim 1, wherein the mounting positions of the fins are set such that the square station number is within the range of 1/4 to 2.0.