JPH08175478A - Hull resistance reducing fin - Google Patents

Abstract

PURPOSE: To provide a hull resistance reducing fin which is effective for ship type which is free from separating in a water stream around a hull. CONSTITUTION: In a ship in which bow section fins and stern section fins protrude symmetrically on the right and left in a sea water immerse section of outer plates on both gunwale sides of a bow section and the stern section, the bow section fins 2 and stern section fins 3 have a blade-type cross section and substantially a triangular plane. Their side ends are bent upward. A front fringe of the bow section fin 2 is above a rear fringe, and the front of the fin faces upward. A front fringe of the stern section fin 3 is below a rear fringe, and the front of the fin faces downward.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hull resistance reducing fin.

[0002]

2. Description of the Related Art Conventionally, as a hull resistance reducing fin, as shown in the side view of FIG. 8, there is known a fin which is attached to a stern side outer plate of a stern to aim to prevent flow separation by a rectifying effect. As shown in FIG. 9, its planar shape is almost rectangular.

[0003]

However, although this type of conventional fin is effective in a large stern ship in which the flow of the stern is separated, it is resistant to a hull form designed so as not to be separated. There is no reduction effect.

The present invention has been proposed in view of the above circumstances, and an object thereof is to provide a hull resistance reducing fin that is effective even for a hull form in which water flow around the hull does not separate.

[0005]

To this end, the present invention is a ship in which bow fins and stern parts are symmetrically projected in seawater dipping parts of both side parts of the bow and stern of the ship on the side of the ship. In the above, the bow fin and the stern fin each have an airfoil cross-sectional shape and also have a substantially triangular plane shape, and each side end portion is bent upward, and the bow fin has a front edge whose rear edge is rearward. The fins are characterized by having the front of the fin facing upwards above the edge and the stern fin having its leading edge below the trailing edge and the front of the fin facing downwards.

[0006]

According to this structure, of the lift components generated by the fins, the forward component acts as a thrust, which reduces the hull resistance. In addition, 3 generated on the back side of the fin
Due to the dimensional separation vortex, the bent portion has a negative pressure, which generates a force to pull the hull forward, thereby further reducing the resistance.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall side view showing a ship equipped with the fins of the present invention, FIG. 2 is a horizontal sectional view taken along the line II-II of FIG. It is a mechanical vector diagram which acts on the fin of the bow part of FIG. 1, and is a principle explanatory drawing of this invention. 4 is a plan view of the bow fin shown in FIG. 3 viewed from below, FIG. 5 is a cross-sectional view taken along the line VV of FIG. 4, and FIG. 6 is a plan view showing the stern fin of FIG.
FIG. 7 is a transverse sectional view taken along the line VII-VII in FIG.

In the above drawing, the same reference numerals as those in FIGS. 8 to 9 indicate the same members as those in FIGS. 8 to 9, respectively. First, in FIGS. A pair of left and right stern fins 2 are projected on the part, and a pair of left and right stern fins 3 are also projected on the water-washing parts of both stern side shell plates. The figure shows the propeller 4 and rudder 5 for reference.
Is filled in. The bow fins 2 and the stern fins 3 each have a wing-shaped cross-sectional shape, and the bow fins 2 face up and the stern fins 3 face down,
It is projected on the hull skin so as to have an elevation angle with respect to the local flow vector 8.

Here, the bow fins 2 and the stern fins 3
Have a substantially triangular planar shape, and the side end 2a of the bow fin 2 is bent upward with a dihedral angle, as shown in FIG. Similarly, the tips of the stern fins 3 are also bent upward with a dihedral angle, as shown in FIG. 7.

The local flow around the hull of such a ship is
As shown in Fig. 1, the downward velocity vector 8 at the bow.
a, and the upward velocity vector 8b at the stern. Therefore, the bow fin 2 is shown in FIG.
As shown in, the lift force L is applied to the flow of the velocity vector 8a.
And the reaction force D acts in the direction shown, and a forward direction component T of the resultant force S of L and D is generated. As a result, the hull resistance is reduced.

Further, since the fins have a substantially triangular plan shape, three-dimensional separation vortices 6 are generated as shown by hatching on the bow fins as seen from the bottom of the ship in FIG. Therefore, the lift will be further increased. This is exactly the same for the stern fins 3.

Further, in the case of the bow fin 2, as shown in FIG. 5, the lower surface (back surface) of the side end portion 2a is directed obliquely forward, and the negative pressure due to the three-dimensional separation vortex causes this surface. The force in the forward diagonal direction will act. The forward direction component of this force becomes the thrust, so that the resistance is reduced.

In the case of the stern fin 3, as shown in FIG. 6 (view from above), the three-dimensional separation vortex 6 is formed above the fin 3 as shown by hatching, so that Negative pressure is on the top side. Therefore, as shown in FIG.
A negative pressure is applied to the upper surface side where the side end portions 3a of the fins are bent upward, so that a force in an obliquely forward direction is generated in this portion, and the forward component acts as thrust, which contributes to the reduction in resistance.

[0014]

In summary, according to the present invention, in a ship in which bow fins and stern portions are symmetrically projected in seawater dipping portions on both side vessels of the bow and stern, respectively, The bow fins and the stern fins each have an airfoil cross-sectional shape, and also have a substantially triangular plane shape, and each side end portion is bent upward. With the fins facing upward and the front of the fins facing upward, and the stern fins with their leading edge below the trailing edge and the front of the fins facing downward, there is no separation of the water flow around the hull. The present invention is extremely useful in industry because it provides an effective hull resistance reduction fin.

[Brief description of drawings]

FIG. 1 is an overall side view showing a ship provided with a hull resistance reduction fin according to an embodiment of the present invention.

FIG. 2 is a horizontal sectional view taken along the line II-II of FIG.

FIG. 3 is a dynamic vector diagram of a water flow acting on the bow fin of FIG. 1 and shows the principle of the present invention.

FIG. 4 is a plan view of the bow fin shown in FIG. 3 as viewed from below.

FIG. 5 is a sectional view taken along the line VV of FIG. 4;

FIG. 6 is a plan view of the stern fin of FIG. 1 viewed from above.

7 is a transverse cross sectional view taken along the line VII-VII in FIG.

FIG. 8 is a side view showing rectifying fins projecting from the conventional stern-side outer plate in a pair of right and left directions.

9 is a transverse cross sectional view taken along the line IX-IX in FIG.

[Explanation of symbols]

 1 Hull 2 Bow fin 2a Side edge 3 Stern fin 3a Side edge 4 Propeller 5 Rudder 6 Three-dimensional separation vortex 8 Local flow velocity vector 8a Bow fin local flow velocity vector (downward) 8b Stern fin local flow Velocity vector (upward)

Claims (1)

[Claims] Claims: 1. A ship comprising a bow and fins, which are bilaterally symmetrically projecting in seawater-immersed portions on both sides of the bow and the stern of the ship, respectively.
The stern fins each have an airfoil cross-sectional shape and a substantially triangular plane shape, and each side end portion is bent upward, and the bow fins have their leading edges above the trailing edges. A hull drag reduction fin characterized in that the front of the fin faces upward, the stern fin has its front edge lower than the rear edge, and the front of the fin faces downward.