JP2513192B2 - Stern section rectifier - Google Patents

Description

TECHNICAL FIELD The present invention relates to a stern rectifying device that can promote energy saving of a ship.

[Prior Art] Various measures have been proposed to rectify the flow around the stern by attaching an additive such as fins to the stern in order to make the flow flowing into the propeller for propelling uniform and improve the propeller efficiency. That is, as shown in FIG. 10, fins b are arranged above the propeller a so as to cover the propeller a, or as shown in FIG. 11, blades c are arranged in multiple stages in front of both sides of the propeller a. As shown in FIG. 12, a semicircular duct e is arranged in front of the upper half of the propeller a.

[Problems to be Solved by the Invention] However, the conventional additive has a problem that its effect cannot be reliably expected. In other words, it is necessary to set the shape and dimensions of each of these appendages so that they will fit the hull form, but depending on the hull form, sufficient effects may not be expected even if optimal design is performed, and the loading of the ship This is because the effect decreases as the state changes.

[Means for Solving Problems] In view of the above-mentioned problems, the present invention reliably rectifies the water flow around the stern and makes the flow flowing into the propeller uniform without being controlled by the hull form and the like, thereby saving energy. The purpose of the present invention is to provide a rectifying device that can be designed, and the structure is such that both ends of the propeller can be freely rotated on the left and right inboard stern sides of the propeller so as to pass through the recesses formed by the stern side. And a drive device for transmitting the rotation of the propeller shaft to the rectifying member so as to rotationally drive the rectifying member in a direction of accelerating the water flow between the rectifying member and the ship side. .

[Operation] The water flow between the rectifying member and the ship side is accelerated by the rotation of the rectifying member driven by the propeller shaft, and this increased flow flows into the upper part of the propeller surface where the flow velocity is slow. The distribution is made uniform. In addition, propulsive force is generated by the Magnus effect acting on the flow regulating member.

[Examples] Examples of the present invention will be described below with reference to the drawings. 1 to 6 show a first embodiment of the present invention, in which the present apparatus has both ends in front of the propeller 1 on the side of the stern 2,2.
It is composed of two columnar rectifying members 3 and 4 rotatably supported by the rectifying member, and a drive device for rotatably driving the rectifying members 3 and 4.

The straightening members 3 and 4 are arranged in a plane substantially vertical to the propeller center line 5 and obliquely pass through the recesses 6 and 6 formed by the stern side 2 and 2 from the ship side portion near the propeller center line 5. The upper part extends upward, and the lower part has a watertight structure, and is rotatably supported in the lower bearings 7, 8. The rectifying members 3 and 4 have a circular cross section, and in order to effectively increase the flow velocity, as will be described later, the diameter d of the central portion is the largest in accordance with the shape of the recesses 6 and 6. The diameter is gradually reduced toward both ends.

The drive unit is one rectifying member 3 (starboard side in FIG. 1).
Bevel gears 9 and 10 rotating in the lower part of arrow in the direction of arrow f, and rectifying members so that both rectifying members 3 and 4 rotate in mutually opposite directions.
It consists of a connecting device 12 etc. that connects the upper part of 3, 4 to each other,
The bevel gear 10 is fixed to the propeller shaft 14 in the engine room 13,
The connecting device 12 is a bevel gear mechanism 15, 15 and this bevel gear mechanism 15,
It is composed of a connecting shaft 16 for connecting 15 and the like.

Next, the operation of this device will be described. While the ship is sailing,
The flow around the stern flows along the ship side 2 as shown in FIG. 3, and a boundary layer is formed in the vicinity 17 of the hull surface of this flow. Further, there are separation points 18, 18 near the stern, and the separation points 18, 18 move forward as the stern becomes fertile, that is, as the stern angle θ increases, and as a result,
This will increase the hull resistance and reduce the flow velocity on the propeller surface 19.

Further, the axial flow velocity V _{X on} the propeller surface 19 corresponds to FIG. 4 showing the distribution of the wake coefficient W [(V _S −V _X ) / V _S : V _S is the ship speed] and the angular position β of the propeller rotation direction. Area near the upper part of the propeller surface 19 as shown in Fig. 5 showing the distribution of V _X / V _S
It's late at 20. That is, in this region 20, the difference from the average flow velocity is large, and propeller cavitation is likely to occur.

Now, when the rectifying members 3 and 4 are rotationally driven in mutually opposite directions, a lift force L and a drag force D are generated in each rectifying member 3 and 4 by the Magnus effect. In general, the Magnus effect is a cylinder 22 having a diameter d in a uniform flow with a flow velocity V as shown in FIG.
Is generated at a rotational speed ω, a lift force L is generated in a direction perpendicular to the flow. The lift force L is expressed by the equations (1) and (2) when the flow is an ideal fluid.

L = π · ρ · V · d · v Equation (1) And the lift coefficient C _L is calculated from equation (1) Becomes Further, when the flow is a viscous viscous body, C _L is, for example, for the cylinder 23 having the size and shape shown in FIG. 8 for the curves g, h, i,
Since the drag coefficient corresponding to each C _L is obtained from the curve g, h, i, j shown in FIG. 9, the drag D is calculated by the equation (4).
Required by.

The curves g, h, i, j shown in FIGS. 8 and 9 are the diameter d of the cylinder 23, the length l, and the diameter n of the end plate 24 of d = 60 m in FIG.
Experimental values corresponding to m, l = 720 mm, n = 180 mm, 120 mm, 90 mm, 0 (without end plate), the straight line k in FIG. 8 shows the theoretical value of C _L for the ideal fluid.

Here, the hull moving direction, that is, determined by the sixth FIG thrust T _R in the x-direction Becomes Α in equation (5) indicates the angle between V and x, and α ≈
Since it is considered to be θ, the larger the θ is, the more fertile the stern is, and the larger the lift-drag ratio (L / D) is, the larger the thrust T is.
_R is obtained, and this thrust T _R can be controlled by the rotational speed ω.

On the other hand, power is required to rotate the rectifying members 3 and 4, but the required power P per unit length of the cylinders 3 and 4 is approximately obtained by the equation (6).

P = π ・ ρ ・ ω ³・ R ⁴・ C _f Equation (6) where Is. Therefore, the diameter d and the rotation speed ω of the rectifying members 3 and 4 may be selected so that the required power is small and the thrust is large.

Further, the flow regulating members 3 and 4 have the function of equalizing the flow to the propeller surface 19. That is, the flow in each region 25, 25 between each rectifying member 3, 4 and the ship side 2, 2 is accelerated by the rotation of the rectifying member 3, 4, and the flow velocity distribution is made uniform as shown by the phantom line in FIG. To do. Therefore, the occurrence of cavitation is reduced, the propeller deployment area can be reduced, and as a result, the propeller efficiency is improved. Furthermore, the acceleration in the areas 25, 25 moves the peeling points 18, 18 rearward, so that the peeling area becomes smaller and the hull resistance is reduced.

Further, if the shapes and rotational speeds of the left and right rectifying members 3 and 4 are changed, the accelerated flow becomes asymmetrical, so by controlling this, the propeller surface 19 of the flow flowing into the propeller surface 19 is controlled.
The flow inside can be opposite to the direction of propeller rotation. That is, it has the same function as the guide vane, and improves the propeller efficiency.

Further, instead of driving the lower end of one of the straightening members, as another driving method (not shown here), the propeller shaft 14 or the intermediate shaft 29 and the connecting shaft 16 are connected by a mechanical rotation transmission mechanism. Good.

It should be noted that the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] As described above, the present invention exhibits the following excellent effects.

(I) A rectifying member, which is driven to rotate by a propeller shaft, is placed in a dent on the inboard side of the stern, so the water flow between the rectifying member and the hull is accelerated, and the velocity distribution in the propeller plane is uniform. Moreover, it is not necessary to provide a special motor or the like for driving the rectifying member, and the equipment can be simplified.

(Ii) For the same reason as in (i), the Magnus effect generated by the rectifying member generates thrust in the rectifying member, which can be used as part of the propulsive force of the ship.

[Brief description of drawings]

1 to 6 show a first embodiment of the present invention, FIG. 1 is a rear view of the apparatus (a view from the direction of the arrow I--I in FIG. 2), and FIG. Fig. 3 is a partially cut arrow view from the II-II direction in Fig. 3, Fig. 3 is an arrow view from the III-III direction in Fig. 2, and Fig. 4 is an explanatory view of the distribution state of the wake coefficient on the propeller surface, FIG. 5 is an explanatory view of the distribution of the axial flow velocity on the propeller surface, FIG. 6 is an explanatory view of the thrust generated by the rectifying member, and FIGS. 7, 8, and 9 are all general Magnus effect. FIGS. 10 to 12 are side views of a stern to which various conventional rectifying additives are attached. In the figure, 1 is a propeller, 2 is a stern side, 3 and 4 are rectifying members,
6 is a recess, 7 and 8 are bearings, 9 and 10 are bevel gears, 12 is a connecting device, 1
4 indicates a propeller shaft.

Claims (1)

(57) [Claims] 1. A straightening member having a circular cross section whose both ends are rotatably supported so as to pass through recesses formed on the stern side of the stern, which are recessed inward in front of a propeller, and the straightening member. And a drive device for transmitting the rotation of the propeller shaft to the rectifying member so as to rotationally drive the rectifying member in a direction of accelerating the water flow between the ship side and the rectifying device of the stern portion.