JP3531813B2 - Rudder fin - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ladder fin for rectifying the wake of a ship's propeller along a rudder blade.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, this type of invention generally shows a suspension rudder type rudder plate 31, and one having a streamlined cross-sectional shape is generally used. There is.

Further, the rudder plate 31 is desired to be miniaturized from the viewpoint of propulsion performance, but there is a tendency for the rudder plate 31 to be enlarged by setting a large safety factor from the viewpoint of ensuring sufficient maneuverability.

The wake of the propeller from some people varies to some extent depending on the shape of the stern of the hull, but the vector of the water flow at the stern becomes more upward than horizontal toward the rear during forward movement of the ship. The theory was published, and based on this theory, Japanese Utility Model Application No. 62-169595 (Actual Fairness 5-136
80) was devised, and an upward vector F1 is shown in FIG. 1 of the devised device.

The conventional technique will be described with reference to FIGS. 4 and 5. The wake of the propeller flows rearward upward from the horizontal and tries to escape from the rudder blade 311. Therefore, the top end plate 351 and the bottom end plate 361 are provided on the top side 331 and the bottom side 341 of the rudder plate 311, in order to suppress the escape of the propeller wake from the rudder plate 311.

Further, the horizontal upward water flow behind the propeller is upward by an angle α with respect to the horizontal line (propeller shaft center line PL), based on the theory that the apex 3
31 and the bottom side 341 are inclined, and the top end plate 35 is attached to the side.
1 and the bottom end plate 361 are similarly installed upward by an angle α, which is a technical idea to stop the escape.

The cross section of the rudder blade has a streamlined shape from the front end portion 391 to the intermediate portion side surface 371, and the intermediate portion side surface 37.
1 to the rear side surface 381 is a linear shape, and further the rear side surface 3
81 to the trailing edge 401 have a straight line shape maintaining a constant tail angle.

The top end plate 351 and the bottom end plate 361 are made large in size in order to prevent the escape of the rudder plate 311 to the upper outside or the lower outside. It is set wider than the maximum width of the plate 311.

[0009]

As described in the prior art, the theory that the wake of the propeller flows horizontally upward does not always occur from the results of our circulating water tank test, and is shown in FIG. As described above, the wake of the propeller flows horizontally, but the dead water area 4 is formed near the top side 331 of the rudder blade 311.
00 is formed. Further, the wake of the propeller has a tendency to contract before the rear edge of the rudder blade 311 and then expand at the rear. In addition, the rudder blade is provided with a streamlined cross section and a straight line portion, and the trailing edge has a cross-sectional shape that widens toward the end. It had more propulsive resistance than the shaped rudder blade. Furthermore, providing the top plate in a wide area over the entire length from the leading edge to the trailing edge in the dead water increases the frictional resistance,
It had a bad influence on the propulsion performance.

The present invention has been made in view of such inadequacies of the prior art, and its object is to eliminate propulsion performance by eliminating three-dimensional flow and eddy resistance. And to improve maneuverability. From the results of the circulating water tank test, the wake of the propeller accelerated by the propeller is about 1/2 of the rudder length from the front end of the rudder blade.
It was confirmed that the flow once contracted near the 2/3 rear and then expanded again, and that the flow velocity was slow near the top of the rudder blade and was close to the dead water area over a wide area. Therefore, we decided to provide the middle fin and the lower fin that have different roles. First, the equipment of the middle-stage ladder fin is intended to improve the steering lift force by forcibly converting the three-dimensional flow generated near the trailing edge of the rudder blade into the two-dimensional flow. The equipment is designed to improve the steering lift and reduce the eddy resistance by suppressing the vortex generated from the lowermost end of the trailing edge of the rudder blade.

[0011]

In order to achieve the above object, the present invention provides a lower fin at the lower end of the trailing edge of the rudder blade , the lower fin extending from the base line 10 along the downward flow.
Middle fins are provided at the trailing edge of a substantially horizontal position of 0.7 R of the propeller with the propeller shaft center line sandwiched by being inclined downward by about 15 deg .

The cross-sectional area of the lower fin and each of the middle fins is approximately 1/6 of the cross-sectional area of the rudder blade.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described with reference to FIGS. 1 and 2. The propeller wake 300 flows rearward horizontally, and the upflow forms a dead water region 400. Further, the propeller wake 300 becomes a contracted flow d in front of the trailing edge 21 of the rudder blade 1 from the diameter Dp of the propeller 2 and then expands in the rear.

The downward flow 302 in the wake of the propeller contracts d and then expands rearward to try to escape from the rudder blade 1. In this case, a separation vortex 23 (shown in FIG. 3) is generated downward from the lower end 22 of the trailing edge 21 of the rudder blade 1 and becomes eddy resistance. In order to reduce the eddy resistance, the lower fin 4 is provided on the lower end 22 of the rear edge 21 of the rudder blade 1, and the lower flow 302 is caused to flow along the lower fin 4 to the rear part of the hull.

Further, the propeller wake 300 forms a three-dimensional flow as it approaches the trailing edge 21 of the rudder blade 1, and the steering lift is reduced. Therefore, the middle fins 6 are formed on the rear edge 21 of the rudder blade 1 respectively.
By equipping a and 6b and forcibly changing the three-dimensional flow into the two-dimensional flow, the steering lift is improved and the steering performance is improved.

[0016]

[Example] As shown in FIG.
The propeller shaft center line PL and the bottom side 7 of the rudder blade 1 are provided horizontally on the base line BL.

The bottom side 7 of the rudder blade 1 is provided on an extension of the base line BL of the hull S, and the top side 8 is provided slightly above the upper end of the diameter Dp of the propeller 2 and has a substantially rectangular side surface. And has a streamlined cross section.

The downward flow 302 in the wake of the propeller contracts d and then expands rearward to try to escape from the rudder blade 1. In this case, a separation vortex 23 (shown in FIG. 3) is generated downward from the lower end 22 of the trailing edge 21 of the rudder blade 1 and becomes eddy resistance. In order to reduce the eddy resistance, the lower fin 4 is provided on the lower end 22 of the rear edge 21 of the rudder blade 1, and the lower flow 302 is caused to flow along the lower fin 4 to the rear part of the hull.

The propeller wake 300 has a trailing edge 21 of the rudder blade 1.
As it approaches, a three-dimensional flow is formed and the rudder lift is reduced. Therefore, at the rear edge 21 of the rudder blade 1, the middle fins 6a,
6b is provided to forcibly change the three-dimensional flow into the two-dimensional flow, thereby improving the steering lift and improving the steering performance.

FIG. 2 shows A of the middle fins 6a and 6b of FIG.
-A cross section. The lower fin 4 also has substantially the same shape. When the length of the rudder blade 1 is L and the width is B, the length of the middle fin is L / 3 and the width is B / 2. Further, the cross-sectional area of the lower fin 4 and the middle fins 6a, 6b is approximately 1/6 of the cross-sectional area of the rudder blade 1, thus realizing downsizing.

The lower fin 4 is inclined downward by 10 to 15 deg. Along the flow of the downward flow 302.

[0022]

Since the present invention is configured as described above, it has the following effects. The present invention improves the maneuverability by providing the lower fin and the middle fin to suppress the generation of eddy resistance and the reduction of the steering lift, which are one of the causes of adversely affecting the maneuverability at a large steering angle. It is intended to try. In addition, the ladder of the minimum size necessary for the eddy resistance generation position and the local of the three-dimensional flow
By providing fins, it is possible to reduce the size of the rudder blade and improve propulsion and maneuverability.

[Brief description of drawings]

FIG. 1 is a side view schematically showing a rudder blade of the present invention.

FIG. 2 is a schematic sectional view of a rudder blade of the present invention.

FIG. 3 is a side view schematically showing a conventional general rudder blade.

FIG. 4 is a schematic side view of a conventional rudder blade.

FIG. 5 is a plan view of a conventional rudder blade and a schematic view from the rear.

[Explanation of symbols]

1 rudder plate 2 propeller 4 lower fin 5 Stern 6a, 6b Middle fin 7 bottom 8 top 21 trailing edge 22 Lower end 23 Separation Vortex 300 Propeller wake 301 Upstream 302 Downstream 400 dead water area Dp diameter (propeller diameter) R radius (propeller radius) d contraction PL propeller shaft center line S hull BL baseline

Claims (2)

(57) [Claims] 1. A lower fin is provided at a lower end of a trailing edge of a rudder blade , and the lower fin extends from a base line along a downward direction from 10 to 10.
Ladder fins which are inclined downward at 15 deg. And each of which is provided with a middle fin at a trailing edge of a substantially horizontal position of 0.7R of a propeller with a propeller shaft center line interposed therebetween. 2. The ladder fin according to claim 1, wherein the cross-sectional areas of the lower fin and each of the middle fins are approximately 1/6 of the cross-sectional area of the rudder blade.