JP2007186204A - Rudder for ship - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a rudder shape having high lift and suppressing increase in rudder resistance as small as possible. <P>SOLUTION: In the rudder shape, a front edge portion of a rudder body in a horizontal section has an arc shape or its similar shape. The sectional width gradually increases toward a rear direction of the rudder body, reaches the maximum width, and then, gradually decreases while changing from an outwardly projecting shape to an outwardly gently recessed shape. In addition, the rudder shape has a linear portion formed by approximately linear lines continuing to a rear end of finite width. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rudder for a ship, and more particularly to a rudder that can improve the maneuvering performance of a ship by generating a high rudder force and that does not deteriorate the propulsion performance.

  As a typical cross-sectional shape of a rudder in the prior art, there is a symmetrical airfoil of NACA (National Advisory Committee for Aeronautics). As an example of the cross-sectional shape of this rudder, divide the front from the maximum rudder thickness position into five equal parts, divide the rear into seven equal parts, express the rudder thickness at those 13 points as a ratio to the maximum rudder thickness, and in order from the front edge Rudder with 0.0, 0.6, 0.820, 0.937, 0.988, 1.000, 0.882, 0.761, 0.611, 0.438, 0.222, 0.0 There is a shape. FIG. 12 shows a shape in which the rudder body 10 has a blade length of 1, the maximum rudder thickness Tmax is 18% of the blade length, and the maximum rudder thickness position is 36% of the blade length from the leading edge 10A. Hereinafter, this technique is referred to as “conventional technique 1”.

Moreover, there exists patent document 1 as a prior art regarding a high lift rudder. This rudder is intended to obtain high lift by making the horizontal cross-sectional shape of the rudder exactly the shape of a fish viewed from the side. This rudder is as shown in FIG. 13, and when the propeller diameter is set to D, the total length C in the fore-and-aft direction of the rudder body 20 is 0.60 to 0.62D. The horizontal cross-sectional profile of the fish has a shape as seen from the side of the fish, and the slope angle α extending from the boundary 20C with the rear portion 20B of the front portion 20A having a streamlined cross-section corresponding to the fish body is 10 to 12 ° side angle, A tail angle β extending from the boundary 20C with the front part 20A of the rear part 20B corresponding to the fish tail part is set to a side angle of 4 to 6 °, and an end plate 21 having a width of 0.4C on the top end face of the rudder body 20; 22 is attached, and only both side edges of the bottom end plate 22 are bent downward at an angle of 15 degrees, and the length C ₁ of the front portion 20A having a streamlined cross section corresponding to the fish body portion is 0.8C. the length C ₂ of the rear portion 20B is a 0.2C equivalent to parts Than is. Hereinafter, this technique is referred to as “conventional technique 2”.

  In addition, there is Patent Document 2 as a conventional technique. This rudder is as shown in FIG. 14, and in consideration of the fact that the rudder is in the accelerating flow behind the propeller, the horizontal cross-sectional shape (the rudder shape shown by a solid line) of the rudder main body 30 is changed to the conventional streamline. Focusing on making the head more round and the tail thinner than the shape (the rudder shape shown by the dotted line), the ratio of the length X from the front edge 30A of the rudder body 30 to the total length C is expressed as X / C. When the ratio of the thickness T in the horizontal section at the X / C portion to the maximum thickness Tmax is T / Tmax, and 1/2 of T / Tmax is Y, 0.25 ≦ Y ≦ 0 .33 (X / C = 0.05), 0.35 ≦ Y ≦ 0.43 (X / C = 0.1), 0.11 ≦ Y ≦ 0.17 (X / C = 0.8), 0.03 ≦ Y ≦ 0.08 (X / C = 0.9). Hereinafter, this technique is referred to as “conventional technique 3”.

JP 10-297593 A JP 2000-280984 A

  When a two-dimensional wing is placed in a uniform flow at an angle (attack angle), the side on which the flow strikes is generally called the face surface, and the opposite side is called the back surface. FIG. 15 shows the definitions of lift L and drag D along with their definitions.

  In the prior art 1 shown in FIG. 12, the cross-sectional width of the rudder increases from the front edge 10A to reach the maximum rudder thickness Tmax, and then the rudder thickness (cross-sectional width) gradually decreases while maintaining a convex shape on the outside. The shape is closed at the rear end. In a general rudder having such a horizontal cross-sectional shape, the lift generated in the latter half of the rudder is small. This is due to the fact that the latter half is convex outward and the cross-sectional width gradually decreases, so this phenomenon is seen especially on the face, but there is almost no change in flow velocity after the maximum rudder thickness. To verify this, CFD (computational fluid dynamics) analysis was performed on a two-dimensional wing having the shape shown in FIG. 12 at an angle of attack of 8 °. It was carried out using the program of .5. The set Reynolds number is 6.0 × 10 6. FIG. 16 shows the pressure distribution on the blade cross section and the lift distribution caused thereby. The horizontal axis in FIG. 16 is X / C (where X is the length from the front edge of the rudder, C is the total length on the horizontal section center line of the rudder), and the vertical axis is the pressure coefficient of the pressure distribution and the lift distribution. Further, for reference, half of the rudder shape in FIG.

It can be seen that on the face surface where the flow hits, the pressure has a positive peak value near the front edge and continues to decrease to near the maximum width, and thereafter has a substantially constant value. The pressure has a lower value as the flow velocity at that point is faster, and becomes higher as the flow velocity is slower, so the flow velocity suddenly decreases near the front edge of the face surface, and then increases to near the maximum width. It will be understood that when the maximum width position is passed, there is no change in flow velocity, and the flow proceeds at a substantially constant speed.
On the other hand, on the back surface, the flow velocity becomes very large due to the inflow from the face surface near the front edge, so the pressure has a large negative peak value, and then the flow velocity gradually decreases to the rear edge, and the pressure increases. It continues to rise and reaches the same pressure as the face surface in the vicinity of 85% (0.85 on the horizontal axis) from the front edge.
That is, since there is no flow velocity change after the maximum width position on the face side, there is no increase in pressure on the face surface, and the lift generated by the pressure difference with the back surface is reduced accordingly. This phenomenon is the same even when the propeller wake flows instead of the uniform flow.

  In the prior art 2, a high lift is obtained by making the rear part of the horizontal cross section of the rudder widened like a fish fin. This is because when the wake of the propeller hits the rudder and flows along the rudder surface, the flow is deviated in the fins on the rear side, so the pressure is especially at the fin constriction on the face surface (the side where the flow strikes) of the rudder. As a result, the lift increases. However, the presence of fins for increasing the lift force increases the amount of vortex shedding due to the large width at the rear end, making the rudder excessively resisted by the fluid and propelling the ship. This is a cause of deterioration in performance. In order to improve the influence on propulsion performance, the A rudder described in Patent Document 1 of Prior Art 2 reduces the vortex resistance by reducing the fin width by reducing the tail angle. This is achieved by reducing the length / propeller diameter ratio (C / D) to about 0.6. However, the means for such improvement is that the rudder area (the side projection area of the movable part of the rudder main body, hereinafter abbreviated as “rudder area” unless otherwise specified) is limited to the size of the propeller. Since the rudder shape and rudder area are determined by the propeller diameter, there is a possibility that the rudder force necessary for the ship cannot be provided, which has a big problem.

  In order to examine the performance of the rudder shape itself, as shown in Patent Document 1, it is only necessary to look at the diagram of the rudder angle versus lift coefficient and the rudder angle resistance coefficient. They are shown in FIG. 17 and FIG. Since these two coefficients are made dimensionless by the rudder area, they are equivalent to the result showing the superiority or inferiority of the cross-sectional shape of the rudder itself. The lift coefficient of A rudder, B rudder, and E rudder at a rudder angle of 10 ° in FIG. 17 is 1.4 times as large as that of M rudder corresponding to the above-described prior art 1, but on the other hand, the drag coefficient of rudder shown in FIG. Is much larger than the M rudder, and demonstrates the advantages and disadvantages described above. Furthermore, this technique has structural strength problems. That is, there is a very thin portion of the rudder width just before the fin portion of the fish at the rear end of the rudder, but in this rudder shape, a large lift is generated in the fin portion, so an excessive bending moment is applied to this thin portion. . Therefore, there is a problem in structural strength when applied to large ships. In addition, advanced manufacturing techniques are required to manufacture the fin portion of the fish and the very thin portion immediately before it.

In the prior art 3, the horizontal cross-sectional shape of the rudder is intended to obtain a high lift by making the head rounder and the tail narrower than in the prior art 1. This is because the front part of the rudder protrudes outward, and the flow on the back surface of the rudder near this area is further accelerated to lower the pressure, and the tail is made thinner, and the cross-sectional shape of the rear part of the rudder is outside. By making it close to a concave shape, the flow on the face surface in the vicinity is stagnated to suppress acceleration of the flow velocity and, in turn, decrease in pressure. As a result, it is considered that the lift can be increased as compared with the conventional one to which the prior art 1 belongs. In addition, since the rudder is in the swirling flow after the propeller, a flow with an angle of attack enters the rudder even when going straight. For this reason, this rudder which generates a large lift at the front edge portion generates a large front edge thrust, and as a result, the rudder resistance can be reduced.
However, as shown in FIG. 19 (cited from Patent Document 2), the effect of increasing the lift is only about 10% compared to the conventional rudder, which is not sufficient. The reason is that the technical measure related to the vicinity of the tail of the rudder is only to reduce the rudder width.

  The present invention has been made in order to solve the above-described problems of the prior art 1 to the prior art 3, and provides a high lift rudder shape in which rudder resistance is kept as small as possible, and has a poor maneuvering performance. For ships with no steering performance problems, the increased steering power can be used to reduce the rudder area to reduce manufacturing costs and adversely affect propulsion performance. It aims at providing the rudder for ships which has the rudder cross-sectional shape which does not give.

  The marine rudder according to the present invention has a horizontal cross-sectional shape of the rudder main body, where the maximum width of the cross-sectional shape is Tmax, the radius of the front edge is not less than 14% and not more than 22% of the maximum width Tmax. The part shape is an arc shape or a similar shape, and the cross-sectional width gradually increases toward the rear of the rudder body to reach the maximum width, and changes from a convex shape on the outside to a concave shape on the gentle outside. However, the cross-sectional width is reduced, and then the rear portion has a linear portion formed by a substantially parallel straight line and has a rudder shape having a rear end having a finite width.

  Moreover, the rudder for ships which concerns on this invention makes the length of the said substantially parallel linear part the range of 3 to 10% of the full length C from a rear end.

  In the marine rudder according to the present invention, the cross-sectional width T of the substantially parallel linear portions is in the range of 4% to 11% of the maximum width Tmax.

Moreover, in this invention, it is preferable to set it as the ship rudder which has the following rudder shapes or structures.
(Means 1)
When the total length from the front edge to the rear edge of the cross section is C, the distance from the front edge is X toward the rear edge, the cross-sectional width at T is T, and the maximum width of the cross-sectional shape is Tmax, X / C = At the position of 0.05, 0.42 <T / Tmax <0.62, and at the position of X / C = 0.1, 0.64 <T / Tmax <0.81, X / C = 0. At the position of 15, 0.78 <T / Tmax <0.92, and at the position of X / C = 0.7, 0.26 <T / Tmax <0.42 and X / C = 0.8. In the position, 0.13 <T / Tmax <0.22, and in the position of X / C = 0.9, in the position of 0.04 <T / Tmax <0.11, and X / C = 0.98. Is a rudder shape having a cross-sectional width of 0.02 <T / Tmax <0.11.
(Means 2)
The position of the maximum width Tmax is set in a range from 26% to 32.5% of the total length C from the front edge.
(Means 3)
The horizontal cross-sectional shape of the rudder body is applied to a suspension rudder for ships.
(Means 4)
When applied to a marine rudder having a rudder horn, the lower movable part below the rudder horn of the movable rudder main body has the horizontal cross-sectional shape described above in any horizontal cross-section. Note that the upper movable part behind the ladder horn may have an arbitrary cross-sectional shape.

  The present invention brings the rudder shape in the latter half of the maximum rudder thickness position in the horizontal section of the rudder closer to the concave shape as a whole, thereby causing the flow on the face surface to stagnate and causing a decrease in flow velocity, resulting in a pressure increase. The rudder is intended to be lifted to increase lift, and is provided with a linear portion approximately parallel to a range of several percent from the rear end of the rudder. This is because when the flow of the fluid flowing along the gradually decreasing cross-sectional shape of the latter half of the rudder reaches the linear portion, the cross-sectional shape slope passes through a discontinuous point. A drift will occur and stagnant. As a result, the effect of increasing the lift occurs. In addition, by providing such a linear portion, the tendency to be concave outside the cross-sectional shape of the latter half of the rudder where the rudder width gradually decreases can be slightly increased at the same time, so further increase in lift is expected. Is done.

  In order to determine the range of the slope shape of the latter half of the rudder and the length of the linear portion provided at the rear end of the rudder, the four types of cross-sectional shapes of the rudder A00 rudder, A05 rudder, A10 rudder and B05 rudder shown in Table 1 Using a general purpose CFD code manufactured by Fluent, a program of Fluent Ver.5, calculations were performed when the flow hits a two-dimensional wing at an angle of attack of 8 °, and changes in lift were investigated. FIG. 1 shows the cross-sectional shape of each rudder and the position of the rudder width T / Tmax = 0.22 at X / C = 0.8. FIG. 1 shows X / C on the horizontal axis and Y / C on the vertical axis (where Y is half the rudder width T, X is the distance from the leading edge of the rudder, and C is the total length on the horizontal section center line of the rudder. (Wing length or rudder cord length)). In addition, the vertical axis is enlarged to clarify the difference in rudder cross-sectional shape. In FIG. 1, 1 is a rudder main body, 1A is a front edge end on the horizontal cross-section center line of the rudder, 1B is a rear end on the horizontal cross-section center line of the rudder, and 1C is a linear portion at the rear end of the rudder.

  The A00 rudder has a gentle concave shape in the latter half of the rudder, but the rudder without the straight portion 1C at the rear end, and the A05 rudder has a parallel straight portion 1C with a 5% blade length at the rear end of the A00 rudder. In the rudder, the slope portion is reduced to the front of the rudder and the concave shape is strengthened. Similarly, the A10 rudder is a rudder in which the parallel straight portions 1C are set to 10% blade length. The B05 rudder is a rudder shape that has a long outward convex shape that extends for a while from the maximum rudder thickness position, then becomes a concave shape, and finally has a parallel straight portion 1C with a 5% blade length. Compared with, the slope after X / C = 0.6 is tight, and the tendency of the concave shape is intensified near the rear end of the rudder.

  Table 2 shows the ratio of the lift of each rudder based on the calculation result of the lift of the A00 rudder. The A05 rudder is 1.04 times larger, and the A10 rudder is 1.05 times larger. By providing a parallel straight part 1C at the rear end of the rudder, even if the shape of the latter half of the rudder has a slope with the same tendency, the concave tendency is slightly strengthened by attaching a slight straight part, and to the vicinity of the rear end It can be seen that the two effects that the flow is deviated and stagnated due to the presence of the linear portion 1C having the gently-decreasing cross-sectional shape and the discontinuous inclination increase the lift. When the straight portion 1C has a 5% blade length, the effect is clearly greater than the case of 0%, but even when it is 10%, there is only a slight effect compared to the case of 5%. Therefore, it is considered that the lift increasing effect starts from a length shorter than 5%, and it is desirable to have a length of 3% or more. However, the upper limit of the length of the straight portion 1C is a limitation mainly for the reasons of structural strength, but preferably the blade length is 10%. Further, the lift of the B05 rudder with a different tendency in the shape of the latter half of the rudder is equivalent to that of the A05 rudder. This means that if the straight line portion 1C at the rear end is the same, it has the same lift characteristics even if the slope tendency of the latter half is slightly different. On the other hand, the lift of the A00 rudder having no straight part at the rear end is smaller than the A05 rudder and A10 rudder having the straight part. The rudder width of A00 rudder at X / C = 0.8 is T / Tmax = 0.243, which is larger than 0.22 described in (Means 1).

  In order to see the difference between the pressure distribution and lift distribution of the rudder having such a cross-sectional shape and those of the prior art 1, FIG. 2 shows the pressure distribution and lift distribution of the B05 rudder. (The rudder shape of the B05 rudder in FIG. 1 is added for reference.) Compared with the prior art 1 in FIG. The most different point is the pressure on the face of the latter half of the rudder. The rear pressure from the maximum rudder thickness position (X / C = 0.36) is constant in the rudder of the prior art 1, but the X / C after the maximum rudder thickness position (X / C = 0.325) in the B05 rudder. = The pressure starts to increase from around 0.5, becomes a positive pressure in the vicinity of the change from the convex surface to the concave surface, and continues to hold the positive pressure to the vicinity of the rear end. Near the rear end, the pressure difference between the face and back faces continues without disappearing. These are the effects of providing a substantially parallel straight portion near the rear end of the rudder and having a rear end having a finite width, and not intentionally satisfying Kutta-Jukovsky's theorem. However, not satisfying this theorem is directly linked to an increase in rudder resistance, so it is necessary to balance the increase in lift and the increase in resistance. Further, in the front half of the rudder of the B05 rudder, the pressure on the back surface rises to the negative side from the front of the maximum rudder thickness position (X / C = 0.2). This is because the pressure drops because it is larger than the rudder of Technology 1. From the comparison between FIG. 16 and FIG. 2, it can be seen that the rudder cross-sectional shape of the present invention is a shape that greatly improves the lift characteristics as compared with the prior art 1.

  In the first half of the rudder, if the width near the front edge is reduced and the shape is continuously increased to the maximum rudder thickness position, the rectifying effect is enhanced by reducing the front edge, and the flow that hits the rudder is smooth. Can flow backwards. Thereby, it is possible to reduce the increase in resistance that occurs because the flow is disturbed near the rudder front edge. However, at the rudder front edge, since the acceleration of the flow velocity flowing into the back side is small, the peak value of lift near the front edge tends to be small. On the other hand, increasing the width near the rudder front edge increases the peak value at the front edge and increases the lift, but also increases the rudder resistance. A model test was conducted to confirm the influence of such conflicting events and to determine the rudder width of the present invention.

A model rudder with a rectangular side as shown in Table 3 and a rectangular rudder with the same size and side rectangle according to the prior art 1, with a propeller having a total length of 8.5 m, a draft of 0.472 m and a diameter of 0.240 m Attached to the model ship, towed at a speed of 1.28 m / s while operating the propeller, took the rudder angle, the rudder direct pressure (force acting perpendicular to the rudder surface) and rudder resistance (in the rudder longitudinal direction) A test for measuring the working force) was carried out in an NKK hull test tank. FIG. 3 shows definitions of the rudder angle δ, the rudder direct pressure F _ry , and the rudder resistance force F _rx . In FIG. 3, 1 is a rudder body, 2 is a rudder shaft, and 3 is a propeller.

In addition, in order to investigate the effect on propulsion performance, a propulsion performance test (ie, resistance test and self-propulsion test) was conducted, and the main engine horsepower equivalent to the actual ship at the planned speed of the ship was also estimated. 4 and 5 show the coefficient of rudder direct pressure and rudder resistance when the left rudder angle is 8 °, and the ratio of the rudder of the prior art 1 to that of the rudder.
The maximum steering thickness position is longer than the 32.5% cord length due to the change in the lift ratio of the rudder (B05A15, B05B15, B05C15) with the rudder leading edge radius (or rudder tip radius) R being 15% of the maximum rudder thickness Tmax. Then, it can be seen that the effect of increasing the lift is lessened. This is because the leading edge of the rudder becomes thinner and the leading edge lift decreases as the maximum rudder thickness position decreases. As seen from the rudder resistance coefficient in FIG. 5, the decrease in the resistance is slightly greater in the rudder with the maximum rudder thickness position / cord length of 37.5% (B05C15) than the rudder with the maximum rudder thickness position / cord length of 32.5% (B05B15). Just go down. Therefore, it is sufficient to keep the maximum rudder thickness position / cord length at 32.5%, and it is meaningless to lower it further. The rudder width of X / C = 0.8 of the rudder (B05C15) with the maximum rudder thickness position / cord length of 37.5% is T / Tmax = 0.233 from Table 3, and larger than 0.22 described in the means 1. From the results of three rudders (B05B15, B05B22, B05B30) having the same maximum rudder thickness position, the influence of the size of the circle radius of the front edge can be seen. From FIGS. 4 and 5, if the front edge radius is increased, the steering straight pressure increases, but the rudder resistance increases. The shape of the rudder front edge is not limited to the arc shape. A shape similar to this, for example, an ellipse or a parabola may be used.

  The effect on propulsion performance cannot be evaluated by the rudder force when the rudder angle is taken. Also, the evaluation is not complete only with rudder resistance when the rudder angle is zero. When the propeller wake hits the rudder, a different flow field is generated near the stern with the propeller or rudder due to the difference in the shape of the rudder, and the effect of this flow on the propeller or the hull part near the rudder. This is because several factors are intertwined in a complicated manner to determine propulsion performance. Therefore, it is most desirable to understand the effect of rudder on propulsion performance by conducting a propulsion performance test in a hull test tank and comparing with the estimated horsepower of the actual ship.

The horsepower of an actual ship is estimated from a test conducted using the same rudder as in the rudder lifting force measurement test, and the comparison is made with the amount of increase from the horsepower when the rudder of the prior art 1 is mounted. The result is shown in FIG. In general, in such a propulsion performance test, an increase or decrease of 1% or less in horsepower can be regarded as a measurement error range of the aquarium test and can be judged as equivalent performance. Among the three rudders with the rudder leading edge radius of 15% of the maximum rudder thickness, it can be said that the B05A15 rudder and the B05B15 rudder have the same propulsion performance as the prior art 1. The B05C15 rudder with a large maximum rudder thickness position and the two rudders (B05B22, B05B30) with larger front edge radii have a larger horsepower increase than the previous two rudders, exceeding 1%. The propulsion performance is slightly degraded.
Therefore, when the leading edge radius is in the range of 15% to 30% of the maximum rudder thickness, the influence on the propulsion performance is small, but when it exceeds 22%, the propulsion performance is adversely affected. Therefore, the upper limit of the leading edge radius is 22%.
Further, the maximum rudder thickness position is determined based on the lift characteristic of FIG. 4 when the leading edge radius is 15% of the maximum rudder thickness, and is based on the range of 27.5% to 32.5% of the rudder cord length. It is reasonable to think.

  From the above, the first rudder shape that maximizes the rudder width in the first half of the rudder and minimizes the rudder width in the second half, the front edge radius is 30% of the maximum rudder thickness, and the maximum rudder thickness position is the rudder code. 26% of the length, the slope tendency of the latter half of the A10 rudder shown in Table 1 for the shape of the latter half of the rudder is applied from the maximum rudder thickness position to the position of the rudder cord length 10% from the rear end, and the rear end parallel part length is The shape of the rudder shall be 10% of the rudder cord length. In addition, the second rudder shape that minimizes the rudder width in the first half of the rudder and maximizes the rudder width in the second half has a front edge radius of 15% of the maximum rudder thickness. Apply to the position of 5% in length, and make the rudder shape with the rear end parallel part length 5% of the rudder cord length. Based on these two rudder shapes, the range of the rudder width described in (Means 1) is determined. The relationship between the two rudder shapes and the rudder width is shown in FIG.

FIG. 7 shows the first and second rudder shapes in a shape half the rudder center line, and the □ marks in the figure indicate the upper and lower limits of the cross-sectional width at each X / C position.
Although the upper limit of the rudder width range at the position of X / C = 0.98 is large, when applied to a marine rudder, the rudder width is often changed at a position in the rudder height direction. At this time, if a rudder is manufactured with a constant width in the height direction of the rudder rear end, the maximum rudder width will change in the rudder height direction. This is because it becomes larger.

  In order to improve the marine rudder to a rudder that generates even higher lift, the straight parallel part 1C near the rear end of the rudder drifts the flow of the fluid and thereby suppresses the acceleration of the fluid, resulting in an increase in pressure. Although there was a work, if a columnar object having a cross section larger than the rudder width at that point is added to the rear end of the rudder, the effect of drifting the flow becomes larger, and the lift increases. The fin portion of the fish at the rear end of the rudder in the prior art 2 also performs the same function. However, as described above, there is a very thin part immediately before, which is a problem in structural strength, and is unsuitable for application to a large ship or difficult to manufacture. The present invention can solve these problems.

  First, the rudder rear end processing at the time of manufacturing the rudder may be performed by a method of welding the rudder plates 5 from both sides of the rudder to a columnar body 4a having a relatively small circular cross section as shown in FIG. Many. Therefore, as shown in FIG. 8B, it is only necessary to use a solid or hollow columnar body 4b having a large diameter instead of the small columnar body 4a. In addition, although this figure has shown the case of cylindrical shape, the same effect is produced also in another shape. At that time, the columnar object 4b may be attached to the entire rudder height, but by partially attaching it, it is possible to adjust lift and increase rudder resistance. In this case, the mounting position or the like of the columnar object 4b is not particularly limited, but more preferably, it is better to mount the columnar object having the same length as the propeller diameter as if it is directly opposed to the propeller. improves. Moreover, even when the width of the rear end portion of the rudder is thin, the distance from the columnar object 4b is very close, so that a large moment is not received, and the problem of structural strength is solved.

  Examples of the present invention include A05 rudder, A10 rudder, B05 rudder shown in Table 1 and FIG. 1, and B05A15 rudder, B05B15 rudder, B05B22 rudder, B05B30 rudder and the like shown in Table 3. However, the rear end of the rudder equipped in an actual ship does not necessarily have a finite width because of the end processing. Therefore, the description of having a finite width rear end in claim 1 excludes such manufacturing end processing and is applied to a cross-sectional shape immediately before end processing ( It should be noted that the cross-sectional shape after the end processing does not matter if it has a finite width.

FIG. 9 shows an embodiment of a suspended rudder, and FIG. 10 shows an embodiment of a semi-suspended rudder with a ladder horn. 9 and 10, 1 is a rudder body, 2 is a rudder shaft, 3 is a propeller, 6 is a ladder horn, and 7 is a hull.
In the suspension type rudder of FIG. 9, the horizontal cross-sectional shape at an arbitrary position of the rudder main body 1 satisfies the present invention, and in the semi-suspended rudder with a ladder horn of FIG. The lower movable portion 11 below the horn 6 has a horizontal sectional shape that satisfies the present invention in an arbitrary horizontal cross section, that is, over the entire height of the upper movable portion 11, and the upper movable portion behind the ladder horn 6. 12 has a horizontal cross-sectional shape that is substantially similar to the shape of the corresponding portion of the lower movable portion 11 in an arbitrary horizontal cross section, that is, over the entire height of the upper movable portion 12. Here, the cross-sectional shape of the ladder horn 6 is not particularly limited.

  FIG. 11 (a) shows the horizontal cross-sectional shape of the B05A15 rudder shown in Table 3, and FIG. 11 (b) shows that the width of the B05A15 rudder having this horizontal cross-sectional shape is larger than the width of the rear end. The rudder shape at the time of attaching the columnar object 4b which has a cross-sectional shape is shown. The columnar object 4b is attached to a part or the whole of the rear end of the marine rudder in the vertical direction. The cross-sectional shape of the columnar object 4b includes a circle, an ellipse, a regular square, a rhombus, and the like, and is not particularly limited. In the case of an ellipse, the major axis direction is attached, in the case of a regular quadrangle, the diagonal line is on the extended line of the center line of the rudder, and in the case of a rhombus, the longer diagonal line is attached.

Examples of the present invention include the B05A15 rudder, B05B15 rudder, B05B22 rudder, and B05B30 rudder shown in Table 3, and models were prepared. Also, create a side-rectangular model rudder of prior art 1 of the same size as those, and attach it to a model ship of a large ship with a propeller with a total length of 8.5 m, draft of 0.472 m, and a diameter of 0.240 m, and operate the propeller The test was conducted in an NKK hull form test water tank while towing the ship at a speed of 1.28 m / s while taking the rudder angle and measuring the fluid force acting on the rudder.
FIG. 4 shows the result of the direct steering pressure, and FIG. 6 shows the result of estimating the horsepower equivalent to the actual ship estimated by the propulsion performance test. As a result, the rudder of this example had the same propulsive performance as compared with the prior art 1, and the steering straight pressure was confirmed to increase by 9%, 17%, 20%, and 24% in order of increasing effect. These are in a larger range compared to the effect of increasing the rudder force by about 10% (see FIG. 19) compared to the conventional rudder (equivalent to the prior art 1) in Japanese Patent Laid-Open No. 2000-280984 of the prior art 3. It shows that the rudder shape of the invention is effective for increasing the rudder direct pressure.

Calculate the reduction effect of the rudder area due to the increase of the rudder direct pressure. For the calculation of the rudder direct pressure _Fry of the rudder placed behind the propeller of the ship, _Equation 1 has been used for the rudder of the prior art 1.

  In the case of a rudder having a direct pressure coefficient larger than that of the rudder of the prior art 1, the rudder direct pressure can be approximately calculated by newly treating the ratio R multiplied by f (λ) as the direct pressure coefficient. When the rudder is a rectangular rudder and the rudder height H is the same, the rudder area ratio in the case where the rudder having an increase rate of the rudder direct pressure R and the rudder of the conventional technique 1 gives the same direct pressure is expressed by the following formula (Equation 2 ).

Using the rudder shape (H = 364.9 mm, C ₀ = 211.3 mm) in Table 3, λ ₀ = H / C ₀ = 1.73, and the rudder angle δ of the B05A15 rudder, B05B15 rudder, B05B22 rudder, and B05B30 rudder If the ratio of the rudder straight pressure coefficient in the case of = 8 ° is used, the reduction rate of the rudder area of each rudder is calculated from the above formula. Table 4 shows the results.

  From Table 4, in the case of the B05A15 rudder having the largest reduction rate of the rudder area within the range of claims 1 to 3, the rudder area is 68% as compared with the prior art 1. In the rudder of the prior art 3, when the rate of increase of the direct pressure coefficient with respect to the prior art 1 is about 1.10 from FIG. 19, the rudder area is 82% of the prior art 1, but the B05A15 rudder is 17% more than that ( It is a small rudder area). However, this is a calculation result when assuming that a rectangular rudder is used, the direct pressure is expressed by the above formula, and the formula of the direct pressure coefficient gradient expressed by the aspect ratio holds even in the case of the rudder of the present invention. It is added that there is.

As a cross-sectional shape of the rudder, as shown in FIG. 11, a columnar object having a circular cross section having a diameter of about 3% of the rudder cord length (6 mm for the model rudder) at the rear end of the rectangular rudder having the rudder cross-sectional shape of the B05A15 rudder 4b was attached from the lower end to the upper end of the movable rudder main body (see FIG. 10). A rudder force measurement test and a propulsion performance test were performed on the rudder of this example shown in FIG. As a result, the steering straight pressure at the steering angle of 8 ° increased by 1.36 times, the rudder resistance increased by 1.47 times compared to the prior art 1, and the increase in horsepower equivalent to the actual ship was 3.3%. It was.
Although the rudder of this embodiment causes a deterioration of about 3% in propulsion performance, the increase in direct pressure is extremely large, and the rudder area necessary for obtaining the same direct pressure as that of the rudder of the prior art 1 is obtained in the same manner as above. Thus, 55% of the rudder area of the rudder of the prior art 1 is sufficient, and the rudder can be extremely miniaturized. Therefore, it is easy to imagine that the rudder resistance will not only be halved, but also the adverse effect on the propeller wake will be reduced, and the adverse effect on the propulsion performance will be reduced to a level where there is no problem, and it can be applied to general ships. .

  As described above, according to the present invention, the shape of the rear half of the rudder is effectively increased in order to obtain a large lift, by combining a concave shape on the outside and a linear portion substantially parallel to the vicinity of the rear end of the rudder, thereby increasing the lift. Because it is possible to realize a rudder for ships with excellent performance and no deterioration in propulsion performance, it is not only applicable to relatively large mainland horsepower ships, but also to large ships that are difficult to profit from operating in the open ocean. Even if equipped, it can achieve a significant improvement in maneuverability and maneuverability without deteriorating its operating profitability, and it can reduce the rudder production cost by downsizing the rudder and reduce equipment procurement cost by downsizing the steering device. It has become possible to create benefits for both the shipowner and the construction side.

It is a rudder shape (however, half shape) figure used in order to determine the horizontal cross-sectional shape of the rudder for ships of this invention. It is a figure which shows the pressure distribution and lift component by CFD calculation with respect to the two-dimensional cross section of the ship rudder of this invention. It is a figure which shows the definition of the rudder direct pressure, rudder resistance force, and rudder angle in a model test. It is the figure which compared the direct pressure of the rudder obtained by the rudder force measurement test by the ratio with the rudder direct pressure of the prior art 1. FIG. It is the figure which compared the resistance force of the rudder obtained by the rudder force measurement test by the ratio with the rudder resistance force of the prior art 1. FIG. It is the result of having investigated the influence which a rudder shape has on the horsepower of an actual ship by a propulsion performance test, and is a figure which expressed the change from horsepower when installing the rudder of prior art 1 in percentage. It is a rudder shape (however, half shape) figure used in order to determine the range of the rudder width in the ship rudder of this invention. It is the figure which showed simply the manufacturing method in the case of attaching a columnar thing to a rudder rear end part. It is a figure which shows the Example of a suspension type rudder. It is a figure which shows the Example of the semi-suspended type rudder with a ladder horn. (A) is a rudder shape figure which shows the Example of this invention, (b) is a rudder shape figure at the time of attaching a columnar object to the rear-end part of the rudder. It is a figure which shows the rudder shape of the prior art 1 (NACA symmetrical wing | blade). It is a figure which shows the rudder shape of the prior art 2 (Unexamined-Japanese-Patent No. 10-297593). It is a figure which shows the rudder shape of the prior art 3 (Unexamined-Japanese-Patent No. 2000-280984). It is a figure which shows the definition of the flow and lift and drag which hit a two-dimensional wing | blade. It is a figure which shows the pressure distribution and lift distribution by CFD calculation with respect to the two-dimensional cross section of the prior art 1. FIG. It is a figure which shows the lift coefficient of the prior art 2. FIG. It is a figure which shows the drag of the rudder of the prior art 2. FIG. It is a figure which shows the lift coefficient of the prior art 3. FIG.

Explanation of symbols

1 rudder body, 1A front edge, 1B rear end, 1C linear portion, 6 ladder horn.

Claims (3)

  In the horizontal cross-sectional shape of the rudder body, when the maximum width of the cross-sectional shape is Tmax, the radius of the front edge is 14% or more and 22% or less of the maximum width Tmax, and the front edge is circular or similar The cross-sectional width gradually increases toward the rear of the rudder body, reaches the maximum width, and the cross-sectional width decreases while changing from a convex shape outward to a concave shape gently outward. Then, a marine rudder having a linear portion formed by substantially parallel straight lines up to the rear end and having a rear end having a finite width.   The rudder for a ship according to claim 1, wherein a length of the substantially parallel linear portion is in a range of 3% to 10% of the entire length C from the rear end.   3. The ship rudder according to claim 1, wherein a cross-sectional width T of the substantially parallel linear portion is in a range of 4% to 11% of a maximum width Tmax.

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