KR101998285B1 - Rudder for special ship - Google Patents

Abstract

The present invention relates to a method for building a battleship, and more specifically, to a method for building a battleship, in a method for building by mounting a rudder on the stern of the battleship, whose propeller shaft is in a linear shape inclined downwards closer to the stern, comprises: a step of placing the rudder to allow the vertical central line of the rudder to escape towards the port or the starboard around the central line of the rotary shaft of the propeller; a step of allowing the propeller to cover only up to a certain height from a lower side of the rudder. Accordingly, the present invention is able to effectively reduce erosion on the rudder by cavitation generated by the difference in pressure due to the high thrust and velocity of flow for the characteristics of the battleship which needs high speeds, to reduce a loss in lift and resistance, and to improve steering performance of the rudder and propulsion.

Description

RUDDER FOR SPECIAL SHIP}

The present invention relates to a method of drying a warship, and more particularly, to a method of drying a warship, which is characterized in that the characteristics of a warship requiring high speed (high speed) To improve the steering performance and propulsion performance of the rudder by reducing the lift loss and the resistance.

In general, ships can be classified according to purpose of use, freight condition, and loading mode.

Ships can be divided into merchant ships, special working ships, warships, fishing boats, etc., depending on the purpose of use. In particular, warships are divided into combat and support, transport, guard, aircraft, and submarines. Combat hulls include battleships, cruisers, destroyers, convoys and helicopters, , It is called a torpedo. (Or light railroads), support ships, high-speed transport boxes, landing ships, and tank landing boxes, and aircraft carriers are for transporting, storing and landing aircraft.

The warships have low drafts except for some transports, because the drafts are fast, and the drafts are as low as 2 meters on the basis of drafts and rarely have drafts of 10 meters unless they are aircraft carriers.

The warship is designed to have a maximum speed of 30 to 40 knots. Due to the nature of the warship that needs high speed, the propeller's high thrust and rapid rotation speed in the backward direction of the hull, compared to other ships, And this cavitation can cause noise, vibration, erosion of the propeller and rudder, which can cause serious problems in naval operation.

A rudder (rudder) is a device used for the steering of a ship, which is rotatably mounted at the rear of the ship, and is responsible for the main function of the ship's maneuverability by steering the direction of the propulsive force obtained by the propeller.

The rudder can be divided into a conventional rudder and a spade rudder. The conventional rudder is a rudder horn structure, and the spade rudder is a rudder horn-free structure.

The rudder has a semi-spade type and a spade type, and the spade rudder has a full spade type, a twist-leading edge full-spade type, and the like.

The rudder is one of the components most commonly used for cavitation erosion in the hull. The rudder cavitation causes erosion and corrosion on the surface of the rudder, and if it continues, the rudder is damaged and the role of the rudder is lost, leading to danger such as stranding of the ship. Therefore, in order to improve this, shape deformations of the rudder, rudder bulb, energy saving device (ESD) of the rudder bulb pin and the like are being developed.

In order to solve the problems of the conventional rudder, Korean Registered Patent No. 10-0346512 entitled "Rudder of a Ship ", in which the front end of the propeller rotational shaft height is separated vertically so that the upper front end and the lower front end are twisted in opposite directions, The bulb of the streamline type is installed in a form corresponding to the asymmetric characteristic of the complex current, so that the energy loss due to the asymmetric characteristic of the complex current is maximally recovered according to the rotation direction of the propeller, And proposed a technique for improving the propulsion efficiency of the ship, and as a similar technique, Japanese Patent Application Laid-Open No. 10-2005-0103137 entitled "Ship Key" has been proposed.

This conventional technique increases the rectification efficiency of the composite rotation current in the port side (the direction of rotation of the propeller) when the rectification efficiency of the bilge vortex and the rotation current by the rudder is increased, So that the propulsion efficiency of the ship can be improved.

However, such a conventional technique increases the resistance by causing a velocity loss of the peripheral fluid due to the vortex that rapidly falls off the rotation shaft of the propeller and the vortex generated discontinuously in the twist portion of the upper front shear and the lower front shear (where the reverse twist meets) There is a problem that the rectification efficiency of the fluid is lowered. In the forward rotation direction of the propeller, the composite rotation current flows upward and does not coincide with the downward flow characteristic in the reverse rotation direction. As a result, the rectification efficiency is lowered, .

Especially, in the case of a full-spade rudder with a twist type, since the span is shorter than the general rudder, the shoulder (bottom portion of the rudder) is placed in the wake of the propeller unlike the general rudder, Unstable cavitation occurs due to the flow velocity, causing erosion and the like.

Korean Patent No. 10-1010998 Korean Patent No. 10-1390852

In order to solve the above-described problems, in order to achieve the above-mentioned object, the first aspect of the present invention is characterized in that a rudder is mounted on a stern of a warship having a linear propeller shaft inclined downward in a stern direction, Wherein the vertical center line of the rudder is disposed in a port or starboard direction with respect to a rotation axis center line of the propeller, and the propeller covers only a certain height from a lower portion of the rudder, It is possible to effectively reduce the rudder erosion caused by the cavitation caused by the high thrust of the propeller and the pressure difference due to the high flow velocity and to improve the steering performance and propulsion performance of the rudder by reducing lift loss and resistance To provide a method of drying a warship.

In order to accomplish the above object, the first aspect of the present invention is a method for drying a warship by mounting a rudder on a stern of a warship having a linear shape in which a propeller shaft is inclined downward in a stern direction, Wherein the vertical center line is arranged to be deviated in the port or starboard direction with respect to the rotation axis center line of the propeller, and the propeller covers only up to a certain height from the lower portion of the rudder. In view of the characteristics of a warship requiring high speed, And to a method of drying a ship which can effectively reduce rudder erosion due to cavitation caused by a pressure difference due to a rapid flow velocity and improve the steering performance of a rudder by reducing lift loss.

The present invention is applicable to a ship having a linear shape in which the propeller shaft is inclined downward in the aft direction (for example, a special ship such as a ship, small vessel, etc.).

According to a second aspect of the present invention, there is provided a method of drying a wartime vessel in which a rudder is rotatably installed at a stern and a propeller is installed at a lower end of a stern, the rudder being manufactured such that the cross- The width gradually increases from the leading edge of the arcuate shape toward the trailing edge with respect to the center line. The width gradually decreases from the maximum width to the trailing edge. Wherein an axis of the transverse section of the rudder relative to a straight line parallel to the propeller shaft is formed at the front edge and the rear edge in a region affected by the flow of the fluid flowing into the rudder due to the rotation of the propeller, (E.g., 0 to 15 degrees) to form a twisted portion; And a rudder disposed at a rear side of the propeller, wherein a vertical center line of the rudder relative to a rotational axis center line of the propeller is arranged to deviate in a port or starboard direction, and an overall length (total diameter) of the propeller covers the entire twist portion And a second step of disposing the rudder.

The cross-sectional shape of the rudder for a special purpose ship according to the present invention is gradually increased from an arc-shaped leading edge toward a rear edge (trailing edge) with respect to a rudder horizontal center line. In a region affected by a flow of fluid entering the rudder due to rotation of the propeller in the forward and rearward edges, the width of the propeller shaft < RTI ID = 0.0 > (For example, 0 to 15 degrees) of the axis of the cross section of the rudder with respect to a straight line parallel to the straight line parallel to the straight line.

In addition, the vertical center line of the rudder is arranged to deviate in the port or starboard direction with respect to the rotation axis center line of the propeller, and the twist portion is installed in a range covering the full length (total diameter) of the propeller.

The propeller shaft is horizontally rotatable about a straight line parallel to the propeller shaft, and the propeller shaft is horizontal. In the case of the propeller shaft, It descends horizontally as it goes to the stern, but it is understood as being extended horizontally.

When the span (rudder height) of the rudder is divided from 0% to 100% from the upper end portion to the lower end portion, the twist portion is not formed in the front edge portion and the front edge portion to less than 0% to 20% To < RTI ID = 0.0 > 100%. ≪ / RTI >

And the twist angle of the twist portion is set to a maximum value at a point of about 30% of the span (rudder height) of the rudder.

In the cross-sectional profile of the rudder (projected area profile), the center of rotation of the twisted portion is located at a point of the maximum width point (e.g., 30% to 40% of the total length of the cross- % (Or more than 30%) to 40%). A rudder stock is provided at or near the center of rotation of the twisted portion (within 10% of the total length of the cross section).

On the other hand, in the wing of the present invention, the cross-sectional shape (projected area profile) gradually increases in width from the arcuate forward portion to the rearward portion with respect to the horizontal center line, and gradually increases from the maximum width point to the rear portion Wherein the forward and rearward portions are provided with a rudder that forms a twist only in a region influenced by fluid flow into the rudder due to rotation of the propeller.

And the cross section of the twisted portion is symmetrical. In other words, in a general ship, since the span of the rudder is influenced by the propeller, the rudder span (the height direction of the rudder) has a twisted portion and the cross section itself is formed in an asymmetric shape. And then rotated at different angles.

According to the invention, the center of rotation of the twist is located in a range of less than 50% from the leading edge of the rudder, the beginning of the twist of the leading edge starts at 10% to 30% of the span and the beginning of the twist of the trailing edge, Starting from a position higher than the beginning of the twist of the edge.

Further, according to the present invention, it is desirable that the leading edge and / or trailing edge of the rudder are continuously twisted in a curve rather than a discontinuity. That is, the cross-section of the rudder can be twisted from 15 degrees, preferably 10 degrees, starting from 0 degrees, depending on the height of the span.

According to a third aspect of the present invention, there is provided a method of manufacturing a twisted rudder for a ship, the method comprising: dividing a cross section of a rudder symmetrically left and right, Showing a bubble line from the dividing point to the outline of the cross section perpendicular to the longitudinal direction of the rudder; Twisting at least one of a front edge portion and a rear edge portion of the rudder with respect to a straight line parallel to the propeller shaft about the maximum width point (center point of the maximum width line) of the rudder by rotating the rudder length at a predetermined angle with respect to the direction; And completing the cross-sectional profile of the twisted rudder by connecting curved ends of adjacent width lines except for the ends or both ends located inside the rotational direction in the heavy line which is the center of rotation among the heavy lines; The present invention also provides a method of manufacturing a twist rudder. In this way, the twist rudder profile can be designed and the twist rudder can be simply fabricated based on such a profile.

And the rotation center is characterized in that the heavy line has a maximum length. If the bellows are not at the maximum position, the cross-sectional profile is completed except for one or more of the ends of the bellows and the bellows at the maximum location.

If other heavy lines are adjacent to the rudder cross-section at a position less than 10% of the full-length heavy line, the cross-section profile may be completed except for the ends of the width line.

When the cross sections of both the front and rear edges of the rudder are twisted with respect to the direction of the rudder, the rotational angles of both are different.

The configuration applicable to the third embodiment among the configurations according to the second embodiment of the present invention is also applied to the third embodiment.

For example, with respect to a straight line parallel to the propeller shaft, the axis of the cross section of the rudder can be twisted from zero to a maximum of 15 degrees depending on the span height, and thereby the leading or trailing edge is formed with a continuous curved twist portion do.

Further, in the cross-sectional profile (projected area profile) of the rudder, the center of rotation of the twisted portion may be located at the maximum width point (e.g., 30% (or more than 30%) to 40% point from the leading edge . A rudder stock is provided at or near the center of rotation of the twisted portion (within 10% of the total length of the cross section).

As described above, the first and second embodiments of the present invention can be applied to at least any one (preferably both) of the forward or rearward portions of the flow of fluid flowing into the rudder due to propeller rotation A rudder is manufactured so as to form a twisted portion in a receiving region. The rudder is arranged so that the vertical center line of the rudder is offset from the center line of the rotation axis of the propeller in the port or starboard direction, and the rudder is appropriately It is possible to effectively solve the problem of continuously forming the twisted portion and causing the velocity loss of the peripheral fluid due to the vortex generated in the discontinuous twist portion as before, Due to the high thrust of the propeller and the pressure difference due to the fast flow velocity, It is possible to reduce rudder erosion effectively by, it is possible by reducing the lift loss and resistance improving steering performance and driving performance of the rudder.

The reason why the rudder of the special ship including the warship is deviated in the lateral direction from the propeller center is that when the propeller rotates, a vortex is generated in the propeller cap located at the center of the propeller. When this vortex hits the rudder, cavitation occurs in the rudder The vortex can be avoided by moving the rudder in the lateral direction.

In the present invention, since the rudder is biased upwardly and the propeller covers only a certain height from the bottom of the rudder, the propeller shaft has a structure suitable for the linear shape of a special ship (small ship) which is inclined downward in the aft direction . In addition, since the twist portion is provided only in the portion covered by the propeller, the manufacturing process is complicated and the costly portion is reduced. In addition, the rudder upper portion, which is not affected by the propeller, has a problem of increasing resistance and cavitation when the upper portion of the rudder is twisted because the fluid flows into the rudder portion at almost zero degree none. In addition, even if the rudder upper part receives a part of the influence of the propeller like the general ship arrangement, since the upper end of the rudder does not have the twist part, the skeg which is located at the upper part of the rudder is generally disposed at zero degree without twist. When twisted, there is a problem that steps are increased at the lower part of the skis and at the uppermost part of the rudder, which adversely affects the resistance and cavitation. In the present invention, such a problem is solved.

Further, the cross section of the twisted portion is symmetrical in the left and right directions, and the rudder profile of the NACA-00 (4-digits) series and the NACA-643 series can be used as it is.

In the cross-sectional shape of the rudder, the center of rotation of the twisted portion of the rudder is centered at the maximum width point (30% to 40% from the leading edge) and is installed at or near the rotation center of the rudder stock, Can be secured and the rudder profile can be designed to be thin.

When the center of rotation is 30% to 40% from the leading edge, the trailing edge (rear edge, front edge, front edge) is smaller than the leading edge (leading edge, trailing edge, trailing edge, and trailing edge) of the trapezoidal curve is large, a sudden shape change point is generated, resistance and cavitation can be increased at the corresponding point, and fabrication is difficult. In contrast, It is resolved.

In the present invention, by starting the twist start portion of the trailing edge from a position higher than the beginning of the twist start of the leading edge, abrupt change in shape of the gradient of the twist curve of the trailing edge is reduced, resistance and cavitation It is possible to solve the difficulty of the present invention.

According to the method of manufacturing a twisted rudder according to the third embodiment of the present invention, the twist rudder can be simply manufactured by simply twisting a rudder whose starting end face is symmetrical, and at the same time, A part of the shape is distorted at the portion located inside the rotation direction to negatively affect the fluid flow and consequently the resistance and cavitation increase can be prevented.

1 is a view for explaining a part name of a general rudder;
Figure 2 shows a projection area profile of a general twist rudder;
3 is a flow chart illustrating a method of drying a wartime vessel according to the present invention.
4 is a perspective view showing a rudder manufactured by the drying method of the present invention.
Fig. 5 is a front view of Fig. 4
Fig. 6 is a cross-sectional view showing the front edge portion and the trailing edge portion of Fig. 4 at the same time
Fig. 7 is a rudder projected area profile in Fig. 4, in which the left and right symmetrical sections of the rudder are twisted in different directions according to the span (rudder height), centering on the widest point of the cross section
8 is a front view for explaining the arrangement structure of the rudder and the propeller in the method of drying a wartime vessel according to the present invention
9 is a side view of Fig. 8
10 is a view for explaining the principle of cavitation generation and the twist of a rudder;
11 is a plan view showing a conventional symmetrical rudder cross section, in which the widest point is the point at which the rudder stock is installed at 30% of the total length of the cross section;
12 is a view showing the rotation of the front end shown by the bold line, in a symmetrical rudder cross section;
Fig. 13 is a diagram showing a curve in a symmetrical rudder cross section except for a point located in the rotational direction in both the spins on the rotation center line, with the point of 30% from the leading edge being the maximum width point as the twist rotation center
Fig. 14 is a cross-sectional view of a symmetrical rudder cross section, in which the leading edge portion is twisted with respect to the rotation center of the maximum width point 30%, and the curve is drawn except for both points on the rotation center line
Fig. 15 is a view for explaining a phenomenon in which the asymmetric cross-sectional shape is distorted when the leading edge portion is twisted with respect to the rotation center of the maximum width point 30% in the symmetric rudder cross section and both points on the rotation center line are connected.
Figure 16 is a cross-sectional view of a symmetrical rudder, in which a trailing edge is twisted with respect to a center of rotation of a maximum width of 30%
Fig. 17 is a cross-sectional view of a symmetrical rudder cross section, in which the forward edge and the trailing edge are twisted at the same angle with respect to the rotation center of the maximum width point 30%
Fig. 18 is a view showing, in a symmetrical rudder cross section, twisted forward and trailing edges at different angles with respect to the rotation center of the maximum width point 30%
Fig. 19 is a cross-sectional view of a symmetrical rudder cross section in which the leading edge portion is twisted with respect to the center of rotation of the maximum width point 35% of the section (NACA-643) having a maximum width point of 35%
20 is a schematic diagram showing that the position of the center of rotation affects the thickness of the entire rudder when the entire cross section is rotated at a certain angle by using the symmetrical cross section according to the present invention

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method of drying a watthouse of the present invention and a watthouse equipped with a rudder manufactured by the drying method will be described in detail with reference to the accompanying drawings.

Prior to describing the present invention, in order to facilitate understanding of the technique of the present invention, general rudder part names are shown in Fig. 1 and cross section shapes (projected area profiles) of general rudders are shown in Fig.

First, as shown in Fig. 1, a general rudder has a rudder blade and a rudder stock, which is a shaft coupled to transmit rotational power to the rudder blade.

The height of the rudder is called the span and the total length of the cross section is called the chord. The former part is called the leading edge and the latter part is called the trailing edge.

2 (a), a common twist rudder forms a twist over the entire rudder span because the majority of the rudder is influenced by the flow of fluid generated by the rotation of the propeller, and the rudder cross- asymmetric shape having a camber is used.

2 (b), in the twist ruder disclosed in Japanese Patent No. 10-1310965, the upper rudder and the lower rudder in the front edge are inclined relative to the rudder horizontal center line L2 with respect to the rotational axis center line of the propeller Are each twisted at angles (?,?) Of 2 to 8 degrees.

Since the upper rudder and the lower rudder are formed discontinuously with respect to the axis of rotation of the propeller, the vortex generated in the hub of the propeller causes cavitation that causes erosion on the surface of the discontinuity formed in the front edge of the rudder.

FIG. 3 is a flow chart for explaining the drying method and the rudder according to the first and second embodiments of the present invention, FIG. 4 is a perspective view showing the rudder manufactured by the drying method of the present invention, Fig. 6 is a rear view and a front view of Fig. 4, Fig. 7 is a rudder projected area profile in Fig. 4, and a left-right symmetrical cross section of the rudder about the maximum cross- Fig. 8 is a front view for explaining the arrangement structure of a rudder and a propeller in a method of drying a wartime vessel according to the present invention, and Fig. 9 is a side view of Fig. 8. Fig.

Referring to the above drawings, a method of drying a ship according to the present invention includes the steps of connecting a rudder stock (see FIG. 1) to a stern (2) of a stern (1) (1) A method for drying a wartime vessel (which means a special ship including a warship) by installing a propeller 20 at a lower end, comprising a first step (S10) of producing a rudder (100) The vertical center line (L2 in FIG. 8) of the rudder 100 is arranged to be deviated in the port-side or starboard direction, that is, shifted from the center line L1 of the rotation axis of the propeller 20 And a second step S20.

That is, in the method for drying a wicket according to the present invention, the first step S10 is to manufacture the rudder 100, wherein the cross-sectional shape (projected area profile, that is, rudder cross- 2, the width gradually increases from the arcuate forward portion toward the rear portion, and the width gradually decreases from the maximum width portion to the rear portion, The rotation of the propeller 20 forms the twist portion 110 only in the region influenced by the fluid flow into the rudder 100. [

That is, when the span (rudder height) of the rudder 100 is divided from 0% to 100% from the upper end portion to the lower end portion, the twist portion And the twist portion 110 is formed from about 20% to about 100% without forming the twist portion 110. It is understood that the present invention is not limited to 'about', but 'about' is included in the range of the same.

In addition, the twist angle of the twist portion 110 can be maximized at the span (rudder height) 30% of the rudder 100.

In the cross-sectional profile (projected area profile) of the rudder 100, the center of rotation of the twisted portion 110 is characterized by centering on the maximum width point (30% to 40% of the total cross-section length (code) . The center of the rudder stock is located at or near the maximum width point.

This is because, when the twist section is rotated at the maximum 30% of the rudder cross section, the rudder cross section covers the hub diameter at which the rudder stock is inserted at the maximum width. However, when the cross section is rotated at 20% Since the maximum width of the hub can not cover all the hub diameters, it is necessary to increase the overall width of the hub to allow the hub to be installed, which results in the increase of the rudder width (thickness) 20)

The conventional twist type rudder is arranged such that the cross-sectional shape (projection area profile) is asymmetrical (see Fig. 2 (a)) and the entire rudder is arranged to be influenced by the fluid flow of the propeller, and the twist portion is formed over the entire rudder span will be.

On the other hand, in the present invention, there is a technical difference in that the rotation of the propeller 20 forms the twist portion 110 only in the region affected by the flow of the fluid flowing into the rudder 100.

That is, in the rudder 100 of the present invention, the rudder span 20 (0% to less than 20%) which is not influenced by the propeller 20 does not form the twisted portion, % Or more to 100%).

This means that the inflow angle of the fluid entering the rudder when there is no influence of the propeller is almost zero, and generates little lift when the rudder is at zero degree position. If a twisted portion is formed in a rudder span (less than 0% to 20%) which is not influenced by the propeller as described above, an unnecessary lift is generated, resulting in increased resistance and cavitation.

The embodiment of the present invention is based on the assumption that at least 20% to 100% of the rudder span region affected by the propeller in order to minimize erosion by resistance and cavitation, Thereby forming a twisted portion 110 at an angle, thereby reducing resistance and cavitation.

Since the skew 2 of the stern 1 is basically disposed at zero degree without twist, when the twist portion is formed at the uppermost end of the rudder 100, the upper end of the rudder 100 is engaged with the skeg 2 There is a disadvantage in that a large step is formed between the uppermost end of the rudder 100 and the skeg 2, which adversely affects resistance and cavitation.

Accordingly, in the present invention, since the twist portion 110 is not formed in less than 20% of the rudder span, the step between the uppermost end of the rudder 100 and the skeg 2 is hardly generated, There is an advantage that it has a positive influence on.

Further, since the rudder with the twist portion is generally higher in manufacturing cost than the rudder without the twist portion, and thus the twist portion 110 is not formed at less than 20% of the rudder span, Can be saved.

The second step S20 is a step of disposing the rudder 100 on the rear side of the propeller 20 so that the rudder 100 is disposed on the rotation axis center line L1 of the propeller 20, (Total diameter) 22 of the propeller 20 is arranged to deviate (shift) in the direction of the port or starboard direction so that the ridge 22 of the propeller 20 covers the entire twist portion 110 100).

This is because, when the propeller rotates, a vortex occurs in the propeller cap located at the center of the propeller. When this vortex hits the rudder, cavitation occurs on the surface of the rudder, so that the rudder is moved away from the port or starboard direction . That is, the vertical center line L2 of the rudder 100 is arranged so as to be deviated in the port or starboard direction with respect to the rotation axis center line L1.

Furthermore, in the present embodiment, the propeller rotational axis center line may be inclined downwardly in the stern direction due to the linear characteristics of the special ship and the small ship. For this reason, less than 20% of the rudder span may not be covered by the propeller electric field.

On the other hand, in the wing of the present invention, the cross-sectional shape (projected area profile) gradually increases from the arcuate forward portion toward the rearward portion with respect to the horizontal center line L2 from the maximum width point to the rearward portion Wherein a rudder forming a twist portion 110 is formed in the front edge portion and the rear edge portion only in a region affected by the flow of the fluid flowing into the rudder 100 through the propeller 20, Respectively.

The rudder 100 is disposed behind the propeller 20 with respect to the rotational axis center line L1 of the propeller 20 so that the vertical center line L2 of the rudder 100 is located on the left or right side of the propeller 20, And the rudder 100 is disposed so that the entire length (total diameter) of the propeller 20 covers the entire twist portion 110. In other words,

Also, the twisted portion may be formed at a certain angle only in the rear edge portion of the rudder span 20% point. The reason why the twist portion 110 is formed only in the rear edge portion of the rudder span 20% instead of forming the twist at a certain angle in both the front edge portion and the rear edge portion is that when the twist portion 110 is formed also in the front edge portion, A point less than 20% rudder span is outside the influence of the flow velocity generated by the propeller 20, so that when the twisted portion 110 is formed in the forward edge because the angle of the fluid inflow is 0 degree, an unnecessary lift is generated, Resistance and cavitation increase. On the other hand, as compared with the twisted portion of the leading edge portion, the gradient of the twisted portion of the trailing edge is large, so that a sudden change in shape occurs, resistance and cavitation increase at the corresponding point, The point of view occurs at about 20 ~ 30% of rudder span.

This is because the angle is zero degree without the twist portion 110 because the influence of the propeller 20 is less than the span 20% of the rudder 100. However, since the twist portion is formed at the span 30% Since the point is near the diameter of the propeller, the inflow angle of the fluid is large, and the angle of the twisted part becomes very large. That is, the angle of the twisted portion 110 is 0 degrees at the rudder span less than 20%, whereas the angle of the twisted portion 110 is close to the maximum value at the rudder span 30% point.

In order to solve the problem that the resistance and cavitation increase in the vicinity of the rudder span of about 20 to 30%, in this embodiment, the twist portion 110 is additionally provided at the span 20% Lt; / RTI >

The reason why the twisted portion is not formed in the front edge portion is that if a twisted portion is formed in the front edge portion, the point at which the rudder span is less than 20% is not influenced by the propeller, Lift occurs and consequently resistance and cavitation can increase.

Furthermore, in order to solve the above-mentioned problem, it is also preferable to form the twisted portions at different angles to the front edge and the rear edge.

In the present invention, it is preferable that the maximum width of the rudder is 30% to 40% from the leading edge. 6, when the twisted portion is formed using a symmetrical section as in the present invention, the gradient of the twist curve of the trailing edge (rear blade, 2) is larger than that of the rudder leading edge It can be seen that there is a change. In this way, if there is a sudden shape change point at the rear end, resistance and cavitation can be increased at the point, and it is difficult to manufacture.

This problem is generally due to the fact that the point at which the maximum width in the rudder cross section, i.e. the center of rotation of the twisted part, is located closer to the front side from the leading edge (for example, less than 50% from the leading edge, generally 30% to 40% At the ring edge, the twist curve gradient becomes relatively large.

Therefore, in order to solve this problem, in the present invention, it is preferable to use a rudder cross-section having a rudder cross-sectional area of 30% (preferably more than 30%) to 40% (for example, NACA-643 series is 35% point). The maximum width point becomes the rotation center of the twist portion.

Further, in order to reduce the sudden shape change of the gradient of the rear twist curve, even if the start of the gradient of the twist of the preceding twist starts from 20% of the span, the rear edge forms a twist gradient from 10% of the rudder span It is possible.

According to an embodiment of the present invention, it is preferable that the leading edge and / or the trailing edge of the rudder are continuously twisted in a curve rather than a discontinuity. This continuous curve image helps to reduce resistance and cavitation.

Referring to FIG. 9, in the present invention, the propeller shaft is inclined downward in the aft direction due to the linear characteristics of the special ship (small ship). Therefore, the present invention can have such a linear structure. In other words, since the rudder is biased upward and the propeller covers only a certain height from the bottom of the rudder, the propeller shaft can have a structure suitable for the linear shape of a special ship (small ship) have. In addition, since the twist portion is provided only in the portion covered by the propeller, the manufacturing process is complicated and the costly portion is reduced. In addition, the rudder upper portion, which is not affected by the propeller, has a problem of increasing resistance and cavitation when the upper portion of the rudder is twisted because the fluid flows into the rudder portion at almost zero degree none. In addition, even if the rudder upper part receives a part of the influence of the propeller like the general ship arrangement, since the upper end of the rudder does not have the twist part, the skeg which is located at the upper part of the rudder is generally disposed at zero degree without twist. When twisted, there is a problem that steps are increased at the lower part of the skis and at the uppermost part of the rudder, which adversely affects the resistance and cavitation. In the present invention, such a problem is solved.

10 is a view for explaining the principle of cavitation generation and the twist of the rudder.

Referring to FIG. 10, as the propeller rotates, the propeller wake flows into the rudder at a constant angle. Even if the angle of the rudder is 0 degrees, lift occurs, resistance increases, and cavitation is more likely to occur. Cavitation occurs when the inflow angle of the rudder and fluid exceeds a certain angle. For example, assuming that cavitation occurs at an inlet angle of 15 degrees of rudder and fluid, if there is no influence of the propeller, cavitation occurs when the rudder angle is 15 degrees because the fluid inlet angle is 0 degree, , The rudder cavitation occurs at a rudder angle of 15 degrees-fluid inflow angle because the fluid is already flowing at a certain angle. That is, cavitation occurs at lesser rudder angles.

Therefore, in the present invention, the rudder is twisted so that the angles of the rudder front edge and the rear edge are designed to be similar to the angle of the wake of the propeller. By forming the twist only in the region influenced by the fluid flowing into the rudder through the propeller, The rudder erosion caused by the rudder can be effectively reduced, and the steering performance of the rudder can be improved by reducing the lift loss.

On the other hand, in the following, with reference to FIG. 11 to FIG. A method of manufacturing a twisted rudder according to the present invention using a symmetric rudder cross section and a twisted rudder manufactured by the method will be described. This embodiment is applied not only to the special line but also to the rudder for general commercial ships.

A third embodiment of the present invention will be described with reference to Figs. 11 to 19. Fig.

First, use a conventional symmetric rudder (NACA-00 series) cross section as shown in FIG. 11, but only twist the front edge based on the maximum width point of the rudder cross section (see FIGS. 13 and 14) (See Fig. 16), or both the front edge and the back edge can be twisted (see Figs. 17 and 18). The maximum width of the cross section is preferably between 30% and 40% of the total length of the cross section (code).

In the case where only the front edge is twisted on the basis of the maximum width point of the rudder (NACA-00 series) cross section as shown in Fig. 13, each point is connected by a curve. In order to smoothly connect the curve without a sharp inflection point, The point located in the middle rotation direction is excluded from the curve, or both points on the rotation center are excluded from the curve as shown in Fig. On the other hand, in Fig. 14, Fig. 16, and the like, if the outline is connected except for the end of the bell at the outer side in the rotational direction, its radius of curvature is maintained. Since the bellows are connected by a spline, The entire line is formed as a curved line.

Here, among the points on the rotational center line, the point located on the rotational direction side is excluded from the curve because, as shown in Fig. 15, unlike the case where a curve is drawn except for a point or both points on the rotational center line, When connecting. A phenomenon in which a portion of the asymmetric cross-sectional shape collapses (indicated by a circle) may occur, which may adversely affect the fluid flow, resulting in increased resistance and cavitation.

Here, the meaning of 'excluded' will be described.

In general, when the rudder cross-sectional profile is designed and manufactured, the leading edge of the rudder changes abruptly with curvature, so that the cord length (rudder cross-sectional length) is increased from the leading edge to the trailing edge by 1.25% % Length unit, then the 5% length unit, then the 10% length unit, and shows the rudder cross-section at the divided point (known as the "Basic Thickness Form" DOVER Publications, Inc. 1959). For example, in FIG. 11, a 5% length heavy line is shown only in the front edge portion, and a 10% length heavy line is shown in the remaining portion. When the profile of the designed rudder cross section shown in the bold line is twisted with respect to the center point of the width line of the maximum width point as shown in Fig. 12 and then the outline forming the outer profile is formed, as shown in Fig. 15, It is assumed that the profile of the rudder is designed and manufactured by connecting both of the rudder and the rudder. In this case, in the rudder utilizing the cross-section in which the transverse section is symmetrical in the lateral direction as in the present invention, There is a problem in that a part of the shape is distorted at the portion located inside the rotational direction out of both ends of the heavy line of the center of rotation when rotating, which adversely affects the fluid flow and consequently increases the resistance and cavitation (circle in Fig. 15) . Further, there arises a problem that the radius of curvature becomes too small outside the rotation direction depending on the profile.

Accordingly, in the present invention, when the outline forming the profile is formed by connecting the ends of the width line as shown in FIG. 13 after the twist, the end of the width line serving as the center of rotation except for the inner end in the rotation direction, To form an outline. By doing so, there is no problem that the portion of the profile is distorted and consequently the resistance and cavitation increase.

In addition, in the case where other heavy lines are adjacent to the rudder cross-sectional length less than 10% of the maximum length heavy line, the cross-sectional profile can be completed except for the end of the width line.

FIG. 16 is a view showing a twist of the trailing edge with respect to the center of rotation of 30% from the front edge of the symmetrical rudder cross section at the maximum width point, and shows an example in which the twisted portion is formed in the rudder trailing edge by the above-described method.

Fig. 17 is a cross-sectional view of a symmetrical rudder cross section, in which the front edge and the trailing edge are twisted at the same angle with respect to the center of rotation of 30% of the maximum width point, It is. As shown in FIG. 17, when the front / rear is rotated at the same angle, there is no break point, so it is not necessary to exclude the point on the 30% width line, and the effect of the third embodiment may not occur.

Here, in the present embodiment, for example, the twist angle can be set to 10 degrees in both of the front edge and the rear edge, wherein the transverse width is 143 mm in the front edge and 334 mm in the rear edge.

18 is a cross-sectional view of the symmetrical rudder in which the front edge portion and the rear edge portion are twisted at different angles with respect to the center of rotation of the maximum width point of 30%, and the twist portions are formed at different angles in the rudder front edge portion and the rear edge portion, Since the position of the center of rotation is closer to the front edge of the rudder, the moving distance of the trailing edge portion becomes relatively longer as compared with the leading edge portion when rotating at the same angle. As a result, the maximum height of the twisted curve becomes larger and the gradient of the curve becomes larger A sudden change in shape occurs compared to the front curve. In this case, the fluid flow is not good at the point of abrupt change in shape, and resistance and cavitation may increase relatively.

Also, the abrupt change of the shape is disadvantageous in terms of composition. In order to minimize such a disadvantage, it is advantageous to set the rotation angle of the rear edge portion smaller than the front edge portion in consideration of the center of rotation when the twist portion is formed in both the front edge portion and the rear edge portion. In the present embodiment, for example, the twist angle can be set to 10 degrees at the front edge and 5 degrees at the rear edge. At this time, the rotational width of the transverse section can be reduced to 143 mm in the front edge and 168 mm in the rear edge. 17, the effect of the present invention is shown when the front edge and the trailing edge are twisted at different angles as shown in FIG.

Figure 19 shows a profile created on a symmetrical rudder cross section except for both extremities of the widest point after twisting the leading edge with respect to the center of rotation of the maximum width point 35% of the cross section (NACA-643) with a maximum width point of 35% .

As described above, the method of forming a twisted rudder type asymmetric rudder cross section of the present invention using a symmetric rudder cross section is applicable to most existing symmetrical cross sections, and asymmetric cross section can be formed simply in a short time, The entire cross section can be formed into a smooth curved line without distortion, thereby reducing unnecessary resistance and cavitation.

The method of forming the twisted rudder type asymmetric rudder cross section of the present invention using a symmetric rudder cross section is applicable to general merchant ships as well as warships.

The terms and words used in the present specification and claims should not be construed to be limited to ordinary or dictionary meanings and the inventor is not limited to the concept of terms in order to describe his invention in the best way. It should be interpreted as meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention, and not all of the technical ideas of the present invention are described. Therefore, It is to be understood that equivalents and modifications are possible.

1: Hull
2: Schedule
20: Propeller
22: Propeller total length (diameter)
100: rudder
110: Twisted portion

Claims (6)

The propeller shaft has a linear shape inclined downward in the aft direction,
The cross-sectional shape of the rudder is a streamlined rudder whose width gradually increases from the arcuate forward portion toward the rear portion with respect to the rudder horizontal center line, and gradually decreases from the widest point of the rudder section to the rearward portion ,
Wherein a rim of the transverse section of the rudder is rotated with respect to a straight line parallel to the propeller shaft in a region affected by the flow of the fluid flowing into the rudder due to rotation of the propeller, And,
The vertical center line of the rudder is arranged to deviate in the port or starboard direction with respect to the rotation axis center line of the propeller,
When the span of the rudder is divided from 0% to 100% from the upper end portion to the lower end portion, the twist portion is not formed from 0% to 20% in the front edge portion, and the twist portion is formed from 20% And a rudder for a special ship. The method according to claim 1,
Wherein the cross section of the twisted portion is symmetrical in the left and right direction and the left and right symmetrical cross section is rotated at different angles according to the span. The method according to claim 1,
Wherein the twist start of the trailing edge begins at a twist start of the leading edge and the twist start of the trailing edge begins at a twist start of the leading edge. Wherein the rudder is started from a position higher than the upper portion. The method according to claim 1,
Wherein the leading edge and the trailing edge of the rudder are continuously twisted in a curve. The method according to claim 1,
Wherein the maximum width point is 30% to 40% from the leading edge. The method according to claim 1,
And a rudder stock is provided at the center of rotation of the twisted portion.

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