KR20070066403A - Rudder of ship - Google Patents

Abstract

A rudder of a ship is provided to minimize cavitations and improve torque by reducing the capacity of a rudder. In a rudder of a ship, the valve of a blade thickness with respect to the X-coordinate has a shape including 5.0% to reduce the capacity of the rudder while minimizing the cavitation. In order to see the pressure distribution characteristics of a cross-section and the cavitation characteristics, a value analysis code is used to perform a calculation with respect to a case of zero degree and five degrees. The cavitation characteristics appear to be excellent as compared with a conventional NACA0021 cross-section or a NACA644-21 cross-section.

Description

 Rudder of the ship {Rudder of ship}

1 is an exemplary diagram comparing the rudder of the present invention with the force and torque related to the rudder obtained in the PMM test for a conventional NACA by dimensionless graphing

Figure 2 is an exemplary view comparing the pressure distribution characteristics according to the cross-sectional shape of the rudder and the existing NACA of the present invention (zero angle 0 °)

Figure 3 is an exemplary view comparing the pressure distribution characteristics according to the cross-sectional shape of the rudder and the existing NACA of the present invention (angle 5 °)

4 is an exemplary view showing the cavitation characteristics of the rudder of the present invention and the existing NACA (3 degrees of steering angle)

5 is an exemplary view showing the cavitation characteristics of the rudder of the present invention and the existing NACA (9 degrees steering angle)

Figure 6 is an exemplary view showing the cavitation characteristics of the rudder and the existing NACA of the present invention (angle 15 degrees)

* Explanation of symbols for main parts of the drawings

10: Rudder 1 20: Rudder 2

30: Rudder 3 (40): NACA0021

50: NACA64 ₄ -021

The present invention relates to a rudder of a ship, and to a rudder of a ship having an optimized cross-sectional shape so as to reduce steering capacity while minimizing cavitation.

Recently, as interest in steering performance of ships is increasing, interest in optimal other design and star capacity calculation considering the steering performance is gradually increasing. At the same time, there is a growing interest in ways to minimize the occurrence of other erosion by cavitation.

In general, the damage to the rudder is caused by the tip vortex cavitation and hub vortex cavitation caused by the propeller and the rudder caused by the increase in the flow velocity or incident angle of the inflow. It can be divided into the effects of its own cavitation. The top of the rudder is mainly damaged by the tip vortex cavitation and the middle part of the rudder is mainly damaged by the hub vortex cavitation. In particular, damage may occur at the lower end of the rudder by sole cavitation and lower end by sole cavitation. As the damage caused by cavitation varies according to the source and type of cavitation, research on the mechanism of occurrence along with the identification of each cavitation behavior should be preceded.

Recent studies have shown that basic research on cavitation behavior has been carried out at multiple angles and provides reliable results, but is limited to the area or size of cavitation to accurately predict behavior under complex flow conditions, such as the rudder behind the propeller. Is a very difficult situation.

In addition, due to the recent increase in speed and size of ships, interest in the capacity calculation of a steering steering gear (Rudder Steering Gear) is increasing due to the satisfaction of the steering performance and the increase of the torque. However, since the operation area of the rudder forms a very complex flow field due to the propeller's rotation, it is not easy to perform accurate numerical analysis on the rudder with diagonal movement. Therefore, it is not easy to calculate the optimal steering gear capacity, so the capacity is determined by referring to the results of the existing earnings line.

Due to this problem, various methods for estimating rudder torque have been proposed, but the reality is that it shows considerable error compared with the result of the test run due to the scale effect and the mutual interference effect of the hull, propeller and rudder.

The present invention is to solve the above problems, the object is to maintain the basic performance of the rudder, to improve the rudder torque performance and to minimize damage due to cavitation, the optimum rudder of the ship suitable for application to the solid line design To provide.

The present invention is a rudder, consisting of a shape having within ± 5.0% of the numerical value of the following Table 1, the dimension of the wing thickness with respect to the Ｘ-coordinate, dimensionless, steering capacity while minimizing cavitation To reduce the

Table 1

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and examples.

Example 1

In order to examine the pressure distribution characteristics and the cavitation characteristics of the cross sections, calculations were performed using numerical codes for the angles of attack of 0 ° and 5 °, respectively. As shown in FIG. 3.

Comparing the calculation results, it can be seen that the cross section of the present invention is superior to the existing NACA0021 cross section or NACA64 ₄ -021 cross section.

Example 2

The cross-sectional shape of the present invention was applied to three rudder shapes to manufacture rudder 1 (10), rudder 2 (20), and rudder 3 (30), and the rudders 1 to 3 (10, 20, 30) and NACA0021 ( 40) Cross section rudders and NACA64 ₄ -021 (50) cross section rudders were compared by performing a cavitation test in a cavity tank, and the results are shown in FIGS. 4 to 6.

At this time, the air content in the water was measured at about 45%, the average flow rate of the cavity tank is 5 m / s, and the change of the angle for cavitation observation was set to 3 °, 9 °, 15 °.

In addition, it was manufactured based on the Honta used in the 7,800TEU container carrier (1532-36), which is a real ship, to perform the cavitation test considering the mutual organic interaction between the hull and the propeller. The return distribution measured from the ship model was used for testing.

In addition, the three rudders to which the cross-sectional shape of the present invention is applied have the features as shown in Table 2 below.

[Table 2]

The results of 4 to 6, in proportion to the degree of cavitation should burn characteristics generated area and delayed together in nature, such as NACA64 ₄ -021 (50) can apply a cross-section seen Tagawa more advantageous since the steering angle increases, but in the 4 to 6, it can be seen that the generation area of the cavitation increases rapidly regardless of the cross-sectional shape. In addition, in the case of the rudders 1 to 3 (10, 20, 30) using the cross section of the present invention, it can be seen that the cavitation characteristics of the form similar to the rudder applied to the NACA64 ₄ -021 (50) cross section.

Example 3

Maneuverability model tests were performed on 7,800 TEU container carriers (1532-35) to investigate the effect of the cross section on the steering performance, and the steering performance was analyzed for a forward speed of 24.67 knots at scantling draft. It was. Initial turning test, turning test, zigzag test, spiral test, etc. were numerically analyzed using the fluid force coefficient obtained from the model test results.

At this time, the specifications of the rudder 1 (10) and R353 is shown in [Table 3], and the results are shown in [Table 4].

Table 3

Table 4

As shown in Table 4, it can be seen that the present invention satisfactorily satisfies the IMO's maneuverability criteria.

Example 4

The force and torque related to the rudder obtained in the steering performance test (PMM) according to Example 3 were expressed by dimensionless, and the results are shown in FIG. 1.

As shown in FIG. 1, the movement of the pressure center can be seen that the test results of the rudder 1 and the test results of the NACA 0021 and NACA 64 ₄ -021 cross sections are almost the same. Since it starts from the front more and moves backward, it can be seen that the size of the other torque is smaller, thereby increasing the balance ratio and reducing the other torque.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

As described above, the present invention has excellent steering performance and at the same time can reduce the occurrence of cavitation and reduce steering capacity, thereby satisfying the cavitation performance and the torque performance.

In addition, the damage caused by the cavitation is minimized, and compared with the conventional rudder, it is easy to manufacture, cost is reduced, and has excellent workability and many effects.

Claims (1)

In a rudder installed at the rear of a ship; The rudder is formed to maintain the maximum thickness in the axis of rotation and have a cross-sectional shape within ± 5.0% with respect to the numerical value of the following Table 1, the dimension of the wing thickness with respect to the y-coordinate dimensionlessly Rudder of the ship. Table 1

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