KR200446855Y1 - Rudder of ship - Google Patents

Abstract

The present invention relates to a rudder bottom shape of a ship to prevent cavitation erosion and damage. By making the existing blunt rudder bottom shape inclined and reducing the bottom thickness, the pressure distribution around the bottom surface is softened and the cavitation generated on the bottom surface is reduced. It is about reducing.

Description

Rudder for Ship {Rudder of ship}

1 is a schematic view of a typical hull side.

Figure 2 is an enlarged side view of the rudder of Figure 1;

3 is a front view of the rudder according to the present invention.

* Code descriptions for the main parts of the drawings

10: Rudder

15: propeller

20: Any lower point where the rudder section thickness becomes thinner

25: hull

H: total height of rudder

h: height of rudder bottom part with slope

S: thickness of the rudder and the thickness of the start of the slope

s': Bottom thickness of inclined rudder

The present invention relates to a rudder of a ship to prevent cavitation erosion and damage.

      The vessel is advanced by moving the fluid backward by the rotation of the propeller. A rudder is installed close to the rear of the propeller, which is axially coupled to the rear end of the ship so that it can be rotated to some extent. The ship obtains propulsion by the rotation of the propeller and by adjusting the direction of action of the propulsion by the axial rotation of the rudder, the ship can be moved in the desired direction.

Cavitation, also called cavitation, refers to a phenomenon in which bubbles are formed when the liquid rotates at a high speed, where the pressure decreases. The present invention is intended to prevent this cavitation occurring in the rudder when the ship is propelled. Conventional low-speed operating vessels did not have a lot of erosion effects due to cavitation on the rudder, but as the mechanical performance of the ship gradually improved, the ship operated at a higher speed and thus the rudder became more eroded by such cavitation. .

Cavitation mainly occurs in centrifugal pumps, hydraulic turbines, marine propeller rudders, etc., and is undesirable because of excessive erosion and knocking vibrations of the rotor blades, which causes noise and changes the flow form, thereby rapidly decreasing efficiency. The cavity occurs when the pressure at any point decreases to reach the vapor pressure, and when the pressure decreases further, the cavity expands and rapidly reaches the high pressure zone. As the bubbles are rapidly generated and extinguished, the rudder is eroded and vibrations are generated in the vessel or concave marks are formed on the surface of the vessel or the rudder.

The present invention devised to solve the above problems, and devised a lower shape of the rudder for ships to prevent erosion and damage by cavitation. Existing blunt rudder bottom shape is made thin to smooth the flow around the floor surface and reduce the cavitation occurring on the floor surface. Since the overall rudder thickness distribution is the same, there is almost no loss of lift.

The present invention aims to improve the cavitation problem that occurs at the bottom of the rudder by maintaining the cross section of the rudder as a whole, and reducing the rudder bottom section thickness by reducing the slope of the bottom of the rudder.

1 shows the side of the hull 25, the cavitation occurs due to the wake of the propeller 15 as the ship moves forward, resulting in erosion and damage to the bottom of the rudder 10. The present invention is to reduce the thickness of the bottom of the rudder 10 in order to reduce the occurrence of cavitation to minimize the erosion and damage of the bottom of the rudder (10), inclined to give an angle from a certain height of the rudder to the bottom of the rudder. The blunt shape of the lower part of the rudder causes erosion by cavitation, so that the lower shape can be inclined to reduce the cavitation by making the surrounding flow smoothly.

FIG. 2 is an enlarged view of the rudder side of FIG. 1, which retains the cross-sectional thickness S of the entire rudder 10 (see FIG. 3) and reduces the thickness from any lower point 20 of the rudder to the end of the rudder. While forming a slope. In this way, by providing a lower shape that is narrower than the thickness of the rudder 10, the flow of the surrounding fluid generated when the ship moves forward becomes smoother. Therefore, smaller and smoother wakes are generated at the bottom of the rudder, which is reduced in thickness than when the bottom is blunt rudder, and the cavitation phenomenon is also reduced as the size of the wake becomes smaller.

3 is a front view of the lower shape of the rudder 10 of FIG. 1, and the rudder bottom thickness s' is preferably 70% or less than the thickness S of the inclined start portion. From the lower point 20 to the lower end of the rudder 10 is formed to be inclined as described above to form a trapezoidal cross-section, the height of the rudder in which the inclination is formed at any lower point 20 where the inclination begins ) Is preferably about 5-30% of the total height H of the rudder.

As described above, the rudder for ships according to the present invention has an effect of reducing the cavitation generated on the bottom surface by softening the pressure distribution around the bottom surface by reducing the bottom thickness by making the bottom shape of the existing blunt rudder inclined. In addition, since the overall thickness distribution except the bottom of the rudder is the same, there is almost no loss of lift and the same steering performance.

Claims (3)

In the rudder 10 of the ship which is mounted close to the propeller 15 and has a constant thickness S, The bottom thickness s' of the rudder is smaller than the thickness S of the rudder 10 from any lower point 20 of the rudder, so that the bottom of the rudder 10 is inclined to form a trapezoidal cross section. A rudder for ships, comprising According to claim 1, wherein any lower point 20 in which the inclination starts in the rudder is positioned at a height (h) of 5 to 30% of the total height (H) of the rudder at the lower end of the rudder. Rudder for ships. The ship rudder according to claim 1, wherein the bottom thickness s' of the inclined rudder is 70% or less of the thickness S of the rudder.

Images