KR880000414B1 - Ship hulls for single-screw vessel - Google Patents

Abstract

The asymmetric aftbody for the hull of a ship has a twisted shape operative to achieve higher efficiency at practically all aftbody block coefficients by improving water flow. A shape is provided where the tangential components of the water are distributed as favourably as possible over the entire propeller circumference. The aftbody has an upper part above the propeller shaft which is combined with a part of the hull below the propeller shaft. The sectional areas of the hull have a bulbous or a ushaped configuration with the center lines of the sectional areas being inclined away from the vertical longitudinal plane through the propeller center in opposite direction to that of propeller rotation.

Description

Uniaxial hull

1 is a rear view of the hull structure according to the present invention.

2 is a diagram showing the "ideal operation" of the propeller post to the propeller disc.

3 is an isometric velocity diagram of axial regurgitation according to three-dimensional measurements of a container ship having a hull hull according to the present invention.

4 is a diagram showing the rotational effect on the propeller rotation direction obtained from the comparison of the tangential components according to the three-dimensional measurement of a container ship with an asymmetric rear hull adapted according to the present invention, where the tangential velocity is related to the model velocity. have).

5 is a rear view of the hull structure similar to the hull structure of FIG.

6 is a side view of the hull according to the rear view of FIG.

7 is a rear view of the hull structure according to another embodiment of the present invention.

8 and 9 are rear views of the hull structure, which are further modified according to the present invention.

The present invention relates to a single-screw bessel hull for the Froude number and the square coefficient as is common in merchant ships.

In a typical hull for a uniaxial ship having a shape of a rear hull in which the starboard and port are symmetrical, it is impossible to vary the angles of introduction of the water on the two ship sides.

It is possible to improve the flow and propulsion efficiency to the propeller by the asymmetric rear hull structure when the flow to the propeller is not slightly placed on the side where the propellers move upward than on the other side. Such asymmetric rear hull forms are described in German patent specification DE-PS 1,207,820. According to the patent, the hull for a single or central axis with a low number of prouds and a high square coefficient has an asymmetric rear hull shape in such a way that the upper part of the stern axis twists against the lower part of the fore axis as opposed to the direction of propeller rotation. Have.

Thus, in the propeller post, it is inclined away from the longitudinal center plane opposite to the direction of the centerline propeller rotation of the horizontal section passing through the hull (the slope increases from the roots of the propeller to the ends of the wing). ) From the stern, the propeller posts on the stern shaft form an inclination angle with the longitudinal central plane in the direction opposite to the propeller rotation direction.

This known hull form has been developed mainly for ships with high square modulus to enhance the flow to the propeller and to increase the hull square modulus compared to the symmetric rear hull without decreasing propeller efficiency. When the square coefficient or the rear hull drainage remained unchanged, an increase in speed or a reduction in propulsion power and fuel consumption at the same speed could be achieved.

Model tests on a variety of vessels with these known hull types resulted in 5-7% savings in propulsion power, ie fuel. In these ships, the upper part of the stern shaft of the hull is twisted about the lower part of the stern as opposed to the direction of propeller rotation, and the typical U-shaped frame below the stern axis is very sensitive to the ideal of rotational symmetry in this area. It shows an isotach line of closely-wake wakes. These ships have a square coefficient of about 0.75-0.83.

In fast ships within the range of high proud numbers and low square coefficients, it is known that the constant velocity line may be more preferably affected by the arrangement of known stern holes. However, in such a stern-shaped or U-shaped frame below the stern axis, additional rotation cannot be imparted to the water flowing towards the propeller.

In addition, due to the fact that the pressure point of the propeller is moved toward the center line so that the attack angle of the key for the straight coarse is negligibly small, the asymmetric rear hull shape exhibits a desirable effect on the resistance and coarse action of the ship compared to the symmetric rear hull shape. It is also known.

For economic reasons, it is desirable to use propellers with maximum diameters and low rotational speeds for reducing power, ie fuel consumption and improving efficiency. However, the propeller whose diameter is very large and the blade is not sufficiently locked at the 12 o'clock position due to the air is sucked, has a bad reflux state, a vibration force is generated, and there is a risk of cavitation. In order to prevent these adverse effects, tunneled hulls, guide plates or propeller nozzles have been successfully deployed according to the particular type, square coefficient and speed of the ship. Also, if the propeller is normally locked and the speed is adequate, nozzles are placed around the propeller or installed in the hull in front of the propeller.

In some types of ships, for example, single-axis Ro-Ro ships, installing the engine and stern shaft on one side of the ship can provide technical advantages, for example, installing a loading ramp next to the engine room. Different grades of fineness or square coefficient may be provided on both sides of the hull.

It is an object of the present invention that the tangential component of the regurgitation is such that the tangential component of the regurgitation is made very close to the ideal in the case of rotational symmetry, in order to achieve a power reduction and at the same time minimize the hydrodynamic forces of the propeller. The shape of the rear hull is designed to be preferably distributed around the circumference, and the asymmetric rear hull in such a way that a reduction in power, ie fuel consumption, is achieved in the square coefficient of virtually all rear hulls by promoting water flow to the screw. To improve form.

According to the invention, the upper part of the stern shaft of the rear hull is twisted in the opposite direction to the direction of propeller rotation, and from the longitudinal center plane where the centerlines of the horizontal sections passing through the hull in the propeller spacing region pass the propeller center in the direction opposite to the direction of propeller rotation. Inclined (the incline increases from the roots of the propeller wings to the ends), and as seen from the stern, the propeller post on the stern axis is opposite to the direction of propeller rotation relative to the longitudinal central plane through the propeller center. The upper part of the stern shaft is connected to the lower part of the stern shaft of the rear hull, and the vertical sections of the rear hull are asymmetrically twisted and have a spherical or U-shape, and the center line of the horizontal section is the propeller rotation direction. Longitudinal center through propeller center in opposite direction to From the roots of the propeller blades to the ends of the wings, and also from the stern, the stern portion of the spherical or U-shape under the stern axis is opposite the longitudinal direction of the propeller rotation. To form the angle of inclination with the face, the hull is designed asymmetrically or twisted.

Assuming that the centerline of the horizontal section below the stern axis extends in the stern direction and protrudes onto the propeller plane, the angle between the stern and the vertical line becomes large in that area.

Its hull form extends longitudinally over the critical area of the hull. Therefore, the bulges above and below the stern axis face in the opposite direction to the propeller rotation direction, and the centerline of the vertical section passing through the rear hull has an S-shaped feature that increases in the stern direction.

According to the present invention, the ship hull has a stern with twisted centerlines of the vertical section intersecting the longitudinal center plane and the centerlines of the horizontal section being curved and one side above the stern axis and the other side below the stern axis. It has a twisted asymmetrical shape that moves opposite to the propeller rotation direction. The flow of water seen in the horizontal plane intersects the ship's forward central plane above the stern axis and to the other below the stern axis.

When the propeller rotates clockwise in the rear hull according to the present invention, a large amount of water flows from the starboard side above the stern shaft to the port side to generate a rotating effect. As shown in Figures 1, 5 and 7, the V-shaped features of the port side frame increase such rotation effects and impart rather large vertical components to the flow. The placement of the twisted stern or twisted U-shaped frames below the stern axis greatly enhances the rotational effect in that area.

In a model test carried out on the hull according to the invention in which the rear hull portion above the stern axis is asymmetrical and arranged under the stern axis, i.e., twisted bulbous bow, the hull shape is defined as a low square coefficient (C _b) Power savings of about 8% could be confirmed by application to fast container ships with = 0.55). In terms of oil prices, it is clear that the economic value of this type of hull is high.

As shown in FIG. 3, another model test that measured the regurgitation three-dimensionally under different conditions confirmed a highly desirable regurgitation distribution. In addition, comparing the tangential component of the regurgitation with that of a symmetrical model with the same main data and curves in the cross-sectional areas, it was demonstrated that the prerotation generated extends over the entire propeller disc surface. In addition, the hull / shape was model tested in catamaran with a square coefficient of C _b = 0.52, and the results of the propulsion test as well as the wake measurement compared to other tests performed on catamaran and biaxial with similar ranges of proud numbers It was good.

Another preferred embodiment of the present invention is to combine a tunnel, guide plate or propeller nozzle in the form of a rear hull according to the invention as shown in FIG. 5, and as shown in FIGS. 7-9. The propulsion efficiency and maneuverability were enhanced when the propellers and keys were moved to one side of.

1 shows a typical rear view of a rear hull designed in accordance with the present invention for a high speed vessel with a stern slew below the stern shaft. The S-shaped centerlines of the vertical sections extend from one side of the ship above the stern axis and to the other side of the ship opposite the direction of propeller rotation below the stern axis.

Referring to FIG. 5, there is shown a rear view of the hull according to the invention with a very large propeller diameter for the odd number under the narrow propeller tunnel. The tunnel can take many prominent forms depending on specific needs to extend over most of the hull hull to encircle the propeller.

In figure 7, a rear view of a hull hull according to the invention with a propeller arranged on one side is shown. Here, for example, the stern and the frame form below the stern shaft have a slightly spherical shape or have a U shape.

In FIG. 8, two keys are typically arranged at the stern side of the asymmetric rear hull. The line labeled "A" represents the axis of the key moved parallel to the vertical longitudinal center plane, and the line labeled "B" represents the axis of the key inclined almost in the propeller post direction.

9 shows that the keys of the asymmetric rear hull are moved parallel to the longitudinal center plane, and thus the stern of the kiwi is moved.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, the invention may be practiced otherwise within the scope of the appended claims.

Claims (7)

The upper part of the stern shaft of the rear hull extends inward to the propeller rotation direction only on one side of the rear hull with respect to the lower part of the stern shaft, so that in the propeller spacing area the centerlines of the horizontal section passing through the hull are opposite to the direction of the propeller rotation. Inclined away from the midplane, the inclination of the wing from the root region of the propeller wing so as to form an angle between the longitudinal midplane and the stern axis of the rear hull away from the direction of propeller rotation. A uniaxial ship body comprising a hull hull which is asymmetrically increased to an opposite end region of The vertical sections below the stern axis are twisted and are U or spherical, and the centerlines of the horizontal sections are inclined away from the longitudinal center plane passing through the propeller center in the opposite direction to the propeller rotation direction, the slope of which is As seen from the stern, the lower part of the stern shaft of the rear hull is formed on the lower part of the stern shaft having a shape that increases from the root of the propeller blade to the end of the blade so as to form an inclination angle with respect to the center plane in a direction opposite to the direction of propeller rotation. One top of the stern shaft is coupled, and the vertical sections have S-shaped centerlines that curve on one side of the vessel above the stern shaft and the other side of the vessel below the stern shaft, as opposed to the propeller rotation direction, such a curved form being the stern shaft region. From the stern propeller diameter area The uniaxial hull characterized by the above-mentioned. 2. The hull of claim 1, wherein the S-shaped centerlines of the vertical section intersect so that the intersection points in the stern direction on the longitudinal central plane passing through the stern axis near the center of the stern axis. The hull of claim 1, wherein guide plates are disposed on one side of the stern. The hull of claim 1, wherein the propeller is disposed off center. 2. The hull of claim 1 wherein the axis of the key behind the propeller is moved to one side of the ship parallel to the longitudinal center plane. The hull according to claim 5, wherein the hull of the key behind the propeller is inclined so as to be disposed in the stern axis direction. The hull of claim 1 wherein two keys are disposed beside the propeller at the port side.

Images