JPH0319835B2 - - Google Patents

Description

[Detailed description of the invention] Industrial applications The present invention relates to a stern hull type of a single-shaft ship.

PRIOR ART In the case of a normal single-shaft ship equipped with one propeller with the propeller axis in the hull center plane at the stern (the vertical plane that includes the hull center line in horizontal section), due to the twisting of the flow through the ship's side and the ship's bottom, In the stern flow field, there is a rotating flow in a plane perpendicular to the length direction of the ship. This rotating flow is generally called a stern bilge vortex, and a deceleration flow, that is, a wake, is concentrated at the center of this vortex due to separation of the boundary layer. In a ship whose stern shape is symmetrical with respect to the hull center plane, the stern bilge vortex occurs symmetrically on both sides, and the rotation direction is inward, that is, clockwise rotation on the left side and counterclockwise rotation on the right side. By installing two propellers that rotate in the opposite direction to the vortices near the center of the stern bilge vortex, the independent efficiency of the propellers will improve, and
Since energy loss due to separation of the boundary layer can be recovered in the form of wake gain, it is expected that propulsion efficiency will improve. However, in the case of a normal single-shaft ship, it is not possible to bring the centers of the stern bilge vortices that occur on both sides close to the propeller center, so it is difficult to obtain sufficient wake gain and make effective use of this. be. Furthermore, for example, in the case of a normal single-shaft ship with a right-handed propeller, the right side stern bilge vortex rotates to the left in the opposite direction to the propeller, so it can be used effectively, but the left side bilge vortex rotates counterclockwise in the opposite direction to the propeller. This cannot be used because it is a clockwise rotation in the same direction as . Additionally, on the right side of the propeller, the angle of attack of the propeller blade increases due to the stern bilge vortex rotating in the opposite direction, and on the left side of the propeller, the angle of attack is increased by the stern bilge vortex rotating in the same direction. Vibrations caused by the propeller occur due to the reduced angle. In the case of a normal single-shaft ship with a counterclockwise-rotating propeller, the left-right relationship is reversed, but a similar problem occurs.

In order to eliminate the above-mentioned drawbacks of ordinary single-shaft ships, various measures have been taken in the past, such as the following.

(a) Make the shape of the stern submerged area in front of the propeller asymmetrical to bring the stern vortices on both sides closer to the center of the propeller.

(b) The shape of the submerged part of the stern is made asymmetrical, so that a stern vortex is generated almost only on one side, and a propeller that rotates in the opposite direction is placed near the center of this vortex.

(c) Install current-variant fins in front of the propeller in the submerged stern section.

However, in (a) and (c) above, even if the center of the Ryogen's stern vortex could be brought closer to the propeller center to some extent, the Ryogen's vortex still exists, and the propulsion efficiency cannot be sufficiently improved. I can't wait. In addition, in (b) above, since the stern vortex is generated only on one side, the stern shape becomes complicated, the hull resistance increases, and problems arise with the arrangement of the propeller and main engine.

In addition, in the case of a normal single-shaft ship, the stern bilge vortex has the advantage of involving the bottom boundary layer and increasing the wake coefficient, but strong bilge vortices that cannot be concentrated within the propeller plane are generated on both sides of the stern. What to do is
This is disadvantageous because it increases the hull resistance. For this reason,
A so-called low-resistance hull type has been proposed in which the cross-sectional shape of the main hull from near the center of the hull to the stern is U-shaped, and the curvature of the main hull surface from near the center of the hull toward the stern is almost the same on the ship side and the bottom. There is. If such a low-resistance hull form is adopted, hull resistance will be reduced because stern bilge vortices will hardly be generated, but propulsion efficiency will generally deteriorate because the wake coefficient cannot be expected to increase due to bilge vortices.

Purpose of the Invention The purpose of the present invention is to provide a stern hull shape that can improve propulsion efficiency by generating a single vortex in the opposite direction within the plane of the propeller in a single-shaft ship adopting a low-resistance hull shape as described above. It's about doing.

Composition of the Invention The stern hull type of the single-shaft boat according to the present invention is equipped with one propeller having a propeller shaft in the center plane of the hull at the stern, and the cross-sectional shape of the main hull from the vicinity of the center of the hull to the stern is U-shaped. In a single-shaft ship where the curvature of the main hull surface from the vicinity to the stern is almost the same on the side and the bottom, there is a curvature on the stern of the main hull that is tilted in the opposite direction to the propeller rotation direction when moving forward with respect to the center plane of the hull. A bossing is provided, and in the cross section of the square station 3/8,
The angle of inclination of the bossing centerline to the hull center plane is 20
~40°, and the lower end shape of the bossing in the cross section of each square station is approximately arc-shaped, and on the side where the propeller blades move upward during forward movement, the bossing in the cross section of each square station is close to the main hull. There is a relationship of 0.65≦l ₁ /D≦1.0 between the distance (l ₁ ) from the point where it intersects with the center plane of the ship and the propeller diameter (D). The distance between the point where the bossing intersects with the main hull in the cross section of the square station to the center plane of the hull (l ₂ ), the height from the baseline of the main hull to this point (h), and the propeller diameter (D). It is characterized by the following relationship: −0.595l ₂ /D+0.9≦h/D h/D≦−0.595l ₂ /D+1.2.

Embodiments and Operations The drawings show the stern of a single-shaft ship adopting the stern hull type according to the present invention, and FIG. 1 is a side view, and FIG. 2 is a side view.
The figure shows Square Station (hereinafter referred to as SQST) 3/
8 is a cross-sectional view, and FIG. 3 is a front view.

This ship is equipped with one propeller 2 having a propeller shaft 1 in the hull center plane C at the stern, and the cross-sectional shape of the main hull 3 from the vicinity of the hull center to the stern is U-shaped and bilaterally symmetrical. The curvature of the surface of the main hull 3 from the vicinity of the center toward the stern is approximately the same on the ship side and on the bottom. The direction of rotation of the propeller 2 during forward movement is clockwise rotation.

A bossing 4 is provided at the stern of the main hull 3, and is inclined counterclockwise in the direction opposite to the rotating direction of the propeller 2 during forward movement, and is attached to the hull center plane C. They are continuously connected by intermediate curved surfaces 5 and 6 having a substantially arcuate cross section. A groove-like recess 7 is formed on the right side of the stern by the bossing 4, the intermediate curved surface 6, and the main hull 3. Further, the shape of the lower end portion 8 of the bossing 4 in the cross section of each sqst is approximately arcuate.

In Figure 3, (B) is the ship width, (B) is the radius of the intermediate curved surface 6 on the right side in the cross section of each sqst, and in sqst3/8 to 1 1/4, this radius (r)
The ratio of ship width to ship width (r/B) is approximately 0.036 to 0.096.

(P ₂ ) is the contact point between the right side intermediate curved surface 6 and the main hull 3 in the cross section of each sqst, and (T) is the height from the baseline bl of the main hull 3 to this contact point (P ₂ ) (contact point height) and (M ₂ ) are contact lines connecting the contact points (P ₂ ) in each sqst. And sqst3/8~
At 1 1/4, this contact point height (T) and ship width
The ratio (T/B) of (B) is approximately 0.28 to 0.103, and the angle (α) of this contact line _M2 with respect to the baseline bl)
is approximately 32.5°. In addition, (P ₁ ) is the contact point between the left side intermediate curved surface 5 and the main hull 3 in the cross section of each sqst,
M ₁ is a contact line connecting these contact points (P ₁ ).

(Q ₁ ) is the intersection point where the bossing 4 intersects with the main hull 3 in the cross section of each sqst on the left side, (l ₁ )
is the distance from this intersection (Q ₁ ) to the hull center plane C (intersection distance), and N ₁ is the intersection line connecting the intersections (Q ₁ ) in each sqst. Further, (D) is the propeller diameter, and there is a relationship of 0.65≦l ₁ /D≦1.0 between the intersection distance (l ₁ ) and the propeller diameter (D).

(Q ₂ ) is the intersection point where the bossing 4 intersects with the main hull 3 in the cross section of each sqst on the starboard side, (l ₂ )
is the distance from this intersection (Q ₂ ) to the hull center plane C (intersection distance), (h) is the height from the baseline bl to this intersection (Q ₂ ) (intersection height), and N ₂ is the distance at each sqst. It is an intersection line connecting the intersection points (Q ₂ ). and,
Between the intersection distance (l ₂ ), intersection height (h), and propeller diameter (D), -0.595l ₂ /D+0.9≦h/D h/D≦−0.595l ₂ /D+1.2 There is a relationship between

cl is the bossing centerline in the cross section of sqst3/8, and (β) is the inclination angle of the bossing centerline cl with respect to the hull center plane C. This angle of inclination (β) is
In this embodiment, the angle is 32 degrees, but it may be in the range of 20 to 40 degrees. The bossing centerline in the cross section of sqst2.1/2 is within the hull center plane C, and the cross-sectional shape forward of this is symmetrical with respect to the hull center plane C. S is a curve connecting the intersection of the bossing center line and the lower part of bossing 4 in the cross section of each sqst between sqst2・1/2 and 3/8, and this curve S is the bossing center line (cl ) in an asymmetrical manner.

Since the so-called low-resistance hull form is adopted in the stern part of the above 1), almost no stern bilge vortex is generated, and the hull resistance is small. Also, propeller shaft 1
On the right side of the vessel, the upward counterclockwise flow that has flowed in from the bottom and side of the ship is further guided upward and counterclockwise by the groove-shaped recess 7, and becomes a large upward counterclockwise flow. On the left side of the propeller shaft 1, the upward clockwise flow flowing in from the bottom and side of the ship is reversely guided downward and counterclockwise by the bossing 4, and becomes a small upward counterclockwise flow. Since the upward and counterclockwise flow on the right side is larger than the upward and clockwise flow on the left side, the flow on both sides becomes a counterclockwise flow centered on the propeller shaft 1 as a whole, and the flow is counterclockwise around the propeller axis 1. Inside, a rotating flow or vortex in the opposite direction to the rotation direction flows into the propeller blade. Therefore, although the hull resistance is reduced because almost no bilge vortices are generated, one vortex in the opposite direction is generated in the plane of the propeller, which improves the propulsion efficiency and reduces the hull resistance caused by the propeller. vibration is significantly reduced, and cavitation and resulting corrosion are prevented.

FIG. 4 shows the results of an electronic computer analysis of the state of water flow in the stern of the single-shaft vessel. From the results in the same figure, it is clear that a large upward counterclockwise flow occurs on the right side of the propeller shaft, and a small upward clockwise flow occurs on the left side. It can be seen that a vortex is generated. This fact has also been confirmed through water tank experiments using models.

The inclination angle (β) of the bossing center line cl with respect to the hull center plane C, and the intersection distance on the left side (l ₁ )
The relationship between and the propeller diameter (D), the relationship between the intersection distance (l ₂ ) on the right side, the intersection height (h), and the propeller diameter (D), etc. are determined by the strength of the vortex generated within the propeller plane and If the position or the like is affected and these are out of the above range, sufficient effects will not be obtained. Further, these relationships are appropriately adjusted within the above range depending on the shape of the ship so that an optimum vortex is generated within the plane of the propeller.

This invention can of course be applied to a single-shaft ship equipped with a counterclockwise rotating propeller. In this case, the shape of the stern section will be opposite to that of the above embodiment.

Effects of the Invention The stern hull type of the single-shaft boat according to the present invention is equipped with one propeller having a propeller shaft in the center plane of the hull at the stern, and the cross-sectional shape of the main hull from near the center of the hull to the stern is U-shaped, and Since the curvature of the main hull surface from the vicinity to the stern is almost the same on the ship side and the bottom, so-called stern bilge vortices hardly occur, and the hull resistance is small. A bossing is provided at the stern of the main hull and is inclined in a direction opposite to the direction of propeller rotation when moving forward with respect to the center plane of the hull, and since there is the above-mentioned relationship between this bossing and the main hull, A single vortex in the opposite direction can be generated within the plane of the propeller. Therefore, the hull resistance can be reduced and at the same time the propulsion efficiency can be improved, and the overall required horsepower can be reduced. In addition, since the vortices are concentrated within the plane of the propeller, vibration of the hull caused by the propeller is significantly reduced, and cavitation and the corrosion caused by it are prevented from occurring. Furthermore, since the main hull has a simple shape with only a bossing provided, the stern section is easy to construct.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a side view of the stern of a single-shaft ship, FIG. 2 is a cross-sectional view along the line of FIG. The figure is a drawing equivalent to Figure 3, showing the results of computer analysis of the state of water flow in the stern section. 1... Propeller shaft, 2... Propeller, 3... Main hull, 4... Bossing, 8... Lower end of bossing.

Claims (1)

[Claims] 1. 1. Having a propeller shaft in the center plane of the hull at the stern.
In a uniaxial ship, the main hull has two propellers, the main hull has a U-shaped cross-sectional shape from the center of the hull to the stern, and the curvature of the main hull surface from the center of the hull to the stern is almost the same on the side and the bottom. At the stern of the main hull, a bossing is installed that is inclined in the direction opposite to the direction of propeller rotation when moving forward with respect to the center plane of the hull.
The angle of inclination of the bossing centerline to the hull center plane is 20
~40°, and the lower end shape of the bossing in the cross section of each square station is approximately arc-shaped, and on the side where the propeller blades move upward during forward movement, the bossing in the cross section of each square station is close to the main hull. There is a relationship of 0.65≦l ₁ /D≦1.0 between the distance (l ₁ ) from the point where it intersects with the center plane of the ship and the propeller diameter (D). The distance between the point where the bossing intersects with the main hull in the cross section of the square station to the center plane of the hull (l ₂ ), the height from the baseline of the main hull to this point (h), and the propeller diameter (D). -0.595l ₂ /D+0.9≦h/D h/D≦-0.595l ₂ /D+1.2.