JP7146437B2 - Marine propellers and ships - Google Patents

Description

TECHNICAL FIELD This disclosure relates to marine propellers and marine vessels.

A marine propeller has a plurality of propeller blades attached to a propeller boss, and is rotationally driven underwater on the stern side. However, when the propeller is rotationally driven in water, separation of the water flow from the blade surfaces of the propeller blades may occur. Since such separation reduces the efficiency of the propeller, various measures to prevent separation have been studied.

For example, Patent Literature 1 discloses a marine propeller in which a separation reducing member for suppressing separation of water flow from the surface of the propeller blade is disposed near the blade root on the back surface of the propeller blade. The flaking reduction member described in Patent Document 1 is a blade member, plate-like member, or the like that is separated from the surface of the propeller blade but formed along the surface of the propeller blade, near the root of the propeller blade. It is attached to the back surface of the propeller blade at a position spaced radially outward from the propeller boss (see Patent Document 1).

JP-A-2008-247078

The separation of the water flow from the blade surface of the propeller blade as described above is more likely to occur on the blade root side than on the radially outer side of the propeller blade. However, in the marine propeller described in Patent Document 1, since the separation reducing member is spaced radially outward from the propeller boss, separation of the water flow is sufficiently prevented in the vicinity of the connecting portion between the propeller boss and the blade root. It may not be contained.

In view of the circumstances described above, at least one embodiment of the present invention aims at suppressing the separation of the water flow from the blade surfaces of the propeller blades.

(1) A marine propeller according to at least one embodiment of the present invention,
propeller boss and
a plurality of propeller blades extending radially outward from the propeller boss;
a plurality of short blades extending radially outward from the propeller boss between two adjacent propeller blades;
The radially outer end of the stub blade is 15% or more of the distance from the outer peripheral surface of the propeller boss to the radially outer end of the propeller blade, and the distance from the rotation axis of the propeller boss to the propeller 60% or less of the distance to said radially outer end of the blade.

According to the above configuration (1), the short blades between the two adjacent propeller blades guide the water flow, making it easier for the water flow to flow along the blade surfaces of the propeller blades, so that the water flow separates from the propeller blades. can be effectively suppressed. In addition, since the short blade extends radially outward from the propeller boss, it is possible to effectively suppress the separation of the water flow, which tends to occur near the blade root, particularly in the vicinity of the joint between the propeller boss and the blade root of the propeller blade. .
Furthermore, according to the configuration (1) above, the propulsive force of the marine propeller can be borne by the plurality of short blades, so the load on the propeller blades can be reduced. As a result, the camber and angle of attack of the propeller blades can be reduced, so that the turning angle of the water flow is reduced, and separation of the water flow from the propeller blades can be suppressed.

The propulsive force generated by the short blades tends to increase as the distance to the radially outer end of the short blades increases. Larger distances are desirable. In addition, as described above, separation of the water flow in the propeller blades is more likely to occur on the root side of the propeller blades than on the radially outer side of the propeller blades. Any distance can be used as long as it can efficiently cover the area where peeling occurs. If the distance to the radially outer end of the short blade is increased, the peripheral speed of the radially outer end of the short blade increases and friction loss increases. A smaller distance to the radially outer edge of the blade is desirable. However, if the distance to the radially outer end of the stub is too small, it becomes difficult to obtain the effect of providing the stub.

Considering the above points, the radially outer end of the stub blade, that is, the radially outermost end of the stub blade, is located from the outer peripheral surface of the propeller boss to the radially outer end of the propeller blade ( 15% or more of the distance to the radially outermost end of the propeller blade) and 60% or less of the distance from the rotation axis of the propeller boss to the radially outer end of the propeller blade It was found that it should exist in
Therefore, according to the above configuration (1), separation of the water flow from the propeller blades can be suppressed while suppressing an increase in loss due to the provision of the short blades.

(2) In some embodiments, in the configuration of (1) above, the distance from the rotation axis to the radially outer end of the stub blade is greater than 30% and less than or equal to 60% of the distance to the end of the

According to the above configuration (2), separation of the water flow from the propeller blades can be effectively suppressed while suppressing an increase in loss due to the provision of the short blades.

(3) In some embodiments, in the configuration of (1) or (2) above, the radial direction of 50% of the distance from the outer peripheral surface of the propeller boss to the radially outer end of the stub blade In a position, the stub and the propeller blade at least partially overlap in the direction of the axis of rotation.

According to the above configuration (3), by setting the positional relationship between the propeller blades and the short blades to the positional relationship described above, at least a portion of the blade surface of the short blades overlaps the propeller blades in the direction of the rotation axis. By installing the short blades, separation of the water flow from the surface of the propeller blades can be suppressed.

(4) In some embodiments, in any one of the configurations (1) to (3) above, 50% of the distance from the outer peripheral surface of the propeller boss to the radially outer end of the stub blade , the position of the chord center of the stub blade is downstream of the position of the chord center of the propeller blade in the direction of the axis of rotation.

The separation of the water flow from the blade surface of the propeller blade is more likely to occur in the trailing edge side region than in the leading edge side region of the blade surface.
In this respect, according to the above configuration (4), by setting the positional relationship between the propeller blades and the short blades to the positional relationship described above, the short blades are offset downstream with respect to the propeller blades. Separation from the propeller blade can be effectively suppressed.

(5) In some embodiments, in any one of the configurations (1) to (4) above, 50% of the distance from the outer peripheral surface of the propeller boss to the radially outer end of the stub blade , at least a portion of the stub blade is 70% or more and 100% or less of the position of the leading edge of the propeller blade when the position of the leading edge of the propeller blade is 0% and the position of the trailing edge is 100% in the direction of the rotation axis. exists at the position of

Separation of the water flow from the blade surface of the propeller blade is particularly likely to occur at 70% or more of the position of the leading edge of the propeller blade when the position of the leading edge of the propeller blade is 0% and the position of the trailing edge is 100% in the direction of the rotation axis. became clear.
In this regard, according to the configuration (5) above, since at least a part of the short blade exists at this position in the rotation axis direction, separation of the water flow from the propeller blade can be effectively suppressed.

(6) In some embodiments, in any one of the configurations (1) to (5) above, 50% of the distance from the outer peripheral surface of the propeller boss to the radially outer end of the stub blade , the position of the maximum blade thickness portion having the maximum blade thickness of the short blade at the radial position is the position of the trailing edge of the propeller blade with the position of the leading edge of the propeller blade as 0% in the direction of the rotation axis When is 100%, it exists at a position of 90% or more and 100% or less.

According to the above configuration (6), upstream from the position of the maximum thickness portion of the short blade, the distance between the short blade and the propeller blade increases from the leading edge of the short blade to the downstream side. You can suppress it from growing as you go. Therefore, on the upstream side of the position of the maximum blade thickness portion of the short blade, the water flow can be accelerated or decelerated.
In the above configuration (6), the position of the maximum blade thickness portion of the short blade can be brought close to the trailing edge of the propeller blade. can be accelerated, and separation of the water flow can be effectively suppressed.

(7) In some embodiments, in the configuration of any one of (1) to (6) above,
The plurality of propeller blades include a first propeller blade and a second propeller blade provided adjacent to the first propeller blade in the circumferential direction and having a pressure surface facing the suction surface of the first propeller blade. including
The pressure surface of the short blade is located between the first propeller blade and the second propeller blade and closer to the first propeller blade in the circumferential direction.

According to the above configuration (7), the short blades can effectively suppress the separation of the water flow that occurs on the suction surface side of the first propeller blades.

(8) In some embodiments, in any of the above configurations (1) to (7),
The plurality of propeller blades include a first propeller blade and a second propeller blade provided adjacent to the first propeller blade in the circumferential direction and having a pressure surface facing the suction surface of the first propeller blade. including
The pressure surface of the short blade is 15% or more of the position of the suction surface of the first propeller blade as 0% and the position of the pressure surface of the second propeller blade as 100% in the circumferential direction. % position.

By bringing the pressure surface of the short blade closer to the suction surface of the first propeller blade in the circumferential direction, the separation of the water flow generated on the suction surface side of the first propeller blade can be effectively suppressed by the short blade. However, if the pressure surface of the short blade is too close to the suction surface of the first propeller blade in the circumferential direction, separation of the water flow may occur on the suction surface of the short blade.
On the other hand, according to the above configuration (8), separation of the water flow on the suction surface side of the first propeller blade can be effectively prevented on the pressure surface of the short blade while suppressing separation of the water flow on the suction surface of the short blade. can be suppressed.

(9) In some embodiments, in the configuration of (8) above, the The pressure surface of the stub and the suction surface of the first propeller blade at least partially overlap in the rotational axis direction.

According to the above configuration (9), it is possible to increase the overlapping area between the pressure surface of the short blade and the suction surface of the first propeller blade in the direction of the rotation axis, thereby suppressing the separation of the water flow by the above configuration (8). can improve effectiveness.

(10) In some embodiments, in any one of the configurations (1) to (9) above, each of the plurality of short blades has an airfoil-shaped cross section.

According to the configuration (10) above, it is possible to effectively obtain a propulsive force from the short blades, thereby effectively reducing the load on the propeller blades. As a result, the camber and angle of attack of the propeller blades can be reduced, so that the turning angle of the water flow is reduced, and separation of the water flow from the propeller blades can be effectively suppressed.

(11) In some embodiments, in any one of the configurations (1) to (10) above, each of the plurality of short blades has a shape similar to that of the propeller blades.

According to the configuration (11) above, the design of the short blade can be simplified.

(12) A ship according to at least one embodiment of the present invention,
a hull;
and a marine propeller according to any one of the configurations (1) to (11) arranged at the stern of the hull.

According to the configuration (12), since the marine propeller of the configuration (1) is provided, it is possible to suppress separation of the water flow from the blade surfaces of the propeller blades, thereby improving the propulsion performance of the marine vessel.

According to at least one embodiment of the present invention, it is possible to suppress separation of the water flow from the blade surface of the propeller blade.

1 is a side view showing a stern portion of a ship to which marine propellers according to some embodiments are applied; FIG. FIG. 2 is a schematic view of a portion of a marine propeller according to some embodiments, viewed from the bow side; (a) is a diagram schematically showing a cross section of a propeller blade and a short blade of a marine propeller of one embodiment on the AA cross section indicated by the dashed line in FIG. 2, and (b) is a diagram showing (a) 1 is a diagram schematically showing a cross section of a propeller blade of a conventional marine propeller in the same cross section as FIG. FIG. 3 is a diagram schematically showing a cross section of a propeller blade and a short blade of a marine propeller of another embodiment on the AA cross section indicated by the dashed line in FIG. 2; 1 is a diagram schematically showing a range in which water flow separation is likely to occur in a marine propeller, and FIG. 1(a) is a diagram schematically showing a range in which water flow separation is likely to occur in a marine propeller according to some embodiments; (b) is a diagram schematically showing a range in which separation of a water stream is likely to occur in a conventional marine propeller in which short blades are not formed.

Several embodiments of the present invention will now be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, and are merely illustrative examples. do not have.
For example, expressions denoting relative or absolute arrangements such as "in a direction", "along a direction", "parallel", "perpendicular", "center", "concentric" or "coaxial" are strictly not only represents such an arrangement, but also represents a state of relative displacement with a tolerance or an angle or distance to the extent that the same function can be obtained.
For example, expressions such as "identical", "equal", and "homogeneous", which express that things are in the same state, not only express the state of being strictly equal, but also have tolerances or differences to the extent that the same function can be obtained. It shall also represent the existing state.
For example, expressions that express shapes such as squares and cylinders do not only represent shapes such as squares and cylinders in a geometrically strict sense, but also include irregularities and chamfers to the extent that the same effect can be obtained. The shape including the part etc. shall also be represented.
On the other hand, the expressions "comprising", "comprising", "having", "including", or "having" one component are not exclusive expressions excluding the presence of other components.

FIG. 1 is a side view showing the stern of a ship to which marine propellers according to some embodiments are applied. FIG. 2 is a schematic view of a portion of a marine propeller according to some embodiments, viewed from the bow side. In a ship 10 according to some embodiments, a ship propeller 3 and a rudder 9 are installed at the stern 2 of the hull 1 . The marine propeller 3 of some embodiments includes a propeller boss 4 , a plurality of propeller blades 5 extending radially outward from the propeller boss 4 , and radially outward from the propeller boss 4 between two adjacent propeller blades 5 . and a plurality of short wings 6 extending therefrom. In the marine propeller 3 of some embodiments, the number of propeller blades 5 and short blades 6 is, for example, four, but the number does not necessarily have to be four.
2, the direction of rotation of the marine propeller 3 is counterclockwise as indicated by an arrow R. As shown in FIG. 3 to 5, the direction of rotation of the marine propeller 3 is indicated by an arrow R. As shown in FIG.

FIG. 3(a) is a diagram schematically showing a cross section of the propeller blades 5 and the short blades 6 of the marine propeller 3 of one embodiment, taken along the AA cross section indicated by the dashed line in FIG. b) is a diagram schematically showing a cross section of a propeller blade 8 of a conventional marine propeller 7 in the same cross section as in FIG. 3(a). 2 is the radially outermost end 6d of the short blade 6 from the outer peripheral surface 4a of the propeller boss 4, that is, the radial position of the short blade 6. 50% of the distance H2 to the outer edge 6d. That is, FIG. 3A shows the propeller of the marine propeller 3 of one embodiment at a radial position of 50% of the distance H2 from the outer peripheral surface 4a of the propeller boss 4 to the radially outer end 6d of the stub 6. FIG. 4 is a diagram schematically showing a cross section of a blade 5 and a short blade 6;
4 is a diagram schematically showing a cross section of the propeller blades 5 and the short blades 6 of the marine propeller 3 of another embodiment, taken along the AA cross section indicated by the dashed line in FIG. 2. As shown in FIG.

For example, as shown in FIG. 3B, when the conventional marine propeller 7 is rotationally driven in water, in the vicinity of the propeller blades 8, along the direction from the leading edge 81 to the trailing edge 82 of the propeller blades 8, A water flow 11 is generated as indicated by the arrow. However, when the conventional marine propeller 7 is rotationally driven underwater, the water flow 11 may separate from the blade surface of the propeller blade 8 in, for example, a range 12 indicated by a two-dot chain line. Such separation reduces the efficiency of the marine propeller 7 .
In addition, in each figure other than FIG. 3(b), a range where separation of the water flow 11 from the blade surface is likely to occur, such as a range 12 indicated by a chain double-dashed line in FIG. is indicated by a chain double-dashed line and denoted by reference numeral 12 . Further, in the following description, this range is also referred to as a range 12 where water flow separation is likely to occur.

Therefore, in the marine propeller 3 of some embodiments, for example, as shown in FIGS. A marine propeller 3 is configured to have wings 6 . The radially outer end 6d of the short blade 6 extends from the outer peripheral surface 4a of the propeller boss 4 to the radially outer end 5d of the propeller blade 5 (that is, the radially outermost end of the propeller blade 5). 5d) and 60% or less of the distance D1 from the rotation axis O of the propeller boss 4 to the radially outer end 5d of the propeller blade 5. A wing 6 was formed.

By providing the short blades 6 between two adjacent propeller blades 5, the pressure surface 64 of the short blades 6 and the suction surface 55 of the propeller blades 5 adjacent to the short blades 6 on the pressure surface 64 side of the short blades 6. A water flow path F1 is formed by the suction surface 65 of the short blade 6 and the pressure surface 54 of the propeller blade 5 adjacent to the short blade 6 on the suction surface 65 side of the short blade 6 forms a water flow path F2. be done. In the following description, the propeller blade 5 adjacent to the short blade 6 on the pressure surface 64 side of the short blade 6 is also called a first propeller blade 5A, and the suction surface of the short blade 6 The propeller blade 5 adjacent to the short blade 6 on the 65 side is also called a second propeller blade 5B.

In the marine propellers 3 of some embodiments shown in FIGS. 3A and 4, the water flow 11 flowing between two adjacent propeller blades 5 is divided into a water flow flowing through the flow path F1 and a water flow flowing through the flow path F2. It splits into a water stream and merges again after passing the short blade 6. Thus, when the water flow 11 flowing between two adjacent propeller blades 5 flows through the flow paths F1 and F2, the short blades 6 between the two adjacent propeller blades 5 guide the water flow 11, Since the water stream 11 easily flows along the blade surfaces of the propeller blades 5 , separation of the water flow 11 from the propeller blades 5 can be effectively suppressed. In addition, since the short blades 6 extend radially outward from the propeller boss 4, separation of the water flow 11 that tends to occur in the vicinity of the blade root 5a (see FIG. 2) is prevented particularly by the propeller boss 4 and the blade root 5a of the propeller blade 5. can be effectively suppressed in the vicinity of the connection portion 15 with the .
Furthermore, in the marine propeller 3 of the several embodiments shown in FIGS. 3A and 4, the propulsive force of the marine propeller 3 can be borne by the plurality of short blades 6, so the load on the propeller blades 5 can be reduced. As a result, the camber and the angle of attack of the propeller blades 5 can be reduced, so that the turning angle of the water flow 11 is reduced, and separation of the water flow 11 from the propeller blades 5 can be suppressed.

On the trailing edge 52 side of the maximum blade thickness portion where the blade thickness of the propeller blade 5 is maximum, the blade thickness decreases toward the trailing edge 52 side. Therefore, the width of the flow passage between two adjacent propeller blades 5 increases from a certain position toward the downstream side. In this way, by increasing the width of the flow path, the area of the flow path is increased. Here, for convenience of explanation, the rate of increase in the channel area per unit distance from the upstream side to the downstream side will be referred to as the expansion rate of the flow.
The separation of the water flow 11 is also affected by the expansion rate of the flow on the trailing edge 52 side of the propeller blade 5 . In general, the blade root of a propeller blade has a larger maximum blade thickness and a shorter blade chord length than the radially outer portion of the blade. Therefore, in the blade root of a propeller blade, the expansion rate of the flow is generally greater on the trailing edge side than the maximum blade thickness portion compared to the radially outer portion of the blade. Therefore, there is a possibility that separation of the water flow 11 is likely to occur on the blade root 5a side.

In this regard, in the marine propellers 3 of some embodiments shown in FIGS. , the required strength can be reduced, and the maximum blade thickness at the blade root 5a of the propeller blade 5 can be reduced. Therefore, the expansion rate of the flow in the vicinity of the blade root 5a can be reduced, and separation of the water flow 11 from the propeller blade 5 can be suppressed.

Compared to a large ship propeller for a large ship, a small ship propeller with a smaller Reynolds number due to its smaller diameter, and even a large ship propeller can be used in a transient state such as when the hull begins to accelerate. In such a high load state, it is considered that separation of the water flow is likely to occur. However, separation of the water stream 11 from the propeller blades 5 can be suppressed by using the marine propellers 3 of several embodiments shown in FIGS.

The propulsive force of the short blades 6 tends to increase as the distance D2 to the radially outer end 6d of the short blades 6 increases. It is desirable that the distance D2 to the radially outer end 6d be large. In addition, since separation of the water flow 11 in the propeller blades 5 is more likely to occur on the blade root 5a side than on the radially outer side of the propeller blades 5, from the viewpoint of suppressing separation, the radially outer end portion 6d of the short blades 6 should be The distance D2 may be any distance that can efficiently cover the region where peeling occurs. Incidentally, if the distance D2 to the radially outer end 6d of the short blade 6 is increased, the peripheral speed of the radially outer end of the short blade 6 increases and the friction loss increases. , the distance D2 to the radially outer end 6d of the stub blade 6 is preferably as small as possible. However, if the distance D2 to the radially outer end 6d of the short blade 6 is too small, it becomes difficult to obtain the effect of providing the short blade.

Considering the above points, the radially outer end 6d of the short blade 6 is 15% or more of the distance H1 from the outer peripheral surface 4a of the propeller boss 4 to the radially outer end 5d of the propeller blade 5, and It has been found that the position should be 60% or less of the distance D1 from the rotation axis O to the radially outer end 5d of the propeller blade 5.
Therefore, according to the marine propellers 3 of several embodiments shown in FIGS. It is possible to suppress peeling from.

FIG. 5 is a diagram schematically showing a range 12 in a marine propeller where water flow separation is likely to occur, and is a view of a portion of the marine propeller viewed from the bow side. FIG. 5(a) is a diagram schematically showing a range 12 where water flow separation is likely to occur in the marine propeller 3 of some embodiments, and FIG. FIG. 10 is a diagram schematically showing a range 12 where water flow separation is likely to occur in a conventional marine propeller 7; In addition, description of the short blade 6 is abbreviate|omitted in Fig.5 (a).
As is clear from a comparison of FIGS. 3(a) and 3(b), and from a comparison of FIGS. 5(a) and 5(b), FIGS. In the marine propeller 3 according to some embodiments shown in FIG. 4, the range 12 where separation of the water flow is likely to occur can be narrowed compared to the conventional marine propeller 7 .

Further, the ship 10 according to some embodiments includes a hull 1, any of the marine propellers 3 of some embodiments shown in FIGS. is provided, separation of the water stream 11 from the blade surface of the propeller blade 5 can be suppressed, and the propulsion performance of the vessel 10 can be improved.

In some embodiments shown in FIGS. 3A and 4, the distance D2 from the rotation axis O to the radially outer end 6d of the stub blade 6 is It may be greater than 30% and 60% or less of the distance D1 to the outer edge.
As a result, separation of the water flow 11 from the propeller blades 5 can be effectively suppressed while suppressing an increase in loss due to the provision of the short blades 6 .

3(a) and 4, at a radial position of 50% of the distance H2 from the outer peripheral surface 4a of the propeller boss 4 to the radially outer end 6d of the stub 6, the rotation The short blades 6 and the propeller blades 5 at least partially overlap in the direction of the axis O.
By setting the positional relationship between the propeller blades 5 and the short blades 6 as described above, at least a part of the blade surface of the short blades 6 overlaps the propeller blades 5 in the rotation axis O direction. By installing the blades 6 , separation of the water flow 11 from the surface of the propeller blades 5 can be suppressed.

In some embodiments shown in FIGS. 3(a) and 4, at a radial position of 50% of the distance H2 from the outer peripheral surface 4a of the propeller boss 4 to the radially outer end 6d of the stub 6, the short A center position 63a of the blade chord 63 of the blade 6 is downstream of a center position 53a of the blade chord 53 of the propeller blade 5 in the direction of the rotation axis O.

The separation of the water stream 11 from the blade surface of the propeller blade 5 is more likely to occur in the area on the trailing edge 52 side than in the area on the leading edge 51 side of the blade surface.
In this regard, in some embodiments shown in FIGS. 3A and 4, the positional relationship between the propeller blades 5 and the short blades 6 is set to the positional relationship described above, so that the short blades 6 are arranged relative to the propeller blades 5. is offset to the downstream side, separation of the water flow 11 from the propeller blades 5 can be effectively suppressed.

In some embodiments shown in FIGS. 3(a) and 4, at a radial position of 50% of the distance H2 from the outer peripheral surface 4a of the propeller boss 4 to the radially outer end 6d of the stub 6, the short At least part of the blade 6 exists at a position of 70% or more and 100% or less when the position of the leading edge 51 of the propeller blade 5 is 0% and the position of the trailing edge 52 is 100% in the direction of the rotation axis O. .

The separation of the water stream 11 from the blade surface of the propeller blade 5 is 70% or more, especially in the direction of the rotation axis O, when the position of the leading edge 51 of the propeller blade 5 is 0% and the position of the trailing edge 52 is 100%. It became clear that it is likely to occur at the position of
In this regard, in some embodiments shown in FIGS. 3A and 4, at least a part of the short blade 6 exists at this position in the direction of the rotation axis O, so that the water flow 11 does not separate from the propeller blade 5. can be effectively suppressed.

In one embodiment shown in FIG. 4, at a radial position of 50% of the distance H2 from the outer peripheral surface 4a of the propeller boss 4 to the radially outer end 6d of the stub 6, the stub 6 The position of the maximum blade thickness portion 66 having the maximum blade thickness tmax is 90% or more and 100% when the position of the leading edge 51 of the propeller blade 5 is 0% and the position of the trailing edge 52 is 100% in the direction of the rotation axis O. % or less.

In the embodiment shown in FIG. 4, the distance between the short blades 6 and the propeller blades 5, that is, the flow passage width, is on the upstream side of the position of the maximum blade thickness portion 66 having the maximum blade thickness tmax of the short blades 6. It is possible to suppress the expansion from the leading edge 61 of the short blade 6 toward the downstream side. That is, in the embodiment shown in FIG. 4, in the section from the leading edge 61 of the short blade 6 to the position where the maximum blade thickness portion 66 exists in the flow paths F1 and F2, the flow area increases toward the downstream side. It is possible to realize the arrangement of the short blades 6 that suppresses this. Therefore, on the upstream side of the position of the maximum blade thickness portion 66 having the maximum blade thickness tmax of the short blade 6, the water flow 11 can be accelerated or decelerated.
Further, in the embodiment shown in FIG. 4, the position of the maximum blade thickness portion 66 having the maximum blade thickness tmax of the short blade 6 is set to be within the above range. Since it can be brought close to the trailing edge 52 of the propeller blade 5, the flow of the water flow 11 in the area where the water flow 11 tends to separate from the blade surface of the propeller blade 5, that is, the area 12 where separation of the water flow tends to occur is accelerated. , and separation of the water flow 11 can be effectively suppressed.
At least part of the maximum blade thickness portion 66 having the maximum blade thickness tmax of the short blade 6 is 0% at the position of the leading edge 51 of the propeller blade 5 and 100% at the position of the trailing edge 52 in the direction of the rotation axis O. If it exists at a position of 90% or more and 100% or less of , the above effects can be obtained.

In some embodiments shown in FIGS. 3(a) and 4, the plurality of propeller blades 5 are a first propeller blade 5A and a first propeller blade 5A provided adjacent to the first propeller blade 5A in the circumferential direction. and a second propeller blade 5B having a pressure surface 54 facing the suction surface 55 of the propeller blade 5A. In some embodiments shown in FIGS. 3(a) and 4, the pressure surface 64 of the stub 6 is located circumferentially between the first propeller blade 5A and the second propeller blade 5B. Located near 5A.
As a result, the short blades 6 can effectively suppress separation of the water flow 11 that occurs on the suction surface 55 side of the first propeller blades 5A.

In some embodiments shown in FIGS. 3(a) and 4, the pressure surface 64 of the stub blade 6 is arranged such that the position of the suction surface 55 of the first propeller blade 5A is 0% in the circumferential direction, and the position of the suction surface 55 of the first propeller blade 5A is 0%. 15% or more and less than 50% of the position of the pressure surface 54 of 100%.
3A and 4, the dashed line with reference numeral 16 indicates that the position of the suction surface 55 of the first propeller blade 5A is 0% and the position of the pressure surface 54 of the second propeller blade 5B is 100%. 15% position when 3A and 4, the dashed line with reference numeral 17 indicates that the position of the suction surface 55 of the first propeller blade 5A is 0% and the position of the pressure surface 54 of the second propeller blade 5B is 100%. shows the 50% position when

By bringing the pressure surface 64 of the short blade 6 closer to the suction surface 55 of the first propeller blade 5A in the circumferential direction, the separation of the water flow 11 generated on the side of the suction surface 55 of the first propeller blade 5A is effectively suppressed by the short blade 6. can. However, if the pressure surface 64 of the short blade 6 is too close to the suction surface 55 of the first propeller blade 5A in the circumferential direction, separation of the water flow 11 may occur on the suction surface 65 of the short blade 6 .
In this respect, by setting the position of the pressure surface 64 of the short blade 6 in the circumferential direction within the range described above, separation of the water flow 11 on the suction surface 65 of the short blade 6 is suppressed, and the negative pressure on the first propeller blade 5A The pressure surface 64 of the short blade 6 can effectively suppress separation of the water flow 11 that occurs on the pressure surface 55 side.

When the position of the pressure surface 64 of the stub blade 6 in the circumferential direction is set within the above range, the outer circumference of the propeller boss 4 is At a radial position of 50% of the distance H2 from the surface 4a to the radially outer end 6d of the stub blade 6, the pressure surface 64 of the stub blade 6 and the suction surface 55 of the first propeller blade 5A in the direction of the rotation axis O. preferably overlap at least partially.
As a result, it is possible to increase the overlapping area between the pressure surface 64 of the short blade 6 and the suction surface 55 of the first propeller blade 5A in the direction of the rotation axis O, so that the effect of suppressing separation of the water flow 11 can be improved.

In some embodiments shown in FIGS. 3( a ) and 4 , each of the plurality of short blades 6 has an airfoil-shaped cross section.
As a result, since the propulsive force of the short blades 6 can be effectively obtained, the load on the propeller blades 5 can be effectively reduced. As a result, the camber and angle of attack of the propeller blades 5 can be reduced, so that the turning angle of the water flow 11 is reduced, and separation of the water flow 11 from the propeller blades 5 can be effectively suppressed.

In some embodiments shown in FIGS. 3( a ) and 4 , each of the plurality of short blades 6 has a shape similar to that of the propeller blades 5 .
This simplifies the design of the short blades 6 .

When the shape of the short blades 6 is similar to the propeller blades 5, for example, at any position in the radial direction of the short blades 6, the extending direction of the chord 63 of the short blades 6 is the blade of the propeller blades 5. The attachment angle of the short blade 6 may be set so as to be in the same direction as the chord 53 extends.
In addition, the shape of the short blade 6 is reduced from the shape of the propeller blade 5, and furthermore, the short blade 6 and the propeller blade 5 have similar camber lines and blade thicknesses at positions at the same distance from the rotation axis O. You may adjust the shape of the short blade 6 so that it may become.

The present invention is not limited to the above-described embodiments, and includes modifications of the above-described embodiments and modes in which these modes are combined as appropriate.
For example, in the above-described several embodiments, the marine propeller 3 has the propeller blades 5 and the short blades 6 alternately arranged in the circumferential direction. That is, in some of the above-described embodiments, short blades 6 are arranged between two propeller blades 5 adjacent to each other. However, between two adjacent propeller blades 5, for example, a short blade 6 is provided between the first propeller blade 5 and the second propeller blade 5 along the direction of rotation of the propeller blades 5. The short blades 6 are provided even between two adjacent propeller blades 5, such as not providing the short blades 6 between the second propeller blade 5 and the third propeller blade 5 along the rotation direction of the propeller blades 5. There may be places where there are none.

In the direction of the rotation axis O, the trailing edge 62 of the stub blade 6 may be positioned upstream, at the same position, or downstream of the trailing edge 52 of the propeller blade 5 .

In the above-described several embodiments, the cross-sectional shape of the stub 6 was airfoil-shaped, but it does not necessarily have to be airfoil-shaped. The cross-sectional shape of the short blade 6 when viewed from the radial direction may be, for example, a partial circular ring shape, a crescent shape, or a rectangular shape. Further, the blade surface of the short blade 6 may not be curved, and may be flat.

1 Hull 3 Marine Propeller 4 Propeller Boss 5 Propeller Blade 5A First Propeller Blade 5B Second Propeller Blade 5a Blade Root 6 Short Blade 10 Ship 51, 61 Leading Edges 52, 62 Trailing Edges 53, 63 Chords 54, 64 Pressure Surface 55 , 65 Suction surface 66 Maximum blade thickness

Claims (11)

propeller boss and
a plurality of propeller blades extending radially outward from the propeller boss;
a plurality of short blades extending radially outward from the propeller boss between two adjacent propeller blades;
the positions of the leading edges of the plurality of short blades are downstream of the leading edges of the plurality of propeller blades in the direction of the rotation axis of the propeller boss;
The radially outer end of the stub blade is 15% or more of the distance from the outer peripheral surface of the propeller boss to the radially outer end of the propeller blade, and the distance from the rotation axis of the propeller boss to the propeller located at 60% or less of the distance to said radially outer edge of the wing ,
At a radial position of 50% of the distance from the outer peripheral surface of the propeller boss to the radially outer end of the stub blade, the position of the midchord of the stub blade is the position of the propeller Downstream of the midchord position of the wing
Marine propeller. The distance from the axis of rotation to the radially outer ends of the stub blades is greater than 30% and less than or equal to 60% of the distance from the axis of rotation to the radially outer ends of the propeller blades. 1. The marine propeller according to 1. The spur and the propeller blade at least partially overlap in the direction of the axis of rotation at a radial position of 50% of the distance from the outer peripheral surface of the propeller boss to the radially outer end of the spur. A marine propeller according to claim 1 or 2. At a radial position of 50% of the distance from the outer peripheral surface of the propeller boss to the radially outer end of the stub blade, at least a portion of the stub blade extends along the axis of rotation of the propeller blade. The marine propeller according to any one of claims 1 to 3 , wherein the position is 70% or more and 100% or less when the position of the leading edge is 0% and the position of the trailing edge is 100%. At a radial position 50% of the distance from the outer peripheral surface of the propeller boss to the radially outer end of the stub, the maximum wing thickness of the stub at that radial position. 5. The position of the propeller blade is located at 90% or more and 100% or less of the position of the leading edge of the propeller blade as 0% and the position of the trailing edge of the propeller blade as 100% in the direction of the rotational axis. or the marine propeller according to 1. The plurality of propeller blades include a first propeller blade and a second propeller blade provided adjacent to the first propeller blade in the circumferential direction and having a pressure surface facing the suction surface of the first propeller blade. including
6. The pressure surface of the short blade according to any one of claims 1 to 5 , wherein the pressure surface is located between the first propeller blade and the second propeller blade and closer to the first propeller blade in the circumferential direction. marine propellers. The plurality of propeller blades include a first propeller blade and a second propeller blade provided adjacent to the first propeller blade in the circumferential direction and having a pressure surface facing the suction surface of the first propeller blade. including
The pressure surface of the short blade is 15% or more of the position of the suction surface of the first propeller blade as 0% and the position of the pressure surface of the second propeller blade as 100% in the circumferential direction. % . At a radial position that is 50% of the distance from the outer peripheral surface of the propeller boss to the radially outer end of the stub blade, the pressure surface of the stub blade and the first propeller blade A marine propeller according to claim 7 , wherein said suction surface at least partially overlaps. The marine propeller according to any one of claims 1 to 8 , wherein each of the plurality of short blades has a wing-shaped cross section. The marine propeller according to any one of claims 1 to 9 , wherein each of the plurality of short blades has a shape similar to that of the propeller blade. a hull;
and a marine propeller according to any one of claims 1 to 10 arranged at the stern of the hull.

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