JP6548062B2 - Stern duct, stern attachment, method of designing stern duct, and ship equipped with stern duct - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stern duct mounted on a stern of a hull, a stern attachment, a method of designing a stern duct, and a ship equipped with a stern duct.

As one of the energy saving devices, a stern duct is attached to the front of a propeller attached to the stern of the hull.
Patent Document 1 proposes a ship attached with an arc-shaped duct. The arc-shaped duct is disposed in front of the propeller and above the center position of the stern longitudinal vortex generated at the stern. In addition, the ducts are provided with main fins extending respectively in the radial direction of the propeller between the lower end portions of the duct and the side surface of the aft portion, and the main fins are inclined forward and forward from the rear of the ship ( In particular, paragraph numbers (0014) to (0016)).
Patent Document 2 discloses a semicircular arc-shaped stern duct consisting of only the upper half of the cylinder (in particular, FIG. 1 and paragraph number (0018)).
Further, in Patent Document 3, a substantially semi-conical truncated outer shell obtained by cutting an approximately frusto-conical shaped cylinder into substantially half with a plane including the central axis, and two connecting plates for fixing the outer shell to the stern portion A duct device is proposed in which the outer shell is disposed such that the smaller diameter of the outer shell is directed to the propeller side and the outer shell faces the upper half of the propeller (in particular, FIG. 1, FIG. 2 and paragraph Number (0020)).
Patent Document 4 discloses a vessel duct in which a first plate-like body is curved in an arc shape and a linear second plate-like body is provided at an end portion of the first plate-like body. (Especially paragraph number (0006)).

JP, 2011-178222, A Unexamined-Japanese-Patent No. 2006-347285 JP 2008-137462 A JP, 2008-308023, A

The arc-shaped duct in Patent Document 1 is attached so as to be symmetrical with respect to the vertical center line of the propeller in a state where the hull is viewed forward from the rear. Further, in Patent Document 1, in the semicircular duct, thrust is mainly generated in the upper part, and no thrust is generated in the side part, that is, thrust is obtained in the side part of the semicircular duct. First, pay attention to the problem that causes the resistance increase at the side part of the semicircular duct (paragraph number (0006)), and to solve this problem, provide the main fin and obtain the auxiliary thrust from the downward flow. There is. In the drawing of Patent Document 1, although an arc-shaped duct having an angle smaller than a semicircle is illustrated, no description is made on the central angle of the arc, and in the illustrated duct, about 145 degrees of It is a central angle. In addition, the central angle is not determined in consideration of the fluid force distribution in the hull propulsion direction acting on the surface of the duct.
In addition, the semi-arcuate stern duct in Patent Document 2 is also mounted so as to be symmetrical with respect to the vertical center line of the propeller in a state where the hull is viewed forward from the rear. In addition, as compared with the case where the stern fins, the stern ducts, and the rudder fins are individually provided in the related art, Patent Document 2 increases the power reduction rate to promote further energy saving, and the stern fins and the stern The mutual relationship between the ducts and the rudder fins is necessary, and the stern ducts are provided to reduce the speed at which the downward flow blocked by the stern fins flows into the propeller (especially, paragraph number (0016)).
In addition, the outer shell of the substantially semi-conical shape in Patent Document 3 is also attached so as to be symmetrical with respect to the vertical center line of the propeller in a state where the hull is viewed forward from the rear. Although Patent Document 3 discloses a duct device having an outer shell whose central angle is smaller than 180 degrees, under the condition that the central axis of the outer shell and the rotational axis of the propeller coincide with each other, the central angle is It only discloses that it will be 150 degrees (FIG. 7 (A) and paragraph number (0037)). Also, the central angle is not determined in consideration of the fluid force distribution in the boat propulsion direction acting on the surface of the duct.
Further, the first plate-like body curved in an arc shape in Patent Document 4 is also attached so as to be symmetrical with respect to the vertical center line of the propeller in a state where the hull is viewed forward from the rear. In addition, in patent document 4, although it does not describe concretely about the central angle of a circular arc, it is a central angle which exceeds 180 degrees (especially FIG. 2 and paragraph number (0026)).

Therefore, according to the present invention, a stern duct, a stern attachment, a stern duct design method, and a stern duct capable of improving the hull efficiency without increasing the resistance of the hull even if the duct body is added to the hull. The purpose is to provide a vessel equipped with ducts.
Further, the present invention is equipped with a stern duct, stern attachment, stern duct design method, and stern duct that can increase the thrust reduction rate or the propeller efficiency ratio and reduce the effective wake rate. Intended to provide ships.

In the stern duct according to the first aspect of the present invention, in the stern duct attached to the front of the propeller attached to the stern of the hull, the duct body is formed in a substantially arc shape having an angle range of 225 degrees to 255 degrees. And the duct body is used as a support means such that the duct center line of the duct body has an inclination angle in the same direction as the propeller rotation direction with respect to the propeller center line in the vertical direction of the propeller when the hull is viewed forward from behind The propeller is attached to the stern, and the inclination angle of the propeller in the rotational direction is in the range of 30 degrees to 60 degrees in the rotational direction of the propeller with respect to the propeller center line upward from the center of the propeller. According to the first aspect of the present invention, by forming the duct main body in a substantially arc shape having an angle range of 225 degrees to 255 degrees, the duct main body can be added to the hull without increasing the resistance of the hull. Hull efficiency can be improved. Also, by attaching the duct body so that the duct center line of the duct body has an inclination angle in the same direction as the propeller rotation direction with respect to the propeller center line in the vertical direction of the propeller, compared to the case where there is no inclination angle. , The thrust reduction rate or the thruster efficiency ratio can be increased, and the effective wake rate can be reduced. Further, by setting the inclination angle of the duct center line of the duct body to an angle range of 30 degrees to 60 degrees, the hull efficiency can be improved without increasing the resistance of the hull even if the duct body is added to the hull. it can.

  The present invention according to claim 2 is characterized in that the cross section of the duct body in the front-rear direction is formed into an inwardly convex wing shape. According to the second aspect of the present invention, the thrust reduction rate can be increased and the propulsion efficiency can be increased by utilizing the propulsion direction component (thrust component) of the lift generated by the airfoil.

  The present invention according to claim 3 is characterized in that the radius of the rear end arc formed at the rear end of the duct main body is smaller than the radius of the front end arc formed at the front end. According to the third aspect of the present invention, the effective wake rate can be reduced by delaying the flow downstream of the duct body, and the thrust component on the front end side of the duct body is increased to enhance the propulsive force. be able to.

  The present invention according to claim 4 is characterized in that the imaginary central axis of the duct body is made coincident with the rotational central axis of the propeller. According to the fourth aspect of the present invention, design and equipment are easy.

  The present invention according to claim 5 is characterized in that the imaginary central axis of the duct body is offset from the rotational central axis of the propeller. According to the fifth aspect of the present invention, for example, the duct body can be shifted to a position where the thrust force can be increased in response to the asymmetric flow generated by the hull and the propeller.

  The present invention according to claim 6 is characterized in that the imaginary central axis of the duct main body is inclined with respect to the central axis of rotation of the propeller in a side view of the hull. According to the invention as set forth in claim 6, the duct body can be mounted to increase the thrust force.

  The present invention according to claim 7 is characterized in that the duct body is attached to the end portion of the stern that covers the stern tube or the stern tube of the hull via a support as a support means. According to the seventh aspect of the present invention, the duct main body can be easily installed, and in particular, can be easily positioned at an appropriate position with respect to the propeller.

  The present invention according to claim 8 is characterized in that the support as a support means is provided within an angle range of 60 degrees or less from the duct center line. According to the eighth aspect of the present invention, the strength of the duct body and the mounting strength of the duct body can be enhanced without increasing the resistance of the hull.

  The present invention according to claim 9 is characterized in that the cross section of the support is formed into an inwardly convex wing shape. According to the ninth aspect of the present invention, the thrusting direction component (thrust component) of the lift generated by the airfoil can be utilized also in the support column.

  The present invention according to claim 10 is characterized in that the flow toward the propeller is countercurrented with respect to the rotational direction of the propeller by forming the support in a twisted shape. According to the tenth aspect of the present invention, the propulsive force of the propeller can be enhanced.

  The present invention according to claim 11 is characterized in that the support is formed such that the duct body side longitudinal width is larger than the aft side longitudinal width. According to the 11th aspect of the present invention, it is possible to reduce the resistance of the support to increase the propulsive force.

In the stern appendage corresponding to the invention according to claim 12, in the stern appendage attached to the front of the propeller attached to the stern of the hull, a pair of support columns supporting the substantially arc-shaped virtual duct main body Attached to the stern so that the angle between the pair of supports is in the range of 225 degrees to 255 degrees, and with the ship body looking forward from the rear, the support center of the pair of supports with respect to the propeller centerline in the vertical direction of the propeller The line has an inclination angle in the same direction as the propeller rotation direction, and the inclination angle in the propeller rotation direction is 30 to 60 degrees in the propeller rotation direction with respect to the propeller center line upward from the propeller center. It is characterized in that it is an angle range. According to the present invention as set forth in claim 12, by attaching the pair of support posts to the stern without mounting the duct body so that the angle between the pair of support ends becomes an angle range of 225 degrees to 255 degrees, Can be added to the hull to improve the hull efficiency without increasing the hull resistance. In addition, since the column center line of the pair of columns has an inclination angle in the same direction as the propeller rotation direction with respect to the propeller center line, the thrust reduction rate or the propeller efficiency ratio can be improved compared to the case where there is no inclination angle. It is possible to increase and reduce the effective wake rate. In addition, by setting the inclination angle of the column center line of a pair of columns to an angle range of 30 degrees to 60 degrees, the hull efficiency is improved without increasing the resistance of the hull even if a pair of columns is added to the hull. be able to.

  A method of designing a stern duct according to the present invention according to claim 13 includes the steps of setting an all-round duct having the same radius as the substantially arc-shaped duct main body and designing the all-round duct in designing the stern duct. Step of calculating resistance and self-propulsion calculation by the numerical calculation of the hull and the fluid force distribution in the direction of hull propulsion acting on the surface of the all-round duct from the resistance and self-propagation calculation results and / or from the back of all circumference duct to propeller surface Determining the flow velocity / flow direction distribution, and determining the shape of the substantially arc-shaped duct body from the whole circumference duct based on the fluid force distribution and / or the flow speed / flow direction distribution from the rear of the all circumference duct to the propeller surface It is characterized by having. According to the invention as set forth in claim 13, the design can be made based on the distribution of fluid force in the direction of hull propulsion acting on the surface of the all-round duct and / or the flow velocity and flow direction distribution from the rear of the all-round duct to the propeller surface. .

  The present invention according to claim 14 comprises the steps of setting the mounting position and the number of mountings of a support as a support means, and performing resistance / self-propagation calculation by numerical calculation of a hull using the set support. It is characterized by According to the present invention as set forth in claim 14, it is possible to design in consideration of the influence of the support.

  The invention according to claim 15 is characterized in that the fluid force distribution is a thrust distribution and a resistance component distribution. According to the fifteenth aspect of the present invention, the duct shape can be easily cut out.

  The present invention according to claim 16 is characterized in that the shape and inclination angle of the duct body are determined based on the energy saving rate with respect to the duct installation angle in the small duct of the angle range of 90 degrees to 180 degrees. According to the sixteenth aspect of the present invention, it is possible to more easily cut out the duct shape.

  A vessel equipped with a stern duct according to the 17th aspect of the present invention is characterized in that the stern duct is equipped at the stern. According to the seventeenth aspect of the present invention, the resistance applied to the duct main body can be reduced, and a ship having a high energy saving effect can be provided.

  The present invention according to claim 18 is characterized in that the hull is a biaxial stern double barrel type hull. According to the eighteenth aspect of the present invention, it is possible to provide a two-shaft stern double-body type ship with high energy saving effect by reducing the resistance applied to the duct body.

  The invention according to claim 19 is characterized in that the hull is an existing hull and the stern duct is retrofitted to the hull. According to the 19th aspect of the present invention, the reduction of the resistance and the improvement of the energy saving effect can be applied to the existing hull.

According to the stern duct of the present invention, by forming the duct body in a substantially arc shape having an angle range of 225 degrees to 255 degrees, the hull can be added without increasing the resistance of the hull even if the duct body is added to the hull. Efficiency can be improved. Also, by attaching the duct body so that the duct center line of the duct body has an inclination angle in the same direction as the propeller rotation direction with respect to the propeller center line in the vertical direction of the propeller, compared to the case where there is no inclination angle. , The thrust reduction rate or the thruster efficiency ratio can be increased, and the effective wake rate can be reduced. Further, by setting the inclination angle of the duct center line of the duct body to an angle range of 30 degrees to 60 degrees, the hull efficiency can be improved without increasing the resistance of the hull even if the duct body is added to the hull. it can.

  When the cross-section of the duct body in the front-rear direction is formed into an inwardly convex wing shape, the thrust reduction rate is increased by utilizing the propulsive directionality (thrust component) of the lift generated by the wing. Promotion efficiency can be raised.

  When the radius of the rear end arc formed at the rear end of the duct main body is smaller than the radius of the front end arc formed at the front end, the effective wake flow can be obtained by slowing the flow downstream of the duct main body. The rate can be reduced, and the thrust component on the front end side of the duct body can be increased to increase the propulsive force.

  In addition, when the virtual central axis of the duct body is made to coincide with the rotational central axis of the propeller, design and installation are easy.

  Further, when the virtual central axis of the duct body is shifted from the rotational center axis of the propeller, for example, the duct body can be shifted to a position where thrust force can be increased corresponding to the asymmetric flow generated by the hull or propeller.

  Further, when the virtual central axis of the duct main body is inclined with respect to the rotation central axis of the propeller in a side view of the hull, the duct main body can be attached so as to increase the thrust force.

  In addition, when the duct body is attached to the end of the stern that covers the stern tube or the stern tube of the hull via a support as a support means, the duct body can be easily installed, and in particular, the proper position for the propeller. Easy to place.

  In addition, when the support as the support means is provided within an angle range of 60 degrees or less from the duct center line, the strength of the duct body and the attachment strength of the duct body can be increased without increasing the resistance of the hull. .

  Further, when the cross section of the support is formed into an inwardly convex wing shape, it is possible to utilize the thrust direction component (thrust component) of the lift generated by the wing also in the support.

  Further, by forming the support columns in a twisted shape, the propulsive force of the propeller can be increased when the flow toward the propeller is counter-flowed in the rotational direction of the propeller.

  Further, in the case where the support on the duct body side is made wider than the aft side, the resistance of the support can be reduced and the propulsive force can be enhanced.

According to the stern appendage of the present invention, a pair of columns supporting the substantially arc-shaped virtual duct body is attached to the stern such that the angle between the pair of columns is in the range of 225 degrees to 255 degrees. Thus, it is possible to improve the efficiency of the hull without increasing the resistance of the hull even if the columns are added to the hull without mounting the duct body. In addition, since the column center line of the pair of columns has an inclination angle in the same direction as the propeller rotation direction with respect to the propeller center line, the thrust reduction rate or the propeller efficiency ratio can be improved compared to the case where there is no inclination angle. It is possible to increase and reduce the effective wake rate. In addition, by setting the inclination angle of the column center line of a pair of columns to an angle range of 30 degrees to 60 degrees, the hull efficiency is improved without increasing the resistance of the hull even if a pair of columns is added to the hull. be able to.

  According to the design method of the stern duct of the present invention, the design based on the fluid force distribution in the hull propulsion direction acting on the surface in the all-round duct and / or the flow velocity and flow direction distribution from the rear of the all-round duct to the propeller surface it can.

  Also, in the case of providing the step of setting the mounting position and the number of mounting of the support as a support means, and performing the resistance / self-propulsion calculation by numerical calculation of the hull using the set support, the influence of the support is The design can be considered.

  Further, based on the thrust distribution of the fluid force distribution and the resistance component distribution, it is possible to easily cut out the duct shape from the whole circular duct shape.

  In addition, when the shape and inclination angle of the duct body are determined based on the energy saving rate for the duct installation angle in a small duct in the angle range of 90 degrees to 180 degrees, the cutout of the duct shape can be performed more easily. .

  According to the vessel having the stern duct of the present invention, the resistance applied to the duct body can be reduced, and a vessel having a high energy saving effect can be provided.

  In addition, when the hull is a biaxial stern double barrel type hull, resistance applied to the duct main body can be reduced, and a twin-shaft stern twin barrel type vessel with high energy saving effect can be provided.

  When the hull is an existing hull and the stern duct is retrofitted to the hull, the resistance reduction and the improvement of the energy saving effect can be applied to the existing hull.

The principal part side view of the ship showing the state where the duct for the stern was attached by one embodiment of the present invention Principal part front view which shows the state which looked the same ship forward from the back The main part perspective view which looked at the ship from diagonally back A perspective view of a stern duct according to the present embodiment Front view of stern duct according to another embodiment of the present invention Side cross-sectional view of the stern duct shown in FIGS. 1 to 4 or 5 A perspective view of a stern duct according to still another embodiment of the present invention Side cross-sectional view of a stern duct according to still another embodiment of the present invention Side cross-sectional view of a stern duct according to still another embodiment of the present invention Explanatory drawing which shows the duct for sterns by further another embodiment of this invention Diagram showing the outline of the enlarged ship model and propeller model used in the test Schematic of partial duct model used for testing Diagram showing the parameters representing the essentials of the duct model tested Diagram showing the gist of the duct model tested Characteristic diagram (the first model) showing the relationship between the inclination angle of the duct body and the self-propagating element Characteristic chart (the second model) showing the relationship between the inclination angle of the duct body and the self-propagating element Characteristic diagram (the third model) showing the relationship between the inclination angle of the duct body and the self-propagating element Characteristic chart (4th model) showing the relationship between the inclination angle of the duct body and the self-propagating element Characteristic diagram showing the relationship between the tilt angle of the duct body and the self-propagating element (5th model) Characteristic chart showing the horsepower reduction rate Characteristic diagram showing the relationship between the duct installation angle and the self-propulsion element Characteristic chart showing the relationship between the duct installation angle and the horsepower reduction rate The figure which shows the whole result of the self-promotion test using the partial duct model carried out by the test Husband essentials and three-dimensional side view of the hull applied to the present embodiment The figure which shows the duct point of a perimeter duct of the same radius as the stern duct by this embodiment, and a three-dimensional shape Diagram showing propeller points of a propeller used in the present embodiment The figure which shows the attachment position of the duct and propeller with respect to the hull applied to this embodiment Circumferential distribution of thrust component and resistance component distribution of all-around duct Contour map of thrust distribution and resistance distribution on the surface of the all around duct Principal part front view which shows the state which looked at a two-shaft stern double-body type ship equipped with a stern duct forward from the back Principal part front view which shows the state which looked at a twin-shaft stern twin-body type ship equipped with other stern ducts from the back from the front.

A stern duct according to an embodiment of the present invention will be described with reference to the drawings.
1 is a side view of the main part of the ship showing the stern duct attached, FIG. 2 is a front view of the main part showing the ship looking forward from the rear, and FIG. 3 is an oblique rear view of the ship It is the principal part perspective view seen from.
As shown in FIG. 1, the stern duct 10 according to the present embodiment is attached to the front of a propeller 3 attached to the stern 2 of the hull 1. In FIG. 1, the stern duct 10 is attached to the end of the stern 2 covering the stern tube, but may be attached to the stern tube of the hull 1.

As shown in FIGS. 2 and 3, the stern duct 10 is composed of a duct body 11 and a support means 12. The duct body 11 is attached to the stern 2 by the support means 12.
The duct body 11 is arranged such that the duct center line Yd of the duct body 11 has an inclination angle θ in the rotational direction of the propeller 3 with respect to the propeller center line Yp in the vertical direction of the propeller 3 in a state where the hull 1 is viewed forward from behind. Are attached to the stern 2 by support means 12.

FIG. 4 is a perspective view of the stern duct according to the present embodiment.
The duct body 11 is formed in a substantially arc shape having a central angle (angle range) β of 180 degrees to 270 degrees, more preferably in a substantially arc shape of 225 degrees to 255 degrees. By forming the duct main body 11 in a substantially arc shape of such a central angle β, the hull efficiency can be improved without increasing the total resistance coefficient by the duct main body 11.
The radius Rr of the rear end arc portion 11r formed at the rear end of the duct body 11 is smaller than the radius Rf of the front end arc portion 11f formed at the front end. As described above, by making the radius Rr of the rear end arc portion 11r smaller than the radius Rf of the front end arc portion 11f, the overall average velocity of the flow downstream of the duct main body 11 can be reduced. The thrust component on the front end side can be increased to increase the propulsive force.

The support means 12 is composed of a support 12 a connected to both sides of the duct main body 11 and an attachment 12 b for attaching the support 12 a to the stern 2. The support 12a has a cross section formed in an inwardly convex wing shape. Thus, by making the cross section of the support 12a into a wing shape, it is possible to utilize the thrust direction component (thrust component) of the lift generated by the wing also in the support 12a.
The column 12a has a duct body side longitudinal width Ly larger than the stern side longitudinal width Lx. Thus, by increasing the duct body side longitudinal width Ly with respect to the stern side longitudinal width Lx on the mounting portion 12b side, the resistance of the column is reduced, and the flow is effectively used to enhance the propulsive force. it can.
The support 12a may be directly attached to the end of the stern 2 covering the stern tube or the stern tube of the hull 1 without the ring-shaped attachment portion 12b.

FIG. 5 is a front view of a stern duct according to another embodiment.
As shown in FIG. 5, the support means 12 may be provided with a support 12 c in addition to the pair of support 12 a connected to both sides of the duct main body 11.
FIG. 5 shows the case where the support 12c is provided along the duct center line Yd. The support 12c is provided in an angle range of 60 degrees or less from the duct center line Yd, more preferably in an angle range of 30 degrees or less from the duct center line Yd. Thus, even if the support 12c is provided, the strength of the duct body 11 and the attachment strength of the duct body 11 to the end of the stern 2 or the stern tube can be enhanced without increasing the resistance of the hull 1.

6 is a side sectional view of the stern duct shown in FIG. 1 to FIG. 4 or FIG.
As shown in FIG. 6, a cross section 11s in the front-rear direction of the duct main body 11 is formed into an inwardly convex wing shape. As described above, by forming the cross section 11s into a convex wing shape inward, it is possible to increase the propulsion efficiency by generating lift in the propulsion direction of the hull 1.
Further, as shown in FIG. 6, the duct main body 11 makes the virtual center axis Xd connecting the centers of the arcs of the duct main body 11 coincide with the rotation center axis Xp of the propeller 3. By matching the virtual center axis Xd and the rotation center axis Xp, design and equipment become easy.
The virtual center axis Xd does not have to correspond to the center of all the arc surfaces of the duct main body 11. For example, the radius may be slightly different between the central portion and both sides, or the central angle β of the front end arc portion 11 f and the central angle β of the rear end arc portion 11 r may be different. The duct body 11 is a perfect arc. It is not necessary, and it may be formed in a substantially arc shape.

FIG. 7 is a perspective view of a stern duct according to yet another embodiment.
The stern duct 10 according to the present embodiment uses a strut 12e in a twisted shape instead of the strut 12a to counterflow the flow toward the propeller 3. That is, the support 12 e has a shape twisted in the opposite direction to the rotation of the propeller 3. As described above, by making the flow toward the propeller 3 counter-flow in the rotational direction of the propeller 3 by using the support 12 e in a twisted shape, the propulsive force of the propeller 3 can be increased.
The support means 12 may adopt a structure in which the support 12a and the support 12e and the stern duct 10 are attached to the hull 1 or a structure in which the support 12 is directly attached to the hull 1 without using the support 12a.

FIG. 8 is a side cross-sectional view of a stern duct according to yet another embodiment.
In FIG. 8, the virtual center axis Xd of the duct main body 11 is shifted from the rotation center axis Xp of the propeller 3. As described above, the stern duct 10 is provided at a position where the thrust force can be increased in response to the asymmetric flow generated by the hull 1, the stern 2, and the propeller 3 by shifting the virtual central axis Xd from the rotational central axis Xp. Can.

FIG. 9 is a side cross-sectional view of a stern duct according to yet another embodiment.
In FIG. 9, the virtual center axis Xd of the duct main body 11 is inclined with respect to the rotation center axis Xp of the propeller 3 in a side view of the hull 1. Thus, the stern duct 10 can be attached so as to correspond to the flow of the stern 2 and to increase the thrust force by inclining the virtual center axis Xd with respect to the rotation center axis Xp.

FIG. 10 is an explanatory view showing a stern duct according to still another embodiment.
FIG. 10 shows the case where the propeller 3 is in the counterclockwise direction B in a state where the hull 1 is viewed forward from the rear.
In the stern duct 10 according to the present embodiment, the duct main body 11 is attached at a central angle β of 210 degrees and an inclination angle θ of 60 degrees.

Next, the influence of each portion in the circumferential direction of the duct main body 11 on the self-propagating element by the relationship with the stern flow will be described based on the test results.
In this test, the duct body 11 with a central angle β of 120 degrees is used as a partial duct model, and the self-propagation test is performed by changing the circumferential position (duct installation angle θ). We investigated the relationship of navigational factors.
Also, in this test, a partial duct model is installed on a model ship of an enlarged ship, the installation angle of the partial duct model (inclination angle θ in the present embodiment) is changed, and a self-propagation test is performed. The relationship between the installation angle and the self-propagation factor was investigated.

FIG. 11 is a schematic view of the enlarged ship model and propeller model used in the test, and FIG. 12 is a schematic view of a partial duct model.
In the partial duct model, the support 12a in the present embodiment is described as a fin. Further, the mounting portion 12b in the present embodiment was installed as a ring-shaped member over the stern tube of a model ship, and in the self-promotion test, the installation angle θ was changed by rotating the ring-shaped portion.
The duct installation angle θ was 0 degrees immediately above the stern side, and was advanced clockwise (clockwise). Therefore, the 12 o'clock position is 0 degrees, the 3 o'clock position is 90 degrees, the 6 o'clock position is 180 degrees, and the 9 o'clock position is 270 degrees.

FIG. 13 shows the parameters representing the requirements of the tested duct model, and FIG. 14 shows the requirements of the tested duct model.
Here, Ddi is the diameter ratio of the duct inlet to the propeller diameter, Ddo is the diameter ratio of the duct outlet to the propeller diameter, Ddi 538 is the diameter ratio of the duct inlet to the propeller diameter 53.8%, and Ddo 493 is the duct to the propeller diameter It shows that the diameter ratio of the outlet is 49.3%. α5 indicates that the opening angle of the partial duct model is 5 degrees, and β120 indicates that the central angle is a duct of 120 degrees.
The duct opening angle α and the duct length Ld were varied while keeping the duct diameter at the duct inlet constant. For the partial duct model, the duct length Ld was fixed at 25.5% of the propeller diameter D _p , and the opening angle α was changed at intervals of 3 degrees from 5 degrees to 14 degrees. Moreover, the test was implemented also about the duct whose circumferential direction angle becomes 210 degrees on the basis of the test result of a partial duct model. Furthermore, the fin for fixing the duct to the hull 1 was also considered to affect the self-propagating element, and a test of the fin alone from which the duct portion was removed was also conducted.
The test was conducted at the Mitaka No. 2 Test Water Tank at the Japan Institute of Marine Technology Safety Research, and the test speed was set to a speed corresponding to Froude number 0.18. In the tank test of the partial duct model, the propeller loading degree is likely to be affected by changes in the propeller loading degree, so the propeller loading degree is changed and the test is performed, and the self-propagating element with a load factor of 1 is interpolated. The influence of the propeller loading degree was eliminated by

The relationship between self-propulsive elements and installation angles obtained from the results of self-propulsion tests for each of the partial duct models and fins is shown in FIG. 15 to FIG.
15 to 19 are characteristic diagrams showing the relationship between the duct installation angle of the duct main body and the self-propagating element, and FIG. 15 is a first model (α5Ddi538Ddo493Ld255β120), FIG. FIG. 18 is a characteristic diagram of the fourth model (α14Ddi538Ddo411Ld255β120), and FIG. 19 is a characteristic diagram of the fifth model (Fin).
As a self-propagating element, a thrust reduction rate (1-t), an effective wake rate (1-w), and a propeller efficiency ratio (ηR) are shown.

  In the partial duct model of any opening angle α, 1-t is maximum at an installation angle of 0 degrees, 1-wTM is minimum at an installation angle of 90 degrees, and ηR is maximum. From the viewpoint of the quality of the self-propagating element, 1-t and the other two self-propagating elements 1-wTM and η R have an inverse correlation, and the same applies to the fin alone. Horsepower estimation was performed using the self-propagation elements obtained by these self-propagation tests, and the horsepower reduction rate at each installation angle θ of each partial duct model and fin unit was calculated.

The calculated horsepower reduction rate is shown in FIG. When the opening angle α is 5 degrees, the horsepower reduction rate at the installation angle of 0 degrees is the largest, and at the installation angle of 180 degrees and the installation angle of 270 degrees, the horsepower reduction effect is almost lost. For one-third ducts with other opening angles α, a setting angle of 90 degrees shows the best horsepower reduction rate, followed by a setting angle of 0 degrees, but also at a setting angle of 180 degrees, 1 to 2% A degree of reduction is shown. After all, there is almost no reduction in horsepower at an installation angle of 270 degrees. In addition, about the installation angle 0 degree and 90 degrees 180 degrees, about 2% of the horsepower reduction effect appears, but there is almost no horsepower reduction effect at the installation angle of 270 degrees even with the fin alone.
In order to investigate the influence of the duct installation angle in more detail, the range of change of the installation angle was made small from near 0 ° installation angle with high horsepower reduction rate to around 90 ° installation angle, and self-propagation test was conducted.

FIG. 21 shows the relationship between the inclination angle of the duct body (duct installation angle) and the self-propagating element. FIG. 22 shows the relationship between the duct installation angle and the horsepower reduction rate.
In FIG. 21 and FIG. 22, an angle 0 is a case where the propeller center line Yp in the vertical direction of the propeller 3 and the duct center line Yd are provided in agreement with each other when the hull 1 is viewed forward from behind The angle θ is inclined to the starboard side, and the negative setting angle θ is inclined to the port side. The propeller 3 is rotated clockwise A. The vertical axis is based on the absence of a duct.
1-t is maximum at an installation angle of 0 degrees and is minimum at an installation angle of 75 degrees. Further, 1-wTM is minimum at an installation angle of 75 degrees and is maximum at an installation angle of 270 degrees. η R is maximum at an installation angle of 75 degrees and is minimum at an installation angle of -15 degrees. The installation angle with a good horsepower reduction rate is two bumps with 0 degree and 90 degrees, and in the case of 0 degree installation angle, 1-t in the case of 90 degree installation angle is due to the improvement of 1-wTM and ηR I understand that.
In FIG. 21 and FIG. 22, the position of the preferred installation angle is indicated by a circle.

  Looking at the test results of the partial duct model (center angle β is 120 degrees), the horsepower reduction effect is high at an installation angle of 0 degrees and an installation angle of 90 degrees. At the installation angle of 180 degrees, the effect of reducing the horsepower is smaller than that of the fin alone. At a 270 degree installation angle, the effect of reducing horsepower is extremely low. Therefore, it was considered that the effect was large if the partial duct model having a duct installation angle of 0 degrees and 90 degrees was combined and the central angle β was 210 degrees, the self-promotion test was performed.

From the test results of the partial duct model (center angle β is 120 degrees), at an opening angle of 11 degrees, the horsepower reduction rate 3.3% at an installation angle 0 degree, and the horsepower reduction rate 3.4% at an installation angle 90 degrees Since the effect of reducing the horsepower was generally high, we conducted a self-promotion test for this 210-degree duct with an opening angle of 11 degrees. A schematic view of a 210 degree duct having an opening angle of 11 degrees is as shown in FIG.
As a result of the self-navigation test, the self-navigation factor was an intermediate value of the partial duct model with an installation angle of 0 degrees and 90 degrees, and the reduction in horsepower was 3.9%, which is larger than both.

FIG. 23 shows the overall results of the self-propagation test using the partial duct model carried out in this test.
As a result of conducting a self-promotion test using a partial duct model, the following was found.
In the case of the clockwise propeller 3, 1-t is the largest when the partial duct model is at a position of 0 degree (12 o'clock) as viewed from the rear. On the other hand, 1-wTM is also the largest, and RR is the smallest. When the partial duct model is at a position of 90 degrees (3 o'clock) when viewed from the rear, 1-t is smallest, 1-wTM is also smallest, and ηR is largest. That is, from the viewpoint of the quality of the self-propagating element, 1-t and the other two self-propagating elements 1-wTM and η R have an inverse correlation. By combining these phenomena, the energy saving effect of the 0 degree (12 o'clock) position or the 90 degree (3 o'clock) position is high, and the energy saving effect of the 210 degree duct combining these two positions is also high. The horsepower reduction rate was 3.9% for the 210 ° duct, but in the case of an all-round duct where only the angle range was 360 degrees under the same conditions, the horsepower reduction rate was 3.5%, compared to the all-round duct It was also confirmed that the horsepower reduction rate was greater with the 210 ° duct.

From the above results, the duct body 11 is formed in a substantially arc shape having an angle range of 180 degrees to 270 degrees, and the duct center line Yd of the duct body 11 with respect to the propeller center line Yp in the vertical direction of the propeller 3 By having the installation angle in the angle range of 30 degrees to 60 degrees in the rotational direction, the hull efficiency can be improved without increasing the resistance of the hull 1 even if the duct body 11 is added to the hull 1.
More preferably, by forming the angle range in a substantially arc shape of 225 degrees to 255 degrees, the hull efficiency can be improved without increasing the resistance of the hull 1.

Next, a method of designing a stern duct according to the present embodiment will be described below.
FIG. 24 is a side view of a ship essential point and a three-dimensional shape of a hull to be applied, and FIG. 25 shows a duct essential point and a three-dimensional shape of an all-around duct having the same radius as the stern duct according to this embodiment. .
In the present embodiment, a hull of the Panamax size bulk carrier (PxBC) having a shape with a high degree of stern hypertrophy was used.
In designing the stern duct 10 according to the present embodiment, first, an all-round duct having the same radius as the substantially arc-shaped duct body 11 is set.
Here, a duct having a so-called Weather Adapted Duct (WAD) as a basic shape is used as the entire circumference duct.
In FIG. 25, D _TE. Is a duct rear end diameter, D _p is a propeller diameter, L _d is a duct blade cross section cord length, and α is an opening angle of the blade cross section.

FIG. 26 shows propeller points for the used propeller.
In FIG. 26, H / D _p represents a pitch ratio, aE represents a developed area ratio, and Z represents the number of blades.

FIG. 27 shows the mounting position of the duct and propeller on the hull.
The coordinate origin is taken to the bow perpendicular (FP) of the hull 1, the direction from FP to stern perpendicular (AP) is x-axis positive, the direction from port to starboard is y-axis positive, the direction from keel to keck The z-axis is in the positive direction. Also, the captain is 1 (that is, x = 0.0 is FP, x = 1.0 is AP).
As can be derived from FIG. 27, the duct rear end has a clearance of propeller leading and about 5% D _p, the duct center is made to coincide with the shaft centerline.

Next, set the hull type, duct and propeller, and perform resistance and self-propulsion calculation by numerical calculation of the hull using ducts all around.
CFD (Computational Fluid Dynamics) analysis was performed using the hull form, duct and propeller shown in FIG. 24 to FIG.
As a result of CFD analysis, compared with the ductless hull, the ducted hull did not increase the resistance and improved the hull efficiency by about 3.2%. The reason why the total drag coefficient hardly increases despite the fact that the duct is attached is considered to be that the duct itself is generating thrust.

Next, the fluid force distribution on the inner surface of the entire duct is obtained from the resistance and self-propulsion calculation results.
FIG. 28 shows circumferential distribution of thrust component and resistance component distribution of the all-around duct.
In FIG. 28, the inclination angle θ is 0 degrees at the position of 12 o'clock when the duct around the circumference is viewed from the rear, and the clockwise direction is positive from the position of 12 o'clock. Further, in FIG. 28, the vertical axis Ctx is a fluid force in the x direction, and a positive value (above the 0 line) provides resistance, and a negative value (below the 0 line) provides a propulsive force.
As shown in FIG. 28, when the propeller 3 is not operating (dotted line in the figure), the x-direction fluid force (Ctxlduct) has a positive value, that is, resistance, over the entire circumference.
However, when the propeller 3 operates, Ctxlduct acts as a negative value, ie, thrust, in the vicinity of 0 degrees <θ <45 degrees and 288 degrees <θ <360 degrees. It is considered that this thrust component is a factor that does not increase the total resistance coefficient even when the duct is attached when the propeller 3 is in operation.

FIG. 29 is a contour map of the thrust distribution and the resistance component distribution on the surface of the all-around duct, which three-dimensionally shows how the resistance / thrust component shown in FIG. 28 is distributed on the duct surface .
It can be seen that the thrust component of the duct seen in FIG. 28 is mainly generated inside the upper surface of the duct in FIG. 29 (area Z indicated by the arrow in the figure).
That is, the region Z where the thrust component is generated is a fan-shaped portion surrounded by an angle range of 0 degree <β <180 degrees, where β is a central angle of the fan shape. Although the thrust itself is also generated near the inner side of the duct, since a greater resistance than this thrust is exerted on the outer side of the duct in that part, the total fluid force integrated in the duct cord direction is shown in FIG. As shown in the vicinity of 90 degrees, it is resistance.

As described above, after the fluid force distribution on the inner surface of the all-around duct is obtained from the resistance / self-propagation calculation result, the shape of the duct body 11 having a substantially arc shape is determined from the all-round duct based on the fluid force distribution. Here, the fluid force distribution is a thrust distribution and a resistance component distribution.
Also, the flow velocity and flow direction distribution from the rear of the entire circumferential duct to the propeller surface may be determined. By determining the flow velocity and flow direction distribution, it is possible to design in consideration of the effective wake rate. Although this flow velocity, flow direction distribution and fluid force distribution on the inner surface can be designed independently or in combination with each other, more detailed design can be realized by using both. .
The shape of the duct main body 11 can be easily cut out by determining the shape of the duct main body 11 and the inclination angle θ based on the energy saving rate for the duct installation angle in the small duct in the angle range of 90 degrees to 180 degrees. it can.
A step of setting the attachment position and the number of attachment of the columns 12a and 12c as the support means 12 and a step of performing resistance / self-propulsion calculation by numerical calculation of the hull 1 using the set columns 12a and 12c Thus, the design can be made in consideration of the influence of the columns 12a and 12c.

FIG. 30 and FIG. 31 are front views of relevant parts showing a state in which a two-shaft stern double-body type boat equipped with a stern duct is viewed forward from the rear.
In FIGS. 30 and 31, the hull 1 is provided with a starboard side propeller 3R in the stern tube 2R of the starboard side skeg, and a port side propeller 3L in the stern tube 2L of the port side skeg.

In FIG. 30, the starboard side propeller 3R is counterclockwise B, and the port side propeller 3L is clockwise A, which indicates that it is inward rotation.
As described above, in the twin-shaft stern double-barrel type ship by inner rotation, the starboard side stern duct 10R corresponding to the starboard side propeller 3R inclines the duct body 11R in the upper left quadrant, and the port side propeller 3L By disposing the duct main body 11L in the upper right quadrant with the port side stern duct 10L corresponding to the above, the thrust reduction rate or the propeller efficiency ratio can be increased and the effective wake rate can be reduced.

In FIG. 31, the starboard side propeller 3R is clockwise A, and the port side propeller 3L is counterclockwise B, which indicates that it is an outer rotation.
As described above, in the twin-shaft stern double-barrel type ship by outer rotation, the starboard side stern duct 10R corresponding to the starboard side propeller 3R inclines the duct body 11R in the upper right quadrant, and the port side propeller 3L By disposing the duct body 11L in the upper left quadrant with the port side stern duct 10L corresponding to the above, the thrust reduction rate or the propeller efficiency ratio can be increased and the effective wake rate can be reduced.

As described above, the stern duct 10 according to the present embodiment can be applied to the twin-shaft stern double-body type hull 1 to reduce the resistance applied to the duct main body 11 and achieve a high energy saving effect. Can provide
In addition, in the case of a twin-shaft stern double-barrel type ship and a single-shaft type ship, the skegs provided with propeller propeller shafts on the left and right and the center of the stern in order to effectively utilize the stern flow and enhance propeller propulsion efficiency. There is a case where a so-called offset is provided by displacing the position, but in such a case, it is also possible to shift the stern duct also or not.
In addition, the stern duct 10 according to the present embodiment can be retrofitted to the existing hull 1. Therefore, the reduction of the resistance by the stern duct 10 according to the present embodiment and the improvement of the energy saving effect can be utilized also in the existing ship.

In each of the above embodiments, the stern duct 10 has been described. However, as shown in the test results, the resistance of the hull 1 is not limited to the duct main body 11, and the pair of supports 12a supporting both ends of the duct main body 11 There is an energy saving effect by improving the hull efficiency without increasing the
That is, in the stern appendage as another embodiment, the angle between the pair of columns 12a in the pair of columns 12a supporting the substantially arc-shaped virtual duct main body is in the range of 180 degrees to 270 degrees. Is attached to the stern 2 and when the hull 1 is viewed from the rear from the front, the column center line of the pair of columns 12 a has an inclination angle θ in the rotation direction of the propeller 3 with respect to the propeller center line Yp in the vertical direction of the propeller 3.

  The stern appendage according to the present embodiment is a hull without increasing the resistance of the hull 1 even if the pair of columns 12a is added to the hull 1 by setting the inclination angle θ to an angle range of 30 degrees to 60 degrees. Efficiency can be improved. In addition, the duct main body 11 with a small angle range can be made to face a position where an especially propulsion direction component (thrust component) above the rotation center axis Xp of the propeller 3 can be obtained particularly.

  Further, the stern appendage according to the present embodiment is easy in design and equipment when the virtual central axis Xd of the pair of columns 12 a is made to coincide with the rotation central axis Xp of the propeller 3.

  Further, in the stern appendage according to the present embodiment, when the virtual center axis Xd of the pair of columns 12 a is shifted from the rotation center axis Xp of the propeller 3, the pair of columns 12 a is generated by the hull 1 or the propeller 3, for example. It can be shifted to a position where the thrust force can be increased corresponding to the asymmetric flow.

  Further, in the stern appendage according to the present embodiment, when the virtual center axis Xd of the pair of columns 12a is inclined with respect to the rotation center axis Xp of the propeller 3 in a side view of the hull 1, the pair of columns 12a can be mounted to increase the thrust force.

  In addition, when the cross section of the support 12a is formed into an inward convex wing shape, the stern appendage according to the present embodiment may utilize the propulsion direction component (thrust component) of the lift generated by the wing. it can.

  Further, the stern appendage according to the present embodiment can be made into a twisted support 12c, and the propulsive force can be enhanced when the flow toward the propeller 3 is counterflowed with respect to the rotation direction of the propeller 3 .

  In the stern appendage according to the present embodiment, the propelling force can be increased by reducing the resistance of the support 12a when the support 12a is made larger on the duct body side longitudinal width Ly than the stern side longitudinal width Lx. it can.

  Moreover, according to the ship having the stern attachment of the present invention, the resistance applied to the support 12a can be reduced, and a ship having a high energy saving effect can be provided.

  Moreover, when the hull 1 is a twin-stern stern double-body type hull, resistance applied to the support 12a can be reduced, and a twin-shaft stern double-body type ship with high energy saving effect can be provided.

  When the hull 1 is an existing hull and the columns 12a are retrofitted to the hull 1, the resistance reduction and the improvement of the energy saving effect can be applied to the existing hull.

  The present invention is particularly applicable to stern ducts mounted on the stern of general ships including low-speed enlarged vessels, and by adding the duct body, it is possible to improve the hull efficiency without increasing the resistance of the hull. There is an energy saving effect.

1 Hull 2 Stern 3 Propeller 10 Stern Duct 11 Duct Body 11s Cross Section 12 Support Means Xp Center of Rotation
Yd duct center line Yp propeller center line β center angle (angle range)
θ inclination angle

Claims (19)

In the stern duct attached to the front of the propeller attached to the stern of the hull, the duct main body is formed in a substantially arc shape of an angle range of 225 degrees to 255 degrees, and the upper and lower sides of the propeller in a state of looking forward from the rear The duct body is attached to the stern by the support means such that the duct center line of the duct body has an inclination angle in the same direction as the propeller rotation direction with respect to the propeller center line of the direction; The stern duct according to claim 1, wherein the inclination angle in the rotational direction is in an angular range of 30 degrees to 60 degrees in the rotational direction of the propeller with respect to the propeller center line above the center of the propeller.   The stern duct according to claim 1, wherein a cross section of the duct body in the front-rear direction is formed into an inwardly convex wing shape.   The stern duct according to claim 1 or 2, wherein the radius of the rear end arc formed at the rear end of the duct main body is smaller than the radius of the front end arc formed at the front end.   The stern duct according to any one of claims 1 to 3, wherein an imaginary central axis of the duct body is made coincident with a rotational central axis of the propeller.   The stern duct according to any one of claims 1 to 3, wherein a virtual central axis of the duct body is offset from a rotational central axis of the propeller.   The stern according to any one of claims 1 to 5, wherein the virtual central axis of the duct main body is inclined with respect to the central axis of rotation of the propeller in a side view of the hull. duct.   The duct body is attached to an end portion of the stern that covers the stern tube of the hull or the stern tube via a column as the support means. The stern duct described in.   The stern duct according to any one of claims 1 to 7, wherein the support as the support means is provided in an angle range of 60 degrees or less from the duct center line.   The stern duct according to claim 7 or 8, wherein a cross section of the column is formed into an inwardly convex wing shape.   The flow toward the propeller can be counter-flowed with respect to the rotational direction of the propeller by forming the support column in a twisted shape. The stern duct described in.   The stern duct according to any one of claims 7 to 9, wherein the column is formed such that the duct body side longitudinal width is larger than the stern side longitudinal width. In a stern appendage attached to the front of a propeller attached to a stern of a hull, a pair of support columns supporting a substantially arc-shaped virtual duct body, an angle range between a pair of the support columns is an angle range of 225 degrees to 255 degrees Attached to the stern so that the ship body is viewed forward from the rear, the column center lines of the pair of columns are inclined in the same direction as the propeller rotation direction with respect to the propeller center line in the vertical direction of the propeller The inclination angle of the propeller in the rotation direction is set to an angle range of 30 degrees to 60 degrees in the rotation direction of the propeller with respect to the propeller center line upward from the center of the propeller while having an angle A stern appendage characterized by   The method for designing a stern duct according to any one of claims 1 to 11, wherein in designing the stern duct, an all-round duct having the same radius as the substantially arc-shaped duct main body is set. Calculating the resistance / self-propagation by numerical calculation of the hull using the all-round duct, the distribution of fluid force in the direction of hull propulsion acting on the surface of the all-round duct from the resistance / self-propagation calculation result and And / or determining the flow velocity and flow direction distribution from the rear of the all-round duct to the propeller surface, and the all-round duct based on the fluid force distribution and / or the flow velocity and flow distribution from the rear of the all-round duct to the propeller surface And D. determining the shape of the duct body substantially in the shape of a circular arc from the above. Claims, characterized in that a step of performing the step of setting the mounting number of the mounting position of the strut as said support means, a resistance-self propulsion calculation by numerical calculation of the hull with the strut set A method of designing a stern duct according to claim 13, wherein one of the items 7 to 11 is cited .   The method for designing a stern duct according to claim 13 or 14, wherein the fluid force distribution is a thrust distribution and a resistance component distribution.   14. The design of the stern duct according to claim 13, wherein the shape of the duct body and the inclination angle are determined based on the energy saving rate with respect to the duct installation angle in a small duct having an angle range of 90 degrees to 180 degrees. Method.   A vessel equipped with a stern duct characterized in that the stern is equipped with the stern duct according to any one of claims 1 to 11.   18. A vessel equipped with a stern duct according to claim 17, wherein said hull is a two-shaft stern double-body type hull.   The ship equipped with the stern duct according to claim 17 or 18, wherein the hull is an existing hull and the stern duct is retrofitted to the hull.