JP6663144B2 - Ship equipped with air lubrication control device - Google Patents

Description

  The present invention relates to a ship provided with a bubble countermeasure device used for air lubrication to reduce frictional resistance by blowing bubbles around a hull.

An air lubrication method that reduces the resistance of a ship by blowing air around the hull and causing air bubbles to intervene in seawater near the hull surface has been used as a frictional resistance reduction technique.
However, when air bubbles flow into the propeller attached to the stern of the hull, the efficiency of the propeller decreases and the hull vibrates. Therefore, a device for removing air bubbles has been conventionally proposed.

Patent Document 1 discloses that a stern appendage such as a tunnel fin is provided on a stern side portion of a hull to rectify and accelerate a water flow at an upper portion of a propeller, and is ejected from an air blowing hole provided at a lower portion of a draft to a ship side on both right and left sides. There is disclosed a drag reduction device for a ship that attempts to prevent bubbles flowing backward along the propeller from flowing into the propeller.
In Patent Document 2, a plurality of air recovery ports are provided on the bottom of the ship, and air blown out from the plurality of air outlets provided on the bottom of the ship is recovered from the air recovery ports into the hull, thereby removing air. An air bubble recovery device for a ship that attempts to prevent inflow is disclosed.
In Patent Literature 3, a water jetting part is provided in front of a propeller, and water is jetted into the water from the water jetting part, so that the water is jetted into the water from an air outlet provided at the bottom on the bow side, and the water is jetted from the bow toward the stern. There is disclosed a propeller vibrating force suppressing device that guides a moving bubble away from the propeller and prevents the bubble from flowing into the propeller.
Although it is not a device for removing air bubbles, Patent Document 4 discloses a swirling member provided in a discharge pipe in a gas-liquid supply device and collecting air at a center side of the discharge pipe by swirling gas-liquid fluid. Have been.

JP 2011-93486 A JP 2011-213303 A JP 2014-125126 A JP-A-2002-52330

However, even if the devices described in Patent Documents 1 to 3 are used, it is difficult to rationally remove bubbles that are going to flow into the propeller.
In Patent Document 1, for example, as shown in FIG. 2A, a long stern appendage 41 is provided so that an air layer 201 located above the propeller 16 at the stern side does not flow into the propeller 16. I have. Further, as shown in FIG. 4A, for example, a large stern appendage 42 is provided near the outer end of the propeller 16, the stern appendage 42 rectifies and accelerates the water flow above the propeller 16, and the air layer 201 near the propeller 16 is formed. It prevents bubbles from staying. For this reason, the stern accessories 41 and 42 become large, and there are problems in terms of an increase in frictional resistance, manufacturing costs, installation and maintenance, and the like. Even if the stern appendages 41 and 42 function on the air layer 201 on the ship side, it is difficult to effectively function on the air layer 200 on the bottom of the ship.
In particular, when an air bubble collecting device described in Patent Literature 2 or a water jetting portion described in Patent Literature 3 is to be provided, the configuration becomes large and the manufacturing cost and maintenance cost increase.
In addition, the invention described in Patent Document 4 relates to a gas-liquid supply device that adds gas to a liquid and supplies the liquid as a gas-liquid fluid, and suppresses an adverse effect caused by bubbles ejected around a hull flowing into a propeller. It does not prevent it.

  Therefore, the present invention rationally prevents the adverse effect on propeller efficiency due to the ejected bubbles flowing into the propeller while maintaining the effect of the air lubrication method of jetting air around the hull to reduce frictional resistance. An object of the present invention is to provide a ship provided with a bubble countermeasure device for air lubrication.

The marine vessel provided with the air lubrication bubble countermeasure device according to claim 1, further comprising an air supply port for jetting air bubbles used for air lubrication for jetting air bubbles around the hull to reduce frictional resistance, As an air lubrication bubble countermeasure device, a propeller provided at the stern of a hull, and a bubble provided in front of a propeller which concentrates the bubbles flowing into the propeller from the air supply port and flows the bubbles to a blade root portion of the propeller Concentrating means, wherein the air bubble concentrating means has a structure for inducing the air bubbles by negative pressure, and the air bubble concentrating means is a duct provided between the hull and the propeller, and supports the duct at the stern of the hull. A duct supporting means having a twisted shape is further provided inside the duct, and the duct supporting means is twisted in the same direction as the rotation direction of the propeller . According to the first aspect of the present invention, the bubble concentration means promotes the inflow of bubbles into the blade root portion of the propeller, where the bubbles are likely to collect, and the bubbles are concentrated on the blade root portion of the propeller and flow backward. Since the thrust generated at the blade root part of the propeller is smaller than the thrust generated at other parts, instead of preventing air bubbles from flowing into the propeller, air bubble concentration means is provided to generate air bubbles at the blade root of the propeller. By encouraging the inflow and causing the bubbles to concentrate on the blade root portion and flow behind the propeller, it is possible to reliably and easily remove the bubbles in a portion that generates a large thrust of the propeller. Therefore, it is possible to suppress the deterioration of the propeller efficiency due to the bubbles flowing into the portion contributing to the generation of the thrust of the propeller, and it is possible to reduce the size of the bubble concentration unit. As a result, air lubrication that rationally prevents the air bubbles ejected from flowing into the propeller and adversely affects the propeller efficiency while maintaining the effects of the air lubrication method that reduces frictional resistance by ejecting air around the hull A ship provided with the air bubble countermeasure device can be provided. In addition, a swirling flow is created by imparting a twist to the duct supporting means, and bubbles are collected at the center of the swirling flow having a low flow velocity. Therefore, the bubbles can be further concentrated on the blade root of the propeller. Further, the swirling flow generated by the duct supporting means is strengthened, and the air bubbles can be further concentrated on the blade root of the propeller.

According to a second aspect of the invention, duct, characterized in that it is a duct forms a circular cylindrical shape. According to the second aspect of the present invention, air bubbles are induced by the negative pressure generated in the duct, the air bubbles are collected in the duct, and the air bubbles concentrate on the blade root of the propeller and flow backward. Also, by providing the duct, the flow on the inflow surface to the propeller is slowed, the wake coefficient is improved, and the propeller efficiency is improved.

The third aspect of the present invention is characterized in that the diameter of the rear end of the duct is 50% or less of the diameter of the propeller. According to the third aspect of the present invention, the air bubbles that have exited the duct are prevented from flowing to portions other than the blade root of the propeller, and the air bubbles are further concentrated on the blade root of the propeller and flow backward. Therefore, it is possible to more reliably prevent the air bubbles from flowing to the portion where the thrust of the propeller is generated, and the size of the duct can be reduced .

請 Motomeko 4 the invention described is characterized in that the airfoil forming a convex cross-sectional shape of the duct on the inside. According to the present invention as set forth in claim 4 , by forming the duct in an airfoil shape, it is possible to increase the flow velocity, collect air bubbles at the center, concentrate the air bubbles on the blade root of the propeller, and flow the air backward. The lift that propels the hull forward can be increased.

The present invention described in claim 5 is characterized in that the duct is an accelerating duct whose inner diameter on the downstream side is smaller than that on the upstream side. According to the fifth aspect of the present invention, by making the duct an accelerating type duct, the flow can be accelerated, the air bubbles can be further collected near the center, and can be concentrated on the blade root of the propeller.

The invention according to claim 6 is characterized in that the center of the duct coincides with the axis of the propeller. According to the sixth aspect of the present invention, by aligning the center of the duct with the axis of the propeller, air bubbles can be correctly concentrated on the blade root of the propeller and flow backward, and the production and installation of the duct Becomes easier.

The present invention described in claim 7 is characterized in that the pitch of the propeller is a gradually decreasing pitch that decreases in the radial direction and has a maximum value at the blade root of the propeller and a minimum value at the blade tip. According to the seventh aspect of the present invention, by increasing the pitch of the blade root of the propeller, the swirling flow near the blade root is strengthened and bubbles are further collected near the center of the swirling flow. You can concentrate on

The present invention according to claim 8 is characterized in that a concave portion for further promoting the concentration of bubbles is provided on the surface of the propeller boss supporting the propeller. According to the eighth aspect of the present invention, by forming a concave portion in the propeller boss that rotates together with the propeller to create a low pressure portion, the air bubbles can be further concentrated on the blade root portion of the propeller.

According to the present invention, the bubble concentration means promotes the flow of bubbles into the blade root of the propeller where bubbles easily collect, and the bubbles flow rearward concentrated on the blade root of the propeller. Since the thrust generated at the blade root part of the propeller is smaller than the thrust generated at other parts, instead of preventing air bubbles from flowing into the propeller, air bubble concentration means is provided to generate air bubbles at the blade root of the propeller. By encouraging the inflow and causing the bubbles to concentrate on the blade root portion and flow behind the propeller, it is possible to reliably and easily remove the bubbles in a portion that generates a large thrust of the propeller. Therefore, it is possible to suppress the deterioration of the propeller efficiency due to the bubbles flowing into the portion contributing to the generation of the thrust of the propeller, and it is possible to reduce the size of the bubble concentration unit. As a result, air lubrication that rationally prevents the air bubbles ejected from flowing into the propeller and adversely affects the propeller efficiency while maintaining the effects of the air lubrication method that reduces frictional resistance by ejecting air around the hull A ship provided with the air bubble countermeasure device can be provided. In addition, a swirling flow is created by imparting a twist to the duct supporting means, and bubbles are collected at the center of the swirling flow having a low flow velocity. Therefore, the bubbles can be further concentrated on the blade root of the propeller. Further, the swirling flow generated by the duct supporting means is strengthened, and the air bubbles can be further concentrated on the blade root of the propeller.

Further, duct, in the case of duct forms a circular cylinder shape, are attracted bubbles by the negative pressure generated in duct, gathered bubble in the duct, the bubbles flows rearward to concentrate on the blade root portion of the propeller . Also, by providing the duct, the flow on the inflow surface to the propeller is slowed, the wake coefficient is improved, and the propeller efficiency is improved.

In addition, when the diameter of the rear end of the duct is 50% or less of the diameter of the propeller, the air bubbles that have exited the duct are prevented from flowing to portions other than the blade root of the propeller, and the air bubbles are further reduced. Concentrate on the wing root and flow backward. Therefore, it is possible to more reliably prevent the air bubbles from flowing to the portion where the thrust of the propeller is generated, and the size of the duct can be reduced .

Also, in the case of the airfoil forming a convex cross-sectional shape of the duct on the inside, by forming the duct airfoil collected around the bubbles increase the flow velocity at the rear to concentrate on the blade root of the propeller In addition to the flow, the lift force for propelling the hull forward can be increased as a component force.

  Also, when the duct is an accelerated duct whose inner diameter on the downstream side is smaller than the inner diameter on the upstream side, the duct is made an accelerated duct to accelerate the flow and move the bubbles further toward the center. To concentrate on the propeller blade root.

  When the center of the duct is aligned with the axis of the propeller, the center of the duct is aligned with the axis of the propeller so that air bubbles can be correctly concentrated on the blade root of the propeller and flow backward. In addition, the production and installation of the duct becomes easy.

  Also, if the pitch of the propeller is a gradually decreasing pitch that decreases in the radial direction and becomes the maximum value at the blade root of the propeller and the minimum value at the blade tip, the pitch of the blade root of the propeller is increased to increase the blade pitch. By strengthening the swirling flow in the vicinity, bubbles can be further collected near the center of the swirling flow and concentrated on the blade root of the propeller.

  Also, if a concave portion is provided on the surface of the propeller boss that supports the propeller to further promote the concentration of bubbles, the concave portion is formed in the propeller boss that rotates with the rotation of the propeller to create a low pressure portion, so that the bubble is reduced. Can be further concentrated on the blade root of the propeller.

1 is a schematic configuration diagram of a ship provided with an air lubrication bubble control device according to an embodiment of the present invention. Schematic configuration diagram showing an air lubrication countermeasure device used for the ship Partial cross-sectional configuration diagram showing the main part of the bubble concentration means (duct) used for the ship Pressure distribution diagram in the duct of the bubble concentration means (duct) used for the ship A graph showing the pitch distribution of a diminishing pitch propeller and a normal propeller used for the same ship Schematic configuration diagram showing the propeller boss of bubble concentration means used for the same ship Diagram showing velocity distribution in cross section of propeller position around stern part with and without duct on model ship The principal part front view which shows the state which looked at the bubble concentration means of the bubble countermeasure device for air lubrication by another embodiment of this invention from the back and front. The principal part front view which shows the state which looked at the duct of the air lubricating bubble countermeasure apparatus by still another embodiment of this invention from the back front.

  Hereinafter, a ship provided with an air lubrication bubble countermeasure device according to an embodiment of the present invention will be described.

  FIG. 1 is a schematic configuration diagram of a ship provided with an air lubricating bubble countermeasure device according to an embodiment of the present invention, FIG. 2 is a partial cross-sectional side view showing an air lubricating bubble countermeasure device used in the ship, and FIG. FIG. 4 is a partial cross-sectional configuration diagram showing a main part of a bubble concentrating means (duct) used in a ship, FIG. 4 is a pressure distribution diagram in a duct of the bubble concentrating means (duct) used in the ship, and FIG. And a graph showing a pitch distribution of a normal propeller, FIG. 6 is a schematic configuration diagram showing a propeller boss of a bubble concentration means used in the same ship, and FIG. 7 is a propeller around a stern portion of a model ship with and without duct. It is a figure which shows the flow velocity distribution in a position cross section.

As shown in FIG. 1, the marine vessel has a propeller 10 provided at the stern of the hull 1 and bubble concentration means 20 provided in front of the propeller 10.
In addition, the ship has a ventilation tube 30 provided on the upper deck of the hull 1 on the bow side, an air supply port 40 provided on the bottom of the hull 1, and an air path 32 communicating the ventilation tube 30 with the air supply port 40. Have. An opening 31 is provided at the upper end of the ventilation tube 30, and an air supply means 34 is provided in a bow warehouse 33 inside the hull 1. The air supply means 34 can be constituted by, for example, a blower (blower) or the like, is provided in the air path 32, sucks air, pressurizes it to a required pressure, and blows out air lubrication air from the air supply port 40 at the bottom of the ship. .
As described above, the air sucked from the opening 31 passes through the air path 32 and is ejected from the air supply port 40 as bubbles. By supplying gas as air bubbles from the air supply port 40, the sea surface S.S. L. By supplying air bubbles around the hull 1 below, a high frictional resistance reducing effect can be obtained.
In addition, a drainage means 35 for discharging water accumulated on the floor surface to the outside of the ship is provided below the bow warehouse 33. Thus, even if water enters the ventilation tube 30, the water can be discharged outboard by the drainage unit 35.
Since the bubbles ejected from the air supply port 40 are bubbles having a diameter of several millimeters, they flow to the stern side along the bottom of the ship so as to stick to the bottom of the ship due to the buoyancy effect.

As shown in FIG. 2, the propeller 10 has a propeller boss 13 at the center, and in this embodiment, the bubble concentration means 20 is a cylindrical duct provided between the hull 1 and the propeller 10.
The diameter of the rear end 21 of the duct (bubble concentrating means) 20 is 50% or less of the diameter Dp of the propeller 10.
As shown in FIG. 4, in the duct 20, the pressure of the convex portion (the portion surrounded by the dotted line α) of the wing surface in the duct 20 becomes low. Therefore, by providing the duct (bubble concentration means) 20 in front of the propeller 10, the bubbles ejected from the air supply port 40 and reaching the stern side are attracted by the negative pressure generated in the duct 20 and collected in the duct 20. , Which are concentrated on the blade root 11 of the propeller 10 and flow backward.
Since the thrust generated by the blade root portion 11 is smaller than the thrust generated by other portions of the propeller 10, the propeller 10 does not prevent air bubbles from flowing into the propeller 10. By encouraging air bubbles to flow into the blade root 11 and by causing the air bubbles to concentrate on the blade root 11 and flow behind the propeller 10, it is possible to reliably and easily remove the air bubbles in a portion that generates a large thrust of the propeller 10. . Therefore, deterioration of propeller efficiency due to air bubbles flowing into the portion of the propeller 10 that contributes to thrust generation can be suppressed, and the duct 20 can be reduced in size.
Also, by setting the diameter of the rear end 21 of the duct 20 to be 50% or less, preferably 40% to 50% of the diameter Dp of the propeller 10, the air bubbles that have exited the duct 20 are reduced to portions other than the blade root 11 of the propeller 10. The air bubbles are further concentrated on the blade root 11 of the propeller 10 and flow backward. Therefore, it is possible to more reliably prevent air bubbles from flowing near 0.7R (a portion 70% of the propeller diameter Dp) where the thrust of the propeller 10 is largely generated, and the duct 20 can be made small.

  As shown in FIGS. 2 and 3, the cross-sectional shape of the duct 20 is an airfoil that is convex inward. By forming the duct 20 in an airfoil shape, it is possible to increase the flow velocity, collect air bubbles at the center, concentrate the air bubbles on the blade root 11 of the propeller 10 and flow the air backward, and at the same time, increase the lifting force for propelling the hull 1 forward as a component force. Can be increased.

As shown in FIGS. 2 and 3, a duct support means 22 having a twisted shape for supporting the duct 20 on the stern 2 of the hull 1 is further provided inside the duct 20. In the present embodiment, the duct support means 22 is a support. The duct 20 is attached to the stern 2 of the hull 1 via the support posts 22.
By imparting a twist to the duct support means 22, a swirling flow is created, and the bubbles are collected at the center where the flow velocity of the swirling flow is slow, so that the bubbles can be further concentrated on the blade root 11 of the propeller 10.
Further, the duct support means 22 is twisted in the same direction as the rotation direction of the propeller 10. By setting the torsion of the duct support means 22 in the same direction as the rotation direction of the propeller 10, the swirling flow can be strengthened and the bubbles can be further concentrated on the blade root 11 of the propeller 10.

  As shown in FIGS. 2 and 3, the duct 20 is an accelerating duct in which the inner diameter of the rear end 21 downstream is smaller than the inner diameter of the front end 23 upstream. By making the duct 20 an accelerating type duct, the flow can be accelerated, the bubbles can be further collected near the center, and can be concentrated on the blade root 11 of the propeller 10.

  As shown in FIG. 3, the center of the duct 20 matches the axis of the propeller 10. By forming the duct 20 in an axially symmetrical shape and attaching the drive shaft of the propeller 10 and the center axis of the duct 20 in alignment with each other, air bubbles can be correctly concentrated on the blade root 11 of the propeller 10 and flow backward. The manufacture and installation of the duct 20 are facilitated.

FIG. 5 shows the pitch distributions of the decreasing pitch propeller and the normal propeller.
In the propeller 10, the radius of the propeller boss 13 is r1, and the blade root 11 is the radius r1 from the radius r1. The radius R of the propeller 10 is 1/2 Dp, and H is the pitch. The blade root 11 (from r1 to r2) is at least 20% and at most 40% of the diameter Dp of the propeller 10.
The pitch H of the propeller 10 according to the present embodiment is a gradually decreasing pitch that decreases in the radius R direction, with the maximum value Hmax at the blade root 11 and the minimum value Hmin at the blade tip 12 of the propeller 10. The comparative example shown in FIG. 5 shows a constant pitch.
By increasing the pitch of the blade root 11 of the propeller 10, the swirling flow in the vicinity of the blade root 11 is strengthened, so that bubbles can be further collected near the center of the swirling flow and concentrated on the blade root 11 of the propeller 10. .

FIG. 6 is a schematic configuration diagram showing a propeller boss of the bubble concentration means used in the ship. FIG. 6 (a) is a front view of a main part showing the propeller boss viewed from the rear and forward, and FIG. 6 (b) is a propeller. It is a principal part side view which shows the state which looked at the boss from the side.
As shown in FIG. 6, a concave portion 14 for further promoting the concentration of bubbles is provided on the surface of a propeller boss 13 supporting the propeller 10. The concave portion 14 is formed in a cut shape between a plurality of blades of the propeller 10, and has a wall surface 14 a in the rotation direction of the propeller 10. The length of the concave portion 14 is formed from the front of the propeller boss 13 to the rear of the propeller 10, and has a wall surface 14b on the front side.
The depression 14 of the propeller boss 13 that rotates with the rotation of the propeller 10 has a low pressure and collects bubbles, so that the bubbles can be further concentrated on the blade root 11 of the propeller 10.

FIG. 7 shows the flow velocity distribution in the cross section of the propeller position around the stern of the model ship with and without duct. FIG. 7A shows the case without the duct, and FIG. 7B shows the case with the duct. The darker the color, the faster the flow velocity.
As shown in FIG. 7B, it can be seen that the flow on the inflow surface to the propeller 10 can be made slower by installing the duct 20 than in the case where the duct 20 is not installed. Air lubrication reduces frictional resistance and reduces the effect of dragging fluid on the hull surface, changing the velocity distribution in the boundary layer that develops on the hull surface, increasing the flow velocity on the propeller surface, Of these, the wake coefficient deteriorates. The duct 20 can improve the wake coefficient by the wake generated by the duct 20 itself. In addition, the wake coefficient may be degraded when other frictional resistance reduction methods such as polymer introduction are performed. However, by installing the duct 20, the wake coefficient can be improved.
Therefore, by installing the duct 20, air bubbles can be concentrated on the blade root portion 11 of the propeller 10 to suppress the deterioration of the propeller efficiency, and the wake coefficient can be improved to improve the propeller efficiency.

Referring to FIG. 8, an air lubricating air bubble countermeasure device according to another embodiment of the present invention will be described. FIG. 8 is a main part front view showing a state where the bubble concentration means of the air lubricating bubble countermeasure device according to another embodiment of the present invention is viewed from the rear and forward. Note that the same reference numerals are given to the same functional members as in the above-described embodiment, and the description is omitted.
The bubble concentration means 20 according to the present embodiment is not a duct having a cylindrical shape, but a duct 200 having a semicircular shape (FIG. 8A), and a duct having a central angle formed in a substantially arc shape having an angle of 120 degrees. 210 (FIG. 8 (b)), a duct 220 (FIG. 8 (c)) formed in a substantially arc shape with a central angle of 210 degrees, or a fin 230 (post) with the duct portion removed. Different from the embodiment.

The duct 200 in FIG. 8A has a central angle of 180 degrees, and the duct center line Yd is positioned between the propeller 10 and the propeller center line Yp in the vertical direction in a state where the hull 1 is viewed from the rear. The hull 1 is attached to the stern 2 of the hull 1 through the duct support means (posts) 201 so as to have an inclination angle θ in the rotation direction.
The central angle of the duct 210 in FIG. 8B is 120 degrees. The duct center line Yd is attached to the stern portion 2 of the hull 1 via the duct support means (post) 211 so that the duct center line Yd coincides with the propeller center line Yp.
The duct 220 in FIG. 8C has a central angle of 210 degrees, and the duct center line Yd is defined by the propeller 10 with respect to the propeller center line Yp in the vertical direction of the propeller 10 in a state where the hull 1 is viewed from the rear. The hull 1 is attached to the stern 2 of the hull 1 via the duct support means (post) 221 so as to have an inclination angle θ in the rotation direction.
By providing the duct 200 (210, 220) as a bubble concentration means in front of the propeller 10, the air bubbles ejected from the air supply port 40 and reaching the stern side are generated by the negative pressure generated in the duct 200 (210, 220). It is attracted and gathers in the duct 200 (210, 220), and can concentrate on the blade root 11 of the propeller 10 and flow backward.
The ducts 200, 210, and 220 according to the present embodiment speed up the flow that passes through the interior, attract air bubbles from the surroundings, and utilize the function of the swirling flow created by the propeller 10 to make the center of the ducts 200, 210, and 220. Based on the idea of collecting air bubbles in the section and concentrating the air bubbles on the blade root 11 of the propeller 10 and flowing the air backwards, an air bubble removal effect that does not substantially impair the propulsive force of the propeller 10 is expected even if the propeller 10 is not a full circumference duct. it can.

  The plurality of fins (posts) 230 in FIG. 8D are attached to the stern 2 of the hull 1, and the fins 230 are twisted in the same direction as the rotation direction of the propeller 10. By setting the twist of the fins 230 in the same direction as the rotation direction of the propeller 10, the swirling flow is strengthened, and the bubbles can be further concentrated on the blade root 11 of the propeller 10.

With reference to FIG. 9, an air lubricating bubble countermeasure device according to still another embodiment of the present invention will be described. FIG. 9 is a main part front view showing a state in which a duct of an air lubricating air bubble countermeasure device according to still another embodiment of the present invention is viewed from the rear and forward. Note that the same reference numerals are given to the same functional members as in the above-described embodiment, and the description is omitted.
The duct support means (post) 300 according to the present embodiment includes four posts, and is arranged radially with respect to the central axis of the duct 20. The duct 20 is attached to the stern 2 of the hull 1 via four columns.
The duct support means 300 is twisted in a direction opposite to the direction of rotation of the propeller 10. The flow that has flowed into the duct 20 is turned into a rotational flow in the direction opposite to the rotation direction of the propeller 10 by the support means 300 having a twist in the direction opposite to the rotation direction of the propeller 10, and flows into the propeller 10 as a counterflow. Therefore, the bubbles are collected by the negative pressure generated in the bubble concentration means (duct) 20 and concentrated on the blade root 11 of the propeller 10 to flow backward, thereby improving the propeller efficiency, and the flow flows into the propeller 10 as a counterflow. By doing so, the propeller efficiency can be further improved.

  As described above, according to the air-lubricating bubble countermeasure device according to the present embodiment, the bubble concentration means 20 such as a duct promotes the flow of bubbles into the blade root portion 11 of the propeller 10 where bubbles are easily collected, and the bubbles are removed from the propeller. It flows rearward concentrated on the wing roots 11 of 10. Since the thrust generated by the blade root portion 11 in the propeller 10 is smaller than the thrust generated by the other portions, instead of preventing air bubbles from flowing into the propeller 10, a bubble concentrating means 20 is provided to provide the blades of the propeller 10. By encouraging air bubbles to flow into the root portion 11 and concentrating the air bubbles on the blade root portion 11 and flowing the air behind the propeller 10, the air bubbles in the portion where the thrust of the propeller 10 generates a large amount of force can be reliably and simply removed. Therefore, it is possible to suppress the deterioration of the propeller efficiency due to the bubbles flowing into the portion of the propeller 10 that contributes to the generation of the thrust, and the bubble concentration unit 20 can be downsized.

  Further, according to the air lubricating air bubble countermeasure apparatus according to the present embodiment, since the air bubble concentrating means is a cylindrical duct 20 provided between the hull 1 and the propeller 10, the negative pressure generated in the duct 20 is reduced. As a result, air bubbles are attracted, the air bubbles are collected in the duct 20, and the air bubbles concentrate on the blade root 11 of the propeller 10 and flow backward. Further, by providing the duct 20, the flow on the inflow surface to the propeller 10 is slowed, the wake coefficient is improved, and the propeller efficiency is improved.

  Further, according to the air lubricating air bubble countermeasure device according to the present embodiment, the diameter of the rear end 21 of the duct 20 is set to 50% or less of the diameter Dp of the propeller 10, so that the air bubbles that have exited the duct 20 can be reduced. The air bubbles are prevented from flowing to portions other than the blade root 11, and the air bubbles are further concentrated on the blade root 11 of the propeller 10 and flow backward. Therefore, air bubbles can be more reliably prevented from flowing to the portion of the propeller 10 that generates thrust, and the duct 20 can be made smaller.

  Further, according to the air lubricating air bubble countermeasure device according to the present embodiment, the duct 20 is further provided on the inner side of the duct 20 with a twisted shape for supporting the duct 20 on the stern portion 2 of the hull 1. As a result, a swirling flow is created, and the bubbles are collected at the center of the low velocity of the swirling flow. Therefore, the air bubbles can be further concentrated on the blade root 11 of the propeller 10.

  Further, according to the air lubricating air bubble countermeasure device according to the present embodiment, by twisting the duct support means 22 in the same direction as the rotation direction of the propeller 10, the swirling flow generated by the duct support means 22 is strengthened, and the air bubbles are further reduced. It can be further concentrated on the blade root 11 of the propeller 10.

  In addition, according to the air lubricating air bubble countermeasure device according to the present embodiment, the duct 20 has an airfoil shape in which the cross-sectional shape is convex inward, so that the flow velocity is increased and the air bubbles are collected mainly, and the blade root 11 of the propeller 10 is formed. And can be made to flow backward, and the lift force for propelling the hull 1 forward can be increased as a component force.

  Further, according to the air lubricating air bubble countermeasure device according to the present embodiment, the duct 20 is an accelerating type duct whose inner diameter on the downstream side is smaller than the inner diameter on the upstream side, thereby accelerating the flow and reducing bubbles. It can be gathered closer to the center and concentrated on the blade root 11 of the propeller 10.

  According to the air lubricating air bubble countermeasure device of the present embodiment, since the center of the duct 20 is aligned with the axis of the propeller 10, air bubbles are correctly concentrated on the blade root 11 of the propeller 10 and flow backward. And the manufacture and installation of the duct 20 are facilitated.

  Further, according to the air lubricating bubble countermeasure device according to the present embodiment, the pitch H of the propeller 20 decreases gradually in the radial direction so that the pitch H becomes the maximum value at the blade root 11 of the propeller 10 and the minimum value at the blade tip 12. By setting the pitch, the pitch of the blade root 11 of the propeller 10 is increased, the swirling flow near the blade root 11 is strengthened, and the bubbles are further collected near the center of the swirling flow and concentrated on the blade root 11 of the propeller 10. Can be done.

  Further, according to the air lubricating air bubble countermeasure device according to the present embodiment, the surface of the propeller boss 13 supporting the propeller 10 is provided with the concave portion 14 that further promotes the concentration of air bubbles, and thus rotates with the rotation of the propeller 10. A low pressure portion is formed in the propeller boss 13, so that air bubbles can be further concentrated on the blade root portion 11 of the propeller 10.

  Further, according to the air lubricating bubble countermeasure device according to the present embodiment, when the duct support means 22 is twisted in the direction opposite to the rotation direction of the propeller 10, the flow can be made counter-current to improve the propeller efficiency. it can.

  In addition, the provision of the air lubricating air bubble countermeasure apparatus according to the present embodiment in the ship allows the jetted air bubbles to be released while maintaining the effect of the air lubrication method of jetting air around the hull 1 to reduce frictional resistance. It is possible to provide a ship provided with an air lubricating bubble countermeasure device that rationally prevents the propeller efficiency from being adversely affected by flowing into the propeller 10.

  The ship provided with the air lubricating air bubble countermeasure device of the present invention can reliably and easily remove air bubbles in a portion that generates a large thrust of the propeller by causing air bubbles to concentrate on the blade root and flow behind the propeller. Since it is possible, deterioration of propeller efficiency due to air bubbles flowing into the propeller can be suppressed. Therefore, the present invention can be applied not only to a ship using an air lubrication method that blows air around the hull to reduce frictional resistance, but also to measures against bubbles flowing from the bottom of an air film type ship and flowing into a propeller.

DESCRIPTION OF SYMBOLS 1 Hull 2 Stern part 10 Propeller 11 Wing root part 14 Recess 20 Bubbles concentration means (duct)
21 rear end 22 duct support means (post)

Claims (8)

Equipped with an air supply port that ejects bubbles used for air lubrication to reduce frictional resistance by blowing bubbles around the hull,
Further, as an air lubricating bubble countermeasure device, a propeller provided at the stern of the hull, and the air bubbles flowing into the propeller from the air supply port are concentrated to forward the air bubbles to the blade root portion of the propeller. And a bubble concentrating means provided in the vessel, wherein the bubble concentrating means has a structure for inducing the bubbles by negative pressure , wherein the bubble concentrating means is a duct provided between the hull and the propeller, and the duct The duct further comprises a duct supporting means having a twisted shape for supporting the stern of the hull inside the duct, wherein the duct supporting means is twisted in the same direction as the rotation direction of the propeller. Ships equipped with air lubricating air bubble countermeasures. It said duct is a vessel provided with a bubble countermeasure device for air lubrication according to claim 1, characterized in that the duct forms a circular cylindrical shape.   3. The ship according to claim 2, wherein the rear end of the duct has a diameter of 50% or less of the diameter of the propeller. The ship provided with the air lubricating bubble countermeasure device according to claim 2 or 3 , wherein a cross-sectional shape of the duct is an airfoil having a convex shape inward. The air-lubricating air bubble countermeasure device according to any one of claims 2 to 4 , wherein the duct is an acceleration duct having a downstream inner diameter smaller than an upstream inner diameter. Equipped ship. The ship provided with the air lubricating bubble countermeasure device according to any one of claims 2 to 5 , wherein a center of the duct is aligned with an axis of the propeller. The pitch of the propeller, the minimum value to the maximum value and becomes blade tip at the blade root portion of the propeller, one of claims 1 to 6, characterized in that a diminishing pitch that decreases in the radial direction A ship equipped with the air lubrication bubble control device according to the above item. The air-lubricating air bubble countermeasure device according to any one of claims 1 to 7 , further comprising a concave portion provided on a surface of the propeller boss supporting the propeller to promote the concentration of the air bubbles. Ship.