A bubble drag reduction system and a ship comprising the same

Abstract

The present invention discloses a bubble drag reduction system and a ship including the system, and belongs to the technical field of ship gas lubrication drag reduction. The device includes a bottom plate, a top wall, a side wall, a rear wall, a vent plate and a cover plate; the bottom plate is fixed on the outer plate of the ship and conforms to the outer surface of the ship, and the side wall is fixed on the bottom plate; the top wall is fixed on the top of the side wall, the vent plate is detachably fixed in the middle, and the cover plate is detachably fixed at the bottom; a support wall is provided between the vent plate and the top wall, and the support wall, the vent plate, the top wall and the side wall together constitute a pressure stabilizing chamber, and an air inlet is provided on the top wall at the pressure stabilizing chamber; the vent plate, the side wall and the cover plate together constitute an exhaust chamber with an opening on one side, and the exhaust chamber is connected to the pressure stabilizing chamber; a rear wall extending obliquely downward and rearward is provided at the top of the opening of the exhaust chamber, and a gap is provided between the rear wall and the cover plate and constitutes an air outlet. The present invention can produce a low-speed, uniform mesoscale bubble layer in the entire length direction of the bottom of the ship, so as to achieve a stable drag reduction effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of ship drag reduction based on gas lubrication, and in particular relates to a bubble drag reduction system and a ship comprising the system. Background Art

[0002] The current development of ship gas lubrication drag reduction technology is still in the stage of combining theory and practice. In practical applications, the ventilation generator, as an important component of ship gas lubrication drag reduction technology, has design parameters that rely on small-scale ventilation experimental research and statistical analysis of actual ship trials, and has not yet formed a relatively unified design criterion. In recent years, the shipping industry's carbon emission reduction goals have promoted theoretical research on gas lubrication drag reduction technology, and some relationships between ventilation and drag reduction effects have been obtained. Continuous and stable air layers can bring better drag reduction effects, and the mesoscale bubble layer can be closer to the bottom of the ship, less susceptible to the impact of incoming flow, and less likely to escape. Some previous bubble drag reduction systems tend to generate small bubbles. For example, the Chinese invention patent CN109641636B describes a bubble drag reduction system using the Kelvin Helmholtz effect. The device includes an air cavity and a built-in wave deflector. Ventilation is performed through the gap between the wave deflector and the side wall of the air cavity to form an optimal air mixing Kelvin Helmholtz interface. At this interface, the air is drawn into the flowing water by the shear force of the Kelvin Helmholtz instability, so that the air and water are mixed to form small bubbles that spread on the bottom of the ship to achieve drag reduction. However, although CN109641636B can form small bubbles using the Kelvin Helmholtz instability, the small bubbles are relatively stable and tend to stay in the water, but the velocity gradient force on the small-sized bubbles in the boundary layer at the bottom of the ship is much greater than the buoyancy on the small bubbles, making it very easy for the small bubbles to move away from the bottom of the ship. As for the bubble drag reduction effect, the bubble loses its drag reduction effect once it moves away from the wall.

[0003] After the gas lubrication drag reduction system was put into use, the bubble drag reduction system generally had the phenomenon of biological attachment. Severe biological attachment would block the gas flow path and affect the use of the device. Therefore, biological antifouling of the ventilation device has also become one of the important goals of its design. For example, Chinese utility model patent CN216002977U describes a pressure stabilizing chamber structure, the pressure stabilizing chamber includes a fixed part and a detachable part, the fixed part is fixed to the bottom plate of the ship to form a pressure stabilizing chamber, there is an anti-corrosion coating in the pressure stabilizing chamber, and the detachable part can open the opening of the pressure stabilizing chamber, thereby facilitating the repair and subsequent maintenance of the anti-corrosion coating. However, CN216002977U has an anti-corrosion coating in the pressure stabilizing chamber, the detachable structure covers the pressure stabilizing chamber, and a small hole is opened on the detachable structure for ventilation. The problem with this design is that it does not achieve the fundamental purpose of biological antifouling, that is, to ensure that the gas path is unobstructed. The small circular holes on the detachable plate designed by it are more susceptible to biological attachment, which will cause the ventilation outlet to be directly blocked.

[0004] In addition, Chinese invention patent CN106335597B describes a ventilation device protruding from the outer plate of the hull, including a first protruding part and a second protruding part, which sprays toward the stern by forming a spraying space between the two protruding parts. However, the disadvantage of this invention is that the ventilation device protrudes from the bottom plate of the ship, significantly increasing the shape resistance of the hull and affecting the deadweight tonnage of the ship at the designed draft. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects in the prior art and provide a bubble drag reduction system and a ship comprising the system.

[0006] Specifically, 1) the mesoscale bubble lubrication layer generated by the present invention is approximately parallel to the incoming flow, and the gas extends backward closely to the bottom of the ship, achieving uniform gas coverage between the bottom of the ship and the water, and achieving stable and lasting drag reduction in the length direction of the ship. Among the existing patents: CN109641636B generates tiny diameter bubbles by shearing the gas discharged vertically by the incoming flow. Although the bubbles are stable, they are easy to move away from the wall; CN106335597B generates a high-speed gas jet layer, and the generated gas turbulence is too large, easy to break and escape, and the coverage effect is poor. The present invention uses a combination of a pressure stabilizing chamber and an exhaust chamber, and the gas is first evenly distributed in the pressure stabilizing chamber, and then guided by the exhaust chamber in the form of a rear step, guiding the gas to change the gas path inside the exhaust chamber of the bubble drag reduction system, and forming a stable gas-liquid stratified flow at the outlet. The exhaust chamber in the form of a rear step reduces the strong shearing effect of the incoming flow when the high-speed airflow is ejected vertically from the hull, and the formed gas lubrication layer is only sheared along the flow direction, which is more uniform and stable. Finally, a low-speed, uniform mesoscale bubble layer is generated along the entire length of the bottom of the ship, and the exhausted gas obtains a certain buoyancy and clings to the wall, achieving a stable drag reduction effect. 2) The present invention divides the bubble drag reduction system into two parts through detachable parts, and the detachable ventilation plate of the middle layer prevents large-scale marine organisms and marine floating objects from entering the internal piping system of the hull. The exhaust chamber in contact with seawater is designed to be a partially detachable structure. The detachable parts can be removed for maintenance during anti-fouling maintenance, which is more convenient and quicker in the actual operation process. The outermost ventilation outlet area is larger, and there is no risk of being completely blocked. 3) Installing the present invention on the hull will not significantly increase the shape resistance of the hull and will not affect the deadweight tonnage of the ship. The present invention is a built-in ventilation device that is not higher than the plane of the bottom surface of the ship and does not increase the shape resistance.

[0007] The specific technical solutions adopted by the present invention are as follows:

[0008] In a first aspect, the present invention provides a bubble drag reduction system, comprising a bottom plate, a top wall, a side wall, a rear wall, a vent plate, and a cover plate;

[0009] The bottom plate is fixed on the outer plate of the ship and conforms to the outer surface of the ship, and the side wall is fixed on the bottom plate; a top wall is fixed on the top of the side wall, a ventilation plate is detachably fixed in the middle, and a cover plate is detachably fixed at the bottom; the lower surface of the cover plate is in the same horizontal plane as the lower surface of the bottom plate; a plurality of ventilation holes are arranged on the ventilation plate; a rear side wall is arranged between the ventilation plate and the top wall, and the rear side wall, the ventilation plate, the top wall and the side wall together constitute a pressure stabilizing chamber, and an air inlet is arranged on the top wall at the pressure stabilizing chamber; the ventilation plate, the side wall and the cover plate together constitute an exhaust chamber with an opening on one side, and the exhaust chamber is connected with the pressure stabilizing chamber; a rear wall extending obliquely downward and rearward is arranged on the top of the opening of the exhaust chamber, and a gap is provided between the rear wall and the cover plate and constitutes an air outlet; the gas entering from the air inlet can pass through the pressure stabilizing chamber and the exhaust chamber in sequence, and then be discharged from the air outlet to form an air lubrication layer between the hull of the ship and the water flowing under the hull, and the channels through which the gas flows in the bubble drag reduction system together constitute an air chamber.

[0010] Preferably, the tail of the rear wall is fixed to the outer plate of the ship.

[0011] Preferably, the length of the air cavity along the axial direction is 0.2m to 5m, and the angle α between the side wall of the air cavity and the axis of the bubble drag reduction system is between 0° and 30°; further preferably, α is within 15°, and most preferably, α is 3° to 6°.

[0012] Preferably, the vertical height from the top wall to the bottom plate is 0.05m to 1m.

[0013] Preferably, a limiting outer step is provided at the bottom of the side wall, and the cover plate is fixed to the limiting outer step by bolts; an limiting inner step is provided at the middle of the side wall, and the vent plate is fixed to the limiting inner step by bolts.

[0014] Preferably, the installed cover plate and bottom plate are conformal to the outer surface of the ship; along the axial direction, the cover plate overlaps with at least 20% of the length of the rear wall; further preferably, the cover plate overlaps with at least 60% of the length of the rear wall.

[0015] Preferably, the width of the air outlet is 0.05m to 2.5m, and the vertical height is 0.01m to 0.2m.

[0016] Preferably, the width of the ventilation holes is 10 mm to 150 mm, and the total opening area accounts for more than 30% of the area of ​​the ventilation plate; each ventilation hole is provided with a 3 mm to 5 mm protrusion in the circumference to prevent the attachment of marine organisms.

[0017] Preferably, a supporting rib is vertically provided between the cover plate and the top wall to increase the structural strength.

[0018] In a second aspect, the present invention provides a ship including a bubble drag reduction system, comprising an air source device, an air intake pipeline and a bubble drag reduction system as described in any one of the first aspects; the air source device is connected to the air inlet of the bubble drag reduction system through the air intake pipeline.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention 1) provides a pressure stabilizing chamber, and the pressure stabilizing chamber must be emptied before the gas is discharged. The gas must accumulate a certain volume and pressure to ensure that the gas has sufficient internal pressure and initial thickness when it is ejected, resist the shearing effect of the incoming flow, and help to form a stable air layer in the initial stage of ejection. 2) An exhaust chamber is provided, and the direction of the gas path is consistent with the direction of the incoming flow, so as to reduce the shearing effect of the incoming flow on the gas when it is just ejected from the hull, and help to form a continuous air layer. 3) A detachable structure is provided to control the biofouling anti-area in the exhaust chamber, effectively avoiding the safety hazards caused by internal water and pollution in the system. During the period when the ship is docked for maintenance, the detachable structure can be conveniently disassembled to clean the interior of the chamber, which reduces the maintenance cycle and cost, and has more practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the connection structure of a ship including a bubble drag reduction system;

[0022] Figure 2 This is an overall diagram of the bubble drag reduction system of the first embodiment;

[0023] Figure 3 A bottom view of the bubble drag reduction system (without detachable parts) of the first embodiment;

[0024] Figure 4 It is a top view of the bubble drag reduction system of the first embodiment;

[0025] Figure 5 The detachable ventilation plate of the first embodiment;

[0026] Figure 6 The detachable cover plate of the first embodiment;

[0027] Figure 7 It is a cross-sectional view of the bubble drag reduction system of the first embodiment;

[0028] Figure 8 This is an overall diagram of the bubble drag reduction system of the second embodiment;

[0029] Fig. 9 The detachable cover plate of the second embodiment;

[0030] Fig.10 A detachable ventilation plate for the second embodiment;

[0031] Fig.11 The overall diagram of the bubble drag reduction system with chambers arranged front and back in the third embodiment;

[0032] Fig.12 Schematic diagram of the bubble drag reduction system with chambers arranged left and right in the third embodiment, wherein (a) is a top view and (b) is a bottom view;

[0033] Fig.13 The detachable ventilation plate of the fourth embodiment;

[0034] Fig.14 This is a bottom view of the bubble drag reduction system of the fifth embodiment;

[0035] The accompanying drawings in the figure are marked as follows:

[0036] 1: outer plate; 2: air source device; 3: air inlet pipeline; 301: air inlet; 4: pressure stabilizing chamber; 5: exhaust chamber; 6: bottom plate; 7: top wall; 8: ventilation plate; 9: cover plate; 10: side wall; 11: rear wall; 12: supporting rib plate; 13: rear side wall; 14: air outlet; 101: inner limit step; 102: outer limit step; 61: opening; 81: ventilation hole; 82: first bolt hole; 91: second bolt hole; 92: third bolt hole; Ⅰ: axis. DETAILED DESCRIPTION

[0037] The present invention is further described and illustrated below in conjunction with the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly without conflicting with each other.

[0038] like Figures 2 to 14 As shown, a bubble drag reduction system provided by the present invention is provided, and the system mainly includes a wall and an air inlet 301. The wall defines an air cavity, and the wall includes a top wall 7, a side wall 10, a rear wall 11 and a rear side wall 13. The side wall 10 is vertically welded and fixed on the bottom plate 6, and is a "U"-shaped structure with one side closed and the other side open. The bottom plate 6 is welded to the hull steel plate and conforms to the outer plate 1 of the ship, and no additional shape resistance is generated. The top wall 7 is welded and fixed to the top of the closed side of the side wall 10, and a ventilation plate 8 is detachably fixed to the middle part, and a vertically arranged rear side wall 13 is welded between the ventilation plate 8 and the top wall 7. The air cavity enclosed by the rear side wall 13, the ventilation plate 8, the top wall 7 and the side wall 10 serves as a pressure stabilizing chamber 4, and an air inlet 301 is provided on the top wall 7 at the pressure stabilizing chamber 4. The bottom of the side wall 10 is detachably fixed with a cover plate 9, the bottom of which is flush with the bottom of the bottom plate 6 and is in the same horizontal plane, and is co-shaped with the outer plate 1. The air cavity enclosed by the vent plate 8, the side wall 10 and the cover plate 9 serves as an exhaust cavity 5, and the exhaust cavity 5 opens to one side toward the rear (the rear in the present invention refers to the direction in which the gas flows along the axis I), and the exhaust cavity 5 is connected to the pressure stabilizing cavity 4 through the vent plate 8 having a plurality of vent holes 81.

[0039] The exhaust cavity 5 has an opening 61 on the bottom plate 6, and a rear wall 11 extending obliquely downward and rearward is provided at the top of the opening 61. A gap is provided between the rear wall 11 and the cover plate 9 to form an air outlet 14. The gas entering from the air inlet 301 can pass through the pressure stabilizing cavity 4 and the exhaust cavity 5 in sequence, and then be discharged from the air outlet 14 to form an air lubrication layer between the hull of the ship and the water flowing under the hull. The channel for the gas to flow in the bubble drag reduction system of the present invention is the above-mentioned air cavity.

[0040] Projecting along the length direction of the exhaust cavity (i.e., horizontal to the axis I), the exhaust cavity can be divided into a top wall section and a rear wall section. When the exhaust cavity 5 is projected onto the plane interface where the bottom plate 6 is located, the length of the opening 61 of the exhaust cavity 5 is L1, the distance between the rear edge of the limiting outer step 102 and the rear edge of the opening 61 is L2, and the length of the rear wall 11 is L3 (as shown in FIG. Figure 3 and Figure 4 The length L1 of the opening 61 (as shown) Figure 3 and 14 As shown) is between 0.2m and 5m, and the opening width W1 (as shown) is between 0.2m and 5m. Figure 3 and 14 The vertical distance between the top wall 7 and the bottom plate 6 is between 0.05m and 1m. Preferably, the side wall of the air cavity forms a small angle α with the axis I of the system of the present invention (such as Fig.14 As shown), α is between 0° and 30°.

[0041] The system of the present invention also has detachable parts, which mainly refer to the vent plate 8 and the cover plate 9. The cover plate 9 has a flat bottom surface and a circle of connecting steps, and a plurality of second bolt holes 91 are provided on the connecting steps at intervals. The flat bottom surface faces the outside of the hull, and the connecting steps are connected to the limiting outer steps 102 on the side wall 10 by screws. After the connection is completed, the cover plate 9 is in the same shape as the outer plane of the bottom plate 6. The rear edge width W2 of the cover plate 9 is between 0.1m and 2.5m. Among them, when the exhaust cavity is projected onto the plane extending from the bottom plate 6 and observed: 1) for Figure 7 In the case where the two corresponding chambers (i.e., the pressure stabilizing chamber and the exhaust chamber) are arranged up and down, the top wall section of the exhaust chamber is completely covered by the flat bottom surface of the cover plate 9, and the flat bottom surface of the cover plate 9 covers at least the first 20% of the length L3 of the rear wall; more preferably, at least the first 40% of the length L3 of the rear wall, and most preferably at least the first 60%; 2) for Fig.11The corresponding two chambers (i.e., the pressure stabilizing chamber and the exhaust chamber) are arranged front to back, and the opening 61 only includes the projection area of ​​the rear wall section on the bottom plate, and the flat bottom surface of the cover plate 9 covers at least the front 20% of the rear wall length L3; more preferably, it covers at least the front 40% of the rear wall length L3, and most preferably at least the front 60%. The vent plate 8 is a flat plate with vent holes 81, and a plurality of first bolt holes 82 are provided in the circumference, which are bolted to the limiting inner step 101 of the side wall 10. There is no gap between the side wall of the vent plate 8 and the air cavity side wall 10, and they fit completely. The plane where the vent plate 8 is located divides the interior of the air cavity into two chambers. The chamber connected to the air inlet 301 is the pressure stabilizing chamber 4, and the chamber connected to the seawater is the exhaust chamber 5.

[0042] In practical application, the vent plate 8 can be parallel to the top wall 7 and the cover plate 9 after the connection is completed (such as Figure 2 and 8 As shown), the pressure stabilizing chamber 4 and the exhaust chamber 5 are divided into a structure of upper and lower chambers. The vent plate 8 can also be arranged vertically with the top wall 7 and the cover plate 9, so as to divide the pressure stabilizing chamber 4 and the exhaust chamber 5 into a structure of left and right chambers. When the pressure stabilizing chamber 4 and the exhaust chamber 5 are arranged side by side up and down, the air inlet is located on the top wall 7, and when the pressure stabilizing chamber 4 and the exhaust chamber 5 are arranged side by side front and back, the air inlet is located on the front side of the side wall 10. Of course, the vent plate 8 can also be tilted at a certain angle, and the volume and shape of the air cavity can be adjusted according to actual conditions, and the installation position of the vent plate 8 can be adjusted to make the pressure stabilizing chamber 4 and the exhaust chamber 5 arranged side by side front and back, side by side up and down, or side by side left and right, so as to fully adapt to the empty space at the bottom of the ship.

[0043] One purpose of the present invention is to utilize the design of the pressure-stabilizing chamber 4 and the rear step (i.e., the cover plate 9 and the rear wall 11) to generate a low-speed, uniform bubble gas layer mixed lubrication layer, which effectively penetrates into the boundary layer between the hull and the seawater. The lubrication layer is extended and spread toward the stern due to the buoyancy, and will spread along the bottom of the ship at a certain angle to cover as much bottom area as possible, thereby achieving a stable and effective effect of reducing viscous resistance.

[0044] Another object of the present invention is to divide the air chamber into zones by arranging a vent plate 8 in the air cavity. The zone connected to the air inlet end is a pressure stabilizing zone. The gas in this zone changes its flow direction and flow velocity through the built-in guide plate and is evenly distributed laterally along the air cavity. The zone connected to the seawater is an exhaust zone. The gas in this zone is again diverted by the rear step structure and discharged toward the stern in a direction approximately parallel to the bottom plate 6 of the ship.

[0045] In the specific implementation process, the vent holes 81 of the vent plate 8 can be in various forms such as round holes, oblong holes, square holes, etc. The total ventilation area of ​​the vent holes 81 preferably occupies more than 30% of the entire vent plate 8 excluding the connection area, and preferably adopts a combination of vent holes with a large number and a small area.

[0046] Taking into account that organisms such as barnacles, diatoms, oysters, and mussels in the ocean will adhere to the outer surface of the hull, the width of the vent hole 81 of the vent plate 8 is controlled to be 3 mm to 15 mm, the biological accumulation area is controlled in the exhaust chamber 5, and the vertical height of the air outlet 14 is controlled between 0.01 m and 0.2 m, ensuring that the inside of the air lubrication system is not contaminated. The cleaning requirements can be achieved by regularly replacing the exhaust chamber 5 composed of detachable parts.

[0047] Preferably, a protrusion structure with a height of 3 mm to 5 mm is arranged around the vent hole 81 of the vent plate 8 to increase the surface roughness, making it difficult for marine organisms to attach near the vent hole 81, and the protrusion structure will not affect the flow and development of gas.

[0048] In a specific implementation, the cover plate 9 of the actual bubble drag reduction system is subjected to the internal and external pressure difference force of the air pressure in the system and the static pressure of the seawater. In order to enhance the structural strength, a vertical support rib plate 12 can be appropriately arranged between the cover plate 9 and the top wall 7. Adaptively, a plurality of third bolt holes 92 can be opened on the cover plate 9 for fixing with the support rib plate 12 by bolts.

[0049] Based on the above-mentioned bubble drag reduction system, the present invention also provides a ship including the bubble drag reduction system, such as Figure 1 In addition to the bubble drag reduction system, the ship also includes an air source device 2 and an air intake pipeline 3, wherein the air source device 2 is connected to the air intake port 301 of the bubble drag reduction system through the air intake pipeline 3. The air source device 2 supplies air to the bubble drag reduction system through the air intake pipeline 3, and the bubble drag reduction system stabilizes and rectifies the gas to form a uniform gas discharge, which covers the outer surface of the ship.

[0050] Example 1

[0051] like Figures 2 to 7 As shown in FIG. 7 , the side wall 10 of the air cavity is vertically welded to the bottom plate 6, and the top wall 7 is parallel to the bottom plate 6 and welded to the side wall 10. The vent plate is shown in FIG. 5 , which has an elongated vent hole 81 and a circle of first bolt holes 82 around it. The vent plate 8 is bolted to the inner limit step 101 of the side wall 10. The cover plate is shown in FIG. 6 , which has a circle of second bolt holes 91 around it. The cover plate 9 is bolted to the outer limit step 102 of the side wall 10, and the cover plate 9 is also co-shaped with the outer plate 1 of the ship. The cross-sectional view of the bubble drag reduction system is shown in FIG. 7 , where the air cavity is divided into a pressure stabilizing chamber 4 and an exhaust chamber 5 by the vent plate 8. The gas enters the pressure stabilizing chamber 4 through the air inlet 301 located on the top wall 7 and is evenly distributed, and then enters the exhaust chamber 5 through the vent hole 81 of the pressure stabilizing chamber 4, changes the flow direction through the rear step structure of the exhaust chamber 5, and finally flows and spreads toward the stern through the outlet 14, forming a stable lubrication layer coverage, achieving drag reduction and energy saving.

[0052] Example 2

[0053] like Figures 8 to 10 As shown, the cover plate 9 of the bubble drag reduction system is subjected to the pressure difference between the air pressure in the system and the static pressure of the seawater. In order to enhance the structural strength, a supporting rib 12 perpendicular to the cover plate 9 can be appropriately arranged. The supporting rib 12 is made of steel plate and welded to the top wall 7 and the side wall 10. The supporting rib 12 can be designed with a skirt and connected to the cover plate 9 by bolts. The supporting rib 12 can also be thickened, and bolt holes can be directly drilled on its side to be connected to the cover plate 9 by bolts, such as Fig. 9 Accordingly, the ventilation plate 8 is cut in the middle and divided into two parts which are bolted to the supporting rib plate 12. Fig.10 .

[0054] Example 3

[0055] like Figures 11-12 As shown, the structure of this embodiment is similar to that of embodiment 1, but in embodiment 1, the vent plate 8 is arranged parallel to the top wall 7 and the cover plate 9, that is, the pressure stabilizing chamber 4 and the exhaust chamber 5 are arranged up and down, while in this embodiment, the vent plate 8 is arranged perpendicular to the top wall 7 and the cover plate 9, that is, the pressure stabilizing chamber 4 and the exhaust chamber 5 are arranged front to back and left to right.

[0056] Example 4

[0057] The structure of this embodiment is similar to that of the first embodiment, but the vent hole 81 of the first embodiment is rectangular, while the vent hole 81 of the present embodiment is configured as an oblong hole, such as Fig.13 In actual use, the vent holes 81 can be in various forms such as round holes, oblong holes, square holes, grids, etc., but it is preferred to use evenly arranged elongated holes because they can better disperse the gas and the gas can be better spread.

[0058] Example 5

[0059] like Fig.14 As shown, the structure of this embodiment is similar to that of embodiment 1, but the angle α between the side wall 10 and the axis I in embodiment 1 is 0°, while the angle α of this embodiment is 5°. This is because, through experiments and numerical calculations, it is found that when the ship is running at 12kn to 20kn, the vortex loss of the air layer in the vent corresponding to the angle of 5° is small, the streamline distribution is uniform, and the lateral expansion of the generated air layer is more uniform.

[0060] The system of the present invention can be applied to water-traveling vehicles, such as surface ships, underwater vehicles, amphibious vehicles, and the like.

[0061] The above-described embodiment is only a preferred solution of the present invention, but it is not intended to limit the present invention. A person skilled in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A bubble drag reduction system, characterized in that: It comprises a bottom plate (6), a top wall (7), a side wall (10), a rear wall (11), a ventilation plate (8) and a cover plate (9); The bottom plate (6) is fixed on the outer plate (1) and conforms to the outer surface of the ship. The bottom plate (6) is fixed with a side wall (10). The top of the side wall (10) is fixed with a top wall (7). A ventilation plate (8) is detachably fixed in the middle. A cover plate (9) is detachably fixed at the bottom. The lower surface of the cover plate (9) is in the same horizontal plane as the lower surface of the bottom plate (6). A plurality of ventilation holes (81) are provided on the ventilation plate (8). A rear side wall (13) is provided between the ventilation plate (8) and the top wall (7). The rear side wall (13), the ventilation plate (8), the top wall (7) and the side wall (10) together form a pressure stabilizing chamber (4). An air inlet (301) is provided on the top wall (7) at the pressure stabilizing chamber (4). The ventilation plate (8), The side wall (10) and the cover plate (9) together form an exhaust chamber (5) with an opening on one side, and the exhaust chamber (5) is connected to the pressure stabilizing chamber (4); the exhaust chamber (5) has an opening (61) on the bottom plate (6), and a rear wall (11) extending obliquely downward and rearward is provided at the top of the opening (61), and a gap is provided between the rear wall (11) and the cover plate (9) to form an air outlet (14); the rear end of the rear wall (11) is fixed to the bottom plate (6); the gas entering from the air inlet (301) can pass through the pressure stabilizing chamber (4) and the exhaust chamber (5) in sequence, and then be discharged from the air outlet (14) to form an air lubrication layer between the hull of the ship and the water flowing under the hull, and the channel through which the gas flows in the bubble drag reduction system together forms an air chamber; The width of the air outlet (14) is 0.05m to 2.5m, and the vertical height is 0.01m to 0.2m; After installation, the cover plate (9) and the bottom plate (6) are both conformal to the outer surface of the ship; along the axis (I), the cover plate (9) overlaps with the rear wall (11) by at least 20% of its length.

2. The bubble drag reduction system according to claim 1, characterized in that: The length of the opening (61) along the axis (I) is 0.2 m to 5 m, and the angle between the side wall of the air cavity and the axis (I) of the bubble drag reduction system is Between 0~30°.

3. The bubble drag reduction system according to claim 2, characterized in that: Said Within 15°.

4. The air bubble drag reduction system according to claim 1, characterized in that: The vertical height from the top wall (7) to the bottom plate (6) is 0.05m to 1m.

5. The bubble drag reduction system according to claim 1, characterized in that: A limiting outer step (102) is provided at the bottom of the side wall (10), and the cover plate (9) is fixed to the limiting outer step (102) by bolts; a limiting inner step (101) is provided at the middle of the side wall (10), and the vent plate (8) is fixed to the limiting inner step (101) by bolts.

6. The air bubble drag reduction system according to claim 1, characterized in that: The cover plate (9) overlaps at least 60% of the length of the rear wall (11).

7. The air bubble drag reduction system according to claim 1, characterized in that: The width of the ventilation holes (81) is 10 mm to 150 mm, and the total opening area accounts for more than 30% of the area of ​​the ventilation plate (8); each ventilation hole (81) is provided with a protrusion of 3 mm to 5 mm in the circumferential direction to prevent the attachment of marine organisms.

8. The air bubble drag reduction system according to claim 1, characterized in that: A supporting rib plate (12) for increasing structural strength is vertically provided between the cover plate (9) and the top wall (7).

9. A ship including a bubble drag reduction system, characterized in that: It comprises an air source device (2), an air intake pipeline (3) and the bubble drag reduction system according to any one of claims 1 to 8; the air source device (2) is connected to the air intake port (301) of the bubble drag reduction system through the air intake pipeline (3).

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