A method for rectifying jet flow at the tail of a ship

Abstract

The present invention relates to a method for jet straightening at the stern of a ship. A straightening assembly is embedded in the stern bilge outer plate, and jet slots are formed on the lower portion of the bilge outer plate, tilted upward and forward and arranged at intervals. Gas is ejected outward through the jet slots, and the upward movement of the gas in the water causes the ejected gas to autonomously rise underwater. As the ship moves forward, the gas ejected from the jet slots on both sides exhibits an upward drift motion obliquely backward, changing the flow characteristics at the stern. This actively controls the flow field at the stern of the ship, thereby effectively improving the flow structure at the stern and enhancing the propulsion efficiency of the propeller. Simultaneously, the gas ejected from the jet slots can suppress the separated flow at the stern and, to a certain extent, reduce the pressure differential resistance during navigation. The present invention can reduce the ship's navigation energy consumption and greenhouse gas emissions by improving propulsion efficiency and reducing navigation resistance. Furthermore, the overall installation is convenient, the required gas volume is small, and the practicality is excellent.

Description

Technical Field

[0001] The present invention relates to the technical field of ships, in particular to a ship tail jet straightening method. Background Art

[0002] Against the backdrop of increasingly severe challenges in energy conservation and emission reduction for ships, the shipping industry is seeking ways to reduce ship resistance and increase propeller efficiency in order to reduce fuel consumption and CO2 emissions.

[0003] Gas lubrication technology, which reduces drag by injecting air into a ship's hull, has seen rapid development in recent years. This technology exploits the fact that air is much less dense than water. By replacing a certain area of water on the hull's surface with air, it reduces frictional resistance during navigation, ultimately achieving energy savings and emissions reductions.

[0004] Model tests have shown that this type of gas lubrication technology can achieve a drag reduction efficiency of 6-8%. However, implementing gas lubrication on a full ship often involves adding additional appendages or docking the hull to ensure the gas remains on the hull surface, resulting in high technical costs and complexity. The large gas coverage area also requires extensive hull modifications, increasing the shipowner's investment and time.

[0005] In addition, gas lubrication technology requires a high-power air supply system to generate enough enveloping gas to achieve a significant drag reduction effect. The energy consumption of the air supply system limits the technology from further reducing the energy efficiency level of the ship. Summary of the Invention

[0006] In response to the shortcomings of the above-mentioned existing production technology, the applicant provides a rationally structured ship tail jet straightening method, which can reduce ship navigation energy consumption and greenhouse gas emissions from two aspects: improving propulsion efficiency and reducing navigation resistance. The overall installation is convenient, the required gas volume is small, and the practicality is good.

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

[0008] A ship tail jet straightening method comprises the following steps:

[0009] The lower part of the bilge outer plate on both sides of the stern of the ship is symmetrically provided with upward and forward inclined long receiving holes, and when the ship is sailing, the long receiving holes are located underwater;

[0010] A through hole is formed through the lower portion of the internal rib of the ship corresponding to the accommodating long hole;

[0011] A lower air chamber and an upper air chamber are sequentially stacked and fixedly mounted on the top surface of the bottom plate. An air inlet hole communicating with the air supply assembly is provided on the top surface of the upper air chamber. A long slot is provided along the length direction between the upper and lower air chambers. A single row of air jet slots spaced apart along the length direction are provided on the interface between the lower air chamber and the bottom plate. The air inlet hole, the long slot, and the air jet slot are sequentially staggered in the vertical direction to form a rectifying assembly.

[0012] The rectifier assembly is inserted into the receiving slot of the bilge outer plate from bottom to top, and the bottom plate is matched with the receiving slot in the circumferential direction and welded to each other to form a butt joint;

[0013] Fit the pipe end of the air supply assembly to the air inlet hole on the top of the upper air chamber;

[0014] A set of fairing components are installed on the lower part of the bilge outer plating on both sides of the stern, forming symmetrical breakpoint-shaped jet slots on the lower part of the bilge outer plating;

[0015] During the navigation of the ship, the air supply component supplies air to the upper air chamber of the rectifier component, and the air flow passes around the lower air chamber and is ejected from the bottom jet slot; the ejected gas floats up autonomously underwater, and as the ship moves forward, the gas ejected from the jet slots on both sides respectively drifts upward obliquely and converges at the stern, actively controlling the flow field at the stern of the ship.

[0016] As a further improvement of the above technical solution:

[0017] The multiple air jet slots in a single set of rectifier components are located on the same straight line, the interval between adjacent air jet slots is 100-200 mm, and the length of a single air jet slot is 100-200 mm.

[0018] The jet slot is inclined upward and forward at an angle of 40-50° relative to the hull; and the outer opening of the jet slot is smoothly transitioned to the bottom plate.

[0019] The width of the air-jet slot is 10-15 mm.

[0020] The lower air chamber is a rectangular tubular structure with both ends closed. Long grooves along the length direction and long air outlet holes spaced apart along the length direction are respectively provided on two side surfaces opposite to each other in the height direction of the lower air chamber. The width of the long grooves is greater than the width of the long air outlet holes, and the straight line where the long grooves are located is staggered with the straight line where the long air outlet holes are located.

[0021] An upper air chamber is welded on the outer side of the lower air chamber with a long groove. The two ends of the upper air chamber are closed and the cross-section is a U-shaped structure facing the lower air chamber. The cross-sectional area of the upper air chamber is smaller than the cross-sectional area of the lower air chamber. The upper air chamber is offset in the direction of the long groove in the width direction relative to the lower air chamber.

[0022] The outer side surface of the lower air chamber with a long air outlet hole is fitted with the bottom plate and welded to each other along the edge of the fitting surface; the bottom plate is provided with air slit holes corresponding to the long air outlet holes one by one, and the air slit holes are larger than the long air outlet holes by two welds in width and length directions. A step structure is formed between the outer side surface of the lower air chamber outside the orifice of the long air outlet hole and the inner side surface of the air slit hole, and welding is performed along the step structure, so that a gas jet with a conical cross-section and an opening facing outward is formed in the air slit hole by the weld.

[0023] The structure of the air supply component is as follows: it includes a Roots blower installed inside the ship, and the air outlet end of the Roots blower is connected to the upper air chamber of the rectifier component via a pipeline; a thermometer, a pressure gauge, a flow meter, a pressure sensor, a regulating valve and a manual butterfly valve are installed in series on the pipeline, and a check valve is also installed at the end of the pipeline near the upper air chamber.

[0024] The ship driving power is a propeller assembly, and a Roots blower is arranged in the front of the tail shaft cooling water tank.

[0025] The patching plates are installed at intervals along the length direction of the rectifier assembly. The patching plates correspond to the ribs one by one and are welded to each other.

[0026] The beneficial effects of the present invention are as follows:

[0027] The present invention has a compact and reasonable structure and is easy to operate. By embedding a rectifying component on the outer plate of the bilge at the stern, air jet slots inclined upward and forward and arranged at intervals are formed on the lower part of the outer plate of the bilge. Gas is ejected outward through the air jet slots, and the upward movement of the gas in the water is utilized to allow the ejected gas to float up autonomously underwater. As the ship moves forward, the gas ejected from the air jet slots on both sides respectively moves upward obliquely backward and converges at the stern, actively controlling the flow field at the stern of the ship, thereby effectively improving the flow structure at the stern and enhancing the propulsion efficiency of the propeller. At the same time, the gas ejected from the air jet slots can suppress the separation flow at the stern and, to a certain extent, reduce the pressure difference resistance when the ship is sailing. Therefore, it can not only reduce the energy consumption of the ship and greenhouse gas emissions from the two aspects of improving propulsion efficiency and reducing navigation resistance, but also is easy to install as a whole, requires a small amount of gas, and has good practicality.

[0028] The present invention also includes the following advantages:

[0029] During navigation, gas is actively injected into the water through the jet slots. Under the influence of the stern flow and buoyancy, the gas drifts upward along the hull obliquely and rearward. This movement changes the flow near the stern shaft outlet, significantly suppressing the formation of bilge vortices at the stern and reducing the low-speed area at the propeller disc. Due to the increased incoming flow velocity, the propeller can obtain the same thrust at a lower speed, thereby reducing the main engine power required for navigation. At the same time, if the improved propeller is designed to adapt to the flow, the propeller pitch can be reduced to improve the propeller's efficiency.

[0030] In the present invention, the gas ejected through the air slit forms a downward airflow at the stern of the ship, which can effectively reduce the pressure differential resistance during the ship's navigation. The upward movement generated by the active introduction of gas weakens the flow separation at the stern, increases the forward thrust of the stern, and thus reduces the front and rear pressure differential resistance during the ship's navigation. The reduction in pressure differential resistance can reach 8%-12%.

[0031] The present invention does not require a large area of gas covering the hull surface, and the ventilation volume requirement is reduced by about 40%-60% compared with the gas lubrication drag reduction technology. The energy consumption of the corresponding air supply system is also relatively low, thereby further improving the energy saving and emission reduction effect of this technology;

[0032] The jet assembly of this invention features simple equipment and low power consumption, reducing the need for hull space and adaptability modifications, lowering both the investment cost and energy consumption of the technology. Furthermore, the modular installation of the air chamber simplifies the equipment installation process, shortens the assembly period, and further reduces technology costs. It can be flexibly applied to new shipbuilding or the retrofitting of existing ships, serving as a new green, energy-saving device for ships. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the position of the present invention on a ship.

[0034] Figure 2 It is a structural schematic diagram of the air supply assembly of the present invention.

[0035] Figure 3 It is a structural schematic diagram of the rectifier assembly of the present invention.

[0036] Figure 4 This is a schematic diagram of the assembly of the rectifier assembly of the present invention when passing through the ribs.

[0037] Figure 5 This is a comparison diagram of the stern water flow when the ship of the present invention is sailing with and without jet straightening.

[0038] Figure 6 This is a comparison diagram of the bilge vortex generated by the hull tail shaft when the ship of the present invention is sailing with and without jet straightening.

[0039] Figure 7 This is a comparison diagram of the propeller position in the low-speed area when the ship of the present invention is sailing with and without jet straightening.

[0040] Figure 8 This is a comparison diagram of stern flow separation when the ship of the present invention is sailing with and without jet straightening.

[0041] Among them: 1. Bilge outer plate; 2. Air supply assembly; 3. Rectifier assembly; 4. Propeller assembly; 5. Rib plate; 6. Filler plate; 7. Through hole;

[0042] 21. Roots blower; 22. Thermometer; 23. Pressure gauge; 24. Flow meter; 25. Pressure sensor; 26. Control valve; 27. Manual butterfly valve; 28. Pipeline; 29. Check valve;

[0043] 30. Air jet seam; 31. Bottom plate; 32. Lower air chamber; 33. Upper air chamber; 34. Butt joint; 35. Air inlet; 36. Long groove; 37. Air outlet long hole; 38. Air slit hole. DETAILED DESCRIPTION

[0044] The specific embodiments of the present invention will be described below with reference to the accompanying drawings.

[0045] like Figure 1 and Figure 2 As shown, the ship tail jet straightening method of this embodiment includes the following steps:

[0046] The lower part of the bilge outer plate 1 on both sides of the stern of the ship is symmetrically provided with upward and forward inclined receiving long holes. When the ship is sailing, the receiving long holes are located underwater.

[0047] A through hole 7 is formed through the lower portion of the internal rib 5 of the ship corresponding to the accommodating long hole. Figure 4 As shown;

[0048] like Figure 3 As shown, a lower air chamber 32 and an upper air chamber 33 are sequentially stacked and fixedly mounted on the top surface of the bottom plate 31. An air inlet 35 communicating with the air supply assembly 2 is provided on the top surface of the upper air chamber 33. A long slot 36 is provided along the length direction between the upper air chamber 33 and the lower air chamber 32. A single row of air injection slots 30 spaced apart along the length direction are provided on the interface between the lower air chamber 32 and the bottom plate 31. The air inlet 35, the long slot 36, and the air injection slots 30 are sequentially staggered in the vertical direction, forming a rectifying assembly 3.

[0049] The rectifier assembly 3 is inserted into the receiving slot of the bilge outer plate 1 from bottom to top. The bottom plate 31 is circumferentially matched with the receiving slot and welded to each other to form a butt joint 34.

[0050] Fit the end of the pipe 28 of the air supply assembly 2 to the air inlet 35 at the top of the upper air chamber 33;

[0051] A set of fairing components 3 are respectively installed at the lower part of the bilge outer plate 1 on both sides of the stern, forming symmetrical breakpoint-shaped air jet slots 30 at the lower part of the bilge outer plate 1;

[0052] During the navigation of the ship, air is supplied from the air supply component 2 to the upper air chamber 33 of the rectifying component 3, and the air flow passes around the lower air chamber 32 and is ejected from the bottom air jet slot 30; the ejected gas rises autonomously underwater, and as the ship moves forward, the gas ejected from the air jet slots 30 on both sides respectively drifts upward obliquely backward and converges at the stern, actively controlling the flow field at the stern of the ship.

[0053] In this embodiment, a rectifying assembly 3 is embedded in the stern bilge outer plate 1, and jet slots 30 are formed on the lower part of the bilge outer plate 1, which are inclined upward and forward and arranged at intervals. Gas is ejected outward through the jet slots 30, and the ejected gas floats up autonomously underwater by utilizing the upward movement of the gas in the water. As the ship moves forward, the gas ejected from the jet slots 30 on both sides respectively drifts upward obliquely backward and converges at the stern, actively controlling the flow field at the stern of the ship, thereby effectively improving the flow structure at the stern and enhancing the propulsion efficiency of the propeller. At the same time, the gas ejected from the jet slots 30 can suppress the separation flow at the stern and, to a certain extent, reduce the pressure difference resistance when the ship is sailing.

[0054] In this embodiment, the air inlet holes 35 , the long slots 36 and the air-jet slots 30 are staggered in sequence in the vertical direction to ensure that the gas flow rate and pressure in the air chamber are stable.

[0055] The multiple air-jet slots 30 in a single group of rectifying components 3 are located on the same straight line, the interval between adjacent air-jet slots 30 is 100-200 mm, and the length of a single air-jet slot 30 is 100-200 mm.

[0056] The jet slot 30 is tilted upward and forward at an angle of 40-50 degrees relative to the hull; the outer opening of the jet slot 30 and the bottom plate 31 have a smooth transition. When the ship is sailing, on the one hand, it ensures that the ejected gas can be effectively collected and flowed to the rear of the ship, driving the formation of an oblique upward flow; on the other hand, the geometric shape of the nozzle and the stern line have a smooth transition, ensuring that the hull slot does not affect the hydrodynamic shape of the ship.

[0057] The width of the air jet slot 30 is 10-15 mm.

[0058] The lower air chamber 32 is a rectangular tubular structure with both ends closed. Long grooves 36 along the length direction and long air outlet holes 37 spaced apart along the length direction are respectively provided on two side surfaces opposite to each other in the height direction of the lower air chamber 32. The width of the long grooves 36 is greater than the width of the long air outlet holes 37. The straight line where the long grooves 36 are located is staggered with the straight line where the long air outlet holes 37 are located, thereby ensuring the stable flow of air in the air chamber while also ensuring the outward jet effect.

[0059] An upper air chamber 33 is welded to the outer surface of the lower air chamber 32 with a long groove 36. The upper air chamber 33 is closed at both ends and has a U-shaped cross-section facing the lower air chamber 32. The cross-sectional area of the upper air chamber 33 is smaller than that of the lower air chamber 32. The upper air chamber 33 is offset in the width direction toward the long groove 36 relative to the lower air chamber 32, thereby achieving reliable and effective communication between the upper and lower air chambers and allowing the gas to flow fully.

[0060] The outer side surface of the lower air chamber 32 with the long air outlet hole 37 is fitted with the bottom plate 31 and welded to each other along the edge of the fitting surface; the bottom plate 31 is provided with air slit holes 38 corresponding to the long air outlet holes 37 one by one, and the air slit holes 38 are larger than the long air outlet holes 37 by the width and length dimensions of two welds. A step structure is formed between the outer side surface of the lower air chamber 32 outside the orifice of the long air outlet hole 37 and the inner side surface of the air slit hole 38, which is welded along the step structure. The weld forms an air jet slit 30 with a conical cross-section and an outward opening in the air slit hole 38. On the one hand, the air jet slit 30 further fixes the connection between the lower air chamber 32 and the bottom plate 31, effectively ensuring the strengthening of the overall structure. On the other hand, it also avoids the influence of the fitting position of the lower air chamber 32 and the bottom plate 31 on the air jet. On the basis of ensuring the overall structure, the air jet effect is effectively guaranteed.

[0061] The structure of the air supply component 2 is as follows: it includes a Roots blower 21 installed inside the ship, and the air outlet end of the Roots blower 21 is connected to the upper air chamber 33 of the rectifier component 3 via a pipeline 28; a thermometer 22, a pressure gauge 23, a flow meter 24, a pressure sensor 25, a regulating valve 26 and a manual butterfly valve 27 are installed in series on the pipeline 28 in sequence, and a check valve 29 is also installed at the end of the pipeline 28 near the upper air chamber 33.

[0062] The ship's driving power is a propeller assembly 4, and a Roots blower 21 is arranged in the front of the tail shaft cooling water tank.

[0063] The Roots blower 21 acts as an air source to ventilate the air chamber and eject air to the outside of the hull through the watertight air chamber. A check valve 29 is arranged on the pipeline connecting the Roots blower 21 and the upper air chamber 33 to prevent water from flowing back into the cabin when the Roots blower 21 stops working.

[0064] Since the demand for air supply in this embodiment is relatively small, a single ship usually only needs to be equipped with one Roots blower 21 of about 20kW, which can be flexibly arranged inside the cabin without occupying deck space.

[0065] Since this embodiment only requires a single row of air-jet slots 30, the ventilation pipeline is relatively simple. The Roots blower 21 and the air chamber can be arranged inside the same cabin, and the pipeline arrangement does not involve cabin penetration, which reduces the difficulty of construction and review of the transformation.

[0066] Filling plates 6 are installed at intervals along the length direction of the rectifier assembly 3 . The filling plates 6 correspond to the ribs 5 one by one and are welded to each other, thereby achieving the installation of the rectifier assembly 3 at the ribs 5 .

[0067] When the ship is sailing, gas is actively injected into the water through the jet slot 30. Under the action of the flow at the stern and the buoyancy, the gas drifts upward obliquely rearward along the hull. This movement changes the flow near the stern shaft outlet of the hull, which can significantly inhibit the generation of bilge vortex at the stern and reduce the low-speed area at the propeller disc position. Due to the increase in the incoming flow speed, the propeller can obtain the same thrust at a lower speed, thereby reducing the main engine power required for the ship's navigation. At the same time, if the improved propeller is designed to be suitable for the wake flow, the propeller pitch can be reduced to improve the efficiency of the propeller.

[0068] like Figure 5 As shown, (a) is a schematic diagram of the water flow at the stern of a ship when sailing without the jet-jet rectifying assembly 3, and (b) is a schematic diagram of the water flow at the stern of a ship when sailing with the jet-jet rectifying assembly 3 installed. In (a), obvious flow separation occurs at the lower part of the stern, while in (b), a relatively uniform air-water mixing phenomenon is formed. The gas ejected through the jet slot 30, under the action of the stern flow and buoyancy, drifts upward along the hull obliquely rearward.

[0069] like Figure 6 As shown, (a) is a schematic diagram of the generation of bilge vortex at the stern shaft of the hull when the ship is sailing in the case of the straightening component 3 without jet, and (b) is a schematic diagram of the generation of bilge vortex at the stern shaft of the hull when the ship is sailing in the case of the straightening component 3 installed with jet; in (a), obvious bilge vortex is generated at the stern shaft of the hull, while in (b) no bilge vortex is generated at the stern shaft. The upward drift motion of the gas changes the flow near the outlet of the stern shaft of the hull, which can significantly suppress the generation of bilge vortex at the stern.

[0070] like Figure 7 As shown, (a) is a schematic diagram of the low-speed area of the propeller position when the ship is sailing in the case of a fairing component 3 without jet, and (b) is a schematic diagram of the low-speed area of the propeller position when the ship is sailing in the case of a fairing component 3 with jet installed; in (a), obvious low-speed areas are generated in the hub area and the propeller area, while in (b), the hub area and the propeller area are significantly improved. Due to the increase in the incoming flow speed, the propeller can obtain the same thrust at a lower speed, thereby reducing the main engine power required for the ship's navigation; at the same time, if the improved propeller is designed to be suitable for the wake flow, the propeller pitch can be reduced to improve the efficiency of the propeller.

[0071] The gas ejected through the air jet slot 30 forms a downward flow at the stern of the ship, which can effectively reduce the pressure difference resistance during the navigation process of the ship; Figure 8 As shown, (a) is a schematic diagram of flow separation at the stern of a ship when sailing in the case of a fairing component 3 without jet, and (b) is a schematic diagram of flow separation at the stern of a ship when sailing in the case of a fairing component 3 with jet installed. Obviously, compared with (a), (b) effectively weakens the flow separation at the stern due to the upward movement generated by the active introduction of gas, thereby increasing the forward thrust of the stern, that is, reducing the front and rear pressure difference resistance when the ship is sailing; the reduction in pressure difference resistance can reach 8%-12%.

[0072] The present invention does not require a large area of gas covering the hull surface, and the ventilation volume requirement is reduced by about 40%-60% compared with the gas lubrication drag reduction technology. The energy consumption of the corresponding air supply system is also relatively small, thereby further improving the energy-saving and emission reduction effects of this technology.

[0073] The jet assembly of this invention features simple equipment and low power consumption, reducing the need for hull space and adaptability modifications, lowering both the investment cost and energy consumption of the technology. Furthermore, the modular installation of the air chamber simplifies the equipment installation process, shortens the assembly period, and further reduces technology costs. It can be flexibly applied to new shipbuilding or the retrofitting of existing ships, serving as a new green, energy-saving device for ships.

[0074] The present invention can not only reduce the energy consumption of ship navigation and greenhouse gas emissions from the two aspects of improving propulsion efficiency and reducing navigation resistance, but also has the advantages of easy overall installation, small gas volume required and good practicality.

[0075] The above description is an explanation of the present invention, not a limitation of the present invention. The scope of the present invention is defined in the claims. Any modifications may be made within the scope of protection of the present invention.

Claims

1. A method for jet straightening at the tail of a ship, characterized by: The steps include: The bilge outer plates (1) on both sides of the stern of the ship are symmetrically provided with upwardly and forwardly inclined long holes, and when the ship is sailing, the long holes are located underwater; A through hole (7) is formed through the lower portion of the ship's internal rib (5) corresponding to the accommodating long hole; A lower air chamber (32) and an upper air chamber (33) are sequentially stacked and fixedly mounted on the top surface of the bottom plate (31); an air inlet (35) communicating with the air supply assembly (2) is provided on the top surface of the upper air chamber (33); a long groove (36) is provided between the upper air chamber (33) and the lower air chamber (32) along the length direction; and a single row of air jet slits (30) spaced apart along the length direction are provided on the interface between the lower air chamber (32) and the bottom plate (31); the air inlet (35), the long groove (36) and the air jet slit (30) are sequentially staggered in the vertical direction; and a rectifying assembly (3) is formed. The rectifier assembly (3) is embedded in the receiving slot of the bilge outer plate (1) from bottom to top, and the bottom plate (31) is circumferentially matched with the receiving slot and welded to each other to form a butt joint (34); Assemble the end of the pipe (28) of the air supply assembly (2) with the air inlet (35) at the top of the upper air chamber (33); A set of fairing components (3) are respectively installed on the lower part of the bilge outer plate (1) on both sides of the stern, forming symmetrical breakpoint-shaped jet slots (30) on the lower part of the bilge outer plate (1); During navigation, the air supply assembly (2) supplies air to the upper air chamber (33) of the rectifying assembly (3), and the air flow passes through the lower air chamber (32) and is ejected from the bottom air jet slot (30); the ejected air rises autonomously underwater, and as the ship moves forward, the air ejected from the air jet slots (30) on both sides respectively drifts obliquely backward and converges at the stern, thereby actively controlling the flow field at the stern of the ship.

2. A method for ship tail jet straightening according to claim 1, characterized in that: The plurality of air jet slots (30) in a single group of rectifying components (3) are located on the same straight line, the spacing between adjacent air jet slots (30) is 100-200 mm, and the length of a single air jet slot (30) is 100-200 mm.

3. A method for ship tail jet straightening according to claim 1, characterized in that: The jet slot (30) is inclined upward and forward at an angle of 40-50° relative to the hull; and there is a smooth transition between the outer opening of the jet slot (30) and the bottom plate (31).

4. A method for ship tail jet straightening according to claim 1, characterized in that: The width of the air jet slot (30) is 10-15 mm.

5. The method for ship tail jet straightening according to claim 1, characterized in that: The lower air chamber (32) is a rectangular tubular structure with closed ends. Two side surfaces of the lower air chamber (32) opposite to each other in the height direction are respectively provided with a long groove (36) along the length direction and long air outlet holes (37) spaced apart along the length direction. The width of the long groove (36) is greater than the width of the long air outlet holes (37). The straight line on which the long groove (36) is located is staggered with the straight line on which the long air outlet holes (37) are located.

6. A ship tail jet straightening method according to claim 5, characterized in that: An upper air chamber (33) is welded on the outer surface of a lower air chamber (32) having a long groove (36). The upper air chamber (33) is closed at both ends and has a U-shaped cross-section facing the lower air chamber (32). The cross-sectional area of the upper air chamber (33) is smaller than the cross-sectional area of the lower air chamber (32). The upper air chamber (33) is offset in the direction of the long groove (36) relative to the lower air chamber (32) in the width direction.

7. A method for ship tail jet straightening according to claim 5, characterized in that: The outer side surface of the lower air chamber (32) with the long air outlet hole (37) is fitted to the bottom plate (31) and welded to each other along the edge of the fitting surface; the bottom plate (31) is provided with air slit holes (38) corresponding to the long air outlet holes (37) one by one, and the air slit holes (38) are larger than the air outlet holes (37) by two welds in width and length directions. A step structure is formed between the outer side surface of the lower air chamber (32) outside the orifice of the long air outlet hole (37) and the inner side surface of the air slit hole (38), and welding is performed along the step structure. The weld forms an air jet (30) with a conical cross section and an outward opening in the air slit hole (38).

8. The method for ship tail jet straightening according to claim 1, characterized in that: The structure of the air supply assembly (2) is as follows: it includes a Roots blower (21) installed inside the ship, and the air outlet end of the Roots blower (21) is connected to the upper air chamber (33) of the rectifier assembly (3) via a pipeline (28); a thermometer (22), a pressure gauge (23), a flow meter (24), a pressure sensor (25), a regulating valve (26) and a manual butterfly valve (27) are installed in series on the pipeline (28) in sequence, and a check valve (29) is also installed at the end of the pipeline (28) near the upper air chamber (33).

9. A ship tail jet straightening method according to claim 8, characterized in that: The ship driving power is a propeller assembly (4), and a Roots blower (21) is arranged in the front part of the tail shaft cooling water tank.

10. The method for ship tail jet straightening according to claim 1, characterized in that: Complementary plates (6) are installed at intervals along the length direction of the rectifier assembly (3), and the complementary plates (6) correspond to the ribs (5) one by one and are welded to each other.

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