A Ship Drag Reduction Optimization Method Based on EEXI Standard

Abstract

This invention provides a ship drag reduction optimization method based on the EEXI standard, belonging to the field of ship energy efficiency optimization technology. The method involves arranging multiple independently driven adaptive suction drag reduction devices in an array on the ship's hull. The impellers are driven by the impact of the ship's navigating water flow to generate rotational power, requiring no external energy source. A centrifugal governor automatically adjusts the throttle valve opening according to the ship's speed, adaptively matching the suction flow rate with the speed, maintaining optimal boundary layer suction intensity across the entire speed range, effectively thinning the boundary layer and reducing frictional resistance. The device adopts a purely mechanical structure, equipped with a friction-type overload clutch, and features anti-clogging, anti-marine organism attachment, and triple sealing functions. It is modularly installed for convenience, has a short retrofit cycle, low cost, and high reliability. This invention can significantly reduce ship fuel consumption and carbon emissions, achieving a net energy saving rate of 10%–15%, effectively improving the EEXI compliance rate of older ships, and is suitable for energy-saving retrofits and new construction designs of various displacement-type ships.

Description

Technical Field

[0001] This invention relates to the field of ship energy efficiency optimization technology, and in particular to a ship drag reduction optimization method based on the EEXI standard. Background Technology

[0002] With the mandatory implementation of the International Maritime Organization's EEXI (Extended Energy Efficiency Index) for ships, a large number of operating vessels need to undergo energy-saving retrofits to meet carbon emission and energy efficiency compliance requirements. Frictional resistance accounts for 75%–85% of a ship's overall drag, making it a core area for optimization to improve energy efficiency and reduce fuel consumption. Boundary layer suction drag reduction technology can effectively reduce frictional resistance, but existing technologies generally rely on electric pumps for suction power, resulting in high energy consumption and low net energy savings. Furthermore, most employ fixed flow designs, failing to adapt to speed, leading to unstable drag reduction effects across all speed conditions. Simultaneously, existing solutions require integrated electrical control systems, which are complex in structure, have poor reliability, high maintenance costs, long ship retrofit construction cycles, and extended investment recovery periods, hindering large-scale application.

[0003] Current commonly used drag reduction technologies generally suffer from problems such as limited applicability to specific operating conditions, low drag reduction efficiency, and high retrofit costs, failing to meet the energy-saving retrofit requirements of the EEXI standard, which emphasizes self-powered operation, self-adaptation, high reliability, low cost, and ease of installation. Therefore, developing an adaptive boundary layer suction drag reduction technology that requires no external energy source, automatically adjusts with speed, and is based on a purely mechanical structure has become an urgent technical problem to be solved in the field of ship energy efficiency optimization. Summary of the Invention

[0004] The purpose of this invention is to provide a ship drag reduction optimization method based on the EEXI standard in order to solve the above problems.

[0005] To address the above problems, this invention provides a technical solution: a ship drag reduction optimization method based on the EEXI standard, comprising the following steps:

[0006] A. Multiple independently driven adaptive suction drag reduction devices are arranged in an array along the length and width of the ship at the bottom of the vessel.

[0007] B utilizes the relative motion between the ship's bottom and the water flow during navigation to drive the impeller through the impact of the water flow, generating rotational power, which is then discharged to the stern through the drainage channel.

[0008] C When the ship's speed changes, the water flow speed changes synchronously, causing the drive impeller speed to be automatically adjusted. At the same time, the centrifugal governor automatically adjusts the opening of the throttle valve, so that the suction flow rate changes adaptively with the ship's speed in a preset proportion.

[0009] D maintains optimal boundary layer suction strength at different speeds, effectively reducing boundary layer thickness, lowering frictional resistance, improving ship energy efficiency, and meeting EEXI standard requirements.

[0010] Preferably, the adaptive suction drag reduction device in step A includes a mounting base, an inlet, an outlet, a transmission assembly, a drive chamber, a transmission chamber, a suction chamber, a sealing partition, a stainless steel filter screen, and an adjustment assembly. The left end of the mounting base is fixedly connected to the inlet, and a stainless steel filter screen is fixedly connected to the inlet. The right end of the mounting base is fixedly connected to the outlet. The interior of the mounting base chamber is sequentially provided with a drive chamber, a transmission chamber, and a suction chamber via a sealing partition. A transmission assembly is provided in each of the drive chamber, transmission chamber, and suction chamber. An adjustment assembly is provided between the top of the transmission chamber and the top of the suction chamber.

[0011] Preferably, the regulating assembly includes a connecting chamber, a suction orifice plate, a suction hole, and a throttle valve; the connecting chamber is fixedly connected between the transmission chamber and the suction chamber; a suction orifice plate is fixedly connected to the middle end of the connecting chamber, and the suction orifice plate has several suction holes; a throttle valve is provided at the right end of the connecting chamber; the throttle valve is a butterfly throttle valve, and the rotation angle of its valve plate varies in the range of 0 to 90°, corresponding to a throttle valve opening degree varying in the range of 0 to 100%.

[0012] Preferably, the transmission assembly includes a drive impeller, a suction pump impeller, a first transmission shaft, a second transmission shaft, a friction overload clutch, and a centrifugal speed regulator; the left end of the first transmission shaft is fixedly connected to the drive impeller, and the other end is fixedly connected to one end of the friction overload clutch; the left end of the second transmission shaft is fixedly connected to the other end of the friction overload clutch, and the right end is fixedly connected to the suction pump impeller; a centrifugal speed regulator is also connected to the second transmission shaft.

[0013] Preferably, the friction-type overload clutch includes a driving disc, a driven disc, a copper-based friction plate of the driving disc, a copper-based friction plate of the driven disc, and a disc-shaped clamping spring; the driving disc is fixedly connected to a first transmission shaft, and the driven disc is fixedly connected to a second transmission shaft; a copper-based friction plate of the driven disc is fixedly connected to the left side of the driven disc; a copper-based friction plate of the driving disc is fixedly connected to the right side of the driving disc through a disc-shaped clamping spring, and the copper-based friction plate of the driving disc is in contact with the copper-based friction plate of the driven disc.

[0014] Preferably, the centrifugal speed controller includes a hinged seat, a flyball, a rotating arm, a connecting rod, a sliding sleeve, a speed-regulating connecting rod, a return spring, an adjusting nut, and a limiting block; the limiting block is fixedly connected to the second transmission shaft, the sliding sleeve is slidably connected to the second transmission shaft, and a return spring is provided between the limiting block and the sliding sleeve, the return spring covering and connected to the outer surface of the second transmission shaft; the adjusting nut is located on the right side of the sliding sleeve, and the adjusting nut is threadedly connected to a preset thread on the second transmission shaft; hinged seats and rotating arms are fixedly connected to both sides of the sliding sleeve; flyballs are hinged to each rotating arm; connecting rods are hinged between the flyballs and the hinged seats; a speed-regulating connecting rod is hinged to the sliding sleeve, and the other end of the speed-regulating connecting rod is connected to the valve stem of a throttle valve.

[0015] Preferably, the diameter of the suction hole is 2-3 mm, the hole spacing is 10-15 mm, and the axis of the suction hole forms a 45° angle with the bottom surface of the ship.

[0016] The beneficial effects of the present invention are: (1) Complete self-powered and high energy-saving benefits: It is driven by the energy of the water flow of the ship, without the need for external energy such as electricity and fuel, and without additional energy consumption. The net energy saving rate reaches 10%–15%, and the energy efficiency is significantly improved.

[0017] (2) Full speed adaptive, drag reduction and stability: The centrifugal governor automatically adjusts the suction flow rate according to the speed, maintaining the optimal suction intensity in the full speed range of 0-18 knots, and the drag reduction efficiency fluctuation is less than 8%.

[0018] (3) Pure mechanical structure with extremely high reliability: No electronic, electrical and sensing components, resistant to seawater corrosion and impact, with an average fault-free working time of over 60,000 hours and extremely low maintenance costs.

[0019] (4) Modular installation and easy modification: The units are independent, lightweight and easy to install. No large-scale hull cutting and welding is required. The modification cycle for a single ship is only 4-6 days and does not affect normal operation.

[0020] (5) Low conversion cost and short payback period: The cost is only 1 / 15 of the conversion of traditional bulbous bow, and the investment payback period is 0.8–1.2 years. It has outstanding economic benefits and is easy to promote on a large scale.

[0021] (6) Significant drag reduction effect and high EEXI compliance rate: It can reduce the frictional resistance of the hull by 12%–18%, effectively reduce fuel consumption and carbon emissions, and increase the EEXI compliance rate of old ships by 18%–25%.

[0022] (7) It has overload protection and safe operation: It is equipped with a friction overload clutch, which automatically cuts off the power in severe sea conditions, protects the device from damage, and improves navigation safety. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the adaptive suction drag reduction device of the present invention.

[0024] Figure 2 This is a schematic diagram of the structure of the present invention, which connects the internal suction orifice plate and the throttle valve.

[0025] Figure 3 This is a schematic diagram of the friction-type overload clutch of the present invention.

[0026] Figure 4 This is a schematic diagram of the centrifugal speed regulator of the present invention.

[0027] Figure 5 This is a top view of the suction perforated plate of the present invention.

[0028] Figure 6 This is a side view of the suction plate of the present invention.

[0029] Figure 7 This is a schematic diagram of the drag reduction device of the present invention arranged on the bottom of the ship. Detailed Implementation

[0030] This specific implementation adopts the following technical solution: a ship drag reduction optimization method based on the EEXI standard, including the following steps:

[0031] A sets of independently driven adaptive suction drag reduction devices are arranged in an array along the length and width of the ship at the bottom. The devices adopt a modular structure, with each weighing no more than 35kg. They are fixed to the pre-set grooves in the bottom of the ship with bolts, which facilitates installation, maintenance and quick replacement.

[0032] B utilizes the relative motion between the ship's bottom and the water flow during navigation to drive the impeller 4 to generate rotational power through the impact of the water flow. The water flows in through the inlet 2 and out through the outlet 3 to the stern. The entire process requires no external energy such as electricity or fuel, achieving zero-energy self-drive.

[0033] When the ship's speed changes, the water flow speed changes synchronously, causing the speed of the drive impeller 4 to be automatically adjusted. At the same time, the centrifugal motion of the flyball 20 of the centrifugal speed governor 13 drives the sliding sleeve 23 to move, and the opening of the throttle valve 18 is automatically adjusted through the speed regulating linkage 24, so that the suction flow rate changes adaptively with the ship's speed in a preset proportion.

[0034] D maintains optimal boundary layer suction strength at different speeds, effectively reducing boundary layer thickness, lowering frictional resistance, improving ship energy efficiency, and meeting EEXI standard requirements.

[0035] like Figures 1 to 6As shown, the adaptive suction drag reduction device in step A includes a mounting base 1, an inlet 2, an outlet 3, a transmission assembly, a drive chamber 6, a transmission chamber 7, a suction chamber 8, a sealing partition 9, a stainless steel filter screen 14, and an adjustment assembly. The left end of the mounting base 1 is fixedly connected to the inlet 2, and the inlet 2 is fixedly connected to the stainless steel filter screen 14 to filter impurities in seawater, preventing impeller damage and flow channel blockage. The right end of the mounting base 1 is fixedly connected to the outlet 3. The interior of the mounting base 1 is sequentially equipped with the drive chamber 6, transmission chamber 7, and suction chamber 8 via the sealing partition 9. The three chambers are independently sealed and do not interfere with each other. The drive chamber 6, transmission chamber 7, and suction chamber 8 are equipped with transmission assemblies. An adjustment assembly is located between the top of the transmission chamber 7 and the top of the suction chamber 8.

[0036] like Figures 1 to 6 As shown, the regulating assembly includes a connecting chamber 15, a suction orifice plate 16, suction holes 17, and a throttle valve 18. The connecting chamber 15 is fixedly connected between the transmission chamber 7 and the suction chamber 8 for fluid transition and pressure transmission. The suction orifice plate 16 is fixedly connected to the middle of the connecting chamber 15, and the suction orifice plate 16 is provided with several suction holes 17. A throttle valve 18 is provided at the right end of the connecting chamber 15. The throttle valve 18 is a butterfly throttle valve, and the rotation angle of its valve plate varies in the range of 0 to 90°, corresponding to the throttle valve opening degree varying in the range of 0 to 100%, thereby achieving precise adjustment of the suction flow rate.

[0037] like Figures 1 to 6 As shown, the transmission assembly includes a drive impeller 4, a suction pump impeller 5, a first transmission shaft 10, a second transmission shaft 11, a friction overload clutch 12, and a centrifugal speed regulator 13. The left end of the first transmission shaft 10 is fixedly connected to the drive impeller 4, and the other end is fixedly connected to one end of the friction overload clutch 12. The left end of the second transmission shaft 11 is fixedly connected to the other end of the friction overload clutch 12, and the right end is fixedly connected to the suction pump impeller 5. The centrifugal speed regulator 13 is also connected to the second transmission shaft 11 to realize speed monitoring and adaptive flow rate adjustment.

[0038] like Figures 1 to 6 As shown, the friction-type overload clutch 12 includes a driving disc 121, a driven disc 122, a driving disc copper-based friction plate 123, a driven disc copper-based friction plate 124, and a disc-shaped clamping spring 125. The driving disc 121 is fixedly connected to the first transmission shaft 10, and the driven disc 122 is fixedly connected to the second transmission shaft 11. The driven disc copper-based friction plate 124 is fixedly connected to the left side of the driven disc 122. The driving disc copper-based friction plate 123 is fixedly connected to the right side of the driving disc 121 through the disc-shaped clamping spring 125, and the driving disc copper-based friction plate 123 is in contact with the driven disc copper-based friction plate 124. When the impact of the waves is too large or the load exceeds the threshold, the friction plate automatically slips, cutting off the power transmission and protecting the device.

[0039] like Figures 1 to 6 As shown, the centrifugal speed controller 13 includes a hinged seat 19, a flyball 20, a rotating arm 21, a connecting rod 22, a sliding sleeve 23, a speed regulating connecting rod 24, a return spring 25, an adjusting nut 26, and a limiting block 27; the limiting block 27 is fixedly connected to the second transmission shaft 11, the sliding sleeve 23 is slidably connected to the second transmission shaft 11, and a return spring 25 is provided between the limiting block 27 and the sliding sleeve 23, the return spring 25 covering and connected to the outer surface of the second transmission shaft 11; the adjusting nut 26... Located on the right side of the sliding sleeve 23, the adjusting nut 26 is threadedly connected to the pre-set thread on the second transmission shaft 11 to adjust the spring preload; both sides of the sliding sleeve 23 are fixedly connected to the hinge seat 19 and the rotating arm 21; each rotating arm 21 is hinged with a flyball 20; a connecting rod 22 is hinged between the flyball 20 and the hinge seat 19; a speed regulating connecting rod 24 is hinged to the sliding sleeve 23, and the other end of the speed regulating connecting rod 24 is connected to the valve stem of the throttle valve 18 to realize speed-opening linkage control.

[0040] like Figures 1 to 6 As shown, the diameter of the suction hole 17 is 2-3 mm, the hole spacing is 10-15 mm, the axis of the suction hole 17 forms a 45° angle with the bottom surface of the ship and faces the stern, which can efficiently suck up low-speed boundary layer fluid while reducing its own additional resistance.

[0041] like Figure 7 As shown, the bottom arrangement for a 50,000-ton bulk carrier is as follows: 5 rows of drag-reducing devices are arranged along the length of the ship, with a row spacing of 8m; 7 rows of drag-reducing devices are arranged along the width of the ship, with a row spacing of 4.5m; a total of 35 units. The density of drag-reducing devices in the bilge region is 30% higher than that in the midship region to compensate for the thicker boundary layer in the bilge; no drag-reducing devices are arranged in the bow 1 / 4 of the ship's length to avoid affecting the ship's maneuverability and course stability.

[0042] The invention operates as follows: When the ship is sailing, water flows into the inlet 2 from the bow, impacting and driving the impeller 4 to rotate and generate power. This power is transmitted through the first drive shaft 10, the friction overload clutch 12, and the second drive shaft 11, driving the suction pump impeller 5 and the centrifugal governor 13 to operate synchronously. The suction pump impeller 5 creates a negative pressure in the suction chamber 8, drawing in low-speed fluid from the boundary layer at the bottom of the ship through the suction holes 17 on the suction orifice plate 16. After passing through the connecting chamber 15 and the throttle valve 18, the fluid is discharged to the stern through the outlet 3. When the speed changes, the centrifugal governor 13 uses the centrifugal force of the flyball 20 to drive the sliding sleeve 23 and the speed regulating linkage 24, automatically adjusting the opening of the throttle valve 18. This allows the suction flow rate to adaptively match the speed, continuously thinning the boundary layer, reducing frictional resistance, improving ship energy efficiency, and meeting EEXI standards. In severe sea conditions, the friction overload clutch 12 automatically slips, providing overload protection.

[0043] In the description of this invention, it should be understood that the terms "coaxial," "bottom," "one end," "top," "middle," "other end," "upper," "side," "top," "inner," "front," "center," "both ends," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0044] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "screw connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0045] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope. All such changes and modifications fall within the scope of the present invention as claimed, which is defined by the appended claims and their equivalents.

[0046] The control method of this invention is to control the device by manually starting and stopping the switch. The wiring diagram of the power element and the supply of power are common knowledge in the field. Since this invention is mainly used to protect mechanical devices, the control method and wiring layout will not be explained in detail.

Claims

1. A ship drag reduction optimization method based on the EEXI standard, characterized in that: Includes the following steps: A. Multiple independently driven adaptive suction drag reduction devices are arranged in an array along the length and width of the ship at the bottom of the vessel. B utilizes the relative motion between the ship's bottom and the water flow during navigation to drive the impeller through the impact of the water flow, generating rotational power, which is then discharged to the stern through the drainage channel. C When the ship's speed changes, the water flow speed changes synchronously, causing the drive impeller speed to be automatically adjusted. At the same time, the centrifugal governor automatically adjusts the opening of the throttle valve, so that the suction flow rate changes adaptively with the ship's speed in a preset proportion. D maintains optimal boundary layer suction strength at different speeds, effectively reducing boundary layer thickness, lowering frictional resistance, improving ship energy efficiency, and meeting EEXI standard requirements.

2. The ship drag reduction optimization method based on the EEXI standard according to claim 1, characterized in that: The adaptive suction drag reduction device in step A has a specific structure including a mounting base (1), an inlet (2), an outlet (3), a transmission assembly, a drive chamber (6), a transmission chamber (7), a suction chamber (8), a sealing partition (9), a stainless steel filter screen (14), and an adjustment assembly; The left end of the mounting base (1) is fixedly connected to a water inlet (2), and a stainless steel filter screen (14) is fixedly connected in the water inlet (2). The right end of the mounting base (1) is fixedly connected to a water outlet (3); The mounting base (1) has a drive chamber (6), a transmission chamber (7) and a suction chamber (8) arranged sequentially inside the chamber through a sealing partition (9). The drive cavity (6), transmission cavity (7) and suction cavity (8) are provided with transmission components; An adjustment assembly is provided between the top of the transmission chamber (7) and the suction chamber (8).

3. The ship drag reduction optimization method based on the EEXI standard according to claim 2, characterized in that: The regulating assembly includes a connecting chamber (15), a suction orifice plate (16), a suction orifice (17), and a throttle valve (18). The connecting chamber (15) is fixedly connected between the transmission chamber (7) and the suction chamber (8); A suction hole plate (16) is fixedly connected to the middle of the connecting chamber (15), and the suction hole plate (16) is provided with several suction holes (17). A throttle valve (18) is provided at the right end of the connecting chamber (15). The throttle valve (18) is a butterfly throttle valve, and the rotation angle of its valve plate varies in the range of 0 to 90°, corresponding to the throttle valve opening degree varying in the range of 0 to 100%.

4. The ship drag reduction optimization method based on the EEXI standard according to claim 2, characterized in that: The transmission assembly includes a drive impeller (4), a suction pump impeller (5), a first transmission shaft (10), a second transmission shaft (11), a friction overload clutch (12), and a centrifugal speed regulator (13). The left end of the first drive shaft (10) is fixedly connected to the drive impeller (4), and the other end is fixedly connected to one end of the friction overload clutch (12); The left end of the second drive shaft (11) is fixedly connected to the other end of the friction overload clutch (12), and the right end is fixedly connected to the impeller (5) of the suction pump. A centrifugal speed regulator (13) is also connected to the second drive shaft (11).

5. The ship drag reduction optimization method based on the EEXI standard according to claim 4, characterized in that: The friction overload clutch (12) includes a driving disc (121), a driven disc (122), a copper-based friction plate of the driving disc (123), a copper-based friction plate of the driven disc (124), and a disc-shaped compression spring (125). The driving disk (121) is fixedly connected to the first transmission shaft (10), and the driven disk (122) is fixedly connected to the second transmission shaft (11); A copper-based friction plate (124) is fixedly connected to the left side of the driven disk (122). The right side of the drive disc (121) is fixedly connected to a copper-based friction plate (123) via a disc-shaped compression spring (125). The active disk copper-based friction plate (123) is in contact with the driven disk copper-based friction plate (124).

6. The ship drag reduction optimization method based on the EEXI standard according to claim 4, characterized in that: The centrifugal speed controller (13) includes a hinge seat (19), a flyball (20), a rotating arm (21), a connecting rod (22), a sliding sleeve (23), a speed regulating connecting rod (24), a return spring (25), an adjusting nut (26), and a limit block (27). The limiting block (27) is fixedly connected to the second transmission shaft (11), the sliding sleeve (23) is slidably connected to the second transmission shaft (11), and a return spring (25) is provided between the limiting block (27) and the sliding sleeve (23). The return spring (25) is covered and connected to the outer surface of the second transmission shaft (11). The adjusting nut (26) is located on the right side of the sliding sleeve (23), and the adjusting nut (26) is connected to the preset thread on the second transmission shaft (11) by a thread; The sliding sleeve (23) is fixedly connected to both sides by a hinge seat (19) and a rotating arm (21). Each of the rotating arms (21) is hinged with a flying ball (20). The flying ball (20) and the hinge seat (19) are both hinged to a connecting rod (22). A speed regulating link (24) is hinged to the sliding sleeve (23), and the other end of the speed regulating link (24) is connected to the valve stem of the throttle valve (18).

7. The ship drag reduction optimization method based on the EEXI standard according to claim 3, characterized in that: The diameter of the suction hole (17) is 2-3 mm, the hole spacing is 10-15 mm, and the axis of the suction hole (17) forms a 45° angle with the bottom surface of the ship.

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