A ship wake energy saving appendage

Abstract

The present application relates to a kind of ship wake energy-saving appendages, including spindle-shaped main body, spindle-shaped main body includes the main body flow section in front section, the main body of removing flow section in rear section, the main body superstructure in the upper portion of main body removing flow section;Main body flow section is installed in the tail end of ship bottom, main body removing flow section is located behind ship stern plate, main body superstructure front end surface is closely attached with ship stern plate and fixedly connected, lower end surface is closely attached with main body removing flow section and fixedly connected;The horizontal section profile of main body flow section gradually increases from front to back width, the middle longitudinal section profile of lower end surface is configured using overall downward spline curve;The horizontal section profile of main body removing flow section gradually becomes smaller from front to back width, the lower edge profile of the middle longitudinal section profile of lower end surface is configured using overall downward spline curve first and then overall lifting spline curve from front to back.The present application can achieve good drag reduction effect in medium-low cruise condition and high speed condition, and improves the rapidity and endurance of ship.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of ship energy-saving appendage design, and particularly relates to a ship wake energy-saving appendage. BACKGROUND

[0002] The submerged waterjet propeller combines the technical characteristics and advantages of the conventional propeller propulsion and the tail plate waterjet propulsion, and can maintain high propulsion efficiency in a wide speed range from low to high. The submerged waterjet propeller is one of the important development directions of high-speed displacement ship propulsion technology. The integration and innovative optimization design of the submerged waterjet propeller corresponding to the new ship type is a key means to improve the comprehensive navigation performance of the ship. In addition, the design and development of the wake energy-saving appendage suitable for the submerged waterjet propeller of large high-speed displacement ship is also one of the important ways to further improve the resistance performance, rapidity and endurance of the ship.

[0003] The submerged waterjet propeller ship corresponds to the ship wake flow environment, the ship tail boundary layer velocity gradient, the ship tail pressure field distribution, and the ship tail wave characteristics caused by the suction and injection process of the propeller. The flow field characteristics are different from other propulsion methods. The conventional tail wedge, spoiler, pressure wave plate and hydrofoil tail energy-saving appendage cannot be directly applied or is not suitable for the submerged waterjet propeller of large high-speed displacement ship due to the differences in ship tail configuration and arrangement scheme, ship tail flow characteristics, etc. In addition, the application of the above-mentioned ship tail energy-saving appendage also has limitations such as a narrow speed range for effective drag reduction, and a mismatch between the effective drag reduction speed range and the cruising speed, which often cannot cover the overall speed range of the high-speed displacement ship in multiple working conditions, and cannot improve the comprehensive navigation energy efficiency of the ship in the entire speed range. SUMMARY

[0004] The technical problem to be solved by the present application is that the conventional ship tail energy-saving appendage cannot improve the comprehensive navigation energy efficiency of the ship in the entire speed range. The present application provides a ship wake energy-saving appendage, which can achieve good drag reduction effect in medium-low cruising conditions and high-speed conditions, further optimize the resistance performance of the submerged waterjet propeller ship in the overall speed range, and improve the rapidity and endurance of the ship.

[0005] The technical solution adopted by the present application to solve the above technical problems is as follows:

[0006] The energy-saving appendage of ship wake flow comprises a spindle-shaped main body, which comprises a main body flow guide section at the front section, a main body flow removal section at the rear section, and a main body superstructure at the upper part of the main body flow removal section. The main body flow guide section is installed at the tail end of the ship bottom, and the upper end surface of the main body flow guide section is closely attached to and fixedly connected with the curved surface of the tail end of the ship bottom. The main body flow removal section is located behind the ship stern plate, and the upper half of the front end surface of the main body flow removal section is closely attached to and fixedly connected with the ship stern plate, and the lower half of the front end surface is smoothly connected with the main body flow guide section. The front end surface of the main body superstructure is closely attached to and fixedly connected with the ship stern plate, and the lower end surface is closely attached to and fixedly connected with the main body flow removal section. The horizontal cross-sectional profile of the main body flow guide section gradually increases in width from front to back, and the middle longitudinal cross-sectional profile of the lower end surface of the main body flow guide section is configured by using a whole downward-inclined spline curve. The horizontal cross-sectional profile of the main body flow removal section gradually decreases in width from front to back, and the lower edge profile of the middle longitudinal cross-sectional profile of the lower end surface of the main body flow removal section is configured by using a whole downward-inclined spline curve followed by a whole upward-inclined spline curve from front to back, and a circular arc is smoothly connected between the two spline curves.

[0007] In the above scheme, the overall outer profile of the spindle-shaped main body is spindle-shaped, that is, the overall outer profile first widens and then narrows from bottom to top, and the overall profile changes in a downward-wide and upward-narrow trend. The spindle-shaped main body is left-right symmetrical about the middle longitudinal cross section.

[0008] In the above scheme, the length of the main body flow guide section is 1% to 2% of the ship length, and the height of the main body flow guide section is 0.9 to 1.1 times the draft height of the ship stern.

[0009] In the above scheme, the lower end surface of the main body flow guide section is a water contact surface, and the transverse cross-sectional profile of the lower end surface is configured by using a V-shaped cross section, and the maximum cross-sectional width is 10% to 20% of the ship width.

[0010] In the above scheme, the length of the main body flow removal section is 3% to 5% of the ship length, the height of the main body flow removal section is 1.6 to 2.0 times the draft height of the ship stern, and the upper end surface of the main body flow removal section is higher than the ship stern waterline.

[0011] In the above scheme, the transverse cross-sectional profile of the lower end surface of the main body flow removal section is configured by using a V-shaped cross section, and the maximum cross-sectional width is 15% to 25% of the ship width.

[0012] In the above scheme, the angle β of the downward inclination of the middle longitudinal cross-sectional profile of the lower end surface of the main body flow guide section is 20 degrees to 30 degrees, and the angle α of the downward inclination of the middle longitudinal cross-sectional profile of the lower end surface of the main body flow removal section is 0 degrees to 10 degrees.

[0013] In the above scheme, the main body superstructure is a conical surface, and the longitudinal cross-sectional profile is triangular.

[0014] In the above scheme, the ship wake energy-saving appendage also includes a main wave-damping plate, which is a plate structure that protrudes outward from the upper outer surface of the main body's outflow section.

[0015] In the above scheme, the ship wake energy-saving appendage also includes an auxiliary wave-damping plate, which is located below the main wave-damping plate and is a plate structure that protrudes outward from the outer surface of the main body de-flow section.

[0016] The beneficial effects of this invention are as follows:

[0017] The energy-saving appendage for ship wakes designed in this invention can achieve good drag reduction effects under both low-to-medium cruising conditions and high-speed conditions, mainly reflected in:

[0018] (1) When the fluid flows through the spindle-shaped body of the wake energy-saving appendage, its spindle-shaped horizontal profile configuration, which is wider at the front and narrower at the back, can expand pressure and decelerate to reduce frictional resistance. In addition, the downward-sloping mid-longitudinal profile configuration, which is higher at the front and lower at the back, can increase the static pressure that propels the boat forward. The spindle-shaped body can provide forward thrust in a relatively wide speed range corresponding to Fr = 0.1 to 0.5, so as to reduce the total resistance of the hull.

[0019] (2) The configuration of the main flow channel of the wake energy-saving appendage has a certain obstruction effect on the stern flow field. By reducing the flow velocity of the local flow field at the stern, the local pressure at the stern in the corresponding area can be increased, thereby reducing the pressure difference between the bow and stern of the hull and thus reducing the wave-making resistance of the hull.

[0020] (3) The wake wave trough generated by the spindle-shaped main body of the wake energy-saving appendage can form a favorable interference with the corresponding wake wave peak of the ship to reduce the height of the stern wake wave, reduce the energy loss in the process of stern wake wave formation, and reduce the wave-making resistance of the ship.

[0021] (4) The wave-damping plate can absorb additional wake waves from the stern of the ship, further reducing the wave-making resistance of the hull and weakening wake characteristics such as the wake stern.

[0022] Therefore, applying the energy-saving appendage of the present invention to the stern of a submersible waterjet propulsion vessel can achieve good drag reduction in both low-to-medium cruising and high-speed conditions, thus further optimizing the drag performance of the submersible waterjet propulsion vessel across the overall speed range and comprehensively improving the speed and endurance of this type of vessel.

[0023] Furthermore, the energy-saving appendage structure of the ship wake of this invention is simple and easy to install. After certain adaptation, adjustment and design, it can also be applied to existing propeller-driven ships. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0025] Figure 1This is a schematic diagram of the stern installation of the ship wake energy-saving appendage of the present invention;

[0026] Figure 2 This is a side view of the spindle-shaped main body;

[0027] Figure 3 This is a front view of the spindle-shaped main body;

[0028] Figure 4 This is a rear view of the spindle-shaped main body;

[0029] Figure 5 It is a bottom view of the spindle-shaped main body;

[0030] Figure 6 This is a schematic diagram of the interference mechanism between the trough of the spindle-shaped main body wake and the crest of the ship's wake;

[0031] Figure 7 A graph showing the drag reduction ratio of the energy-saving appendage for the spindle-shaped wake.

[0032] In the diagram: 10. Spindle-shaped main body; 11. Main body flow diversion section; 12. Main body flow outflow section; 13. Main body upper structure;

[0033] 20. Main wave-absorbing plate; 21. Auxiliary wave-absorbing plate. Detailed Implementation

[0034] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0035] like Figure 1 As shown, this is an embodiment of the present invention that provides a ship wake energy-saving appendage. The wake energy-saving appendage is directly fixed to the stern plate and the stern end of the bottom of a large high-speed displacement ship by welding.

[0036] like Figures 2-5 As shown, the ship's wake energy-saving appendage includes a spindle-shaped main body 10, which has a symmetrical structure about its longitudinal section. The spindle-shaped main body 10 includes a main flow-guiding section 11 located at the front, a main flow-departing section 12 located at the rear, and a main superstructure 13 located above the main flow-departing section 12. The main flow-guiding section 11 is installed at the stern end of the ship's bottom, and its upper end face is tightly fitted and fixedly connected to the curved surface of the stern end of the ship's bottom; the main flow-departing section 12 is located behind the stern endplate of the hull, and the upper half of its front end face is tightly fitted and fixedly connected to the stern endplate of the hull, while the lower half of its front end face is smoothly connected to the main flow-guiding section 11; the front end face of the main superstructure 13 is tightly fitted and fixedly connected to the stern endplate of the hull, and its lower end face is tightly fitted and fixedly connected to the main flow-departing section 12.

[0037] like Figure 5As shown, the main diversion section 11 has a length of 1% to 2% of the ship's length, and its height is 0.9 to 1.1 times the stern draft. The horizontal cross-sectional profile of the main diversion section 11 gradually increases in width from front to back, while the arc of the corresponding spline curve decreases continuously from front to back. The lower end face of the main diversion section 11 is the water-contacting surface. The mid-longitudinal cross-sectional profile of the lower end face of the main diversion section 11 is configured using a downwardly sloping spline curve with a downward sloping angle β of 20 to 30 degrees. The transverse cross-sectional profile of the lower end face is configured using a V-shaped cross-section, with a maximum cross-sectional width of 10% to 20% of the ship's breadth. The specific configuration of the main diversion section 11 is affected by various factors such as ship speed, stern structure, stern arrangement, wake, and propeller jet. When designing the lower end face configuration of the main diversion section 11, the comprehensive effects of drag reduction caused by the local pressure increase at the stern of the hull due to the main diversion section 11 under different speed conditions, and drag increase caused by fluid stagnation upstream of the appendages should be considered. Hydrodynamic performance optimization design should be carried out through model tests or numerical calculations to obtain the main diversion section configuration scheme with the best comprehensive performance across multiple speed conditions, including the main diversion section's own resistance and the corresponding local pressure increase at the stern, within a relatively wide speed range of Fr = 0.1 to 0.5.

[0038] See also Figure 5The length of the main flow-deflecting section 12 is 3% to 5% of the ship's length, and its height is 1.6 to 2.0 times the stern draft. Its upper end should be higher than the stern waterline. The horizontal profile of the main flow-deflecting section 12 gradually decreases in width from front to back, while the arc of the corresponding spline curve gradually increases from front to back. The horizontal profile lines at the front end of the main flow-deflecting section 12 and the corresponding positions of the main flow-inducing section 11 are smoothly connected. The lower edge profile of the mid-longitudinal section of the lower end face of the main flow-deflecting section 12 is configured using a spline curve that first slopes downward and then rises upward, with a smooth transition between the two spline curves using an arc of radius R. The downward slope angle α of the lower edge profile of the mid-longitudinal section can be 0 to 10 degrees; the transverse profile of the lower end face is configured with a V-shaped section, with a maximum section width of 15% to 25% of the ship's breadth. The configuration of the main flow-departure section 12 is mainly affected by factors such as ship speed, stern wake, propeller jet, and flow field disturbance of the upstream main flow-departure section 11. When designing the lower end face configuration of the main flow-departure section 12, the combined effects of hydrostatic pressure, dynamic pressure, and friction should be considered comprehensively. Hydrodynamic performance optimization design should be carried out using methods such as model tests or numerical calculations. The wall pressure distribution, near-wall flow field velocity distribution, and overall force variation trend of the main flow-departure section should be compared and analyzed within a relatively wide speed range corresponding to Fr = 0.1 to 0.5. The configuration of the lower edge profile of the longitudinal section, the profile of the transverse section, and the length of the main flow-departure section should be optimized in multiple schemes to obtain the main flow-departure section 12 configuration scheme with the best comprehensive performance in terms of thrust enhancement of the spindle-shaped main body 10 and favorable interference of the stern wake under multiple speed conditions.

[0039] See Figures 3-4 The spindle-shaped main body 10 exhibits a spindle shape in both its front and rear views, meaning its overall outline widens and narrows from bottom to top, showing a trend of being wider at the bottom and narrower at the top. (See also...) Figure 5 The horizontal cross-sectional profiles of the main diversion section 11 and the main outflow section 12 also exhibit a spindle-shaped configuration. Figure 5 The dotted line shown is the horizontal section line corresponding to the upper end face of the main body drainage section 11, that is, the width of the horizontal section configuration of the spindle-shaped main body 10 shows a trend of being wider in the front and narrower in the back.

[0040] During ship navigation, the spindle-shaped main body 10 is partially submerged in water. Fluid flowing through this spindle-shaped main body 10 is subjected to a combination of static pressure, dynamic pressure, and friction. Specifically, the main flow-out section 12 of the spindle-shaped main body 10 has a converging configuration from front to back. Fluid flowing over the wall of the main flow-out section 12 experiences diffusion and deceleration, and this reduced flow velocity helps decrease the frictional resistance experienced by the main flow-out section 12. On the other hand, the lower edge of the main flow-out section 12 has a downward-sloping profile, and the static pressure it experiences is generally directed towards the bow (at this point, it is a forward thrust). The static pressure plays a dominant role in the resultant force experienced by the main flow-out section 12, which is a forward thrust pointing towards the bow. The main guide section 11 of the spindle-shaped main body 10 has a relatively compact configuration, with a length approximately 25% to 35% of the length of the main flow-out section 12, and a height of 45% to 55% of the height of the main flow-out section 12. The rearward resistance (pointing towards the stern) experienced by the main diversion section 11 is less than the forward thrust generated by the main deflection section 12 over a wide speed range.

[0041] Therefore, considering the forces acting on the main diversion section 11 and the main deflection section 12 under various speed conditions and their influence on the stern flow field, the spindle-shaped main body 10 can provide forward thrust to the hull within a relatively wide speed range (Fr = 0.1 to 0.5) corresponding to the main operating conditions of high-speed displacement ships, thereby reducing the total hull resistance.

[0042] Further optimization is achieved by designing the main superstructure 13, which does not come into contact with water. It is not an effective drag-reduction structure for the wake-energy-saving appendages, but primarily serves as a fixed connection between the wake-energy-saving appendages and the hull. The configuration of the main superstructure 13 should comprehensively consider various aspects, including appendage installation and structural strength, stern configuration and layout, ship weight reduction requirements, and ship aesthetics. In this embodiment, the main superstructure 13 is a conical surface, with a triangular longitudinal profile.

[0043] Further optimization includes a main wave-damping plate 20, which is a plate structure protruding outward from the upper outer surface of the main body wake section 12. The main wave-damping plate 20 absorbs the energy of the stern wake and the wake of the spindle-shaped main body 10, further reducing wave-making resistance and weakening wake characteristics such as the stern tail. The main wave-damping plate 20 can adopt an equilateral trapezoidal or rectangular configuration. Its vertical arrangement, overall configuration, and inclination angle can be analyzed through model tests or numerical calculations to compare multiple schemes, with the goal of minimizing the total resistance of the entire ship to obtain the final configuration scheme.

[0044] Further optimization includes an auxiliary wave-damping plate 21 for the ship's wake energy-saving appendages. Located below the main wave-damping plate 20, the auxiliary wave-damping plate 21 is a plate structure protruding outward from the outer surface of the main flow-deflecting section 12. The auxiliary wave-damping plate 21 is primarily designed for ships with a wide range of navigation speeds. When these ships navigate across the entire speed range, the stern draft differs significantly between low-speed cruising and high-speed voyages. While the main wave-damping plate 20 improves the hull's drag performance at medium to high speeds, the addition of the auxiliary wave-damping plate 21 effectively meets the drag reduction requirements at low speeds, ensuring the comprehensive drag reduction effect of the wake energy-saving appendages across the entire speed range. When both the main wave-damping plate 20 and the auxiliary wave-damping plate 21 are used simultaneously, their vertical arrangement, overall configuration, and inclination angle can be compared and analyzed using model tests or numerical calculations, with the goal of minimizing the total ship drag to obtain the final configuration.

[0045] Further optimization is needed, and the thickness of the main wave-damping plate 20 and the auxiliary wave-damping plate 21 should be specifically set according to the structural strength requirements under the corresponding ship design speed conditions.

[0046] The ship wake energy-saving appendage proposed in this invention can achieve the following four functions:

[0047] (1) When the fluid flows through the spindle-shaped body 10 of the wake energy-saving appendage, its spindle-shaped horizontal profile configuration, which is wide at the front and narrow at the back, can expand pressure and decelerate to reduce frictional resistance. In addition, the downward-sloping mid-longitudinal profile configuration, which is high at the front and low at the back, can increase the static pressure that propels the boat forward. The spindle-shaped body 10 can provide forward thrust in a wide range of speeds to reduce the total resistance of the hull.

[0048] (2) The main flow section 11 configuration of the wake energy-saving appendage has a certain obstruction effect on the stern flow field. By reducing the flow velocity of the local flow field at the stern, the local pressure at the stern in the corresponding area can be increased, thereby reducing the pressure difference between the bow and stern of the hull and thus reducing the wave-making resistance of the hull.

[0049] (3) Figure 6 As shown, the wake wave trough generated by the spindle-shaped main body 10 of the wake energy-saving appendage can form a favorable interference with the corresponding wake wave peak of the ship to reduce the height of the wake wave behind the ship, reduce the energy loss in the wake wave formation process, and reduce the wave-making resistance of the ship.

[0050] (4) The wave-damping plate can absorb additional wake waves from the stern of the ship, further reducing the wave-making resistance of the hull and weakening wake characteristics such as the wake stern.

[0051] See Figure 7 This case involves the installation of a certain type of submersible waterjet propulsion large high-speed displacement vessel. Figure 1The wake-flow energy-saving appendages shown reduce drag by 4.5%, 6%, and 3% at length Fr=0.15, Fr=0.26, and Fr=0.41, respectively, with good drag reduction effects at all speeds.

[0052] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A ship wake energy-saving appendage, characterized in that, It includes a spindle-shaped main body, which includes a main body drainage section at the front, a main body dewatering section at the rear, and a main body upper structure above the main body dewatering section; The main flow-diverting section is installed at the stern of the hull, with its upper surface tightly fitted and fixedly connected to the curved surface of the stern. The main flow-depleting section is located behind the stern sealing plate, with its upper half tightly fitted and fixedly connected to the stern sealing plate, and its lower half smoothly connected to the main flow-diverting section. The front surface of the main superstructure is tightly fitted and fixedly connected to the stern sealing plate, and its lower surface is tightly fitted and fixedly connected to the main flow-depleting section. The horizontal profile of the main drainage section gradually increases in width from front to back, and the longitudinal profile of the lower end face of the main drainage section is configured using an overall downward-sloping spline curve. The horizontal profile of the main body de-flow section gradually decreases in width from front to back. The lower edge profile of the longitudinal profile of the lower end face of the main body de-flow section is constructed by a spline curve that first slopes downward and then rises upward from front to back, with a smooth arc transition between the two spline curves.

2. The ship wake energy-saving appendage according to claim 1, characterized in that, The spindle-shaped main body has an overall spindle shape, that is, the overall outer contour first widens and then narrows from bottom to top, and the overall structure shows a trend of being wider at the bottom and narrower at the top; the spindle-shaped main body is symmetrical about the middle longitudinal section.

3. The ship wake energy-saving appendage according to claim 1, characterized in that, The length of the main diversion section is 1% to 2% of the ship's length; the height of the main diversion section is 0.9 to 1.1 times the stern draft.

4. The ship wake energy-saving appendage according to claim 1, characterized in that, The lower end face of the main diversion section is the water-contacting surface, and the cross-sectional profile of the lower end face adopts a V-shaped profile, with a maximum cross-sectional width of 10% to 20% of the ship's width.

5. The ship wake energy-saving appendage according to claim 1, characterized in that, The length of the main body deflector section is 3% to 5% of the ship's length; the height of the main body deflector section is 1.6 to 2.0 times the stern draft; and the upper surface of the main body deflector section should be higher than the stern waterline.

6. The ship wake energy-saving appendage according to claim 1, characterized in that, The cross-sectional profile of the lower end face of the main body de-flow section adopts a V-shaped profile, and its maximum cross-sectional width is 15% to 25% of the ship's width.

7. The ship wake energy-saving appendage according to claim 1, characterized in that, The downward tilt angle β of the longitudinal profile of the lower end face of the main body diversion section is 20 degrees to 30 degrees, and the downward tilt angle α of the longitudinal profile of the lower end face of the main body de-flow section is 0 degrees to 10 degrees.

8. The ship wake energy-saving appendage according to claim 1, characterized in that, The upper structure of the main body is a conical surface, in which the longitudinal section outline is triangular.

9. The ship wake energy-saving appendage according to claim 1, characterized in that, The ship wake energy-saving appendage also includes a main wave-damping plate, which is a plate structure that protrudes outward from the upper outer surface of the main body's wake section.

10. The ship wake energy-saving appendage according to claim 9, characterized in that, The ship wake energy-saving appendage also includes an auxiliary wave-damping plate, which is located below the main wave-damping plate and is a plate structure that protrudes outward from the outer surface of the main body de-flow section.

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