Marine stepped flow guide fin

Abstract

The invention relates to a marine stepped flow guide fin, which consists of a plurality of sections of elliptic guide pipes and a plurality of radially distributed stepped fins, the elliptic guide pipes are connected through straight line sections and are connected with a ship body through the plurality of fins, and the fins take a plurality of parallel lines of the axis of a propeller as the center and are connected with the ship body through the straight line sections. The radiating fins are radially and outwards distributed on the inner side and the outer side of the elliptical guide pipe; the fins comprise guide pipe outer fins and guide pipe inner fins, one ends of the guide pipe outer fins are fixedly arranged on the outer side of the oval guide pipe, and the two ends of the guide pipe inner fins are connected with the inner side of the oval guide pipe and the ship body respectively; the multiple guide pipe inner fins are distributed in a stepped mode when viewed from the ship side direction, the guide pipe outer fins are the same as or staggered with the guide pipe inner fins in longitudinal position when viewed from the ship side direction, and the guide pipe outer fins are the same as or staggered with the guide pipe inner fins in circumferential position when viewed from the stern direction. Through reasonable layout and proper connection of the stepped fins and the oval guide pipes, obvious improvement and energy conservation of a ship tail flow field are achieved.

Description

Technical Field

[0001] The present invention relates to a hydrodynamic energy-saving device for ships, especially a device for optimizing the propeller flow field through stepped guide fins. Background Art

[0002] At present, energy conservation and emission reduction have become a common understanding. In the ship industry, the Marine Environment Protection Committee of the International Maritime Organization has set clear energy conservation and emission reduction targets for almost all operating ships at its 76th and 77th meetings held in 2021, and these targets have been implemented since January 1, 2023. And ship hydrodynamic energy-saving technology is a very important, effective, and competitive emission reduction measure.

[0003] Hydrodynamic energy-saving technology has been widely studied in the past forty years, and various energy-saving devices such as compensation ducts, rudder appendage thrust fins, and Mewis ducts have been developed and widely applied to actual ships. In recent years, some new combined energy-saving devices have emerged, such as:

[0004] "A marine front guide vane" disclosed in Application No. CN201710152823.X includes a left arc wing plate, a right arc wing plate, and multiple guide vanes. However, the radius of the left arc wing plate is limited within 0.4 - 0.7R (R is the propeller radius), and it cannot change the adverse flow outside 0.7R; the right arc wing plate and the left arc wing plate are not closed below the propeller shaft, and it cannot improve the adverse flow within 0.4R below the propeller shaft, so the energy-saving effect is limited.

[0005] "A marine spiral-shaped duct fin" disclosed in Application No. CN202111325560.0 proposes a solution for the fine matching of the duct fin with the flow. Through the organic combination of a spiral-shaped duct and multiple radial fins, the energy-saving effect is significantly improved. However, the structural form is relatively complex.

[0006] None of the above applications consider the influence of the flow difference along the ship length direction on the design. The present invention will propose a new solution aiming at the limitations of existing patents. Summary of the Invention

[0007] Aiming at the above problems and limitations existing in the prior art, the present invention proposes a stepped guide fin that is more matched with the flow at the ship's tail and has an obvious energy-saving effect. Through the reasonable layout and proper connection of stepped fins and an elliptical duct, the flow field at the ship's tail is significantly improved and energy is saved.

[0008] To achieve the above object, the technical solution of the present invention is: a marine stepped flow guiding fin, which is composed of multiple elliptical ducts and several radially distributed stepped fins. The elliptical ducts are connected by straight line segments and are connected to the hull through several fins. The fins are radially distributed outward on the inner and outer sides of the elliptical ducts with multiple parallel lines of the propeller axis as the center; the fins include outer duct fins and inner duct fins. One end of several outer duct fins is fixedly arranged on the outer side of the elliptical duct, and both ends of several inner duct fins are respectively connected to the inner side of the elliptical duct and the hull; several inner duct fins are arranged in a stepped manner when viewed from the ship side, and the outer duct fins are longitudinally aligned or offset from the inner duct fins when viewed from the ship side, and the outer duct fins are circumferentially aligned or offset from the inner duct fins when viewed from the stern direction.

[0009] Furthermore, the multiple elliptical ducts are composed of a port elliptical duct, a starboard elliptical duct and a straight line segment connecting section, and the multiple elliptical ducts are in a vertical or inclined state; the connection positions at the upper ends of the elliptical ducts are arranged with a longitudinal front-back offset; or the connection positions at the upper ends of the elliptical ducts are flush in the longitudinal front-back positions.

[0010] Furthermore, the connection positions at the upper ends of the elliptical ducts are arranged with an angle of attack offset; or the connection positions at the upper ends of the elliptical ducts have the same angle of attack. When the connection positions at the upper ends of the elliptical ducts are offset, a partition is used for connection.

[0011] Furthermore, the elliptical ducts satisfy the following equations:

[0012] The equation of the port duct is (x - x 0 ) 2 / a 1 2 + y 2 / b 1 2 = 1, and the foci are located on the X axis;

[0013] The equation of the starboard duct is (y - y 0 ) 2 / a 2 2 + (x - x 1 ) 2 / b 2 2 = 1, and the foci are located on the parallel line of the Y axis;

[0014] Wherein, x 0 , y 0 are the central coordinates of the ellipse, a 1 , a 2 are the major axes of the ellipse, b 1 , b 2 are the minor axes of the ellipse; x 1It is the offset coordinate of the center line of the ellipse. It precisely adapts to the flow field at the stern of the hull and optimizes the water flow in the low-speed and high-speed areas.

[0015] Furthermore, the distance from the intersection point B of the elliptical duct and the Y-axis to the origin O is 0.4R - 0.9R. The starting point A is located in the second or third quadrant, with a length of 0.5R - 1.0R from the O point, and the included angle α with the positive Y-axis is -45° to 45°; the end point C is located in the first or fourth quadrant, with a length of 0.3 - 0.8R from the O point, and the included angle with the positive Y-axis is -30° to 75°. And the left and right hull layouts are adjusted by mirroring according to the rotation direction of the propeller. R is the radius of the propeller. It covers the adverse flow in the large-radius area of the propeller, enhances the uniformity of the flow field, and is adaptable to propellers with different rotation directions, with strong versatility.

[0016] Furthermore, when viewed from the ship side direction, the stepped fins are alternately overlapped and combined by 2 - 5 vertical segments and inclined segments; the stepped fins are inclined towards the bow of the ship or towards the stern; the stepped fins are connected to the hull by the vertical segments, or by the inclined segments, or different fins are alternately arranged.

[0017] Furthermore, the outer fins of the duct are inclined towards the bow or the stern of the ship, with an inclination angle of 10° - 20° and a length of 0.05R - 0.5R. It can suppress the adverse pre-rotation flow and reduce the eddy resistance.

[0018] The outer fins of the duct are distributed in the adverse pre-rotation area on the left hull side, with a quantity of 3 - 5 pieces; the inner fins of the duct are distributed in the low-speed area on the right hull side, with a quantity of 2 - 4 pieces. It can improve the flow field in the high-resistance area, and the energy-saving effect is increased by 3% - 5%.

[0019] Furthermore, the inner fins of the duct are arranged in a layer-by-layer manner and are staggered in the clockwise or counterclockwise direction. It adapts to the rotation direction of the propeller and maximally eliminates the adverse tangential flow.

[0020] Furthermore, the cross-section of all stepped guiding fins is an airfoil cross-section, and the chord length, cross-section shape, and angle of the guiding wing are variable along the circumferential direction. It can balance the structural strength and the flow control efficiency.

[0021] The beneficial effects of the present invention are:

[0022] The stepped guiding fins for ship hydrodynamic energy saving developed by the present invention make the fluid entering the small-radius range of the propeller, especially the fluid near the propeller hub, flow uniformly through the elliptical duct; the stepped fins change the flow direction entering the large-radius range of the propeller, forming a tangential flow opposite to the rotation direction of the propeller, so as to improve the propulsion efficiency of the propeller. The stepped design enables the fins to perfectly adapt to the change of the water flow along the ship length direction, and finally achieves the purpose of reducing the main engine power required at the same ship speed. Among them:

[0023] (1) The duct is composed of multiple sections of elliptical ducts, which can better adapt to the flow field at the stern of the hull. It not only makes the fluid flow entering the small radius range of the propeller, especially near the propeller hub, uniform, thereby improving the propulsion efficiency of the propeller, and ultimately achieving the purpose of reducing the main engine power required at the same ship speed;

[0024] (2) Thrust can also be generated by the duct through changes and selections of airfoil, angle, chord length, and position;

[0025] (3) The fins are radially distributed, which can change the flow direction of the fluid entering the propeller disk surface, forming a tangential flow opposite to the rotation direction of the propeller. The stepped design enables the fins to perfectly adapt to the changes in the water flow along the ship length direction, so as to improve the propulsion efficiency of the propeller, and ultimately achieve the purpose of reducing the main engine power required at the same ship speed.

[0026] (4) By combining the stepped fins and the elliptical duct, the water flow distribution on the propeller disk surface is improved, and the main engine power consumption is reduced. Brief Description of the Drawings

[0027] Figure 1 It is the layout diagram of the marine stepped fairing fin of the present invention;

[0028] Figure 2 It is the schematic diagram of the division of the favorable and unfavorable regions on the propeller disk surface;

[0029] Figure 3 It is the side view of the marine stepped fairing fin of the present invention;

[0030] Figure 4 It is the schematic cross-sectional view of the fairing wing of the present invention;

[0031] In the figure: 1, duct; 11, left side elliptical duct; 12, right side elliptical duct; 13, straight connection section between elliptical ducts; 2, fins; 21, fins outside the duct; 22, fins inside the duct; 3, hull. Detailed Embodiment

[0032] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the following embodiments are combined with the attached Figure 1 to Figure 4 to specifically elaborate on a marine hydrodynamic energy-saving stepped fairing fin provided by the present invention.

[0033] In this embodiment, referring to Figures 1 to 4 , the marine hydrodynamic energy-saving stepped fairing fin mainly includes a duct 1, a left side elliptical duct 11, a right side elliptical duct 12, a straight connection section 13 between elliptical ducts, a stepped fin 2, a fin 21 outside the duct, a fin 22 inside the duct, and a hull 3. Figure 1A virtual rectangular coordinate system is set on the plane perpendicular to the central axis of the propeller. The origin O of the rectangular coordinate system is set at the intersection point of the central axis of the propeller and the plane where the propeller is located. The positive direction of the X-axis faces the starboard side of the hull, and the positive direction of the Y-axis is perpendicular to the horizontal plane and upward.

[0034] The stepped fairing fin is arranged at the stern of the ship in front of the propeller and close to the propeller. The stepped fairing fin includes a duct 1 and a number of fins 2. The duct 1 consists of a port elliptical duct 11, a starboard elliptical duct 12 and a straight connection section 13 between the elliptical ducts. The upper ends of the port elliptical duct 11 and the starboard elliptical duct 12 are inclined towards the bow direction and are partially or completely connected to the hull and are connected to the hull 3 through a number of fins 2. The left end of the port elliptical duct 11 is fixedly connected or freely arranged with the fin 2. The inner side of the elliptical duct 12 far from the left end is fixedly connected with the fin 2. One end of the multi-segment non-circular ring duct 11 is connected to the hull 3, and the other end of the multi-segment non-circular ring duct 11 is directly connected to one end of the elliptical duct 12

[0035] The distance between the intersection point B of the elliptical ring duct and the positive Y-axis and the origin O is 0.6R. The starting point is set as point A located in the third quadrant. The line segment between point A and the origin O is set as AO, and the length of AO is 0.8R. The angle α between AO and the positive Y-axis is -45 to 0°. It is arranged at the place with a lower water flow velocity on the port side of the hull. The values of AO and α are determined by the size of the low-speed area on the port side of the propeller disk surface; the focus of the starboard elliptical ring duct is located on the parallel line of the y-axis, and the control equation is (y - y 0 ) 2 / a 2 2 +(x - x 1 ) 2 / b 2 2 = 1. The end point is set as point C located in the first or fourth quadrant. The line segment between point C and the origin O is set as CO, and the length of CO is 0.4R. The angle β between CO and the positive Y-axis is 0 to 15°. It is arranged at the place with a lower water flow velocity and a stronger adverse pre-rotation on the starboard side of the hull. The values of AO and α are determined according to Figure 3 the size of the adverse flow area on the starboard side of the propeller disk surface in

[0036] A number of fins 2 are radially distributed outward around the propeller axis on the inner and outer sides of the elliptical duct 12. The fins 2 include outer duct fins 21 and inner duct fins 22. One end of a number of outer duct fins 21 is fixedly arranged on the outer side of the elliptical duct 12. Both ends of a number of inner duct fins 22 are respectively connected to the inner side of the elliptical duct 12 and the hull 3. The cross-sectional shape of the fin 2 is as Figure 4As shown in the figure, side a is the wing back and side b is the wing surface. The fins 22 inside the duct are arranged in a stepped manner starting from the leftmost fin and gradually increasing towards the bow end in layers. The longitudinal position of the fins 21 outside the duct is arranged in a staggered manner with respect to the fins 22 inside the duct towards the stern direction. There are 5 fins 22 inside the duct, among which 3 are arranged in the area with a relatively low water flow velocity on the port side and 2 are arranged in the area with a relatively strong adverse pre-rotation of the hull on the starboard side; there are 4 fins 21 outside the duct and all are arranged in the area with a relatively strong adverse pre-rotation of the hull on the port side. The first vertical section A of the fin 22 inside the duct is connected to the hull, and its length is 0.05R - 0.15R; the inclined section C is inclined at an angle γ 1 of 15 - 30° and its length is 0.1R - 0.3R; the second vertical section B is arranged between the duct 1 and the inclined section fin. The angle of inclination of the fin 21 outside the duct towards the bow direction is γ 2 of 10 - 20°, and its length is 0.05R - 0.5R. The lengths of the vertical section and the inclined section of the fin and the angle of inclination γ 1、 γ 2 are determined according to Figure 2 the flow variation of the water along the ship length direction, ensuring that each section of the fin can provide the maximum pre-rotation for the propeller.

[0037] The design of the duct 1 and the fins 2 is mainly to make the fluid entering the small radius range of the propeller, especially the fluid near the propeller hub, flow uniformly, so as to improve the propulsion efficiency of the propeller and ultimately achieve the purpose of reducing the required main engine power at the same ship speed.

[0038] The stepped guide fins for ship hydrodynamic energy saving developed by the present invention make the fluid entering the small radius range of the propeller, especially the fluid near the propeller hub, flow uniformly through the elliptical duct; the stepped fins change the flow direction of the fluid entering the large radius range of the propeller, forming a tangential flow opposite to the rotation direction of the propeller, so as to improve the propulsion efficiency of the propeller. The stepped design enables the fins to perfectly adapt to the change of the water flow along the ship length direction, and ultimately achieves the purpose of reducing the required main engine power at the same ship speed.

[0039] The following embodiments provide the actual design process of applying the stepped guide fins for ship hydrodynamic energy saving to a type of cargo ship:

[0040] First, according to market research and the requirements of the shipowner, a type of target ship is determined, and the main dimensions and technical indicators are as follows:

[0041] Overall length: 185.05 m, molded breadth: 32.26 m, designed draft: 12.54 m, displacement: 53000 t, ship speed 11.4 kn

[0042] , propeller rotation direction: right-handed, propeller diameter: 5.9 m, propeller designed rotational speed: 88.6 r / min.

[0043] Then, the best implementation plan of the hydrodynamic energy-saving device is determined as follows:

[0044] The longitudinal distance from the trailing edge of the energy-saving device (stepped guide fin) to the propeller disk is 1.25 m;

[0045] The shape of the duct in the spanwise direction (outer circumferential direction) is in the form of a combination of an elliptical duct with its major axis on the X-axis on the port side and an elliptical duct on the Y-axis on the starboard side according to the right-handed rotation of the propeller. The duct changes its chord length along the spanwise direction (outer circumferential direction). The chord length of the duct at the mid-longitudinal section of the hull is the longest, and the chord lengths at both ends of the duct are the shortest, gradually decreasing from the middle to both ends. The top view of each duct is set as a right trapezoid, and the top view is two right trapezoids spliced together; the chord length of the duct at the mid-longitudinal section is the largest, which can make the duct close to the hull here, facilitating the lap reinforcement between the duct and the hull. The cross-sections on both sides of the duct can contract according to the flow field, reducing the duct resistance.

[0046] Three inner fins of the duct are arranged on the port side, and their circumferential angular distributions are as follows. One is located at a position 10° above the horizontal plane where the propeller axis is located, and the other two are respectively arranged at positions 35° above and 30° below the inner fin of the duct at the determined position; two are arranged on the starboard side, and their circumferential angles are respectively arranged at positions 5° and 45° above the horizontal plane. The first vertical section of the inner fin of the duct is connected to the hull, and its length is 0.1R; the inclined section is inclined at an angle of 15° towards the bow, and its length is 0.2R; the second vertical section is arranged between the duct 1 and the inclined fin. Four outer fins of the duct are used, and their circumferential angular distributions are as follows. One is located at the position on the horizontal plane where the propeller axis is located, the second is located at a position 20° above the horizontal plane where the propeller axis is located, and the other two have the same installation angles as the inner fins of the ducts on both sides. The outer fins of the duct are inclined at an angle of 10° towards the bow, and the outer ends of the fins are at the propeller radius.

[0047] This design plan of the energy-saving device can reduce the fuel consumption of the ship by 3% - 5%.

[0048] Example 2: On the basis of Example 1, the inclined section of the inner fin of the duct is connected to the hull and is inclined at an angle of 15° towards the stern, and its length is 0.2R; the vertical section is arranged between the duct 1 and the inclined fin; the outer fin of the duct is inclined at an angle of 5° towards the stern, and the outer end of the fin is at the propeller radius. The energy-saving effect of this example can be increased by about 1% - 2% compared with that of Example 1.

[0049] The above are only the preferred embodiments of the present invention, and do not impose any formal or substantial limitations on the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the present invention, several improvements and supplements can still be made, and these improvements and supplements should also be regarded as within the protection scope of the present invention. Any equivalent changes, such as slight modifications, decorations, and evolutions made by those who are familiar with the technology in this field without departing from the spirit and scope of the present invention by using the technical content disclosed above, are equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications, and evolutions made to the above embodiments based on the substantial technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A stepped guide fin for a ship, characterized in that: The invention is composed of a plurality of sections of elliptical ducts and a plurality of radially distributed stepped fins. The elliptical ducts are connected by straight line sections and are connected to the hull through a plurality of fins. The fins are radially distributed outward on the inner and outer sides of the elliptical duct with a plurality of parallel lines of the propeller axis as the center. The fins include fins outside the duct and fins inside the duct. One end of a plurality of fins outside the duct is fixed on the outer side of the elliptical duct, and the two ends of a plurality of fins inside the duct are respectively connected to the inner side of the elliptical duct and the hull. The plurality of fins inside the duct are distributed in a stepped manner when viewed from the side of the ship. The fins outside the duct are the same as or staggered in longitudinal position with the fins inside the duct when viewed from the side of the ship. The fins outside the duct are the same as or staggered in circumferential position with the fins inside the duct when viewed from the stern.

2. The marine stepped guide fin according to claim 1, characterized in that: The multi-segment elliptical duct is composed of a port side elliptical duct, a starboard side elliptical duct and a straight segment connecting segment. The multi-segment elliptical duct is in a vertical or inclined state; the upper end connection of the elliptical duct is staggered in the longitudinal position front and back; or the upper end connection of the elliptical duct is flush in the longitudinal position front and back.

3. The marine stepped guide fin according to claim 1, characterized in that: The connection at the upper end of the elliptical conduit is staggered in angle of attack; or the connection at the upper end of the elliptical conduit is at the same angle of attack. When the connection at the upper end of the elliptical conduit is staggered, a partition is used for connection.

4. The marine stepped guide fin according to claim 1, characterized in that: The elliptical conduit satisfies the following equation: The port duct equation is (x-x0) 2 / a1 2 +y 2 / b1 2 =1, the focus is on the X axis; The equation of the starboard duct is (y-y0) 2 / a2 2 +(x-x1) 2 / b2 2 =1, the focus is on the line parallel to the Y axis; Among them, x0 and y0 are the center coordinates of the ellipse, a1 and a2 are the major axes of the ellipse, b1 and b2 are the minor axes of the ellipse; x1 is the center line offset coordinate of the ellipse.

5. The marine stepped guide fin according to claim 4, characterized in that: The distance between the intersection point B of the elliptical conduit and the Y-axis and the origin O is 0.4R-0.9R, the starting point A is located in the second or third quadrant, the length from the point O is 0.5R-1.0R, and the angle α between the starting point A and the positive axis of the Y-axis is -45° to 45°; the end point C is located in the first or fourth quadrant, the length from the point O is 0.3-0.8R, and the angle between the starting point A and the positive axis of the Y-axis is -30 to 75°, and the port and starboard layouts are adjusted according to the propeller rotation direction mirror image, and R is the propeller radius.

6. The marine stepped guide fin according to claim 1, characterized in that: The stepped fin is composed of 2-5 vertical sections and inclined sections alternately overlapped when viewed from the side of the ship; the stepped fin is inclined toward the bow side, or inclined toward the stern; the stepped fin is connected to the hull by a vertical section, or connected to the hull by an inclined section, or different fins are arranged alternately.

7. The marine stepped guide fin according to claim 1, characterized in that: The outer fin of the duct is inclined toward the bow or stern, with an inclination angle of 10°-20° and a length of 0.05R-0.5R.

8. The marine stepped guide fin according to claim 1, characterized in that: The fins outside the duct are distributed in the unfavorable pre-spin area on the port side, and the number is 3-5; the fins inside the duct are distributed in the low-speed area on the starboard side, and the number is 2-4.

9. The marine stepped guide fin according to claim 1, characterized in that: The fins in the conduit are arranged in layers and staggered in a clockwise or counterclockwise direction.

10. The marine stepped guide fin according to claim 1, characterized in that: The cross-sections of all stepped guide fins are wing cross-sections, and the cross-section chord length, cross-section shape and angle of the guide fins are variable along the circumferential direction.

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