Energy-saving device in front of ship propeller and design method of energy-saving device

Abstract

The invention relates to a ship oar front energy-saving device and a design method thereof, and the device comprises a circumferential guide blade which is a part of a cylinder surrounding the tail part of a ship, and the central angle corresponding to the circumferential guide blade is 0-180 degrees; one end of each radial guide vane is connected with the inner wall of the circumferential guide vane, and the other end of each radial guide vane is connected with the stern of the ship; for a right-handed propeller, the number of the left side blades is larger than that of the right side blades, the distribution range of the left side blades is larger than that of the right side blades, and for a left-handed propeller, the number of the right side blades is larger than that of the left side blades. The distribution range of the right blades is larger than that of the left blades. According to the energy-saving device in front of the ship propeller, the water flow direction in front of the propeller can be more effectively improved, so that pre-rotational flow opposite to the propeller in direction is formed, and the propulsion of the propeller is improved.

Description

Technical Field

[0001] The invention relates to the field of ships, and in particular to a ship propeller front energy-saving device and a design method thereof. Background Art

[0002] The ship's propeller-front energy-saving device is a device installed in front of the ship's propeller. By changing the direction of the oncoming flow in front of the propeller, the propeller can work under more ideal conditions, reduce eddy currents and energy losses, thereby improving propulsion efficiency and reducing fuel consumption. The ship's propeller-front energy-saving device can reduce emissions, vibration and noise, and extend the service life of the equipment. The propeller-front energy-saving device is mainly used in large ships, such as container ships, tankers, and bulk carriers. With the improvement of environmental protection and economic requirements, its application is becoming more and more extensive. The design of the propeller-front energy-saving device needs to take into account the characteristics of the ship, including the hull shape, propeller type, and sailing speed. The installation is generally carried out during the ship's construction phase, and can also be installed during the ship's modification. As an important energy-saving device, the propeller-front energy-saving device has become an indispensable part of modern ship design and operation.

[0003] The current energy-saving appendage structure in front of the propeller of a ship generally includes a guide fin, which includes a first sheet body arranged horizontally. Some guide fins are provided with a second sheet body arranged vertically in addition to the first sheet body. The front sides of both are fixed to the stern of the ship. The first sheet body is vertically connected to the second sheet body in a cross shape. The first sheet body is inclined upward from front to back. The guide fin type structure of these two structures is simple, easy to install, and has low processing cost. It can improve the water flow state at the stern of the ship to a certain extent, but its effect of changing the water flow is relatively limited, and it is impossible to make the water flow adapt to the shape of the propeller. Summary of the invention

[0004] The invention provides a ship propeller front energy-saving device, which can more effectively improve the direction of water flow in front of the propeller, so as to form a pre-swirl flow opposite to the propeller direction, thereby improving the propulsion of the propeller.

[0005] The ship propeller front energy-saving device of the present invention comprises:

[0006] A circumferential guide blade, wherein the circumferential guide blade is a cylindrical part surrounding the tail of the ship, and the corresponding central angle thereof is 0°-180°. The cross section formed by cutting the circumferential guide blade with a plane passing through the axis of the circumferential guide blade and extending radially is an aerodynamic airfoil cross section. The inner side profile of the circumferential guide blade is the upper camber line in the cross section, and the outer side profile of the circumferential guide blade is the lower camber line in the cross section. The circumferential guide blade is opposite to the upper disk surface of the propeller;

[0007] A plurality of radial guide blades, each of which has one end connected to the inner wall of the circumferential guide blade and the other end connected to the stern of the ship, a cross section of the radial guide blade cut along a plane perpendicular to a certain radial guide blade being an aerodynamic airfoil cross section, and the plurality of radial guide blades are opposite to the upper disk surface of the propeller;

[0008] The angle between the radial guide blade and the wake flowing through the radial guide blade is the angle of attack α. The radial guide blade opposite to the left disk surface of the propeller is called the left blade, and the radial guide blade opposite to the right disk surface of the propeller is called the right blade. For a right-hand propeller, the number of left blades is greater than the number of right blades, the distribution range of the left blades is greater than the distribution range of the right blades, and the angle of attack of the left blade is 10°-

[0009] -10°, the angle of attack of the right blade is 0°-30°, for a left-hand propeller, the number of right blades is greater than the number of left blades, the distribution range of the right blades is greater than the distribution range of the left blades, and the angle of attack of the left blades is 0°—30°, and the angle of attack of the right blades is 10°—-10°.

[0010] Preferably, for a right-hand propeller, the radial guide vane located at the bottom and leftmost position is opposite to the dividing line between the upper disk surface and the lower disk surface of the propeller. For a right-hand propeller, the radial guide vane located at the bottom and rightmost position is opposite to the dividing line between the upper disk surface and the lower disk surface of the propeller.

[0011] Preferably, the diameter of the front end of the cross section of the circumferential guide vane is larger than the diameter of the rear end, and an angle θ is formed between the chord of the cross section of the circumferential guide vane and a horizontal line passing through the front end of the cross section and extending in the front-to-back direction.

[0012] Preferably, the angle θ is 0°-30°.

[0013] Preferably, the diameter of the circumferential guide blades is 0.8 to 1 times the diameter of the propeller.

[0014] Preferably, the chord length of the circumferential guide blade section is approximately 0.15 to 0.25 times the propeller diameter.

[0015] Preferably, the circumferential guide vane completely covers the radial guide vane in the radial inward direction, and the distance between the front end of the radial guide vane and the front end of the axial guide vane is greater than 100 mm, and the distance between the rear end of the radial guide vane and the rear end of the axial guide vane is greater than 100 mm.

[0016] Preferably, the circumferential guide vanes are integrally formed with the radial guide vanes.

[0017] The present invention also provides a design method for a ship propeller front energy-saving device, which is used to design the ship propeller front energy-saving device as described above, comprising the following steps:

[0018] S1, predicting the ship resistance of the target ship type at the design speed based on computational fluid dynamics to obtain the flow field information at the propeller disk of the target ship type;

[0019] S2, after dimensionless processing of the flow velocity at the propeller disk position, the nominal wake diagram and the velocity vector diagram at the propeller disk position are obtained;

[0020] S3, combined with the nominal wake diagram and velocity vector diagram at the propeller disk position, the flow field characteristics at the propeller disk are analyzed to obtain the distribution range and direction of the wake;

[0021] S4, designing the diameter and circular position of the circumferential guide blades according to the propeller diameter, designing the circumferential distribution of the radial guide blades according to the flow field distribution at the propeller disk surface, and determining the circumferential size of the circumferential guide blades according to the circumferential distribution range of the radial guide blades;

[0022] S5, designing the airfoil of the circumferential guide blade, the chord length of the cross section of the circumferential guide blade, and the angle θ between the chord of the cross section of the circumferential guide blade and a horizontal line passing through the front end of the cross section and extending in the front-rear direction, using a ship self-propulsion test based on computational fluid dynamics to verify the energy-saving effect of the above parameters of the circumferential guide blade, adjusting the parameters to conduct the test again, and selecting the parameters with the best energy-saving effect as the design scheme of the circumferential guide blade;

[0023] S6, design the airfoil of the radial guide vane and the chord length of the radial guide vane section, design the angle of attack α of the radial guide vane according to the flow field direction at various locations on the propeller disk, use a ship self-propulsion test based on computational fluid dynamics to verify the energy-saving effect of the above parameters of the radial guide vane, adjust the parameters and conduct the test again, and select the parameters with the best energy-saving effect as the design scheme for the radial guide vane.

[0024] Compared with the prior art, the present invention has the following beneficial effects: the circumferential guide blades and radial guide blades of the ship's propeller-front energy-saving device of the present invention are aerodynamic airfoils with better flow-guiding performance, and the distribution range of the radial guide blades is determined according to the flow field distribution of the propeller, so that the distribution range of the pre-swirl flow generated by the ship's propeller-front energy-saving device is relative to the flow field distribution of the propeller, and the angle of attack of each radial guide blade is determined according to the direction of each swirl flow generated by the propeller. Therefore, the ship's propeller-front energy-saving device can target multiple pre-swirl flows with opposite directions generated by the propeller, and the water flow is more uniform and the direction of the water flow is more precise, thereby producing better energy-saving effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a structural schematic diagram of a ship propeller front energy-saving device installed at the stern of a ship according to an embodiment of the present invention.

[0026] Figure 2The present invention is a schematic structural diagram of a ship propeller front energy-saving device according to an embodiment of the present invention.

[0027] Figure 3 The present invention is a schematic diagram of the cross-sectional structure of the circumferential guide vanes of a ship propeller front energy-saving device according to an embodiment of the present invention.

[0028] Figure 4 The present invention is a schematic diagram of the cross-sectional structure of the radial guide vanes of the energy-saving device in front of a ship propeller according to an embodiment of the present invention.

[0029] Figure 5 This is a schematic diagram of the circumferential uniform distribution of radial guide blades when the ship propeller front energy-saving device according to one embodiment of the present invention is applied to a right-hand propeller.

[0030] Figure 6 This is a schematic diagram of the circumferential non-uniform distribution of radial guide blades of a right-hand propeller when the ship propeller front energy-saving device according to one embodiment of the present invention is applied to the right-hand propeller.

[0031] Figure 7 It is a disk nominal wake diagram and a velocity vector diagram of the propeller water flow corresponding to the ship propeller front energy-saving device according to one embodiment of the present invention.

[0032] Figure 8 The present invention is a flowchart of a method for designing a propeller-front energy-saving device for a ship according to an embodiment of the present invention.

[0033] Reference numerals

[0034] 1 energy-saving device in front of ship propeller, 11 circumferential guide blade, 111 lower arc line, 112 upper arc line, 113 chord, 12 radial guide blade, 121 chord, 13 horizontal line, 14 water flow direction;

[0035] 2 propellers;

[0036] 3The stern of a ship. DETAILED DESCRIPTION

[0037] The present invention provides a ship propeller front energy-saving device, which is used to be installed at the tail of the ship and in front of the propeller. In the present invention, the disk surface of the propeller is a circular surface where the propeller is located, the left disk surface refers to the left half of the disk surface, the right disk surface refers to the right half of the disk surface, the upper disk surface refers to the upper half of the disk surface, and the lower disk surface refers to the lower half of the disk surface.

[0038] like Figure 1As shown, the ship propeller front energy-saving device of this embodiment includes: a circumferential guide blade and a plurality of radial guide blades, wherein the circumferential guide blade is a cylindrical part surrounding the tail of the ship, and its corresponding central angle is 0°-180°, and the circumferential guide blade is coaxial with the propeller. The cross section formed by cutting the circumferential guide blade with a plane passing through the axis of the circumferential guide blade and extending radially is an aerodynamic airfoil section. In this embodiment, the NACA airfoil section is used. The NACA airfoil is a series of aircraft airfoils developed by the National Advisory Committee for Aeronautics (NACA) of the United States. Figure 5 As shown, its left end, i.e., the tip, is the rear end, and the right end, i.e., the blunt end, is the front end. The inner profile of the circumferential guide blade is the upper arc line in the cross section, and the outer profile of the circumferential guide blade is the lower arc line in the cross section. The circumferential guide blade is opposite to the upper disk surface of the propeller. One end of each radial guide blade is connected to the inner wall of the circumferential guide sheet, and the other end is connected to the stern of the ship. The cross section obtained by cutting the radial guide blade with a plane perpendicular to a certain radial guide blade is an aerodynamic airfoil cross section. In this embodiment, a NACA airfoil cross section is used, as shown in FIG. Figure 6 As shown, the left end, i.e. the tip, is the rear end, and the right end, i.e. the blunt end, is the front end. A plurality of radial guide blades are opposite to the upper disk surface of the propeller.

[0039] The angle between the radial guide vane and the wake of the ship flowing through the radial guide vane is the angle of attack α. Figure 7 As shown, a schematic diagram of a cross section of the ship wake in front of the propeller, the cross section is perpendicular to the axis of the propeller, the shape of the lines shows the direction of the wake, the color in the figure shows the speed of the wake, and the red arrow represents the tangent mapping of the speed vector direction on the propeller disk. The radial guide vanes opposite to the left disk of the propeller are called left blades, and the radial guide vanes opposite to the right disk of the propeller are called right blades. For right-handed propellers, the number of left blades is greater than the number of right blades, and the angle of attack of the left blades is 10°-10°, and the angle of attack of the right blades is 0°-30°. For left-handed propellers, the number of right blades is greater than the number of left blades, and the angle of attack of the left blades is 0°-30°, and the angle of attack of the right blades is 10°-10°.

[0040] The circumferential guide blades and radial guide blades of the ship's propeller-front energy-saving device of the present invention are aerodynamic airfoils with better flow-guiding performance. The distribution range of the radial guide blades is determined according to the flow field distribution of the propeller, so that the distribution range of the pre-swirl flow generated by the ship's propeller-front energy-saving device is relative to the flow field distribution of the propeller. The angle of attack of each radial guide blade is determined according to the direction of each swirl flow generated by the propeller. Therefore, the ship's propeller-front energy-saving device can target multiple pre-swirl flows in opposite directions to the multiple swirl flows generated by the propeller, making the water flow more uniform and the direction of the water flow more precise, thereby producing better energy-saving effects.

[0041] Figure 5 and Figure 6 The figure shows the distribution range of radial guide vanes for a right-hand propeller. Figure 5 The figure shows a uniform distribution, that is, the angles of adjacent radial guide vanes are the same. Figure 6 The figure shows a non-uniform distribution. The angles between adjacent radial guide vanes are not the same, but both are determined based on the flow field distribution characteristics of the right-hand propeller, which is related to the shape of the stern. Figure 5 and Figure 6 In the embodiment shown in , the radial guide vane located at the bottom and the leftmost side is opposite to the dividing line between the upper disk surface and the lower disk surface of the propeller. For a right-hand propeller, the radial guide vane located at the bottom and the rightmost side is opposite to the dividing line between the upper disk surface and the lower disk surface of the propeller.

[0042] The diameter of the front end of the cross section of the circumferential guide blade is greater than the diameter of the rear end, and an angle θ is formed between the chord of the cross section of the circumferential guide blade and a horizontal line passing through the front end of the cross section and extending in the front-to-back direction. The acceleration effect on the stern flow can be adjusted by adjusting θ, and the angle is 0°-30°.

[0043] As a preferred solution, the diameter of the circumferential guide blade is 0.8 to 1 times the diameter of the propeller. Such a duct design can improve the uniformity of the stern water flow, especially the flow field of the upper half of the propeller disk, thereby improving the propulsion efficiency of the propeller. The chord length of the circumferential guide blade section is about 0.15 to 0.25 times the diameter of the propeller.

[0044] The circumferential guide blades completely cover the radial guide blades in the radial inward direction, and the distance between the front end of the radial guide blade and the front end of the axial guide blade is greater than 100 mm, and the distance between the rear end of the radial guide blade and the rear end of the axial guide blade is greater than 100 mm. In this embodiment, the circumferential guide blades also completely cover the radial guide blades in the circumferential direction.

[0045] In this embodiment, the circumferential guide vanes and the radial guide vanes are both made of stainless steel plates, and the two are fixed together by welding.

[0046] The present invention also provides a design method for a ship propeller front energy-saving device, such as Figure 8 As shown, the design of the energy-saving device in front of the propeller of a ship as described above includes the following steps:

[0047] S1, perform CFD (based on computational fluid dynamics) ship resistance prediction on the target ship type at the design speed to obtain the flow field information at the propeller disk of the target ship type;

[0048] S2, the flow velocity at the propeller disk position is dimensionlessly processed to obtain the nominal wake diagram and the velocity vector diagram at the propeller disk position, such as Figure 7 As shown;

[0049] S3, combined with the nominal wake diagram and velocity vector diagram at the propeller disk position, the flow field characteristics at the propeller disk are analyzed to obtain the distribution range and direction of the wake;

[0050] S4, design the diameter and circular position of the circumferential guide blade according to the propeller diameter, design the circumferential distribution of the radial guide blade according to the flow field distribution at the propeller disk surface, and determine the circumferential size of the circumferential guide blade according to the circumferential distribution range of the radial guide blade, wherein the cross section refers to the cross section formed by intercepting the circumferential guide blade with a plane passing through the axis of the circumferential guide blade and extending radially, and the cross section is an aerodynamic airfoil cross section;

[0051] S5, designing the airfoil of the circumferential guide blade, the chord length of the cross section of the circumferential guide blade, and the angle between the chord of the cross section of the circumferential guide blade and a horizontal line passing through the front end of the cross section and extending in the front-rear direction, using a ship self-propulsion test based on computational fluid dynamics to verify the energy-saving effect of the above parameters of the circumferential guide blade, adjusting the parameters to conduct the test again, and selecting the parameters with the best energy-saving effect as the design scheme of the circumferential guide blade;

[0052] S6, design the airfoil of the radial guide vane and the chord length of the cross section of the radial guide vane, design the angle of attack of the radial guide vane according to the flow field direction at various locations on the propeller disk, use a ship self-propulsion test based on computational fluid dynamics to verify the energy-saving effect of the above parameters of the radial guide vane, adjust the parameters and conduct the test again, and select the parameters with the best energy-saving effect as the design scheme for the radial guide vane.

[0053] The above embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention. The protection scope of the present invention is defined by the claims. Various modifications or equivalent substitutions made by those skilled in the art to the present invention within the essence and protection scope of the present invention also fall within the protection scope of the present invention.

Claims

1. A ship propeller front energy-saving device, characterized in that: include: A circumferential guide blade, wherein the circumferential guide blade is a cylindrical part surrounding the tail of the ship, and the corresponding central angle thereof is 0°-180°. The cross section formed by cutting the circumferential guide blade with a plane passing through the axis of the circumferential guide blade and extending radially is an aerodynamic airfoil cross section. The inner side profile of the circumferential guide blade is the upper camber line in the cross section, and the outer side profile of the circumferential guide blade is the lower camber line in the cross section. The circumferential guide blade is opposite to the upper disk surface of the propeller; A plurality of radial guide blades, each of which has one end connected to the inner wall of the circumferential guide blade and the other end connected to the stern of the ship, a cross section of the radial guide blade cut along a plane perpendicular to a certain radial guide blade being an aerodynamic airfoil cross section, and the plurality of radial guide blades are opposite to the upper disk surface of the propeller; The angle between the radial guide blade and the wake flowing through the radial guide blade is the angle of attack α. The radial guide blade opposite to the left disk surface of the propeller is called the left blade, and the radial guide blade opposite to the right disk surface of the propeller is called the right blade. For a right-handed propeller, the number of left-side blades is greater than the number of right-side blades, the distribution range of the left-side blades is greater than the distribution range of the right-side blades, and the angle of attack of the left-side blades is 10°-10°, and the angle of attack of the right-side blades is 0°-30°. For a left-handed propeller, the number of right-side blades is greater than the number of left-side blades, the distribution range of the right-side blades is greater than the distribution range of the left-side blades, and the angle of attack of the left-side blades is 0°-30°, and the angle of attack of the right-side blades is 10°-10°.

2. The ship propeller front energy saving device according to claim 1, characterized in that: For a right-hand propeller, the radial guide vane located at the bottom and farthest left is opposite to the dividing line between the upper disk surface and the lower disk surface of the propeller. For a right-hand propeller, the radial guide vane located at the bottom and farthest right is opposite to the dividing line between the upper disk surface and the lower disk surface of the propeller.

3. The energy-saving device in front of a ship propeller according to claim 1, characterized in that: The diameter of the front end of the cross section of the circumferential guide blade is larger than the diameter of the rear end, and an angle θ is formed between a chord of the cross section of the circumferential guide blade and a horizontal line passing through the front end of the cross section and extending in the front-rear direction.

4. The ship propeller front energy saving device according to claim 2, characterized in that: The angle θ is 0°-30°.

5. The ship propeller front energy saving device according to claim 1, characterized in that: The diameter of the circumferential guide blades is 0.8 to 1 times the propeller diameter.

6. The energy-saving device in front of a ship propeller according to claim 1, characterized in that: The chord length of the circumferential guide blade section is approximately 0.15 to 0.25 times the propeller diameter.

7. The energy-saving device in front of a ship propeller according to claim 1, characterized in that: The circumferential guide vane completely covers the radial guide vane in the radial inward direction, and the distance between the front end of the radial guide vane and the front end of the axial guide vane is greater than 100 mm, and the distance between the rear end of the radial guide vane and the rear end of the axial guide vane is greater than 100 mm.

8. The energy-saving device in front of a ship propeller according to claim 1, characterized in that: The circumferential guide vanes are integrally formed with the radial guide vanes.

9. A design method for a ship propeller front energy-saving device, characterized in that: The energy-saving device for the propeller front of a ship according to any one of claims 1 to 8 is designed, comprising the following steps: S1, predicting the ship resistance of the target ship type based on computational fluid dynamics at the design speed to obtain the flow field information at the propeller disk of the target ship type; S2, after dimensionless processing of the flow velocity at the propeller disk position, the nominal wake diagram and the velocity vector diagram at the propeller disk position are obtained; S3, combined with the nominal wake diagram and velocity vector diagram at the propeller disk position, the flow field characteristics at the propeller disk are analyzed to obtain the distribution range and direction of the wake; S4, designing the diameter and circular position of the circumferential guide blades according to the propeller diameter, designing the circumferential distribution of the radial guide blades according to the flow field distribution at the propeller disk surface, and determining the circumferential size of the circumferential guide blades according to the circumferential distribution range of the radial guide blades; S5, designing the airfoil of the circumferential guide blade, the chord length of the cross section of the circumferential guide blade, and the angle θ between the chord of the cross section of the circumferential guide blade and a horizontal line passing through the front end of the cross section and extending in the front-rear direction, using a ship self-propulsion test based on computational fluid dynamics to verify the energy-saving effect of the above parameters of the circumferential guide blade, adjusting the parameters to conduct the test again, and selecting the parameters with the best energy-saving effect as the design scheme of the circumferential guide blade; S6, design the airfoil of the radial guide vane and the chord length of the radial guide vane section, design the angle of attack α of the radial guide vane according to the flow field direction at various locations on the propeller disk, use a ship self-propulsion test based on computational fluid dynamics to verify the energy-saving effect of the above parameters of the radial guide vane, adjust the parameters and conduct the test again, and select the parameters with the best energy-saving effect as the design scheme for the radial guide vane.

Images