A toroidal propeller and method of use

Abstract

The application provides a ring propeller and a use method thereof, and belongs to the propeller field. The propeller blade comprises a blade root part, a blade tip part, a variable framework, a memory alloy part and a skin. Two ends of the variable framework in the extending direction are arranged on the blade root part and the blade tip part respectively. A window is arranged in the variable framework. Two memory alloy parts are arranged on the side of the variable framework away from the window in the extending direction of the variable framework. The memory alloy part is elastically extended by heating or elastically contracted by cooling, and the width of the window in the extending direction of the variable framework is increased or reduced. The skin is arranged on the outer surface of the memory alloy part and the variable framework and exposes the window. When the memory alloy part is contracted by cooling, the skin is tightened. The ring structure of the blade tip of the propeller suppresses the blade tip vortex, and the deformation of the memory alloy part after being heated or cooled controls the opening or closing of the window in the middle of the ring propeller structure, so that the propeller reaches the best hydrodynamic state under high speed and low speed working conditions.

Description

Technical Field

[0001] This invention relates to the field of propeller technology, and more particularly to a ring propeller and its method of use. Background Technology

[0002] Propellers are an important form of propulsion in the marine industry. Existing propeller designs have become quite mature and are no longer sufficient to meet the ever-increasing hydrodynamic and acoustic performance requirements of next-generation ships and unmanned underwater vehicles. Therefore, it is necessary to develop new propeller configurations.

[0003] During propeller operation, a suction zone is generated on the surface in front of the blade, and a pressure zone is generated on the surface behind it. Under the influence of the pressure difference, the fluid moves along the blade tip from the pressure surface to the suction surface and interacts with the low-pressure fluid on the suction surface to generate vortices, known as blade tip vortices. The periodic shedding of blade tip vortices causes drastic changes in the pressure on the propeller surface, which not only affects propulsion efficiency but also produces cavitation, one of the main sources of flow noise.

[0004] Publication number CN115892412A discloses a design for an annular blade propeller, characterized by the tip-to-tip connection of two blades forming an annular blade structure. This configuration can suppress fluid movement from the pressure surface to the suction surface at the blade tip, thereby suppressing the generation of tip vortices and improving the propeller's acoustic performance. However, a problem with this design is that at low operating speeds, when the tip vortex is weak, the hydrodynamic performance of the annular propeller blades may be weaker than that of conventional propeller configurations. Summary of the Invention

[0005] In view of this, the present invention proposes an annular propeller and its usage method to solve the problem that the hydrodynamic performance of current annular propeller blades may be weaker than that of traditional propeller configurations when the tip vortex is weak at low speeds.

[0006] The technical solution of this invention is implemented as follows: This invention provides a ring-shaped propeller with blades, each blade including a blade root, a blade tip, a variable frame, a shape memory alloy portion, and a skin. The variable frame is disposed between the blade root and the blade tip, with its two ends along the extension direction respectively disposed on the blade root and the blade tip. A window is provided inside the variable frame. Two shape memory alloy portions are laid along the extension direction of the variable frame on the side of the variable frame away from the window and are symmetrically disposed on both sides of the extension direction of the variable frame. The shape memory alloy portions elastically expand when heated or elastically contract when cooled, thereby increasing or decreasing the width of the window along the extension direction of the variable frame. The skin covers the shape memory alloy portion and the outer surface of the variable frame and exposes the window. The skin can elastically expand or contract and tighten. When the shape memory alloy portion contracts when cooled, the skin tightens.

[0007] Based on the above technical solutions, preferably, the variable skeleton includes two rows of rhomboid pieces; several rhomboid pieces are connected end to end along the extension direction of the variable skeleton to form a row, and the two rows of rhomboid pieces are symmetrically arranged between the leaf root and the leaf tip, with the two rows forming a window; adjacent rhomboid pieces are hinged at adjacent corners along the extension direction of the variable skeleton, so that each rhomboid piece rotates relative to the adjacent rhomboid piece around the hinge connection part, and the two corners on both sides of each rhomboid piece along the extension direction of the variable skeleton are respectively connected to the shape memory alloy part and the skin; the side corners of the rhomboid pieces at the head end of each row of rhomboid pieces away from the window are hinged to the leaf tip, and the side corners of the rhomboid pieces at the tail end of each row of rhomboid pieces away from the window are hinged to the leaf root.

[0008] More preferably, the variable skeleton further includes a first contour plate and a second contour plate; a plurality of first contour plates are arranged along the extension direction of the variable skeleton and on both sides of each row of rhombuses, one end face of each first contour plate is fixed to the shape memory alloy part or the skin, and the other end face of the first contour plate is hinged to the side of the rhombus along the extension direction of the variable skeleton, so that the first contour plate rotates relative to the rhombus about the hinge connection part; two second contour plates are respectively arranged at both ends of the variable skeleton and located between the two rows of rhombuses, and the second contour plates are simultaneously hinged to the side angles of the two rhombuses at the beginning of the row or the two rhombuses at the end of the row, and the second contour plates are also fixed to the shape memory alloy part or the skin.

[0009] More preferably, it also includes a telescopic mechanism, which is disposed between the end of the variable skeleton in the extension direction and the leaf tip or leaf root, with the two ends of the telescopic mechanism connected to the leaf tip or leaf root and the second contour plate, respectively.

[0010] More preferably, the second contour plate is U-shaped; when the shape memory alloy part elastically extends and increases the width of the window, the U-shaped opening of the second contour plate elastically expands; when the shape memory alloy part elastically contracts and reduces the width of the window to zero, the second contour plate clamps the two layers of skin.

[0011] Based on the above technical solutions, preferably, the cross-section of the shape memory alloy part includes a shape memory alloy layer and a carbon nanotube electrothermal layer; the shape memory alloy layer is laid along the extension direction of the variable skeleton on the side of the variable skeleton away from the window, and the two ends of the shape memory alloy layer are respectively inserted into the tip and root of the blade; the carbon nanotube electrothermal layer is disposed on the surface of the shape memory alloy layer away from the variable skeleton, and the carbon nanotube electrothermal layer is heated by electricity and causes the shape memory alloy layer to deform and extend due to heat.

[0012] More preferably, the cross-section of the shape memory alloy portion also includes a cooling pipe layer; the cooling pipe layer is disposed on the surface where the shape memory alloy layer connects to the variable skeleton, and a cooling medium flows through the cooling pipe layer to cause the shape memory alloy layer to deform and shrink due to cooling.

[0013] A more preferred embodiment includes a power supply and a switching switch. The power supply is located inside the annular propeller and is connected in series with two carbon nanotube heating layers. The power supply powers the carbon nanotube heating layers by energizing them and releasing heat. The switching switch is electrically connected to the power supply and can turn the power supply on or off.

[0014] Based on the above technical solutions, preferably, steps are provided on the outer peripheral wall of the leaf tip and leaf root, and the skin is fixedly attached to the steps at both ends along the extension direction of the variable skeleton.

[0015] On the other hand, the present invention also provides a method of using a ring propeller, which includes the following steps: Step 1, in the initial state of the shape memory alloy part, the two shape memory alloy parts are arc-shaped and the middle part protrudes in the direction away from the window, the variable skeleton bends with the shape memory alloy part and forms the window, and the skin is elastically stretched; Step 2, the shape memory alloy part is elastically extended by heat and drives the variable skeleton to bend and deform accordingly, so that the width of the window increases; Step 3, the shape memory alloy part is elastically contracted by cold and drives the variable skeleton to deform accordingly, so that the width of the window decreases until the width of the window is zero, the shape memory alloy part and the variable skeleton extend straight at both ends, and the skin contracts and tightens.

[0016] The annular propeller and its method of use of the present invention have the following advantages over the prior art: This invention uses the annular structure at the propeller blade tip to suppress the movement of fluid from the pressure surface to the suction surface of the propeller under high-speed conditions, thereby suppressing blade tip vortices and improving the propeller's propulsion efficiency and acoustic performance. At the same time, the deformation of the shape memory alloy part after heating and cooling controls the opening or closing of the window in the middle of the annular propeller structure, so that the propeller can achieve the optimal hydrodynamic state under both high-speed and low-speed conditions. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a side view of the blade of the present invention; Figure 2 This is a side view schematic diagram of another embodiment of the blade of the present invention; Figure 3 This is a schematic front sectional view of the blade of the present invention; Figure 4 This is a front sectional view of another embodiment of the blade of the present invention; Figure 5 For the present invention Figure 3 Enlarged view of point A in the middle; Figure 6 This is a cross-sectional schematic diagram of the shape memory alloy layer of the present invention.

[0019] In the diagram: 1. Blade; 11. Blade root; 12. Blade tip; 13. Variable frame; 131. Rhomboid component; 132. First contour plate; 133. Second contour plate; 14. Shape memory alloy section; 141. Shape memory alloy layer; 142. Carbon nanotube electrothermal layer; 143. Cooling pipe layer; 15. Skin; 101. Window; 102. Step; 2. Telescopic mechanism; 3. Power supply; 4. Switch. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] like Figure 1 As shown, combined with Figure 2 The present invention provides an annular propeller comprising a hub and a plurality of blades 1 arranged around the hub.

[0022] At high speeds, compared to traditional fan-bladed propellers, the annular structure of the blades in a ring propeller can suppress fluid movement from the pressure side to the suction side, thereby suppressing the generation of tip vortices. However, at low speeds, the annular structure of the blades in a ring propeller can actually increase fluid movement from the pressure side to the suction side, which is detrimental to the propeller achieving optimal hydrodynamic performance. Based on these reasons, the design concept of this invention is to control the deformability of the central structure of the propeller, so that it is in an open state to form an annular propeller blade at high speeds, and in a closed state to form a traditional fan-bladed propeller blade at low speeds.

[0023] The blade 1 includes a blade root 11, a blade tip 12, a variable skeleton 13, a shape memory alloy part 14, and a skin 15.

[0024] The blade root 11 and blade tip 12 are the rigid parts of the blade 1. The blade root 11 is mounted on the hub and rotates under the drive of the hub. The blade tip 12 is the end of the blade 1, and a blade tip vortex is generated at the blade tip 12 when the propeller rotates. In order to limit the length of the blade 1 and to prevent the length of the blade 1 from changing when the shape memory alloy part 14 extends or retracts, the blade root 11 and blade tip 12 are usually connected by a frame structure formed by multiple connecting rods. The frame structure is shaped to conform to the outer contour of the blade 1, and at the same time, the frame structure also provides a basic shaping framework for the skin 15.

[0025] The variable frame 13 is disposed between the blade root 11 and the blade tip 12. The two ends of the variable frame 13 extending in the same direction are respectively disposed on the blade root 11 and the blade tip 12. A window 101 is provided within the variable frame 13; alternatively, the window 101 can be formed by two symmetrically arranged variable frames 13 and the blade root 11 and blade tip 12. The variable frame 13 can significantly improve the structural strength of the blade 1, preventing structural collapse that may occur due to deformation.

[0026] Two shape memory alloy sections 14 are laid along the extension direction of the variable frame 13 on the side of the variable frame 13 away from the window 101 and are symmetrically arranged on both sides of the extension direction of the variable frame 13. The shape memory alloy sections 14 elastically expand when heated or elastically contract when cooled, thereby increasing or decreasing the width of the window 101 along the extension direction of the variable frame 13. Since the deformation of the shape memory alloy sections 14 causes the blade 1 to change in the width direction, the fixing link between the blade root 11 and the blade tip 12 is generally located in the thickness direction of the blade 1. In addition, the reaction force generated by the elastic stretching of the skin 15 also limits the spacing between the blade root 11 and the blade tip 12, preventing the shape memory alloy sections 14 from causing the blade 1 to change only in the length direction when it expands or contracts.

[0027] The skin 15 covers the outer surface of the shape memory alloy part 14 and the variable skeleton 13 and exposes the window 101. The skin 15 can elastically stretch or contract and tighten. When the shape memory alloy part 14 contracts due to cooling, the skin 15 tightens. The skin 15 is generally made of high-strength and high-toughness elastic rubber material, such as methyl vinyl silicone rubber or polyether ester elastic fiber.

[0028] It should be noted that the propeller of the present invention differs from the conventional propeller in that the purpose of the present invention is to eliminate the tip vortex generated at the tip of the propeller blade as much as possible. Therefore, the window 101 in the present invention is mainly set near the tip of the blade 1. Although the width of the window 101 in the open state will increase with the increase of the propeller speed, when the size of the window 101 increases to a certain range, its effect of reducing the generation of tip vortex will also reach its peak, or even be reversed. Therefore, the window 101 does not need to be able to open very wide. The purpose of the present invention is to provide a technical implementation method so as to solve the problem that the propeller can open or close the window 101 at the tip of the blade 1 according to the operating conditions under high speed and low speed conditions.

[0029] exist Figure 3 In a preferred embodiment shown, combined with Figure 4 In order to enable the variable skeleton 13 to deform synchronously with the deformation of the shape memory alloy part 14, the variable skeleton 13 includes two rows of rhomboid parts 131.

[0030] Several rhomboid pieces 131 are connected end to end along the extension direction of the variable skeleton 13 to form a row. Two rows of rhomboid pieces 131 are symmetrically arranged between the leaf root 11 and the leaf tip 12, and the two rows form a window 101. The rhomboid frame structure of the rhomboid pieces 131 has good structural strength.

[0031] Two adjacent rhomboid pieces 131 are hinged at their adjacent corners along the extension direction of the variable skeleton 13, so that each rhomboid piece 131 rotates relative to the adjacent rhomboid piece 131 around the hinge connection. The two corners on both sides of each rhomboid piece 131 along the extension direction of the variable skeleton 13 are respectively connected to the shape memory alloy part 14 and the skin 15.

[0032] The rhomboid members 131 at the head end of each row are hinged to the leaf tip 12 at the side angle away from the window 101, and the rhomboid members 131 at the tail end of each row are hinged to the leaf root 11 at the side angle away from the window 101, so that the relative positional relationship between the leaf root 11 and the leaf tip 12 will not change when the variable skeleton 13 is deformed.

[0033] exist Figure 5 In a preferred embodiment shown, in order to ensure that the skin 15 can still tightly cover the variable skeleton 13 after the variable skeleton 13 is deformed, the variable skeleton 13 further includes a first contour plate 132 and a second contour plate 133.

[0034] In this arrangement, several first contour plates 132 are arranged along the extension direction of the variable skeleton 13 and on both sides of each row of rhomboid parts 131. One end face of each first contour plate 132 is fixed to the shape memory alloy part 14 or the skin 15, and the other end face of the first contour plate 132 is connected to the side of the rhomboid part 131 along the extension direction of the variable skeleton 13 by an angle hinge, so that the first contour plate 132 rotates relative to the rhomboid part 131 around the hinge connection, thereby adapting to the shape change of the shape memory alloy part 14 or the skin 15 after the variable skeleton 13 bends and deforms.

[0035] Two second contour plates 133 are respectively disposed at both ends of the variable frame 13 and located between the two rows of rhomboid pieces 131. The second contour plates 133 are simultaneously connected to the side angle hinges of the two rhomboid pieces 131 at the head of the row or the two rhomboid pieces 131 at the tail of the row. The second contour plates 133 are also fixed to the shape memory alloy part 14 or the skin 15. The function of the second contour plates 133 is to keep the shape of the window 101 from being distorted.

[0036] exist Figure 4 In a preferred embodiment shown, when the variable skeleton 13 deforms and changes the width of the window 101, the length of the window 101 will change accordingly without changing the distance between the leaf root 11 and the leaf tip 12. This will cause the distance between the second contour plate 133 and the leaf root 11 or the leaf tip 12 to change. Therefore, the telescopic mechanism 2 is also included.

[0037] The telescopic mechanism 2 is located between the end of the variable frame 13 extending in the direction of extension and the leaf tip 12 or leaf root 11. The two ends of the telescopic mechanism 2 are respectively connected to the leaf tip 12 or leaf root 11 and the second contour plate 133. The telescopic mechanism 2 provides a certain supporting function and can also keep the shape of the window 101 from being distorted.

[0038] exist Figure 3 In a preferred embodiment shown, combined with Figure 4 The second contour plate 133 is U-shaped, allowing it to change shape according to the window 101. Therefore, the second contour plate 133 is typically made of a material with elastic restoring capabilities, such as elastic plastic or elastic rubber. When the shape memory alloy portion 14 elastically extends and increases the width of the window 101, the U-shaped opening of the second contour plate 133 elastically expands; when the shape memory alloy portion 14 elastically contracts and reduces the width of the window 101 to zero, the second contour plate 133 clamps the two layers of skin 15.

[0039] exist Figure 6In a preferred embodiment shown, in order to enable the shape memory alloy portion 14 to elastically expand when heated, the material cross-section of the shape memory alloy portion 14 includes a shape memory alloy layer 141 and a carbon nanotube electrothermal layer 142.

[0040] The shape memory alloy layer 141 is laid along the extension direction of the variable frame 13 on the side of the variable frame 13 away from the window 101, and its two ends are respectively inserted into the blade tip 12 and the blade root 11. In order to prevent the shape memory alloy layer 141 from only extending or contracting in the length direction of the blade 1 when deformed, the ends of the shape memory alloy layer 141 inserted into the blade tip 12 and the blade root 11 are inserted at an angle, thereby generating bending deformation potential energy in the middle of the shape memory alloy layer 141. The shape memory alloy layer 141 can also be integrally formed with the rigid metal material of the blade tip 12 and the blade root 11, and the three can be made by additive manufacturing technology.

[0041] A carbon nanotube electrothermal layer 142 is disposed on the surface of the shape memory alloy layer 141 away from the variable skeleton 13. The carbon nanotube electrothermal layer 142 is heated by electricity, causing the shape memory alloy layer 141 to deform and extend due to heat.

[0042] It should be noted that modern research has found that some metallic materials, after undergoing significant plastic deformation, will stretch back to their original shape upon heating, and then shrink upon cooling. The same material, within a certain temperature range, can exhibit strains as high as 10%, and will still return to its original shape upon unloading. These unusual effects are respectively called thermo-shape memory and superelasticity (elastic shape memory). Both effects depend on the occurrence of a specific type of phase transformation, called thermoelastic martensitic transformation. The shape memory alloy layer 141 in this case is made of such a metal, generally a nickel-titanium based alloy, such as titanium-nickel alloy, titanium-nickel-niobium alloy, titanium-nickel-palladium alloy, etc., but copper-based alloys or iron-based alloys can also be used. Specifically, the composition of shape memory alloy layer 141 is nickel, titanium, and copper, with the mass percentages of nickel, titanium, and copper being Ni 48.0-51.0%, Ti 43.5-47.5%, and Cu 4.5-5.5%.

[0043] exist Figure 6 In a preferred embodiment shown, in order to enable the shape memory alloy portion 14 to undergo elastic contraction upon cooling, the material cross-section of the shape memory alloy portion 14 further includes a cooling pipe layer 143.

[0044] The cooling pipe layer 143 is disposed on the surface of the shape memory alloy layer 141 that connects to the variable skeleton 13. A cooling medium flows through the cooling pipe layer 143, causing the shape memory alloy layer 141 to deform and shrink due to cooling. Both the cooling pipe layer 143 and the carbon nanotube electrothermal layer 142 can be printed onto the two surfaces of the shape memory alloy layer 141 using additive manufacturing technology.

[0045] In addition, since the propeller of the present invention is typically used in water or underwater vehicles, the cooling medium of the cooling pipe layer 143 can be directly taken from the ambient water.

[0046] exist Figure 3 In a preferred embodiment shown, in order to control the heating temperature and heating time of the carbon nanotube heating layer 142, a power supply 3 and a switching switch 4 are also included.

[0047] The power source 3 is located inside the annular propeller. The power source 3 is connected in series with two carbon nanotube heating layers 142. The power source 3 supplies power to the carbon nanotube heating layers 142 to release heat.

[0048] The switch 4 is electrically connected to the power supply 3, and the switch 4 can disconnect or connect the power supply 3.

[0049] exist Figure 3 In a preferred embodiment shown, steps 102 are provided on the outer peripheral walls of the leaf tip 12 and the leaf root 11. The two ends of the skin 15 along the extension direction of the variable skeleton 13 are fixedly attached to the steps 102, so that the outer surface of the skin 15 can smoothly transition with the outer surface of the leaf tip 12 and the leaf root 11.

[0050] like Figure 3 As shown, combined with Figure 4 The present invention provides a method for using a ring propeller, employing any of the ring propellers described above, comprising the following steps.

[0051] Step 1: In the initial state of the shape memory alloy parts 14, the two shape memory alloy parts 14 are arc-shaped and protrude in the middle away from the window 101. The variable skeleton 13 bends with the shape memory alloy parts 14 and forms the window 101. The skin 15 is elastically stretched.

[0052] Step two, the shape memory alloy part 14 is stretched elastically by heat and causes the variable skeleton 13 to bend and deform accordingly, thereby increasing the width of the window 101.

[0053] Step 3: The shape memory alloy part 14 is cooled and elastically contracts, causing the variable skeleton 13 to deform accordingly, reducing the width of the window 101 until the width of the window 101 is zero. At this point, the shape memory alloy part 14 and the variable skeleton 13 extend straight at both ends, and the skin 15 contracts and tightens.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A ring-shaped propeller having blades (1), characterized in that: The blade (1) includes a blade root (11), a blade tip (12), a variable skeleton (13), a shape memory alloy part (14), and a skin (15); The variable skeleton (13) is disposed between the leaf root (11) and the leaf tip (12), and the two ends of the variable skeleton (13) in the extension direction are respectively disposed on the leaf root (11) and the leaf tip (12). A window (101) is provided inside the variable skeleton (13). Two memory alloy parts (14) are laid on the side of the variable skeleton (13) away from the window (101) along the extension direction of the variable skeleton (13) and are symmetrically arranged on both sides of the extension direction of the variable skeleton (13). The memory alloy parts (14) are elastically extended when heated or elastically contracted when cooled, which increases or decreases the width of the window (101) along the extension direction of the variable skeleton (13). The skin (15) covers the outer surface of the shape memory alloy part (14) and the variable skeleton (13) and exposes the window (101). The skin (15) can elastically stretch or shrink and tighten. When the shape memory alloy part (14) is cooled and shrinks, the skin (15) tightens.

2. The annular propeller according to claim 1, characterized in that: The variable skeleton (13) includes two rows of rhomboid pieces (131); Several of the diamond-shaped pieces (131) are connected end to end along the extension direction of the variable skeleton (13) to form a row. Two rows of diamond-shaped pieces (131) are symmetrically arranged between the leaf root (11) and the leaf tip (12), and the two rows form a window (101). Two adjacent rhomboid pieces (131) are hinged at their adjacent corners along the extension direction of the variable skeleton (13), so that each rhomboid piece (131) rotates relative to the adjacent rhomboid piece (131) around the hinge connection. The two corners on both sides of each rhomboid piece (131) along the extension direction of the variable skeleton (13) are respectively connected to the shape memory alloy part (14) and the skin (15). The rhombus (131) at the head end of each column is hinged to the leaf tip (12) at the side angle away from the window (101), and the rhombus (131) at the tail end of each column is hinged to the leaf root (11) at the side angle away from the window (101).

3. The annular propeller according to claim 2, characterized in that: The variable skeleton (13) also includes a first contour plate (132) and a second contour plate (133); A plurality of first contour plates (132) are arranged along the extension direction of the variable skeleton (13) and on both sides of each row of rhomboid parts (131). One end face of each first contour plate (132) is fixed to the shape memory alloy part (14) or the skin (15), and the other end face of the first contour plate (132) is connected to the side of the rhomboid part (131) along the extension direction of the variable skeleton (133) by an angle hinge, so that the first contour plate (132) rotates relative to the rhomboid part (131) around the hinge connection part. Two second contour plates (133) are respectively disposed at both ends of the variable skeleton (13) and located between the two rows of rhomboid pieces (131). The second contour plates (133) are simultaneously connected to the side angle hinges of the two rhomboid pieces (131) at the head of the column or the two rhomboid pieces (131) at the tail of the column. The second contour plates (133) are also fixed to the shape memory alloy part (14) or the skin (15).

4. The annular propeller according to claim 3, characterized in that: It also includes a telescopic mechanism (2), which is disposed between the end of the variable skeleton (13) in the extension direction and the leaf tip (12) or the leaf root (11). The two ends of the telescopic mechanism (2) are respectively connected to the leaf tip (12) or the leaf root (11) and the second contour plate (133).

5. A ring-shaped propeller according to claim 3, characterized in that: The second contour plate (133) is U-shaped; When the shape memory alloy part (14) elastically extends and increases the width of the window (101), the U-shaped opening of the second contour plate (133) elastically expands. When the shape memory alloy part (14) elastically contracts and reduces the width of the window (101) to zero, the second contour plate (133) clamps the two layers of skin (15).

6. The annular propeller according to claim 1, characterized in that: The cross-section of the shape memory alloy part (14) includes a shape memory alloy layer (141) and a carbon nanotube electrothermal layer (142); The shape memory alloy layer (141) is laid along the extension direction of the variable skeleton (13) on the side of the variable skeleton (13) away from the window (101), and the two ends of the shape memory alloy layer (141) are respectively inserted into the leaf tip (12) and the leaf root (11). The carbon nanotube electrothermal layer (142) is disposed on the surface of the shape memory alloy layer (141) away from the variable skeleton (13). The carbon nanotube electrothermal layer (142) is electrically heated and causes the shape memory alloy layer (141) to deform and extend due to heat.

7. A ring-shaped propeller according to claim 6, characterized in that: The material cross-section of the shape memory alloy part (14) also includes a cooling pipe layer (143); The cooling pipe layer (143) is disposed on the surface of the shape memory alloy layer (141) connected to the variable skeleton (13). The cooling pipe layer (143) is filled with a cooling medium and causes the shape memory alloy layer (141) to deform and shrink due to cold.

8. A ring-shaped propeller according to claim 6, characterized in that: It also includes a power supply (3) and a switch (4), The power source (3) is located inside the annular propeller. The power source (3) is connected in series with two carbon nanotube electrothermal layers (142). The power source (3) supplies power to the carbon nanotube electrothermal layers (142) by energizing and releasing heat. The switching switch (4) is electrically connected to the power supply (3), and the switching switch (4) cuts off or connects the power supply (3).

9. A ring-shaped propeller according to claim 1, characterized in that: Steps (102) are provided on the outer peripheral walls of the leaf tip (12) and leaf root (11), and the skin (15) is fixedly attached to the steps (102) at both ends along the extension direction of the variable skeleton (13).

10. A method of using a ring-shaped propeller, employing the ring-shaped propeller according to any one of claims 1 to 9, characterized in that: Includes the following steps, Step 1: In the initial state of the shape memory alloy part (14), the two shape memory alloy parts (14) are arc-shaped and the middle part protrudes in a direction away from the window (101). The variable skeleton (13) bends with the shape memory alloy part (14) and forms the window (101). The skin (15) is elastically stretched. Step 2: The shape memory alloy part (14) is stretched elastically by heat and causes the variable skeleton (13) to bend and deform accordingly, thereby increasing the width of the window (101); Step 3: The shape memory alloy part (14) is cooled and elastically contracts, causing the variable skeleton (13) to deform accordingly, reducing the width of the window (101) until the width of the window (101) is zero. At this point, the shape memory alloy part (14) and the variable skeleton (13) extend straight at both ends, and the skin (15) contracts and tightens.

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