A ducted propeller with a rear stator movable

Abstract

The application provides a movable post-stator duct propeller, which comprises a pipe body, an inflow end and an outflow end at two ends respectively, a propeller body arranged in the pipe body and provided with a propeller blade, and a stator arranged on the inner wall of the pipe body and located between the propeller body and the outflow end, wherein the end of the propeller blade towards the stator is a trailing edge, the trailing edge has the ability to be elastically deformed by heating or cooling, and the end of the trailing edge towards the stator rotates around the pipe body in the radial direction; the end of the stator towards the propeller blade is a leading edge, the leading edge has the ability to be elastically deformed by heating or cooling, and the end of the leading edge towards the propeller blade rotates around the pipe body in the radial direction; the trailing edge of the propeller blade and the leading edge of the stator can simultaneously deform and deflect, which helps the inflow angle of the propeller blade and the post-stator to be zero to form an ideal hydrodynamic state, and the trailing edge of the propeller blade and the leading edge of the stator simultaneously deflect, which solves the problem that only the leading edge of the stator deflects and needs to deflect a large angle.

Description

Technical Field

[0001] This invention relates to the field of duct propeller technology, and more particularly to a duct propeller with a movable rear stator. Background Technology

[0002] A ducted propeller consists of a propeller and an externally mounted annular duct, originally designed to protect the propeller. Studies have shown that ducted propellers also offer advantages such as improved propulsion efficiency, reduced noise, and reduced energy loss from the wake. As an important form of propulsion, ducted propellers are widely used in the marine industry. To meet the ever-increasing hydrodynamic and acoustic performance requirements of surface ships and underwater vehicles, it is necessary to develop and innovate existing propulsion methods such as ducted propellers.

[0003] Most surface ships and underwater vehicles use fixed-blade propellers, which cannot change the blade shape during navigation. They cannot adjust the blade shape in real time at specific speeds and rotational speeds to improve propulsion efficiency, delay cavitation, or reduce noise. Chinese patent CN111094125A discloses a propeller pump-type hydraulic propulsion device, which sets the trailing edge of the front stator and the leading edge of the rear stator as rotatable flaps, thereby achieving a zero inflow angle between the propeller blades and the rear stator, creating an ideal hydrodynamic state.

[0004] However, when the propeller rotates at extremely high speeds, the flaps need to rotate at a large angle to make the inflow angle of the blades or the rear stator zero. Since both the blades and the stator are airfoils, excessively large flap rotation angles will disrupt the outer contour of the airfoil and affect its guiding effect, and may even generate vortices at the flap corners, making it difficult to achieve an ideal hydrodynamic state. Summary of the Invention

[0005] In view of this, the present invention proposes a rear-stator movable ducted propeller to solve the problem that if the rotation angle of the stator flap is too large, it will destroy the outer contour of the airfoil and affect its airflow guiding effect, and may even generate vortices at the corner of the flap, thus making it difficult to form an ideal hydrodynamic state.

[0006] The technical solution of the present invention is implemented as follows: The present invention provides a duct propeller with a movable rear stator, including a tube body with an inflow end and an outflow end at both ends; a propeller body disposed within the tube body and having blades; a stator disposed on the inner wall of the tube body and located between the propeller body and the outflow end; wherein, the end of the blade facing the stator is the trailing edge, which has the ability to undergo elastic deformation when heated or cooled, causing the end of the trailing edge facing the stator to rotate radially around the tube body; the end of the stator facing the blades is the leading edge, which has the ability to undergo elastic deformation when heated or cooled, causing the end of the leading edge facing the blades to rotate radially around the tube body.

[0007] Based on the above technical solutions, preferably, both the blade and the stator are airfoil-shaped, with the trailing edge of the blade (20) bent toward the middle of the tube and the leading edge of the stator bent toward the inner wall of the tube.

[0008] In a further preferred embodiment, one of the propeller rotation speeds is preset as the initial operating condition; the component of the propulsion velocity generated by the propeller along the tangent direction of the free end of the trailing edge arc is preset as the first outflow velocity component; the component of the propulsion velocity generated by the propeller along the radial direction of the tube is preset as the circumferential velocity component; the absolute velocity generated by the propeller can be calculated by combining the first outflow velocity component and the circumferential velocity component; the tangent direction along the free end of the leading edge arc is preset as the inflow direction; when the propeller rotation speed increases, the free end of the trailing edge rotates away from the center of the arc, and the free end of the leading edge rotates towards the center of the arc, so that the direction of the absolute velocity is consistent with the inflow direction.

[0009] More preferably, when the propeller speed decreases, the trailing edge free end rotates towards the center of the mid-arc circle, and the leading edge free end rotates away from the center of the mid-arc circle, so that the direction of the absolute velocity is consistent with the inflow direction.

[0010] More preferably, the free end of the leading or trailing edge has a rotation angle range of 1-10 degrees.

[0011] More preferably, the tangent direction along the end of the stator arc away from the leading edge is preset as the second outflow direction, and the second outflow direction is consistent with the axial direction of the tube body.

[0012] More preferably, the material cross-section of the leading edge or trailing edge includes a shape memory alloy layer and a carbon nanotube electrothermal layer; the shape memory alloy layer is disposed in the middle of the leading edge and fixedly connected to the part of the stator excluding the leading edge, or the shape memory alloy layer is disposed in the middle of the trailing edge and fixedly connected to the part of the blade excluding the trailing edge; the carbon nanotube electrothermal layer is disposed on at least one side of the leading edge or trailing edge along the middle arc line, and the carbon nanotube electrothermal layer is energized and heated to cause the shape memory alloy layer to deform and extend due to heat.

[0013] More preferably, the material cross-section of the leading or trailing edge also includes a cooling pipe layer; the cooling pipe layer is sandwiched between the shape memory alloy layer and the carbon nanotube electrothermal layer, and a cooling medium flows through the interior of the cooling pipe layer, causing the shape memory alloy layer to deform and shrink due to cooling.

[0014] In a further preferred embodiment, a carbon nanotube electrothermal layer and a cooling pipe layer are provided on both sides of the central arc line at the leading edge or trailing edge.

[0015] More preferably, the length of the trailing edge along the arc of the blade is no greater than one-third of the length of the arc of the blade; and the length of the leading edge along the arc of the stator is no greater than one-third of the length of the arc of the stator.

[0016] The rear-stator movable ducted propeller of the present invention has the following advantages over the prior art:

[0017] (1) The present invention sets the trailing edge of the blade and the leading edge of the stator to deform and deflect simultaneously, and the two deflect and rotate in opposite directions. This allows the angle between the direction of the first outflow velocity component along the tangent direction of the trailing edge of the blade and the direction of the inflow velocity along the tangent direction of the leading edge of the stator to increase as the circumferential velocity component increases with the increase of the propeller speed. This helps to make the inflow angle between the blade and the rear stator zero and form an ideal hydrodynamic state. At the same time, the trailing edge of the blade and the leading edge of the stator deflect simultaneously, which solves the problem that only the leading edge of the stator needs to deflect at a large angle, and avoids generating more eddies in the duct that affect the propulsion efficiency of the propeller.

[0018] (2) The present invention uses a shape memory alloy layer as the main material of the leading edge or trailing edge, and lays a carbon nanotube electrothermal layer and a cooling pipe layer on the shape memory alloy layer. The shape memory alloy layer is heated or cooled by the carbon nanotube electrothermal layer or the cooling pipe layer, so that the shape memory alloy layer undergoes deformation and bending in a corresponding manner, which can change the angle between the direction of the first outflow velocity component at the trailing edge of the blade and the direction of the inflow velocity at the leading edge of the stator. Attached Figure Description

[0019] 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.

[0020] Figure 1 This is a front view of the duct propeller of the present invention;

[0021] Figure 2 This is a side sectional view of the duct propeller of the present invention;

[0022] Figure 3 This is a schematic diagram of the initial operating condition of the ducted propeller of the present invention;

[0023] Figure 4 This is a schematic diagram of the acceleration operation of the ducted propeller of the present invention;

[0024] Figure 5 This is a cross-sectional view of the blade and stator of the present invention.

[0025] In the figure: 1. Tube body; 101. Inlet end; 102. Outlet end; 2. Propeller body; 20. Propeller blade; 21. Trailing edge; 211. Shape memory alloy layer; 212. Carbon nanotube electrothermal layer; 213. Cooling pipe layer; 3. Stator; 31. Leading edge. Detailed Implementation

[0026] 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.

[0027] like Figure 1 As shown, combined with Figure 2 The present invention provides a rear-stator movable ducted propeller, comprising a tube body 1, a propeller body 2, and a stator 3.

[0028] In this design, tube 1 is the conduit portion, which is a tube that extends through both ends, with the two ends being the inflow end 101 and the outflow end 102, respectively. Although tube 1 is cylindrical in the accompanying drawings of this application, in actual aircraft, tube 1 can also be conical, drum-shaped, or bottleneck-shaped.

[0029] The propeller body 2 is the propeller section of the ducted propeller, and blades 20 are arranged circumferentially on the propeller body 2. The propeller body 2 is located inside the tube body 1 and is situated in the middle of the tube body 1 or near the inlet end 101 of the tube body 1. After the water flows into the tube body 1 from the inlet end 101, it is accelerated by the rotation of the propeller body 2 and becomes a wake, which is then ejected from the outlet end 102 of the tube body 1. The end of the blade 20 facing the stator 3 is the trailing edge 21.

[0030] The stator 3 is disposed on the inner wall of the tube body 1 and located between the propeller body 2 and the outlet end 102. A front stator and a rear stator, or at least one of them, can be disposed in front of and behind the propeller body 2 within the tube body 1. It should be noted that the front and rear stators are essentially fixed frame structures for fixing the rotor. The two ends of the rotor shaft of the propeller body 2 are respectively axially connected to the middle of the front and rear stators, and the middle of the front and rear stators are fixed to the inner wall of the tube body 1 by several plate-shaped fasteners. In this embodiment, the stator 3 refers to these plate-shaped fasteners, and in this embodiment, the stator 3 refers to the rear stator. The end of the stator 3 facing the blade 20 is the leading edge 31. Since one of the functions of the stator 3 is to rectify the water flow entering the tube body 1 and passing through the propeller body 2 to improve the propulsion efficiency of the ducted propeller, the leading edge 31 of the stator 3 is movable. Generally, the movable plate is connected to the fixed plate by a hinge connection to achieve this mobility.

[0031] However, as mentioned earlier, the function of the stator 3 is to rectify the water flow from the trailing edge 21 of the propeller body 2 by oscillating its movable leading edge 31. The higher the speed of the propeller, the larger the angle that the leading edge 31 of the stator 3 needs to oscillate. However, the stator 3 usually has a certain streamlined outer contour to ensure that the water flow can flow smoothly through the two side plates of the stator 3 to achieve the purpose of guiding the water flow for rectification. If the oscillation angle of the leading edge 31 is too large, it will not only destroy the streamlined outer contour of the stator 3 and affect its rectification effect, but also the angle formed by the hinge between the trailing edge 31 and the rest of the stator 3 will also become much smaller. The trailing edge 31 will obstruct part of the water flow, and the vortex formed at the hinge will further have an adverse effect on the propeller's propulsion efficiency.

[0032] Considering the above reasons, in this embodiment, both the trailing edge 21 of the blade 20 and the leading edge 31 of the stator 3 have the ability to undergo elastic deformation under heat or cold, allowing the end of the trailing edge 21 facing the stator 3 to rotate radially around the tube body 1, and the end of the leading edge 31 facing the blade 20 to rotate radially around the tube body 1. Compared to existing ducted propellers where only the rear stator is movable, the above design has two advantages:

[0033] Firstly, since both the trailing edge 21 of the blade 20 and the leading edge 31 of the stator 3 are movable, their rotation angles can be coordinated with each other. This allows the rectification effect, which originally required a large rotation angle of the movable part of the rear stator, to be achieved, to be achieved by rotating the trailing edge 21 of the blade 20 and the leading edge 31 of the stator 3 simultaneously by a smaller angle. This avoids the problem that the large rotation angle of the movable part of the rear stator in the existing system has an adverse effect on the propeller propulsion efficiency.

[0034] Secondly, the trailing edge 21 of the blade 20 is an integral part of the blade 20, and the trailing edge 21 achieves end swing through deformation. Similarly, the leading edge 31 of the stator 3 is also an integral part of the stator 3, and the leading edge 31 also achieves end swing through deformation. Compared with the existing rear stator, where the movable part is connected to its rigid fixed part by a hinge, the connection between the trailing edge 21 and the blade 20 and the connection between the leading edge 31 and the stator 3 in this embodiment will not form a significant angle due to the swing of the trailing edge 21 and the swing of the leading edge 31, thereby avoiding the formation of vortices in the water flow that hinder propulsion.

[0035] In addition, in specific implementation, in order to enable the trailing edge 21 of the blade 20 and the leading edge 31 of the stator 3 to rotate simultaneously and cooperate, a water flow velocity measuring device is usually installed on the inner wall of the tube body 1 in front of the blade body 2, and a control system is installed inside the propeller. The control system is connected to the trailing edge 21, the leading edge 31 and the water flow velocity measuring device. The relationship between the propeller speed, the incoming flow velocity, the rotation angle of the trailing edge 21 of the blade 20 and the swing angle of the leading edge 31 of the stator 3 can be measured by simulation test, and the test data is stored in the control system in advance. In actual use, the control system 5 controls and adjusts the swing angle of the trailing edge 21 and the leading edge 31 according to the propeller speed and the incoming flow velocity measured by the water flow velocity measuring device.

[0036] exist Figure 2 In a preferred embodiment shown, the outer contours of both the blade 20 and the stator 3 are streamlined. Specifically, the cross-sections of both the blade 20 and the stator 3 are airfoil-shaped. The trailing edge 21 of the blade 20 bends towards the middle of the tube 1, and the leading edge 31 of the stator 3 bends towards the inner wall of the tube 1, in accordance with the propeller propulsion principle. The blade 20 is typically spirally twisted to a certain extent. The typical shape of an airfoil is a smooth front end and a pointed rear end. Generally, the pointed end is called the trailing edge, and the point farthest from the trailing edge is called the leading edge. The straight line connecting the leading and trailing edges is called the chord, and its length is called the chord length. A series of inscribed circles tangent to the upper and lower airfoil surfaces are drawn inside the airfoil, and the line connecting the centers of these circles is called the mid-arc line of the airfoil.

[0037] exist Figure 3 and Figure 4 In a preferred embodiment shown, the process of water flow being accelerated by the paddle 2 and then rectified by the stator 3 can be divided into four parts by the dashed lines: paddle 20 inflow, paddle 20 outflow, stator 3 inflow, and stator 3 outflow.

[0038] The initial operating condition is set at one of the lower rotational speeds of the propeller 2. The direction of the absolute velocity v1 of the inlet section of the blade 20 is along the axial direction of the tube 1. Since the direction of the circumferential velocity component u1 of the propulsion velocity generated by the propeller 2 is known to be along the radial direction of the tube 1, the relative velocity component w1 of the inlet section of the blade 20 can be calculated through the velocity triangle.

[0039] The water flow is assumed to reach an absolute velocity v2 after being accelerated by the impeller 2. Since the tube 1 is cylindrical and has the same inner diameter at the front and back, the circumferential velocity component u2 = u1 of the outflow section of the impeller 20. It is known that the direction of the first outflow velocity component w2 of the water flow over the surface of the impeller 20 is along the tangent direction of the free end of the arc in the trailing edge 21. By combining the first outflow velocity component w2 and the circumferential velocity component u2, the direction of the absolute velocity v2 of the outflow section of the impeller 20 can be obtained.

[0040] The tangent direction of the free end of the arc along the leading edge 31 is assumed to be the inflow direction of the stator 3. In order to form an ideal hydrodynamic state, the inflow angle between the blade 20 and the stator 3 needs to be zero. It is also assumed that the velocity of the water flowing into the inflow section of the stator 3 is not lost. Therefore, the absolute velocity of the inflow section of the stator 3 is v3 = v2 and the direction is the same.

[0041] When the rotational speed of the propeller 2 increases, the absolute velocity v1 of the inlet section of the blade 20 increases while its direction remains unchanged, and the circumferential velocity components u1 and u2 also increase accordingly. If the first outflow velocity component w2 of the outflow section of the blade 20 also increases while its direction remains unchanged, it can be calculated that the angle between the absolute velocities v2 and w2 of the outflow section of the blade 20 will increase. At this time, if the inflow angle between the blade 20 and the stator 3 is to be zero, the free end of the leading edge 31 of the stator 3 needs to rotate towards the center of the arc circle in the stator 3 so that the absolute velocity v3 of the inlet section of the stator 3 is in the same direction as the absolute velocity v2 of the outflow section of the blade 20. The larger the absolute velocity v1 of the inlet section of the blade 20, the larger the first outflow velocity component w2 and the circumferential velocity component u2 of the outflow section of the blade 20, the larger the angle between the absolute velocities v2 and w2 of the outflow section of the blade 20, and the larger the angle that the leading edge 31 needs to rotate.

[0042] In this embodiment, the free end of the trailing edge 21 of the blade 20 rotates simultaneously in a direction away from the center of the arc, thereby changing the direction of the first outflow velocity component w2 of the outflow section of the blade 20. Figure 4 The direction of the first outflow velocity component w2 can be regarded as rotating counterclockwise. With the circumferential velocity component u2 unchanged, the direction of the absolute velocity v2 of the outflow section of the blade 20 also rotates counterclockwise. This makes the leading edge 31 rotate by a smaller angle than before, so that the direction of the absolute velocity v3 of the inflow section of the stator 3 is consistent with the direction of the absolute velocity v2 of the outflow section of the blade 20, that is, the inflow angle between the blade 20 and the stator 3 is zero.

[0043] exist Figure 4 In a preferred embodiment shown, similarly, when the rotational speed of the propeller 2 decreases, the trailing edge 21 and the leading edge 31 rotate in opposite directions simultaneously. The free end of the trailing edge 21 rotates towards the center of the arc, and the free end of the leading edge 31 rotates away from the center of the arc, so that the direction of the absolute velocity is consistent with the inflow direction.

[0044] exist Figure 4 In a preferred embodiment shown, the free end of the leading edge 31 or the trailing edge 21 rotates at an angle ranging from 1 to 10 degrees, or more precisely, in the case of the propeller 2 accelerating or decelerating, the free end of the leading edge 31 or the trailing edge 21 rotates at an angle ranging from 1 to 5 degrees.

[0045] exist Figure 4In a preferred embodiment shown, the tangent direction along the arc of the stator 3 away from the leading edge 31 is preset as the second outflow direction. The second outflow direction is consistent with the axial direction of the tube body 1. Making the absolute velocity v4 of the outflow section of the stator 3 consistent with the axial direction of the tube body 1 helps to improve the propeller propulsion efficiency.

[0046] exist Figure 5 In a preferred embodiment shown, the material cross-section of the leading edge 31 or the trailing edge 21 includes a shape memory alloy layer 211, a carbon nanotube electrothermal layer 212, and a cooling pipe layer 213.

[0047] In this design, the shape memory alloy layer 211 is disposed in the middle of the leading edge 31 and fixedly connected to the stator 3 excluding the leading edge 31, or the shape memory alloy layer 211 is disposed in the middle of the trailing edge 21 and fixedly connected to the blade 20 excluding the trailing edge 21. Modern research has found that some metallic materials, after undergoing significant plastic deformation, will stretch back to their original shape when heated, and shrink and deform again when cooled. The same material, within a certain temperature range, can exhibit strains up to 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 of these effects depend on the occurrence of a specific type of phase transformation, called thermoelastic martensitic transformation. The shape memory alloy layer 32 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 shape memory alloy layer 32 is composed of nickel, titanium and copper, with the mass percentages of nickel, titanium and copper being 48.0-51.0% Ni, 43.5-47.5% Ti and 4.5-5.5% Cu.

[0048] A carbon nanotube electrothermal layer 212 is disposed on at least one side of the leading edge 31 or the trailing edge 21 along the mid-arc line. The carbon nanotube electrothermal layer 212 is electrically heated, causing the shape memory alloy layer 211 to deform. The deformation of the leading edge 31 or the trailing edge 21 is controlled by controlling the intensity of the electrical excitation applied to the carbon nanotube electrothermal layer 212. When the temperature reaches the phase transition temperature, the shape memory alloy layer 32 will deform, and its phase transition temperature is not lower than 50 degrees Celsius. Generally speaking, the intensity of the electrical excitation applied to the carbon nanotube electrothermal layer is in the range of 1-10A.

[0049] The cooling pipe layer 213 is sandwiched between the shape memory alloy layer 211 and the carbon nanotube electrothermal layer 212. Cooling medium flows through the cooling pipe layer 213, causing the shape memory alloy layer 211 to deform due to cooling. The deformation of the leading edge 31 or trailing edge 21 is controlled by controlling the flow rate of the cooling medium per unit time in the cooling pipe layer 213, and its phase transition temperature is not greater than 10 degrees. When the temperature reaches the phase transition temperature, the shape memory alloy layer 32 will deform.

[0050] In this embodiment, the carbon nanotube electrothermal layer 212 is placed on the outermost layer, while the cooling pipe layer 213 is sandwiched between the shape memory alloy layer 211 and the carbon nanotube electrothermal layer 212, so that the carbon nanotube electrothermal layer 212 is in direct contact with the water, and the shape memory alloy layer 211 can be cooled more quickly to return to its initial state after the carbon nanotube electrothermal layer 212 has finished heating.

[0051] When preparing the blade 20 or the stator 3, first prepare the shape memory alloy layer 32 in the middle layer, then print the rigid part of the blade 20 or the stator 3 using additive manufacturing technology, and integrate the shape memory alloy layer 32 at the trailing edge 21 or the leading edge 31 with the rigid part. Then, arrange cooling pipes on both ends of the shape memory alloy layer 32 to form a cooling pipe layer 33. Finally, print carbon nanofiber material on the outermost layer using additive manufacturing technology to form a carbon nanofiber electrothermal layer 31.

[0052] exist Figure 5 In a preferred embodiment shown, a carbon nanotube electrothermal layer 212 and a cooling pipe layer 213 are provided on both sides of the central arc line of the leading edge 31 or the trailing edge 21. When the leading edge 31 or the trailing edge 21 is deformed, the carbon nanotube electrothermal layer 212 and the cooling pipe layer 213 can be connected on both sides of the central arc line of the leading edge 31 or the trailing edge 21 respectively, so that the two end faces of the shape memory alloy layer 211 are heated and cooled respectively, thereby causing one end face of the shape memory alloy layer 211 to expand when heated and the other end face to contract when cooled, so that the shape memory alloy layer 211 can achieve deformation more quickly.

[0053] exist Figure 2 In a preferred embodiment shown, the length of the trailing edge 21 along the arc of the blade 20 is no greater than one-third of the length of the arc of the blade 20; the length of the leading edge 31 along the arc of the stator 3 is no greater than one-third of the length of the arc of the stator 3.

[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 rear-stator movable ducted propeller, characterized in that, include: The pipe body (1) has an inflow end (101) and an outflow end (102) at its two ends, respectively. The propeller (2) is disposed inside the tube (1) and has blades (20); The stator (3) is disposed on the inner wall of the tube (1) and located between the paddle (2) and the outlet end (102); Among them, the end of the blade (20) facing the stator (3) is the trailing edge (21), and the trailing edge (21) has the ability to undergo elastic deformation when heated or cooled, so that the end of the trailing edge (21) facing the stator (3) can rotate radially around the tube body (1); The stator (3) has a leading edge (31) at one end facing the blade (20). The leading edge (31) has the ability to undergo elastic deformation when heated or cooled, so that the end of the leading edge (31) facing the blade (20) can rotate radially around the tube body (1).

2. The rear-stator movable duct propeller according to claim 1, characterized in that: Both the blade (20) and the stator (3) are airfoil-shaped. The trailing edge (21) of the blade (20) bends toward the middle of the tube (1), and the leading edge (31) of the stator (3) bends toward the inner wall of the tube (1).

3. A rear-stator movable duct propeller according to claim 2, characterized in that: The initial working condition is set by one of the rotational speeds of the propeller (2). The component of the propulsion speed generated by the propeller (2) along the tangent direction of the free end of the arc in the trailing edge (21) is set as the first outflow velocity component. The component of the propulsion speed generated by the propeller (2) along the radial direction of the tube (1) is set as the circumferential velocity component. The absolute velocity generated by the propeller (2) can be calculated by combining the first outflow velocity component and the circumferential velocity component. The tangent direction along the free end of the arc in the leading edge (31) is preset as the inflow direction; When the rotational speed of the propeller (2) increases, the free end of the trailing edge (21) rotates away from the center of the arc, and the free end of the leading edge (31) rotates towards the center of the arc, so that the direction of the absolute velocity is consistent with the inflow direction.

4. A rear-stator movable duct propeller according to claim 3, characterized in that: When the rotational speed of the propeller (2) decreases, the free end of the trailing edge (21) rotates toward the center of the middle arc, and the free end of the leading edge (31) rotates away from the center of the middle arc, so that the direction of the absolute velocity is consistent with the inflow direction.

5. A rear-stator movable duct propeller according to claim 4, characterized in that: The free end of the leading edge (31) or trailing edge (21) has a rotation angle range of 1-10 degrees.

6. A rear-stator movable duct propeller according to claim 3, characterized in that: The tangent direction along the arc of the stator (3) away from the leading edge (31) is set as the second outflow direction, which is consistent with the axial direction of the tube body (1).

7. A rear-stator movable duct propeller according to claim 2, characterized in that: The material cross-section of the leading edge (31) or trailing edge (21) includes a shape memory alloy layer (211) and a carbon nanotube electrothermal layer (212); The shape memory alloy layer (211) is disposed in the middle of the leading edge (31) and fixedly connected to the part of the stator (3) excluding the leading edge (31), or the shape memory alloy layer (211) is disposed in the middle of the trailing edge (21) and fixedly connected to the part of the blade (20) excluding the trailing edge (21); The carbon nanotube electrothermal layer (212) is disposed on at least one side of the leading edge (31) or trailing edge (21) along the middle arc line. The carbon nanotube electrothermal layer (212) is electrically heated and causes the shape memory alloy layer (211) to deform and extend due to heat.

8. A rear-stator movable duct propeller according to claim 7, characterized in that: The material cross-section of the leading edge (31) or trailing edge (21) also includes a cooling pipe layer (213); The cooling pipe layer (213) is sandwiched between the shape memory alloy layer (211) and the carbon nanotube electrothermal layer (212). The cooling medium flows through the interior of the cooling pipe layer (213) and causes the shape memory alloy layer (211) to deform and shrink due to cold.

9. A rear-stator movable duct propeller according to claim 8, characterized in that: A carbon nanotube electrothermal layer (212) and a cooling pipe layer (213) are provided on both sides of the central arc line of the leading edge (31) or the trailing edge (21).

10. A rear-stator movable duct propeller according to claim 2, characterized in that: The length of the trailing edge (21) along the arc in the blade (20) is no greater than one-third of the length of the arc in the blade (20); the length of the leading edge (31) along the arc in the stator (3) is no greater than one-third of the length of the arc in the stator (3).

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