Catheter paddle based on cavitation delay of super-hydrophobic slippage effect and manufacturing method thereof

Abstract

The invention relates to a cavitation-delayed ducted paddle based on a super-hydrophobic slippage effect and a manufacturing method of the cavitation-delayed ducted paddle. The stator is fixedly arranged in the guide pipe; the rotor comprises a rotating shaft rotationally connected with the stator and further comprises a plurality of blades fixedly connected with the rotating shaft, and the blade tip of each blade is provided with a first super-hydrophobic layer; wherein a tip gap is formed between the first super-hydrophobic layer and the inner wall of the guide pipe, and the surface of the first super-hydrophobic layer has a gas-liquid interface slippage effect, so that tip gap vortex cavitation is delayed, noise is reduced, and the cavitation risk is weakened on the basis of not changing the guide pipe wall of the guide pipe paddle and a rotor blade tip structure.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater propellers, in particular to a ducted propeller based on super-hydrophobic sliding effect cavitation delay and a manufacturing method thereof. Background Art

[0002] Ducted propellers are the most common type of propeller currently installed on ships and other navigation bodies, especially those sailing at high speeds, due to their advantages such as high critical speed, low radiated noise, and high propulsion efficiency. At the same time, the existence of the duct has also led to some new flow phenomena, which have brought new technical challenges. Among them, tip gap flow is a typical flow unique to ducted propellers, which is significantly different from traditional propeller propulsion. Depending on the duct profile (contraction type or expansion type), the tip gap size is slightly different, but it is basically in the millimeter range. Inside the tip gap, as the rotor blades rotate, the water flows from the rotor pressure surface (upstream surface) to the rotor suction surface (backstream surface), causing significant flow separation at the rotor blade tip to form a tip separation vortex, which interacts with the turbulent boundary layer flow on the inner wall of the duct, forming a tip separation vortex, a tip leakage vortex and its induced vortex in the tip gap and entangles with each other, forming a spiral vortex system that blocks the flow channel and reduces the propulsion efficiency; as the rotor speed increases, the strength of the tip gap vortex structure increases, and the pressure in the vortex core area is lower than the saturated vapor pressure of the water body. Combined with the gas core originally existing in the water body, the water body in the vortex core area undergoes a phase change, that is, the tip gap vortex cavitation begins; as the rotor speed further increases, the tip gap vortex cavitation area further expands to the back of the rotor blade (suction surface). At the same time, cavitation noise, cavitation erosion and shaft vibration noise are generated, forming significant radiation noise, which seriously affects the acoustic performance of the navigation body.

[0003] At present, the common practice to improve the noise and cavitation of ducted propellers is to cut grooves on the duct wall, or to set a spoiler structure at the rotor blade tip to change the tip gap flow pattern. By changing the tip gap vortex ring volume, the tip gap vortex structure strength is reduced and the tip gap vortex formation is inhibited. However, it is difficult to avoid the formation of flow separation vortex, which has an adverse effect on the propulsion efficiency and noise of the ducted propeller. Summary of the invention

[0004] In view of the shortcomings of the above-mentioned existing production technology, the applicant provides a ducted propeller with cavitation delay based on super-hydrophobic sliding effect and a manufacturing method thereof, thereby delaying tip gap vortex cavitation, reducing noise and weakening cavitation risk without changing the duct wall and rotor blade tip structure of the ducted propeller.

[0005] The technical solution adopted by the present invention is as follows: A ducted propeller based on super-hydrophobic sliding effect cavitation delay, comprising: catheter; A stator, fixedly disposed in the guide tube; A rotor, the rotor includes a rotating shaft rotatably connected to the stator, and further includes a plurality of blades fixedly connected to the rotating shaft, and a first superhydrophobic layer is provided at the tip of each blade; Wherein, a tip gap is formed between the first superhydrophobic layer and the inner wall of the conduit, and the surface of the first superhydrophobic layer has a gas-liquid interface slip effect.

[0006] The inner wall is provided with a second superhydrophobic layer, the surface of the second superhydrophobic layer has a gas-liquid interface slip effect, and the tip gap is the gap between the first superhydrophobic coating and the second superhydrophobic coating.

[0007] As a further improvement of the above technical solution: Both the first superhydrophobic layer and the second superhydrophobic layer satisfy: the hydrophobic angle is greater than or equal to 150°, and the oleophobic angle is greater than or equal to 150°.

[0008] The thickness of both the first superhydrophobic layer and the second superhydrophobic layer is 20μm to 50μm.

[0009] Both the first superhydrophobic layer and the second superhydrophobic layer are flexible materials.

[0010] The flexibility of the flexible material is greater than or equal to 1mm.

[0011] The forming methods of both the first superhydrophobic layer and the second superhydrophobic layer are spraying. The adhesion of the first superhydrophobic layer is grade 0 or 1, the adhesion of the second superhydrophobic layer is grade 0 or 1, and the impact resistance of both the first superhydrophobic layer and the second superhydrophobic layer is greater than or equal to 25kg·cm.

[0012] The size of the tip gap is 1mm to 100mm.

[0013] A manufacturing method of a duct propeller based on superhydrophobic slip effect cavitation delay, including the following steps: Surface treatment: Perform surface treatment on the tips of the blades of the rotor of the duct propeller and the inner wall of the duct; Spraying: Uniformly spray a liquid material on the tips and the inner wall of the duct. After the liquid material dries and cures, a first superhydrophobic layer is formed on the tips, and a second superhydrophobic layer is formed on the inner wall of the duct. The surfaces of both the first superhydrophobic layer and the second superhydrophobic layer have a gas-liquid interface slip effect; Assembly: Rotatably install the rotating shaft of the assembled rotor in the duct through a stator provided in the duct, and a tip gap is formed between the first superhydrophobic coating and the second superhydrophobic coating.

[0014] As a further improvement of the above technical solution: The liquid material includes a first liquid material and a second liquid material, Uniformly spraying the liquid material on the tips and the inner wall of the duct includes the following steps: Spray the first liquid material evenly on the tip of the blade and the inner wall of the duct. After the first liquid material dries and cures, a primer coating is formed. Spray the second liquid material evenly on the surface of the primer coating. After the second liquid material dries and cures, a surface coating is formed, and the surface of the surface coating has a gas-liquid interface slip effect.

[0015] The beneficial effects of the present invention are as follows: The structure of the present invention is compact, reasonable, and easy to operate. By providing a first superhydrophobic layer at the tip of the blade and utilizing the gas-liquid interface slip effect on the surface of the first superhydrophobic layer, the separation length of the tip clearance vortex is increased, thereby delaying the tip clearance vortex cavitation and reducing noise and weakening the cavitation risk without changing the structure of the inner wall of the duct and the tip of the blade (i.e., the vorticity).

[0016] At the same time, the present invention also has the following advantages: Superhydrophobic layers are provided on both the tip of the blade and the inner wall of the duct. By utilizing the gas-liquid interface slip effect on the superhydrophobic surface, the separation length of the tip clearance vortex is increased, the onset of tip clearance vortex cavitation is delayed, the wall shear is reduced, the onset of shear cavitation on the inner wall of the duct is delayed, the noise and cavitation risk are reduced, and the acoustic performance of the ducted propeller is comprehensively improved. Description of the Drawings

[0017] Figure 1 It is a schematic structural diagram of the ducted propeller of the present invention.

[0018] Figure 2 It is a three-dimensional view of the ducted propeller of the present invention.

[0019] Figure 3 It is the superhydrophobic microstructure morphology on the surface of the superhydrophobic layer of the present invention.

[0020] Figure 4 It is a schematic diagram of the increase in the separation length of the tip clearance vortex of the present invention.

[0021] Figure 5 It is a dimensionless average flow velocity profile of the scale in the near-wall region of Newtonian fluid.

[0022] Figure 6 It is a comparison diagram of the radiated noise between the ducted propeller of Example 2 and the conventional ducted propeller under the operating conditions of the critical cavitation number of the conventional ducted propeller.

[0023] Figure 7 It is a comparison diagram of the cavitation onset speed between the ducted propeller of Example 2 and the conventional ducted propeller under their respective critical cavitation numbers.

[0024] Figure 8 It is a schematic diagram of the process of manufacturing the ducted propeller and the implementation scheme for realizing the cavitation delay performance.

[0025] Among them: 2, stator; 3, duct; 4, rotor; 5, rotating shaft; 6, pressure surface; 7, suction surface; 8, blade tip; 9, inner wall; 10, hub; 11, axis. Specific embodiments

[0026] The following describes the specific embodiments of the present invention with reference to the accompanying drawings.

[0027] Embodiment 1: As Figure 1 , Figure 2 shown, the duct propeller based on the cavitation delay of the superhydrophobic slip effect in this embodiment includes a duct 3, a stator 2 and a rotor 4.

[0028] The stator 2 is fixedly arranged in the duct 3; The rotor 4 includes a rotating shaft 5 rotatably connected to the stator 2, and also includes a plurality of blades fixedly connected to the rotating shaft 5. The blade tip 8 of each blade is provided with a first superhydrophobic layer; Among them, a tip clearance is formed between the first superhydrophobic layer and the inner wall 9 of the duct 3, and the surface of the first superhydrophobic layer has a gas-liquid interface slip effect.

[0029] The specific structure of the duct propeller is as Figure 1 , Figure 2 shown. The stator 2 is a bracket structure with a streamlined shape. The stator 2 includes a connecting seat located at the center of the duct 3. The rotating shaft 5 is rotatably installed on the connecting seat, and the rotating shaft 5 is in transmission connection with a driving mechanism, and the driving mechanism is usually a motor.

[0030] When the duct propeller works, the rotating shaft 5 rotates relative to the stator 2, and a tip clearance vortex is formed in the tip clearance. The pressure surface 6 of the rotor 4 faces the stator 2, the suction surface 7 faces away from the stator, and a hub 10 is installed at the end of the rotating shaft 5 facing away from the stator 2. The hub 10, the rotating shaft 5 and the axis 11 of the duct 3 coincide, and the duct propeller can be installed at the tail of a ship.

[0031] The surface of the superhydrophobic layer usually has a micro-nano rough structure. When water contacts this surface, air will be trapped in the grooves of the surface microstructure. The liquid does not directly contact most of the area of the solid substrate, and only the top of the protrusions of the microstructure contacts the liquid. As Figure 3 shown, this forms a gas-liquid interface between the liquid and the solid substrate. It is precisely because there is a large area of gas-liquid interface region under the liquid that under the superhydrophobic gas-liquid interface slip effect, the wall friction resistance suffered by Newtonian fluids (such as water and seawater) when flowing over the superhydrophobic surface is significantly reduced, and a slip length and a slip velocity are generated on the superhydrophobic surface.

[0032] The tip clearance vortex is located in the separation boundary layer at the tip 8. Due to the gas-liquid interface slip effect on the surface of the first superhydrophobic layer, compared with the ducted propeller with the same-sized duct 3 and stator 2, the ducted propeller of this embodiment has an increased tip clearance vortex separation length. The scale of the tip clearance vortex depends on and is proportional to the tip clearance vortex separation length. With the vortex circulation unchanged, the increase in the vortex scale leads to an increase in the vortex core pressure. Therefore, when the tip clearance vortex separation length increases and the tip clearance vortex scale increases, the strength of the vortex structure decreases, the low-pressure area at the vortex core can be restored, the tip clearance vortex cavitation is delayed, the critical cavitation number is increased, and the onset of cavitation becomes more difficult. There is no cavitation under the original cavitation number, reducing the overall noise reduction level of the ducted propeller.

[0033] As Figure 4 shown, since the structures of the rotor 4 and the inner wall 9 of the duct 3 remain unchanged, the starting position of the tip clearance vortex remains unchanged. The tip clearance vortex separation length extends and grows towards the suction surface 7 along the three-dimensional twisting direction of the tip 8. After the tip clearance vortex separation length at the tip 8 becomes larger, the tip clearance vortex scale increases, and the tip clearance vortex moves away from the tip. When the cavitation bubble collapses, it is far from the wall surface, which can reduce the cavitation erosion of the rotor surface by the collapse of the cavitation bubble. The red color indicates the increase in the tip clearance vortex separation length.

[0034] Compared with the ducted propeller with the same-sized duct 3 and stator 2, the ducted propeller of this embodiment does not cavitate under the original cavitation number, the onset of cavitation is delayed, and the overall noise level of the ducted propeller is reduced. Due to the gas-liquid interface slip effect of the superhydrophobic layer, the cavitation position of the tip clearance vortex is far from the solid surface, and both cavitation erosion and noise are significantly reduced. Furthermore, under the critical state, the cavitation noise is significantly reduced, the cavitation onset speed is increased, and the acoustic performance of the ducted propeller is significantly improved.

[0035] For the ducted propeller of this embodiment, a first superhydrophobic layer is provided at the tip 8. By utilizing the gas-liquid interface slip effect on the surface of the first superhydrophobic layer, the separation length of the tip clearance vortex is increased, thereby delaying the tip clearance vortex cavitation, reducing noise, and weakening the cavitation erosion risk without changing the structures of the inner wall 9 of the duct 3 and the tip 8 (i.e., the vortex circulation).

[0036] Embodiment 2: For a ducted propeller based on superhydrophobic slip effect cavitation delay in this embodiment, on the basis of Embodiment 1, a second superhydrophobic layer is provided on the inner wall 9. The surface of the second superhydrophobic layer has a gas-liquid interface slip effect, and the tip clearance is the gap between the first superhydrophobic coating and the second superhydrophobic coating.

[0037] Since shear cavitation occurs in the attached boundary layer in the near-wall region of the inner wall 9 of the duct 3, and the surface of the second superhydrophobic layer on the inner wall 9 has a gas-liquid interface slip effect, by reducing the shear stress on the fluid, the onset of shear cavitation can be delayed, so that the onset of cavitation will only form at a higher rotational speed, reducing the radiated noise.

[0038] Figure 5 where U+ is the dimensionless mean flow velocity in the near-wall region, and y + represents the dimensionless normal height in the near-wall region. The straight line is the dimensionless mean flow velocity profile of Newtonian fluid in the near-wall region, which is a linear distribution function satisfying a fixed slope. Figure 5 In [reference], the black straight line represents an ordinary hydraulically smooth surface (solid surface), whose average velocity on the wall is zero. The red straight line represents the slip velocity and slip length on the wall of the superhydrophobic surface, as shown in Figure 5 The dimensionless slip velocity U + in the normal height has a downward height, which is the dimensionless slip length L + . U + and y + are expressed as follows: U + =U(y) / u * , where U(y) is the mean flow velocity along the flow direction with the normal y height, and u * is the wall friction velocity. , where τ is the wall shear stress and U ∞ is the free-stream velocity; y + =y×u * / ν, where y is the normal height, u * is the wall friction velocity, and ν is the kinematic viscosity of the fluid.

[0039] Due to the gas-liquid interface slip effect with slip velocity and slip length on the surface of the second superhydrophobic layer, the shear stress of the fluid on the wall is reduced, the shear strength is decreased, the onset of shear cavitation can be delayed, and cavitation onset will only occur at a higher rotational speed, reducing the radiation noise.

[0040] A ducted propeller based on the cavitation delay of superhydrophobic slip effect in this embodiment is provided with superhydrophobic layers on both the tip 8 of the blade and the inner wall 9 of the duct 3. By utilizing the gas-liquid interface slip effect of the superhydrophobic surface, the separation length of the tip clearance vortex is increased, the onset of tip clearance vortex cavitation is delayed, the wall shear is reduced, the onset of shear cavitation on the inner wall 9 of the duct 3 is delayed, the noise and cavitation risk are reduced, and the acoustic performance of the ducted propeller is comprehensively improved.

[0041] The ducted propeller of this embodiment is applicable to various ducted propellers and water pump impeller machinery, especially suitable for the rotor 4 and the duct 3 with high requirements for radiation noise and large tip loads. It can effectively suppress the tip clearance vortex cavitation at the tip 8 of the rotor 4 and the shear cavitation on the inner wall 9 of the duct 3, reduce the radiation noise and structural vibration noise, weaken the cavitation risk, and reduce the harm of the noise pollution generated by ship navigation to marine organisms, especially large marine organisms that rely on hearing or sonar systems for predation, and develop a green marine economy.

[0042] Exemplarily, both the first superhydrophobic layer and the second superhydrophobic layer satisfy: the hydrophobic angle is greater than or equal to 150°, and the oleophobic angle is greater than or equal to 150°. This ensures the excellent superhydrophobic performance parameters of the superhydrophobic layer, and guarantees effective slip length and slip speed.

[0043] Exemplarily, the thicknesses of both the first superhydrophobic layer and the second superhydrophobic layer are 20 μm to 50 μm. Setting a superhydrophobic layer with a certain thickness can ensure the structural strength and stability of the material, and does not affect the value of the vortex circulation.

[0044] Exemplarily, both the first superhydrophobic layer and the second superhydrophobic layer are flexible materials. Adding a buffer between the fluid and the solid can reduce the shear stress of the fluid on the solid surface.

[0045] Furthermore, the flexibility of the flexible material is greater than or equal to 1 mm. The detection standard for flexibility is GB / T 1731–93. Utilizing the excellent buffering effect of the material can improve the slip effect.

[0046] Exemplarily, the forming method of both the first superhydrophobic layer and the second superhydrophobic layer is spraying. The adhesion of the first superhydrophobic layer is grade 0 or 1, and the adhesion of the second superhydrophobic layer is grade 0 or 1. The impact resistance strengths of both the first superhydrophobic layer and the second superhydrophobic layer are greater than or equal to 25 kg·cm.

[0047] Grade 0 adhesion is the best, indicating no grid peeling and good coating adhesion. Grade 1 means that there is a little coating peeling at the intersection of the cuts, but the peeling area does not exceed 5%. The detection standard for adhesion is GB 9286–1998; The impact resistance strengths of both the first superhydrophobic layer and the second superhydrophobic layer are greater than or equal to 25 kg·cm. The detection standard for impact resistance strength is GB / T 1732–93, which ensures the anti-scouring ability of the superhydrophobic layer and can meet the operating conditions of the ducted propeller; The surfaces of the blade tip 8 and the inner wall 9 of the duct 3 can specifically be copper surfaces.

[0048] In this embodiment, the size of the tip clearance is 1 mm to 100 mm. The cavitation delay performance within this size range is significant.

[0049] Figure 6 、 Figure 7 For the comparison of the acoustic performance tests between a conventional ducted propeller of the same specification and the ducted propeller of this embodiment, the diameters of both ducted propellers are 0.24 meters. The blade tip 8 and the inner wall 9 of the duct 3 of the conventional ducted propeller are not provided with a superhydrophobic layer.

[0050] As Figure 6Among them, the radiated noise generated when the conventional duct propeller cavitates at the critical cavitation number (i.e., at the onset of cavitation) is at least 15 dB higher than the radiated noise of the duct propeller in this embodiment under the same operating conditions as the conventional duct propeller. That is, the duct propeller in this embodiment has cavitation delay.

[0051] As Figure 7 Among them, the cavitation inception speed of the duct propeller in this embodiment under its own critical cavitation number condition is at least 7% higher than the cavitation inception speed of the conventional duct propeller under its own critical cavitation number condition. That is, the cavitation inception speed is increased.

[0052] As Figure 6 、 Figure 7 As shown in

[0053] Example 3: The manufacturing method of the duct propeller based on cavitation delay by superhydrophobic slip effect in Example 2 includes the following steps: Surface treatment: The tip 8 of the blade of the rotor 4 of the duct propeller and the inner wall 9 of the duct 3 are surface-treated to remove the old paint film, rust, oil stain, oxide scale and sundries on the surface, so as to achieve no rust, no oil stain, no dust and no water mark; Protection treatment: The positions other than the upper inner wall 9 of the duct 3 are covered for protection, and the positions other than the tip 8 on the blade are covered for protection, and it can be covered with a seamless tape; Spraying: A liquid material is evenly sprayed on the tip 8 and the inner wall 9 of the duct 3. After the liquid material dries and cures, a first superhydrophobic layer is formed on the tip 8, and a second superhydrophobic layer is formed on the inner wall 9 of the duct 3. The surfaces of the first superhydrophobic layer and the second superhydrophobic layer both have the gas-liquid interface slip effect; Assembly: The rotating shaft 5 of the assembled rotor 4 is rotatably installed in the duct 3 through the stator 2 arranged in the duct 3, and a tip clearance is formed between the first superhydrophobic coating and the second superhydrophobic coating.

[0054] Example 4: The manufacturing method of the duct propeller in this embodiment is further optimized on the basis of Example 3, and includes the following steps: Surface treatment: The tip 8 of the blade of the rotor 4 of the duct propeller and the inner wall 9 of the duct 3 are surface-treated to remove the old paint film, rust, oil stain, oxide scale and sundries on the surface, so as to achieve no rust, no oil stain, no dust and no water mark.

[0055] Protection treatment: The positions other than the upper inner wall 9 of the duct 3 are covered for protection, and the positions other than the tip 8 on the blade are covered for protection, and it can be covered with a seamless tape.

[0056] Spraying: Uniformly spray liquid materials on the inner wall 9 of the blade tip 8 and the conduit 3. After the liquid materials dry and solidify, a first superhydrophobic layer is formed on the blade tip 8, and a second superhydrophobic layer is formed on the inner wall 9 of the conduit 3. The surfaces of the first superhydrophobic layer and the second superhydrophobic layer both have the gas-liquid interface slip effect; During spraying, it needs to be carried out in an environment without dust, with an exhaust device or corresponding air suction equipment. In addition, the formation of the superhydrophobic layer by spraying is mainly divided into two steps. First, form a primer coating, and second, form a surface coating. The superhydrophobic layer is formed by spraying, which is convenient for operation. The double-layer spraying method is adopted to improve the stability of the superhydrophobic layer; Among them, the liquid materials include a first liquid material and a second liquid material. Uniformly spraying the liquid materials on the inner wall 9 of the blade tip 8 and the conduit 3 includes the following steps: Uniformly spray the first liquid material on the inner wall 9 of the blade tip 8 and the conduit 3. When the first liquid material dries and solidifies, a primer coating is formed; Uniformly spray the second liquid material on the surface of the primer coating. When the second liquid material dries and solidifies, a surface coating is formed, and the surface of the surface coating has the gas-liquid interface slip effect; Finally, the primer coating and the surface coating on the blade tip 8 are superimposed and combined to form a first superhydrophobic layer, and the primer coating and the surface coating on the inner wall 9 of the conduit 3 are superimposed and combined to form a second superhydrophobic layer.

[0057] Both the primer coating and the surface coating meet the requirements that the flexibility is greater than or equal to 1 mm, the adhesion is grade 0 or 1, and the impact resistance strength is greater than or equal to 25 kg·cm.

[0058] Assembly: Rotationally install the rotating shaft 5 of the assembled rotor 4 in the conduit 3 through the stator 2 arranged in the conduit 3. A tip clearance is formed between the first superhydrophobic coating and the second superhydrophobic coating. The axes 11 of the hub 10, the rotating shaft 5, and the conduit 3 coincide. Adjust the tip clearance size evenly, and then the assembly is completed and can be used normally.

[0059] Finally, start the motor of the ducted propeller. The rotor 4 rotates to generate thrust to push the vehicle. The water flows through the ducted propeller and flows between the first superhydrophobic layer on the blade tip 8 and the second superhydrophobic layer on the inner wall 9. The superhydrophobic surfaces of the first superhydrophobic layer and the second superhydrophobic layer produce the gas-liquid interface slip effect, which is mainly manifested in the following two aspects: On the one hand, Newtonian fluids (such as water, seawater) form a slip length L + and a slip velocity U s +, reducing the wall friction resistance and translating the dimensionless average flow velocity profile in the near-wall region downward, indicating that the superhydrophobic gas-liquid interface slip effect reduces the wall shear and delays the onset of shear cavitation on the inner wall 9 of the conduit 3, as Figure 5 shown; On the other hand, Newtonian fluids (such as water and seawater) form a slip length L + and a slip velocity U s + on the superhydrophobic surface of the blade tip 8, increasing the separation length of the tip clearance vortex, increasing the scale of the tip clearance vortex structure, weakening the tip clearance vortex intensity without changing the vortex circulation, and restoring the low-pressure region at the vortex center of the tip clearance vortex, delaying the onset of tip clearance vortex cavitation, indicating that the superhydrophobic gas-liquid interface slip effect increases the separation length of the tip clearance vortex and delays the onset of tip clearance vortex cavitation, as Figure 4 shown.

[0060] Therefore, the onset of cavitation in the conduit propeller of this embodiment is delayed, significantly reducing the radiation noise, increasing the cavitation onset speed of the conduit propeller, and improving the acoustic performance of the conduit propeller, as Figure 6 , Figure 7 shown.

[0061] The schematic diagram of the process of manufacturing the conduit propeller in this embodiment and the implementation scheme for achieving cavitation delay performance is as Figure 8 shown.

[0062] A specific implementation manner of the spraying process in the manufacturing method of the conduit propeller in this embodiment is as follows: Forming a primer coating: Fully stir the first liquid material (primer) evenly. It can be applied by air spraying and can be sprayed multiple times thinly and evenly using an HVLP gun (high flow rate and low pressure, such as the German SCHUTZE S941 model). The model of the first liquid material can be JN-SS002; After spraying is completed, wait for 20 - 30 minutes. After the first liquid material (primer) dries, a primer coating is formed, and the coating thickness is 10 μm to 25 μm. During this period, a hot air gun and a hair dryer can be used to accelerate the drying of the primer.

[0063] Forming a surface coating: Fully stir the second liquid material (topcoat) evenly. Do not share the same spray gun with the primer coating. A new spray gun needs to be selected, but an HVLP gun (high flow rate and low pressure, such as the German SCHUTZE S941 model) is also used to spray the second liquid material multiple times thinly and evenly. After drying, the coating thickness is 10 μm to 25 μm. Therefore, the total thickness of the superhydrophobic layer is 20 μm to 50 μm. The model of the second liquid material can be JN-SS003.

[0064] Specifically, the spray pressure of the HVLP gun used for spraying: 0.138 Mpa to 0.241 Mpa, the nozzle diameter: 0.5 mm to 1.27 mm, the spraying distance: 15 cm to 25 cm; the construction environment temperature for spraying: 10°C to 30°C, the relative humidity: 45% to 75%; it can be sprayed after the overall assembly of the rotor 4, or the blade tip 8 of the blade can be sprayed and then assembled into the rotor 4.

[0065] After spraying is completed, let it stand and cure. The curing time is about 5 - 10 minutes. The superhydrophobic performance on the surface of the surface coating will appear 30 minutes after spraying the surface coating, and the best superhydrophobic performance is formed after 2 hours, achieving a hydrophobic angle of not less than 150°, an oleophobic angle of not less than 150°, the anti-ultraviolet duration of the first superhydrophobic layer and the second superhydrophobic layer is not less than one year, the working temperature is -31°C to 150°C, the adhesion of the superhydrophobic coating is not greater than grade 1 (i.e., the coating peeling area is less than or equal to 5%), the flexibility of the superhydrophobic coating is greater than or equal to 1 mm, the impact resistance strength is not less than 25 kg·cm, forming a superhydrophobic blade tip 8 and a superhydrophobic inner wall 9.

[0066] The above description is an interpretation of the present invention, not a limitation of the invention. For the scope defined by the present invention, refer to the claims. Any form of modification can be made within the protection scope of the present invention.

Claims

1. A duct propeller based on cavitation delay by superhydrophobic slip effect, characterized in that: Comprising: A conduit (3); A stator (2), fixedly arranged in the conduit (3); A rotor (4), the rotor (4) includes a rotating shaft (5) rotatably connected to the stator (2), and further includes a plurality of blades fixedly connected to the rotating shaft (5), and a first superhydrophobic layer is provided at the tip (8) of each blade; Wherein, a tip clearance is formed between the first superhydrophobic layer and the inner wall (9) of the conduit (3), and the surface of the first superhydrophobic layer has a gas-liquid interface slip effect.

2. The duct propeller based on cavitation delay by superhydrophobic slip effect according to claim 1, characterized in that: The inner wall (9) is provided with a second superhydrophobic layer, the surface of the second superhydrophobic layer has a gas-liquid interface slip effect, and the tip clearance is the gap between the first superhydrophobic coating and the second superhydrophobic coating.

3. The duct propeller based on cavitation delay by superhydrophobic slip effect according to claim 2, wherein: Both the first superhydrophobic layer and the second superhydrophobic layer satisfy: the hydrophobic angle is greater than or equal to 150°, and the oleophobic angle is greater than or equal to 150°.

4. The duct propeller based on cavitation delay with superhydrophobic slip effect according to claim 2, wherein: The thickness of both the first superhydrophobic layer and the second superhydrophobic layer is 20μm to 50μm.

5. The duct propeller based on cavitation delay with superhydrophobic slip effect according to claim 2, characterized in that: Both the first superhydrophobic layer and the second superhydrophobic layer are flexible materials.

6. The cavitation-delayed duct propeller based on the superhydrophobic slip effect as claimed in claim 5, wherein: The flexibility of the flexible material is greater than or equal to 1mm.

7. The duct propeller based on cavitation delay with superhydrophobic slip effect according to claim 2, wherein: The forming methods of both the first superhydrophobic layer and the second superhydrophobic layer are spraying, the adhesion of the first superhydrophobic layer is grade 0 or 1, the adhesion of the second superhydrophobic layer is grade 0 or 1, and the impact resistance strength of both the first superhydrophobic layer and the second superhydrophobic layer is greater than or equal to 25kg·cm.

8. A duct propeller based on cavitation delay with superhydrophobic slip effect according to claim 1, characterized in that: The size of the tip clearance is 1mm to 100mm.

9. A manufacturing method of a ducted propeller based on cavitation delay by superhydrophobic slip effect, characterized in that: Including the following steps: Surface treatment: Perform surface treatment on the tip (8) of the blade of the rotor (4) of the conduit paddle and the inner wall (9) of the conduit (3); Spraying: Uniformly spray a liquid material on the tip (8) and the inner wall (9) of the conduit (3). After the liquid material dries and cures, a first superhydrophobic layer is formed on the tip (8), and a second superhydrophobic layer is formed on the inner wall (9) of the conduit (3). The surfaces of the first superhydrophobic layer and the second superhydrophobic layer both have a gas-liquid interface slip effect; Assembly: Rotatably install the rotating shaft (5) of the assembled rotor (4) in the conduit (3) through the stator (2) arranged in the conduit (3), and a tip clearance is formed between the first superhydrophobic coating and the second superhydrophobic coating.

10. The manufacturing method according to claim 9, characterized in that: The liquid material includes a first liquid material and a second liquid material, Uniformly spraying the liquid material on the tip (8) and the inner wall (9) of the conduit (3) includes the following steps: Uniformly spray the first liquid material on the tip (8) and the inner wall (9) of the conduit (3). When the first liquid material dries and cures, a primer coating is formed; Uniformly spray the second liquid material on the surface of the primer coating. When the second liquid material dries and cures, a surface coating is formed, and the surface of the surface coating has a gas-liquid interface slip effect.

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