A drag reduction device for bulb tubular pump based on non-smooth surface and its using method

Abstract

This invention relates to the field of axial flow pump technology, and in particular to a drag reduction device for a bulb-type axial flow pump based on non-smooth walls and its usage method. The drag reduction device includes several connectors, several non-smooth wall devices, and passive settling control devices corresponding to each non-smooth wall device. One end of each passive settling control device is connected to the inner wall of the bulb body, and the other end is connected to the corresponding non-smooth wall device. By absorbing the fluid vibration energy during the flow process, it drives the non-smooth wall device to reciprocate along the radial direction of the bulb body. The several non-smooth wall devices are evenly arranged in the circumferential and axial directions of the bulb body, and adjacent non-smooth wall devices are in close contact with both sides of the connectors. The outer surface of each non-smooth wall device has an inwardly concave curved surface. Through this drag reduction device and its usage method, near-wall turbulent dissipation can be further reduced, turbulent resistance can be reduced, and energy efficiency can be improved.

Description

Technical Field

[0001] This invention relates to the field of cross-flow pump technology, and in particular to a drag reduction device for a bulb cross-flow pump based on a non-smooth wall surface and its usage method. Background Technology

[0002] To achieve low-resistance and high-efficiency operation of bulb-type axial flow pumps, current methods primarily focus on optimizing the bulb body structure, impeller, and guide vane morphology. For example, Chinese invention patent document CN104989653A, published on October 21, 2015, discloses a pump selection method for low-head pump devices based on the nominal average flow velocity of the impeller. This method aims to better and more extensively utilize high-performance axial flow pumps with lower specific speeds and guide vane mixed-flow pumps in low-head pump devices, thereby maximizing the hydraulic performance of the low-head pump device. Another prior art invention patent document, CN103557186A, published on February 5, 2014, discloses an axial flow pump with adjustable front guide vanes, which improves operating conditions in the saddle area through guide vane optimization. In addition, there are other methods such as adding drag-reducing agents into the pump set. For example, Chinese invention patent document with publication number CN113653643A and publication date November 16, 2021 discloses a coupling relationship between the rate of change of liquid level in the pump and the degradation rate of drag-reducing agent, so as to realize the scientific and precise automatic control of the amount and concentration of drag-reducing liquid added.

[0003] In practical use, the above-mentioned technical solutions are limited by hydraulic operation and engineering realities. It is difficult to further improve the operating efficiency by optimizing the impeller guide vanes and bulb body, while adding drag-reducing agents makes them less environmentally friendly.

[0004] In the prior art, there is also a Chinese invention patent document with publication number CN116123148A and publication date of February 20, 2023, which discloses a method for achieving energy saving and noise reduction by setting hexagonal recesses on the bulb body.

[0005] The above-mentioned technical solution presents the following problems in practical use: Creating hexagonal recesses in the bulb body requires multiple cutting operations at different locations, increasing manufacturing costs. Furthermore, since the hexagonal recesses are individual discrete bodies, they are easily clogged by sediment particles. While this technical solution can achieve a certain degree of drag reduction, the drag reduction effect still needs improvement. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a bulb-type cross-flow pump drag reduction device based on a non-smooth wall and its usage method. Combining the groove structure of a dolphin's flexible skin and a shark's dermal scutes, it can effectively absorb vibration energy in the flow field. At the same time, it can leverage the drag reduction characteristics of the dolphin's flexible skin to further reduce near-wall turbulent dissipation, reduce turbulent resistance, and improve energy efficiency, while also having a relatively low manufacturing cost.

[0007] This invention is achieved by adopting the following technical solution:

[0008] A drag reduction device for a bulb-type cross-flow pump based on a non-smooth wall includes several connectors, several non-smooth wall devices, and passive settling control devices corresponding to the non-smooth wall devices. One end of the passive settling control device is connected to the inner wall of the bulb body, and the other end is connected to the corresponding non-smooth wall device. By absorbing the fluid vibration energy during the flow process, it drives the non-smooth wall device to reciprocate along the radial direction of the bulb body. Several non-smooth wall devices are evenly arranged in the circumferential and axial directions of the bulb body, and adjacent non-smooth wall devices are in close contact with both sides of the connectors. The outer surface of the non-smooth wall device is provided with an inwardly concave curved surface.

[0009] The passive settlement control device includes a connected hydraulic cylinder and a hydraulic control terminal, which is used to control the magnitude of the force required for the settlement rod of the hydraulic cylinder to settle.

[0010] The passive settlement control devices that move upwards in the same cycle share the same hydraulic control terminal.

[0011] The bulb body includes a gradually expanding section, a cylindrical section, and a contracting section arranged in sequence, and the drag reduction device is installed in the cylindrical section of the bulb body.

[0012] The ratio of the axial length of the curved surface of the non-smooth wall device to the axial length of the bulb body is 0.0273~0.0314:1.

[0013] The ratio of the diameter-to-depth of the curved surface of the non-smooth wall device to the inner diameter of the cylindrical section is 0.0142~0.0332:1.

[0014] The inner side of the non-smooth wall device is also provided with a recessed cavity, and the passive settlement control device is installed in the recessed cavity.

[0015] The connector includes a first connector and a second connector. The first connector is disposed between two adjacent non-smooth wall devices disposed along the axial direction, and the second connector is disposed between two adjacent non-smooth wall devices disposed along the circumferential direction.

[0016] The ratio of the axial width of the first connector to the axial length of the curved surface of the non-smooth wall device is 0.0435:1; the outer surface of the first connector is arc-shaped.

[0017] The second connector extends through the axial direction of the bulb body, and the non-smooth wall devices on the same axis are respectively in close contact with one side of the same second connector.

[0018] The second connector has a central angle formed by the two sides of the connector, and the outer surface of the second connector is provided with several inwardly recessed curved sections corresponding to the adjacent non-smooth wall device. The size of the curved sections is the same as the curved surface size of the non-smooth wall device.

[0019] The central angle between two adjacent non-smooth wall devices arranged circumferentially is 0.1°~0.01°.

[0020] A method for using a bulb-shaped cross-flow pump drag reduction device based on a non-smooth wall is disclosed. The turbulent force in the flow changes with the local flow velocity. When the turbulent force is strong, the non-smooth wall device is pressed down by the force. The passive settling control device provides support and absorbs the fluid vibration energy during the flow process through settling, thereby reducing the turbulent kinetic energy and thus reducing the wall turbulent resistance. When the turbulent force is removed or weakened, the passive settling control device supports the non-smooth wall device to reset or shows a tendency to reset.

[0021] A control terminal connected to the passive settlement control device is set up to adjust the settlement force required by the passive settlement control device: when the incoming flow is less than 0.9 times the rated flow rate, the wall turbulence pulsation intensity is low, so the settlement force required by the passive settlement control device is increased to reduce the radial settlement stroke; when the incoming flow is more than 1.1 times the rated flow rate, the wall turbulence pulsation intensity is high, so the settlement force required by the passive settlement control device is decreased to form a larger radial settlement stroke.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. In this invention, the outer surface of the non-smooth wall device is provided with an inwardly concave curved surface, which can reduce wall turbulence dissipation and thus reduce turbulence resistance. At the same time, the non-smooth wall devices are evenly arranged in the circumferential and axial directions of the bulb body, so that the non-smooth wall devices are arranged in a ring shape in the radial direction and in a "wave-like" arrangement in the axial direction. In actual construction, they can be cut in one go, instead of cutting multiple times at different positions separately. Since the radial ring-shaped continuous structure is formed, the risk of radial blockage can be reduced.

[0024] Since the turbulent forces in a flow vary with the local flow velocity, and the local flow velocity changes constantly during the actual operation of a cross-flow pump (i.e., there is a pulsation intensity), the pulsation intensity controls the strength of the turbulent forces. Therefore, this invention incorporates a passive settling control device connected to a non-smooth wall surface device. When the turbulent forces in a certain area are strong at a certain moment, the passive settling control device is forced to settle to absorb pressure and reduce turbulent kinetic energy, thereby reducing the wall surface turbulent resistance. When the turbulent forces in that area are weak at a certain moment, the pressure on the passive settling control device decreases, causing the passive settling control device to reset or tend to reset, and this process repeats.

[0025] By combining the non-smooth wall device with the passive settling control device, the non-smooth wall device can characterize the dermal fins of a shark, thereby reducing viscous drag and turbulent drag during flow. The passive settling control device can characterize the flexible skin of a dolphin, absorbing vibrational energy in the flow field and leveraging the drag-reducing properties of the flexible skin to further reduce near-wall turbulent dissipation, lower turbulent drag, and improve energy efficiency and operational stability.

[0026] 2. Since the intensity of turbulent pulsation varies with different pump types and operating conditions, i.e. the magnitude of turbulent force applied by the fluid to the wall varies, the hydraulic control end can be set to adjust the magnitude of the compression force, i.e., adjust the pressure damping, to cope with the magnitude of vibration energy under different operating conditions, so that the passive settlement control device can be driven to settle under the turbulent force under different operating conditions, thus realizing the "flexible wall" function.

[0027] 3. The passive settling control devices in the same circumferential direction share the same hydraulic control end, which makes the non-smooth wall device in this invention reciprocate in the radial direction in units of rings. When the fluid impacts, it can absorb the vibration energy in the flow field more evenly and the drag reduction effect is also better.

[0028] 4. The drag reduction device is installed in the cylindrical section of the bulb body, making the structural layout more reasonable.

[0029] 5. By designing the dimensions of the curved surface's axis length and diameter depth, drag reduction performance can be better guaranteed.

[0030] 6. The passive settlement control device is set inside the recessed cavity, which can ensure the compression movement of the non-smooth wall device, ensuring sufficient compression space while avoiding getting stuck in the passive settlement control device.

[0031] 7. The arrangement of the first and second connecting parts ensures the structural and operational stability of the non-smooth wall surface device. The non-smooth wall surface devices on the same axis are closely connected to one side of the same second connecting part, simplifying the structure and further improving stability.

[0032] 8. The two sides of the second connector are enclosed to form a central angle, which makes the second connector form an arc-shaped structure, which helps to distribute force and displacement more evenly and better adapt to the circular structure of the bulb body.

[0033] 9. The outer surface of the second connector is provided with several inwardly recessed curved sections, and the size of the curved sections is the same as the size of the curved surface of the non-smooth wall device, which can better ensure the drag reduction performance.

[0034] 10. The central angle between two adjacent non-smooth wall devices arranged circumferentially is 0.1°~0.01°. The specific central angle can be determined according to the size of the bulb body, which can ensure that the non-smooth wall device exists as a small independent structure.

[0035] 11. By using this drag reduction device, a near-flexible characteristic of a non-smooth wall surface can be achieved, enabling it to absorb vibration energy in the flow field. At the same time, it can also leverage the drag reduction characteristics of a dolphin-like flexible skin, further reducing near-wall turbulent dissipation, lowering turbulent resistance, and improving energy efficiency.

[0036] 12. This method of use can also be adjusted by setting a control terminal to adjust the settlement force required by the passive settlement control device in order to cope with the magnitude of vibration energy under different working conditions. Attached Figure Description

[0037] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, wherein:

[0038] Figure 1 This is a three-dimensional schematic diagram of the arrangement of the non-smooth wall surface device in this invention;

[0039] Figure 2 This is a schematic diagram of the arrangement of the non-smooth wall device in the circumferential direction in this invention;

[0040] Figure 3 This is a cross-sectional schematic diagram showing the drag reduction device arranged along the axial direction in this invention.

[0041] Figure 4 This is a cross-sectional schematic diagram of the drag reduction device arranged along the circumferential direction in this invention;

[0042] Figure 5 This is a schematic cross-sectional view of the drag reduction device in this invention;

[0043] Figure 6 This is a schematic diagram of the structure of the second connector in this invention;

[0044] Figure 7 This is a schematic diagram of the arrangement of the present invention on the rear-mounted long olive-shaped bulb body;

[0045] Figure 8 This is a numerical simulation diagram of drag reduction according to the present invention;

[0046] Marked in the image:

[0047] 1. Non-smooth wall device; 2. Passive settlement control device; 3. Cylinder; 4. Settlement rod; 5. Hydraulic control end; 6. Expanding section; 7. Cylindrical section; 8. Contracting section; 9. First connecting piece; 10. Second connecting piece; 11. Curved section; 12. Recessed cavity. Detailed Implementation

[0048] Example 1

[0049] As a basic embodiment of the present invention, the present invention includes a bulb-type flow pump drag reduction device based on a non-smooth wall surface, comprising several connectors, several non-smooth wall surface devices 1, and passive settling control devices 2 corresponding to the non-smooth wall surface devices 1 one by one. One end of the passive settling control device 2 is connected to the inner wall of the bulb body, and the other end is connected to the corresponding non-smooth wall surface device 1. By absorbing the fluid vibration energy during the flow process, it drives the non-smooth wall surface device 1 to reciprocate along the radial direction of the bulb body.

[0050] Several non-smooth wall devices 1 are evenly arranged in the circumferential and axial directions of the bulb body. The outer surface of each non-smooth wall device 1 has an inwardly concave curved surface, and the outer surface of each non-smooth wall device 1 constitutes the outer wall of the bulb body. Adjacent non-smooth wall devices 1 are in close contact with both sides of a connector, which is fixed to the inner wall of the bulb body. Relative movement can occur between the non-smooth wall devices 1 and the connector.

[0051] Example 2

[0052] In a preferred embodiment of the present invention, the present invention includes a bulb-type flow pump drag reduction device based on a non-smooth wall surface, comprising several connectors, several non-smooth wall surface devices 1, and passive settling control devices 2 corresponding to each non-smooth wall surface device 1. The passive settling control device 2 may include a connected hydraulic cylinder and a hydraulic control terminal 5. The hydraulic cylinder is fixed to the inner wall of the bulb body, and the other end of the settling rod 4 of the hydraulic cylinder is connected to the inner wall of the corresponding non-smooth wall surface device 1. The hydraulic control terminal 5 is used to control the magnitude of the force required for the settling rod 4 of the hydraulic cylinder to settle. By absorbing the fluid vibration energy during the flow process, the settling rod 4 extends and retracts, driving the non-smooth wall surface device 1 to reciprocate along the radial direction of the bulb body.

[0053] Several non-smooth wall surface devices 1 are uniformly arranged in the circumferential and axial directions of the bulb body. The outer surface of each non-smooth wall surface device 1 has an inwardly concave curved surface, which constitutes the outer wall of the bulb body. The ratio of the axial length of the curved surface of the non-smooth wall surface device 1 to the axial length of the bulb body is 0.0273~0.0314:1, and the ratio of the diameter depth of the curved surface of the non-smooth wall surface device 1 to the inner diameter of the bulb body's cylindrical section 7 is 0.0142~0.0332:1.

[0054] The two adjacent non-smooth wall devices 1 are respectively in close contact with the two sides of the connector. The connector is fixed on the inner wall of the bulb body, and the non-smooth wall device 1 and the connector can move relative to each other.

[0055] Example 3

[0056] In another preferred embodiment of the present invention, the present invention includes a bulb-type flow pump drag reduction device based on a non-smooth wall surface, comprising several connectors, several non-smooth wall surface devices 1, and passive settling control devices 2 corresponding to each non-smooth wall surface device 1. One end of the passive settling control device 2 is connected to the inner wall of the bulb body, and the other end is connected to the corresponding non-smooth wall surface device 1. By absorbing the fluid vibration energy during the flow process, it drives the non-smooth wall surface device 1 to reciprocate along the radial direction of the bulb body. Specifically, the passive settling control device 2 can be a conventional spring damper in the art. The passive settling control device 2 provides a certain supporting force when the non-smooth wall surface device 1 is pressed down, and when the force is removed or weakened, it can support the non-smooth wall surface device 1 to reset or exhibit a reset tendency, thereby realizing the "flexible wall surface" function.

[0057] Several non-smooth wall surface devices 1 are evenly arranged in the circumferential and axial directions of the bulb body. The outer surface of each non-smooth wall surface device 1 is a concave curved surface, forming the outer wall of the bulb body. Adjacent non-smooth wall surface devices 1 are in close contact with both sides of a connecting member. Specifically, the connecting member includes a first connecting member 9 and a second connecting member 10. Several first connecting members 9 are respectively disposed between two adjacent non-smooth wall surface devices 1 arranged in the axial direction, and several second connecting members 10 are respectively disposed between two adjacent non-smooth wall surface devices 1 arranged in the circumferential direction. Both the first connecting members 9 and the second connecting members 10 are fixed to the inner wall of the bulb body, allowing relative movement between the non-smooth wall surface devices 1 and the connecting members.

[0058] Example 4

[0059] As the preferred embodiment of the present invention, the present invention includes a drag reduction device for a bulb-shaped cross-flow pump based on a non-smooth wall surface. (See attached specification.) Figure 7The bulb body comprises a gradually expanding section 6, a cylindrical section 7, and a converging section 8 arranged sequentially. Since the gradually expanding section 6 and the converging section 8 of the bulb body have tapered sides with an angle, it is difficult to install drag-reducing devices. Furthermore, the gradually expanding section 6 contains devices such as a drive motor, making its internal space valuable and unsuitable for drag-reducing devices that would encroach on this space. Therefore, this invention places the drag-reducing device in the cylindrical section 7, which resembles a column. The drag-reducing device includes several connectors, several non-smooth wall devices 1, and passive settlement control devices 2 corresponding to each non-smooth wall device 1. The passive settlement control device 2 is located between the non-smooth wall device 1 and the inner wall of the bulb body, connecting the two.

[0060] The outer surface of the non-smooth wall device 1 forms the outer wall of the bulb body and is in direct contact with the fluid in the flow channel. (Refer to the attached instruction manual.) Figure 5 The outer surface of the non-smooth wall device 1 has an inwardly concave curved surface with a large-arc, wave-like shape, which reduces turbulent resistance by reducing wall turbulence dissipation. The ratio of the axial length of the curved surface of the non-smooth wall device 1 to the axial length of the bulb body is 0.0273~0.0314:1. The ratio of the diameter-depth of the curved surface of the non-smooth wall device 1 to the inner diameter of the cylindrical section 7 is 0.0142~0.0332:1. Here, the axial length of the curved surface refers to its axial length, and the axial length of the bulb body is the sum of the axial lengths of the expanding section 6, the cylindrical section 7, and the contracting section 8. Preferably, the non-smooth wall device 1 is made of wear-resistant, corrosion-resistant, and rust-resistant stainless steel.

[0061] Furthermore, the inner side of the non-smooth wall device 1 is also provided with a recessed cavity 12. The recessed cavity 12 is connected to and located outside the passive settlement control device 2. The passive settlement control device 2 is set inside the recessed cavity 12 and can accommodate the passive settlement control device 2 in a compressed state. This ensures the compression movement of the non-smooth wall device 1, guaranteeing sufficient compression space while avoiding jamming of the passive settlement control device 2. The passive settlement control device 2 includes a connected hydraulic cylinder and a hydraulic control end 5. The hydraulic cylinder includes a settlement rod 4 and a cylinder body 3. The settlement rod 4 can be a miniature hydraulic settlement rod 4. The miniature hydraulic compressibility absorbs the fluid vibration energy during the flow process, ensuring stable operation of the bulb body and improving its service life. Specifically, the miniature hydraulic settlement rod 4 is a radial motion rod that can reciprocate radially and is fixedly connected to the non-smooth wall device 1. The cylinder body 3 is a receiving end that provides a radial motion guide for the miniature hydraulic settlement rod 4, ensuring that it only reciprocates radially and accommodating the radial motion rod in a compressed state. Preferably, a high-precision, long-life miniature hydraulic device is used.

[0062] Refer to the instruction manual appendix Figure 1Several non-smooth wall surface devices 1 are evenly arranged in the circumferential and axial directions of the bulb body, such that the non-smooth wall surface devices 1 are arranged in a ring shape in the radial direction and in a "wave-like" arrangement in the axial direction. (Refer to the attached instruction manual.) Figure 2 The hydraulic control terminal 5 is located inside the inner wall of the bulb body, and all the miniature hydraulic sinking rods 4 distributed circumferentially in the same radial direction are connected to the same hydraulic control terminal 5. The magnitude of the force required for the miniature hydraulic sinking rods 4 to sink is controlled by hydraulic action to cope with the magnitude of vibration energy under different working conditions.

[0063] When the incoming flow is low (less than 0.9 times the rated flow), the wall turbulence pulsation intensity is low, so the force required for settlement is increased, the wall settlement is reduced, the radial settlement stroke is decreased, and the drag increase effect of the non-smooth wall surface under low flow conditions is weakened. When the incoming flow is high (more than 1.1 times the rated flow), the wall turbulence pulsation intensity is high, so the force required for settlement is reduced, so as to form a larger radial settlement stroke and absorb more vibration energy.

[0064] The connector includes a first connector 9 and a second connector 10. (See attached instruction manual.) Figure 3 The first connector 9 is disposed between two adjacent non-smooth wall surface devices 1 arranged along the axial direction. The first connector 9 is fixedly connected to the inner wall surface of the bulb body and in close contact with the non-smooth wall surface device 1. The first connector 9 can be constructed from a vertical plate with a small radius of curvature. Preferably, the ratio of the axial width of the first connector 9 to the axial length of the curved surface of the non-smooth wall surface device 1 is 0.0435:1. The small radius of curvature refers to the small radius formed by rotating the first connector 9 coaxially with the central axis of the bulb body, about the radius from the central axis to the outer edge of the first connector 9, thus making the outer surface of the first connector 9 arc-shaped. Preferably, the first connector 9 is made of a corrosion-resistant, smooth-surfaced material.

[0065] Refer to the instruction manual appendix Figure 4 The second connecting member 10 is disposed between two adjacent non-smooth wall surface devices 1 arranged in the circumferential direction, and the second connecting member 10 extends through the axial direction of the bulb body, so that a plurality of second connecting members 10 can be spaced apart in the circumferential direction of the bulb body. The second connecting member 10 is fixed to the inner wall surface of the bulb body and is in close contact with the non-smooth wall surface device 1. Furthermore, the non-smooth wall surface devices 1 on the same axis are respectively in close contact with one side of the same second connecting member 10. The two sides of the second connecting member 10, i.e., the two sides in close contact with the non-smooth wall surface device 1, form a central angle, as shown in the appendix to the specification. Figure 6The outer surface of the second connector 10 is provided with several inwardly recessed curved sections 11 corresponding to the adjacent non-smooth wall device 1. The dimensions of the curved sections 11 are the same as the dimensions of the curved surface of the non-smooth wall device 1, that is, the axial length and diameter depth of the curved sections 11 are the same as those of the curved surface of the non-smooth wall device 1. The second connector 10 is made of a corrosion-resistant, smooth-surfaced material.

[0066] In this embodiment, the tight connection specifically refers to the sealing connection achieved through precision machining. Even if there is a small amount of water seepage, the passive settlement control device 2 has waterproof capabilities and will not affect the overall function.

[0067] Furthermore, the central angle between two adjacent non-smooth wall devices 1 arranged circumferentially is 0.1°~0.01°, and the specific central angle is determined by the size of the bulb body; the larger the bulb body size, the smaller the equal angle value; the smaller the bulb body size, the larger the equal angle value; to ensure that the non-smooth wall device 1 exists with a smaller independent structure.

[0068] The above structure reduces viscous and turbulent resistance during flow, while passive settling control via the non-smooth wall device 1 absorbs fluid vibration energy, improving unit operational stability. Specifically, numerical calculations are performed using ANASYS CFX, yielding the results shown in the appendix to the manual. Figure 8 As can be seen from the cloud diagram, the non-smooth wall device 1 can effectively reduce the resistance of the bulb body wall, achieving the purpose of reducing resistance and increasing efficiency.

[0069] Example 5

[0070] As another preferred embodiment of the present invention, the present invention includes a method of using a bulb-shaped cross-flow pump drag reduction device based on any of the above embodiments 1 to 4. The turbulent force in the flow changes with the local flow velocity. When the turbulent force is strong, the non-smooth wall device 1 is pressed down by the force. The passive settling control device 2 provides support and absorbs the fluid vibration energy during the flow process through settling, thereby reducing the turbulent kinetic energy and reducing the wall turbulent resistance. When the turbulent force is removed or weakened, the passive settling control device 2 supports the non-smooth wall device 1 to reset or shows a reset trend.

[0071] Example 6

[0072] As another preferred embodiment of the present invention, this invention further supplements and explains the usage method based on Embodiment 5. Since the turbulent pulsation intensity varies with different pump types and operating conditions, i.e., the magnitude of the turbulent force exerted by the fluid on the wall varies, this usage method additionally sets up a control terminal to adjust the pressure damping, so that the settling device can be driven to settle under different operating conditions by the turbulent force, achieving the "flexible wall" function. Specifically, when the incoming flow is small, i.e., less than 0.9 times the rated flow, the wall turbulent pulsation intensity is low. The settling force required by the passive settling control device 2 is increased to reduce the radial settling stroke and weaken the resistance increase effect of the non-smooth wall under small flow conditions. When the incoming flow is large, i.e., more than 1.1 times the rated flow, the wall turbulent pulsation intensity is high. The settling force required by the passive settling control device 2 is decreased to form a larger radial settling stroke and absorb more vibration energy.

[0073] In summary, any other corresponding modifications made by those skilled in the art after reading this invention document, without requiring creative mental effort, based on the technical solutions and concepts of this invention, are all within the scope of protection of this invention.

Claims

1. A drag reduction device for a bulb-type axial flow pump based on a non-smooth wall surface, characterized in that: It includes several connectors, several non-smooth wall devices (1), and passive settling control devices (2) corresponding to each non-smooth wall device (1); one end of the passive settling control device (2) is connected to the inner wall of the bulb body, and the other end is connected to the corresponding non-smooth wall device (1). By absorbing the fluid vibration energy during the flow process, it drives the non-smooth wall device (1) to move back and forth along the radial direction of the bulb body; several non-smooth wall devices (1) are evenly arranged in the circumferential and axial directions of the bulb body, and the two adjacent non-smooth wall devices (1) are respectively in close contact with the two sides of the connectors; the outer surface of the non-smooth wall device (1) is provided with an inwardly concave curved surface.

2. The drag reduction device for a bulb-type axial flow pump based on a non-smooth wall surface according to claim 1, characterized in that: The passive settlement control device (2) includes a connected hydraulic cylinder and a hydraulic control end (5), the hydraulic control end (5) being used to control the magnitude of the force required for the settlement rod (4) of the hydraulic cylinder to settle.

3. The drag reduction device for a bulb-type axial flow pump based on a non-smooth wall surface according to claim 2, characterized in that: The passive settlement control device (2) in the same upward direction shares the same hydraulic control terminal (5).

4. The drag reduction device for a bulb-type axial flow pump based on a non-smooth wall surface according to claim 1, characterized in that: The bulb body includes a gradually expanding section (6), a cylindrical section (7), and a contracting section (8) arranged in sequence, and the drag reduction device is arranged in the cylindrical section (7) of the bulb body.

5. The drag reduction device for a bulb-type axial flow pump based on a non-smooth wall surface according to claim 4, characterized in that: The ratio of the axial length of the curved surface of the non-smooth wall device (1) to the axial length of the bulb body is 0.0273~0.0314:

1.

6. The drag reduction device for a bulb-type axial flow pump based on a non-smooth wall surface according to claim 4, characterized in that: The ratio of the diameter of the curved surface of the non-smooth wall device (1) to the inner diameter of the cylindrical section (7) is 0.0142~0.0332:

1.

7. The drag reduction device for a bulb-type axial flow pump based on a non-smooth wall surface according to claim 1, characterized in that: The non-smooth wall device (1) is further provided with a recessed cavity (12) on its inner side, and the passive settlement control device (2) is installed in the recessed cavity (12).

8. The drag reduction device for a bulb-type axial flow pump based on a non-smooth wall surface according to claim 1, characterized in that: The connector includes a first connector (9) and a second connector (10). The first connector (9) is disposed between two adjacent non-smooth wall devices (1) disposed along the axial direction, and the second connector (10) is disposed between two adjacent non-smooth wall devices (1) disposed along the circumferential direction.

9. The drag reduction device for a bulb-type axial flow pump based on a non-smooth wall surface according to claim 8, characterized in that: The ratio of the axial width of the first connector (9) to the axial length of the curved surface of the non-smooth wall device (1) is 0.0435:1; the outer surface of the first connector (9) is arc-shaped.

10. The drag reduction device for a bulb-type axial flow pump based on a non-smooth wall surface according to claim 8, characterized in that: The second connector (10) extends through the axial direction of the bulb body, and the non-smooth wall device (1) on the same axis is in close contact with one side of the same second connector (10).

11. The drag reduction device for a bulb-type axial flow pump based on a non-smooth wall surface according to claim 10, characterized in that: The second connector (10) has a central angle formed by the two sides of the connector, and the outer surface of the second connector (10) is provided with a number of inwardly recessed curved sections (11) corresponding to the adjacent non-smooth wall device (1). The size of the curved section (11) is the same as the curved size of the non-smooth wall device (1).

12. The drag reduction device for a bulb-type axial flow pump based on a non-smooth wall surface according to claim 1, characterized in that: The central angle between two adjacent non-smooth wall devices (1) arranged along the circumference is 0.01°~0.1°.

13. A method of using a bulb-type flow pump drag reduction device based on a non-smooth wall surface as described in any one of claims 1 to 12, characterized in that: The turbulent force in the flow changes with the local flow velocity. When the turbulent force is strong, the non-smooth wall device (1) is pressed down by the force. The passive settling control device (2) provides support and absorbs the fluid vibration energy during the flow process through settling, thereby reducing the turbulent kinetic energy and reducing the wall turbulent resistance. When the turbulent force is removed or weakened, the passive settling control device (2) supports the non-smooth wall device (1) to reset or shows a reset trend.

14. The method of using the bulb-type cross-flow pump drag reduction device based on a non-smooth wall surface according to claim 13, characterized in that: Set up a control terminal connected to the passive settlement control device (2) to adjust the settlement force required by the passive settlement control device (2): when the incoming flow is less than 0.9 times the flow rate under rated conditions, the wall turbulence pulsation intensity is low, so increase the settlement force required by the passive settlement control device (2) to reduce the radial settlement stroke; when the incoming flow is more than 1.1 times the flow rate under rated conditions, the wall turbulence pulsation intensity is high, so decrease the settlement force required by the passive settlement control device (2) to form a larger radial settlement stroke.

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