Low axial force multi-stage turbocharged axial flow pump

Abstract

This invention discloses a low-axial-force multi-stage turbocharged axial flow pump, comprising a motor, a pump cover, and a pump shaft. A connecting flange with an inlet and a water inlet is provided on the opposite side of the pump cover. Multiple composite guide vanes are fixedly installed between the connecting flange and the pump cover, loosely fitted onto the pump shaft. Each composite guide vane includes a positioning sleeve, a blade fixing ring, an inner ring, an outer guide vane, and an inner guide vane. The positioning sleeve is fixedly connected to the pump cover and / or the end of the connecting flange, and the axial length of the positioning sleeve is greater than the axial length of the blade fixing ring and the inner ring. An axial flow impeller, fitted and fixed onto the pump shaft, is provided within the positioning sleeve of each composite guide vane. The axial flow impeller includes an outer impeller column and an inner impeller column. Multiple outer guide vanes are provided on the outer impeller column, and multiple inner guide vanes are provided between the outer and inner impeller columns. The outer and inner guide vanes are oriented in opposite directions. A first guide flow annular channel and a second guide flow annular channel are formed within the housing formed by the pump cover, the composite guide vane body, and the connecting flange.

Description

Technical Field

[0001] This invention relates to the field of water pumps, and more specifically to an axial flow pump with low axial force and multi-stage turbocharging. Background Technology

[0002] Axial flow pumps are primarily suitable for low-head, high-flow-rate applications, such as waterjet propulsion in ships, dock drainage, and water level regulation in canal locks. They are also frequently used as large circulating water pumps in power plants. Because the blades of axial flow pumps are typically cantilevered, they may experience fatigue failure and other strength problems under heavy loads and cyclically unstable operation. Furthermore, with the demands of societal development, higher requirements are being placed on the reliability and stability of axial flow pumps, necessitating stable operation under high speeds and high loads.

[0003] Existing axial flow pumps mainly include: a housing assembly with an inlet and an outlet; a stator assembly housed within the housing assembly; and a rotor assembly comprising a cylindrical rotor body and blades. The rotor body is housed within the stator assembly, with both ends rotatably connected to the housing assembly. Multiple blades are circumferentially arranged on the inner wall of the rotor body. When energized, the rotor assembly can rotate relative to the stator assembly, allowing the blades to drive liquid from the inlet to the outlet. The rotatable connection of the rotor body to the housing assembly prevents axial movement of the rotor body within the housing and stator assemblies, improving the accuracy of the stator and rotor assembly's fit, increasing the rotor assembly's rotational efficiency, and ultimately improving liquid delivery efficiency. In this axial flow pump, the inlet and outlet are located at opposite ends in the axial direction. Liquid is driven axially by the blades on the rotor as it rotates, reaching the outlet. While this method results in a short liquid delivery stroke, it requires a high rotational speed to meet the axial thrust, and the axial thrust generated by the rotor is primarily produced by the rotation of a few blades, resulting in a relatively small head.

[0004] To increase the head, a multi-stage axial pump is provided, which includes a pump shaft, multiple guide vanes loosely fitted on the pump shaft, and multiple axial flow impellers fitted and fixed on the pump shaft. The guide vanes and axial flow impellers are spaced apart on the pump shaft, and the guide vanes remain fixed when the pump shaft drives the axial flow impellers to rotate. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the existing technology, the purpose of this invention is to provide a low axial force multi-stage turbocharged axial flow pump, which solves the problem that the existing axial flow pumps have a small head, and that the axial length of the multi-stage axial flow pump increases after setting multiple guide vanes and axial flow impellers, thus increasing the pump body volume.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A low axial force multi-stage turbocharged axial flow pump includes a motor, a pump cover, and a pump shaft. The motor is fixedly connected to the pump cover, and the output end of the motor is fixedly connected to the pump shaft. A connecting flange with an inlet and a water inlet is provided on the opposite side of the pump cover. At least one composite guide vane body is fixedly installed between the connecting flange and the pump cover, loosely fitted onto the pump shaft. The composite guide vane body includes a positioning sleeve, a blade fixing ring, and an inner ring arranged concentrically from the outside to the inside. The positioning sleeve is fixedly connected to the pump cover and / or the end of the connecting flange. The axial length of the positioning sleeve is greater than the axial length of the blade fixing ring and the inner ring. Outer guide vanes and inner guide vanes are provided circumferentially evenly distributed between the positioning sleeve and the blade fixing ring, and between the blade fixing ring and the inner ring, respectively. The outer guide vanes and inner guide vanes both spiral upwards in the axial direction, and the spiral directions are opposite. Each composite guide vane... Each positioning sleeve of the pump body is equipped with an axial flow impeller that is fixed to the pump shaft. The axial flow impeller includes an outer impeller and an inner impeller arranged concentrically. Multiple outer guide vanes are evenly arranged circumferentially on the outer end face of the outer impeller, and multiple inner guide vanes are arranged circumferentially between the outer impeller and the inner impeller. The outer guide vanes and the inner guide vanes both spiral upward in the axial direction, and the spiral directions are opposite. The blade fixing ring is correspondingly arranged with the outer impeller, and there is a gap between the adjacent ends. The blade fixing ring and the outer impeller form a cylinder. The outer side of the cylinder forms a first flow guiding ring channel that communicates with the inlet between the inner wall of the positioning sleeve and the inner side of the pump cover. The inner sleeve ring is correspondingly arranged with a gap between the adjacent ends. The inner sleeve ring and the inner impeller form a cylinder. The outer wall of the cylinder forms a second flow guiding ring channel between the inner wall of the cylinder and the outer wall of the cylinder. The two ends of the second flow guiding ring channel are respectively connected to the first flow guiding ring channel and the outlet. After the motor starts, the pump shaft rotates under the motor's drive, which in turn drives the axial flow impeller fitted on it to rotate. During the rotation, a pressure difference is formed between the inside and outside of the sealed cavity formed by the positioning sleeve of the composite guide vane body, the pump cover, and the connecting flange. Under this pressure difference, the liquid flows axially towards the axial flow impeller and, under the guiding action of the outer guide vane in the first guide ring, flows axially along the first guide ring until it reaches the pump cover. Then, under the opposing force of the inner guide vanes of each axial flow impeller, it is guided to the outlet on the same side as the inlet. Since the outer and inner guide vanes have different helical directions during the rotation of the axial flow impeller, but are rotating synchronously, the liquid flow direction generated in the first and second guide rings is also opposite. This not only allows the fluid to experience opposite axial forces during flow, achieving a balanced state, but also allows the liquid to generate a greater head by passing through the outer and inner guide vanes in different axial directions for the same flow axial length. Compared to an axial flow pump with the same design parameters (flow rate and head), the axial length can be reduced by half. By setting up multiple axial impellers and composite guide vanes, the head of each stage can be superimposed to achieve the boosting function without causing the rotor formed by the axial impeller and pump shaft to be subjected to too much axial force.The positioning sleeve on the composite guide vane body connects between the pump cover and the connecting flange, forming the pump casing together with the pump cover and connecting flange. Simultaneously, the axial impeller is encased within the positioning sleeve, resulting in a compact overall structure. The outer and inner guide vanes on the composite guide vane body eliminate fluid circulation and diffuse, converting some of the kinetic energy into pressure potential energy and reducing flow losses. The inner sleeve ring corresponds to the inner impeller column, and the blade fixing ring corresponds to the outer impeller column, thus forming two interconnected annular flow channels within the pump casing for fluid guidance.

[0008] Furthermore, the inner wall of the pump cover is arc-shaped at the locations corresponding to the first and second guide ring channels. This arc shape facilitates fluid passage and acts as a guide for the fluid as it passes through.

[0009] Furthermore, the outlet is a straight channel connected to the second guide ring channel. The outlet and the second guide ring channel are on the same axis. After the fluid enters the second guide ring channel from the first guide ring channel, it is directly discharged from the outlet, resulting in a short flow path and smooth fluid discharge.

[0010] Furthermore, the inlet can be a ring-shaped inlet channel or multiple arc-shaped guide channels distributed on the connecting flange. A ring-shaped inlet provides more space for external water to enter the pump, resulting in smoother and faster flow. Using multiple arc-shaped guide channels also allows for rapid circumferential fluid introduction into the pump body. While the inlet is smaller than a single ring-shaped channel, the flow rate is faster.

[0011] Furthermore, there is a gap between the end of the outer guide vane and the inner wall of the positioning sleeve. A connecting ring plate is provided at the connecting end of each positioning sleeve, and a connecting disc corresponding to the connecting ring plate is provided at the end where the pump cover connects to the positioning sleeve. Adjacent positioning sleeves, the positioning sleeve and the pump cover, and the positioning sleeve and the connecting flange are all connected and fixed by fasteners. The gap between the outer guide vane and the inner wall of the positioning sleeve prevents friction between the outer end of the axial flow guide wheel and the inner wall of the positioning sleeve during rotation.

[0012] Furthermore, the axial impeller and the pump shaft together form a rotor, and the axial force of the rotor is zero. During the rotation of the axial impeller and the pump shaft, different axial forces are generated between the outer blades and the fluid, and between the inner blades and the fluid. If the difference between the two is large, it will affect the stability of the rotor operation. However, when the forces between the two are equal or the difference is minimal, the axial force is zero, the rotor operation stability is better, and the generated vibration and noise are lower.

[0013] Furthermore, a mounting bracket is provided on both the pump cover and the connecting flange for connection. The mounting bracket provides support for the pump body, allowing it to rest flat on the ground. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of a multi-stage axial flow pump in the prior art;

[0015] Figure 2 This is a schematic diagram of the multi-stage axial flow pump in Example 1;

[0016] Figure 3 This is a schematic diagram of the multi-stage axial flow pump in Example 2;

[0017] Figure 4 This is a schematic diagram of the multi-stage axial flow pump in Example 3;

[0018] Figure 5 This is a schematic diagram of the axial flow impeller in the embodiment;

[0019] Figure 6 This is a schematic diagram of the composite guide vane body in the embodiment;

[0020] Figure 7 This is a comparison of the total head performance curves of a conventional four-stage impeller axial flow pump and a two-stage booster impeller axial flow pump in this embodiment.

[0021] Figure 8 This is a comparison of the total axial force curves of a conventional four-stage impeller axial flow pump and a two-stage booster impeller axial flow pump in this embodiment. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0023] It should be noted that similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the figures, or the orientation or positional relationship commonly used when the product is in use. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance. In addition, the terms "horizontal," "vertical," etc., do not indicate that the component is required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Example

[0024] like Figure 2 , Figure 5 , Figure 6As shown, this embodiment provides a low axial force multi-stage turbocharged axial flow pump, including a motor 1, a pump cover 2, and a pump shaft. The motor 1 is fixedly connected to the pump cover 2, and the output end of the motor 1 is fixedly connected to the pump shaft via a coupling (the pump shaft is vertically arranged). On the opposite side of the pump cover 2, there is a connecting flange 3 with an inlet 31 and a connecting flange 31. Multiple composite guide vanes 4, loosely fitted on the pump shaft, are fixedly installed between the connecting flange 3 and the pump cover 2. The composite guide vane 4 includes a positioning sleeve 41 concentrically arranged from the outside to the inside, and a blade fixing... The positioning sleeve 41 is fixedly connected to the pump cover 2 and / or the end of the connecting flange 3, with the axial length of the positioning sleeve 41 being greater than the axial length of the blade fixing ring 42 and the inner sleeve 43. External guide vanes and internal guide vanes, evenly distributed circumferentially, are respectively provided between the positioning sleeve 41 and the blade fixing ring 42, and between the blade fixing ring 42 and the inner sleeve 43. Both the external and internal guide vanes spiral upwards in the axial direction, with opposite spiral directions. An axial flow guide vane is provided within the positioning sleeve 41 of each composite guide vane body 4, and is sleeved and fixed to the pump shaft. The impeller 5, together with the pump shaft, forms a rotor, including an outer impeller 51 and an inner impeller 52 arranged concentrically (the axial heights of the outer impeller 51 and the inner impeller 52 are equal). Multiple outer guide vanes 53 are evenly arranged circumferentially on the outer end face of the outer impeller 51, and multiple inner guide vanes 54 are circumferentially arranged between the outer impeller 51 and the inner impeller 52. Both the outer guide vanes 53 and the inner guide vanes 54 spiral upwards along the axial direction, and the spiral directions are opposite. The blade fixing ring 42 is correspondingly arranged with the outer impeller 51, and adjacent ends have a gap (the gap is set at 0.5-1.5mm). Between the inner ring 42 and the outer wheel column 51, a cylinder is formed by the blade fixing ring 42 and the outer wheel column 51. The outer side of the cylinder forms a first guide ring channel 6 that is connected to the inlet 31. The inner ring 43 and the inner wheel column 52 are correspondingly arranged, with a gap between adjacent ends (the gap is set between 0.5-1.5mm). The inner ring 43 and the inner wheel column 52 form a cylinder. The outer wall of the cylinder and the inner wall of the cylinder form a second guide ring channel 7. The two ends of the second guide ring channel 7 are connected to the first guide ring channel 6 and the outlet 32, respectively. After the motor 1 starts, the pump shaft rotates under the drive of the motor 1, which in turn drives the axial flow impeller 5 sleeved on it to rotate. During the rotation, a pressure difference is formed between the positioning sleeve 41 of the composite guide vane body 4 and the sealed cavity formed by the pump cover 2 and the connecting flange 3. Under this pressure difference, the liquid flows axially towards the axial flow impeller 5 and flows axially along the first guide flow ring 6 under the guiding action of the outer guide vane 53 at the first guide flow ring 6 until it reaches the pump cover 2. Then, under the reverse action of the inner guide vane 54 of each axial flow impeller 5, it is guided to the outlet 32 ​​on the same side as the inlet 31.Because the outer guide vane 53 and the inner guide vane 54 rotate in different directions but are synchronously rotating during the rotation of the axial impeller 5, the liquid flow directions generated by the first guide ring 6 and the second guide ring 7 are also opposite. This not only allows the axial forces to be opposite during the fluid flow process, achieving a balanced state, but also allows the liquid to generate a greater head by passing through the different axial directions of the outer guide vane 53 and the inner guide vane 54 under the same flow axial length. Compared with an axial flow pump with the same design parameters (flow rate and head), the axial length can be reduced by half. After setting multiple axial impellers 5 and composite guide vane bodies 4, the head of each stage is superimposed, which can achieve the pressurization function without causing the rotor formed by the axial impeller 5 and the pump shaft to be subjected to too much axial force. The positioning sleeve 41 set on the composite guide vane body 4 is connected between the pump cover 2 and the connecting flange 3, forming the pump housing together with the pump cover 2 and the connecting flange 3. At the same time, the axial impeller 5 is covered inside the positioning sleeve 41, making the overall structure relatively compact. The outer and inner guide vanes on the composite guide vane body 4 can eliminate fluid circulation and diffuse pressure, converting some of the kinetic energy of velocity into pressure potential energy and reducing flow losses. The inner sleeve ring 43 corresponds to the inner impeller column 52, and the blade fixing ring 42 corresponds to the outer impeller column 51, thus forming two interconnected annular flow channels inside the pump casing for fluid guidance.

[0025] like Figure 2 As shown, the inner wall of the pump cover 2 is arc-shaped (arch-shaped in this embodiment to facilitate fluid diversion) at the location corresponding to the first guide ring channel 6 and the second guide ring channel 7. The side end of the connecting flange 3 has one L-shaped channel or at least two evenly distributed L-shaped channels, which form the inlet 31. In specific implementations, more than two L-shaped channels can be provided, connected to the first guide ring channel 6. The arc shape facilitates fluid passage and provides guidance during fluid flow. In this embodiment, the radial cross-section of the outer guide vane 53 and the inner guide vane 54 is airfoil-shaped, thicker in the middle and slightly thinner on both sides.

[0026] The outlet 32 ​​on the connecting flange 3 is a straight channel connected to the second guide ring channel 7, with the same diameter as the second guide ring channel 7, and is circular. The outlet 32 ​​and the second guide ring channel 7 are on the same axis. After the fluid enters the second guide ring channel 7 from the first guide ring channel 6, it is directly discharged from the outlet 32, resulting in a short flow path and smooth fluid discharge.

[0027] Furthermore, there is a gap between the end of the outer guide vane 53 and the inner wall of the positioning sleeve 41. A connecting ring plate is provided at the connecting end of each positioning sleeve 41, and a connecting disc corresponding to the connecting ring plate is provided at the end where the pump cover 2 connects to the positioning sleeve 41. Adjacent positioning sleeves 41, the positioning sleeve 41 and the pump cover 2, and the positioning sleeve 41 and the connecting flange 3 are all connected and fixed by fasteners. The gap between the outer guide vane 53 and the inner wall of the positioning sleeve 41 prevents friction between the outer end of the axial flow guide wheel and the inner wall of the positioning sleeve 41 during rotation.

[0028] Furthermore, the axial impeller 5 and the pump shaft together form a rotor, and the axial force of the rotor is zero. During the rotation of the axial impeller 5 together with the pump shaft, different axial forces are generated between the outer blades and the fluid, and between the inner blades and the fluid. If the difference between the two is large, it will affect the stability of the rotor operation. However, when the forces between the two are equal or the difference is minimal, the axial force is zero, the rotor operation stability is better, and the generated vibration and noise are lower.

[0029] Furthermore, a mounting bracket is provided on both the pump cover 2 and the connecting flange 3 to connect thereto. The mounting bracket provides support for the pump body, allowing it to rest flat on the ground.

[0030] A comparison is made between a conventional four-stage axial flow pump and the two-stage axial flow pump in this embodiment (since the axial flow impeller in this embodiment is a double-layer impeller, the first-stage impeller is equivalent to a conventional two-stage impeller, i.e.) Figure 7 , Figure 8 (Designed for low to medium axial force), in this embodiment, the total axial length of the multi-stage axial flow pump is about 3 / 4 of the total length of a conventional four-stage impeller axial flow pump, and the radial dimension is slightly larger than that of a conventional axial flow pump.

[0031] CFD simulations were used to predict the head and efficiency of a conventional four-stage impeller axial flow pump and the four-stage axial flow pump described in this application. The force exerted by the axial fluid on the impeller wall was statistically analyzed as the rotor water thrust, and the total axial force Fz of the rotor was calculated (as shown in the table below, where positive and negative values ​​represent direction, and absolute values ​​represent magnitude). Performance comparison curves and axial force comparison curves are shown below. Figure 7 , Figure 8 As shown, where Figure 7 This is a comparison chart of the total head performance curves of the axial flow pump and the conventional axial flow pump in this embodiment. Figure 8 This is a comparison diagram of the axial force of the axial flow pump and the conventional axial flow pump in this embodiment.

[0032] Simulation performance data comparison table

[0033] Relative operating condition Q / Qopt Double-layer impeller axial flow pump head / m Conventional axial flow pump head / m Double-layer impeller axial flow pump efficiency Conventional axial flow pump efficiency Axial force of double-layer impeller axial flow pump / N Axial force of conventional axial flow pump / N 0.2 45.08 50.3 0.38 0.35 -6589 -32639 0.4 33.42 37.02 0.45 0.43 -3368 -23438 0.6 24.45 27.32 0.53 0.56 -190 -19430 0.8 21.83 22.44 0.63 0.72 -908 -13300 1 20.76 24.62 0.73 0.83 -271 -11615 1.2 15.14 20.69 0.74 0.85 1337 -14068 1.4 5.14 13.59 0.67 0.82 4098 -12485

[0034] Comparison curves of head and efficiency (see details) Figure 7 , Figure 8 As can be seen, under rated operating conditions, the head of the low axial force multi-stage axial flow pump in this embodiment can meet the design requirements, the efficiency is slightly lower than that of multi-stage axial flow pumps designed by conventional methods, and the received axial force is far lower than that of conventional four-stage impeller axial flow pumps.

[0035] Specifically, the axial force comparison curve shows that the axial force calculated by the simulation at the rated point is slightly higher than the design axial force. Compared to axial flow pumps designed using conventional design methods, the axial force on the rotor of the axial flow pump designed using the low axial force hydraulic design method is lower in the range of 0.2 times the rated operating condition (0.2Qopt, where Qopt is the rated operating flow rate) to 1.4 times the rated operating condition (1.4Qopt). Under rated operating conditions, the axial force on the axial flow pump designed using the low axial force design method is about 1 / 4 that of the axial flow pump designed using the conventional design method, and at 0.2 Qopt, it is only 1 / 5 of the axial force on the axial flow pump designed using the conventional design method. The lower the axial force, the higher the structural reliability and stability. The axial length of the axial flow pump in this embodiment is also smaller than that of conventional axial flow pumps, resulting in lower axial force and smoother operation. Moreover, among axial flow pumps of the same class, the smaller axial length and similar head make it easier to transport. Example

[0036] like Figure 3 As shown, the only difference between the axial flow pump in this embodiment and that in Embodiment 1 is the structure of the connecting flange 3. Specifically, the connecting flange 3 in this embodiment includes a connecting cylinder connected to the positioning sleeve 41 at its lower end and a water guide pipe connected to the lower end of the connecting cylinder. The connecting cylinder and the positioning sleeve 41 are concentric, and their inner diameters are equal to those of the second guide channel. The connecting cylinder is fixed together by a connecting rod. An annular water inlet channel is formed between the connecting cylinder and the positioning sleeve 41, which is the water inlet 31. The hollow parts of the connecting cylinder and the water guide pipe form the water outlet 32. With the water inlet 31 being annular, there is more space for external water to enter the pump, resulting in smoother and faster flow. Setting the water inlet 31 as multiple arc-shaped guide channels can also quickly introduce fluid into the pump body circumferentially. Compared to setting an annular water inlet channel, the water inlet 31 is smaller, but the flow rate is faster than setting a single channel. Example

[0037] like Figure 4 As shown, the axial flow pump in this embodiment has the same structure as that in embodiment 1, the only difference being that the axial flow pump in this embodiment is arranged horizontally, and is a horizontal axial flow pump.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A low-axial-force multi-stage turbocharged axial flow pump, comprising a motor, a pump cover, and a pump shaft, wherein the motor is fixedly connected to the pump cover, and the output end of the motor is fixedly connected to the pump shaft, characterized in that, A connecting flange with an inlet and a water inlet is provided on the opposite side of the pump cover. At least one composite guide vane body is fixedly installed between the connecting flange and the pump cover, loosely fitted onto the pump shaft. The composite guide vane body includes a positioning sleeve, a blade fixing ring, and an inner ring arranged concentrically from the outside to the inside. The positioning sleeve is fixedly connected to the pump cover and / or the end of the connecting flange. The axial length of the positioning sleeve is greater than the axial length of the blade fixing ring and the inner ring. Outer guide vanes and inner guide vanes, evenly distributed circumferentially, are respectively provided between the positioning sleeve and the blade fixing ring, and between the blade fixing ring and the inner ring. Both the outer and inner guide vanes spiral upwards in the axial direction, and the spiral directions are opposite. An axial flow impeller, fitted and fixed onto the pump shaft, is provided within the positioning sleeve of each composite guide vane body. The impeller includes an outer impeller and an inner impeller arranged concentrically. Multiple outer guide vanes are evenly distributed circumferentially on the outer end face of the outer impeller, and multiple inner guide vanes are distributed circumferentially between the outer and inner impellers. Both the outer and inner guide vanes spiral upwards along the axial direction, with opposite spiral directions. A blade fixing ring is correspondingly arranged with the outer impeller, with a gap between adjacent ends. The blade fixing ring and the outer impeller form a cylinder. A first flow guide channel, connected to the inlet, is formed between the outer side of this cylinder, the inner wall of the positioning sleeve, and the inner side of the pump cover. An inner sleeve ring is correspondingly arranged with a gap between adjacent ends. The inner sleeve ring and the inner impeller form a cylinder. A second flow guide channel is formed between the outer wall of the cylinder and the inner wall of the cylinder. The two ends of the second flow guide channel are connected to the first flow guide channel and the outlet, respectively.

2. The low axial force multi-stage turbocharged axial flow pump according to claim 1, characterized in that, The inner wall of the pump cover is arc-shaped at the locations corresponding to the first and second guide ring channels.

3. The low axial force multi-stage turbocharged axial flow pump according to claim 1 or 2, characterized in that, The outlet is a straight channel connected to the second guide ring channel.

4. The low axial force multi-stage turbocharged axial flow pump according to claim 3, characterized in that, The inlet is a ring-shaped inlet channel or multiple arc-shaped guide channels distributed on the connecting flange.

5. The low axial force multi-stage turbocharged axial flow pump according to claim 1, 2, or 4, characterized in that, There is a gap between the end of the outer guide vane and the inner wall of the positioning sleeve. A connecting ring plate is provided at the connecting end of the positioning sleeve. A connecting plate corresponding to the connecting ring plate is provided at the end where the pump cover connects to the positioning sleeve. Adjacent positioning sleeves, positioning sleeves and pump cover, and positioning sleeves and connecting flanges are all connected and fixed by fasteners.

6. The low axial force multi-stage turbocharged axial flow pump according to claim 5, characterized in that, The axial impeller and the pump shaft together form a rotor, and the axial force of the rotor is zero.

7. The low axial force multi-stage turbocharged axial flow pump according to claim 6, characterized in that, A mounting bracket is provided on both the pump cover and the connecting flange for connection.

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