A structure for balancing radial forces of multi-stage side channel pumps

Abstract

The present invention discloses a structure for balancing the radial force of a multi-stage side flow channel pump, the structure being a transition section flow channel, the transition section flow channel being arranged between the secondary side flow channel and the tertiary side flow channel; the transition section flow channel being provided with a transition section flow channel inlet, a transition section flow channel outlet, and an arc-shaped flow channel; the transition section flow channel inlet being arranged opposite to the secondary side flow channel outlet, the transition section flow channel outlet being arranged opposite to the tertiary side flow channel inlet, the arc-shaped flow channel being rotated with the transition section flow channel inlet as the starting point in the direction of rotation of the pump impeller until it is connected to the transition section flow channel outlet; the line connecting the center of the transition section flow channel outlet and the center of the secondary side flow channel inlet is connected to the rotation center line of the multi-stage side flow channel pump, so that the circumferential phase difference between the tertiary side flow channel inlet and the secondary side flow channel inlet is 180°, so that the radial forces applied to the secondary side flow channel pump and the tertiary side flow channel pump at the same time are in opposite directions, thereby balancing the radial forces of the secondary side flow channel pump and the tertiary side flow channel pump during operation.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-stage side channel pump design in fluid mechanical equipment, in particular to a structure for balancing radial forces of the multi-stage side channel pump. Background Art

[0002] Due to the poor cavitation performance of single-stage side channel pumps, multi-stage side channel pumps with a centrifugal impeller in the first stage are mostly used in practical engineering applications. Side channel pumps have an extremely low specific speed, generally ranging from 9 to 40. Their simple structure and compact size offer low flow rates and high head. They are radial vane pumps, a type of vortex pump, intermediate between positive displacement and centrifugal pumps. Due to the spiral fluid motion path, side channel pumps experience significant hydraulic losses and generally low pump efficiency, typically between 20% and 40%. Furthermore, radial force is the primary excitation force during operation of multi-stage side channel pumps. Due to the significant pressure differential between the impeller outlet and the impeller inlet, a large radial force is generated on the blades. The overall radial force fluctuation amplitude is much greater than that of a centrifugal impeller. Furthermore, the flow pattern of side channel pumps prevents the radial forces from canceling out as they do in centrifugal impellers. This results in high radial forces in side channel pumps, seriously impacting their operational safety and stability.

[0003] The study found that when the existing multi-stage side channel pump with a centrifugal impeller in the first stage and side channel impellers in the secondary and third stages is working, the magnitude of the radial force in the secondary and third stage side channel pumps is almost the same, and the period of their fluctuation is exactly the same. At the same time, the direction of the radial force in the secondary and third stage side channel pumps is also almost the same, resulting in the superposition of the radial forces in the secondary and third stage side channel pumps to produce a larger radial force. The excessive radial force affects the working performance and service life of the multi-stage side channel pump. Therefore, it is urgent to design a structure to balance the radial forces in the secondary and third stage side channel pumps. Summary of the Invention

[0004] In response to the problem of excessive radial force within a multi-stage side channel pump during operation, which has a centrifugal impeller in the first stage and side channel impellers in the secondary and tertiary stages, the present invention provides a structure for balancing the radial force of the multi-stage side channel pump. By adding a transition section between the secondary and tertiary side channels, the circumferential phase difference between the inlet of the tertiary side channel and the inlet of the secondary side channel is 180°, so that the radial forces acting on the secondary and tertiary side channel impellers at the same time are in opposite directions, thereby balancing the radial forces acting on the secondary and tertiary side channel impellers during operation of the multi-stage side channel pump.

[0005] The technical solution adopted by the present invention is:

[0006] A structure for balancing the radial force of a multi-stage side flow channel pump, the structure being a transition section flow channel, the transition section flow channel being arranged between the secondary side flow channel and the tertiary side flow channel; the transition section flow channel being provided with a transition section flow channel inlet and a transition section flow channel outlet respectively located on both sides, and an arc-shaped flow channel being arranged inside the transition section flow channel and connecting the transition section flow channel inlet and the transition section flow channel outlet; the transition section flow channel inlet being arranged opposite the secondary side flow channel outlet, the transition section flow channel outlet being arranged opposite the tertiary side flow channel inlet, the arc-shaped flow channel being rotated with the transition section flow channel inlet as the starting point in the direction of rotation of the pump impeller until it is connected with the transition section flow channel outlet, so that the flow direction of the fluid in the arc-shaped flow channel is the same as the rotation direction of the pump impeller; the line connecting the center of the transition section flow channel outlet and the center of the secondary side flow channel inlet is the rotation center line of the multi-stage side flow channel pump, so that the circumferential phase difference between the tertiary side flow channel inlet and the secondary side flow channel inlet is 180°.

[0007] Furthermore, the transition section flow channel inlet and the transition section flow channel outlet are circular holes, the transition section flow channel inlet diameter is equal to the width of one end of the arc-shaped flow channel connected to the transition section flow channel inlet, and the transition section flow channel outlet diameter is equal to the width of one end of the arc-shaped flow channel connected to the transition section flow channel outlet.

[0008] Furthermore, the width of the arc-shaped flow channel gradually shrinks / expands from the width of one end communicating with the inlet of the transition section flow channel to the width of one end communicating with the outlet of the transition section flow channel.

[0009] Furthermore, the distance from each point on the arc-shaped flow channel to the rotation center of the multi-stage side flow channel pump gradually increases / decreases from the end connected to the transition section flow channel inlet to the end connected to the transition section flow channel outlet.

[0010] Furthermore, the axial cross-section of the arc-shaped flow channel is rectangular.

[0011] Furthermore, the outer dimensions of the transition section flow channel match those of the secondary side flow channel and the tertiary side flow channel.

[0012] The beneficial effects of the present invention are:

[0013] The present invention adds a transition section flow channel between the secondary side flow channel and the tertiary side flow channel, and the line connecting the center of the transition section flow channel outlet and the center of the secondary side flow channel inlet crosses the rotation center line of the multi-stage side flow channel pump, so that after the transition section flow channel is installed between the secondary side flow channel and the tertiary side flow channel, the circumferential phase difference between the tertiary side flow channel inlet and the secondary side flow channel inlet is 180°, thereby staggering the radial force fluctuation period of the secondary side flow channel impeller and the tertiary side flow channel impeller by 180°, that is, the radial forces exerted on the secondary side flow channel impeller and the tertiary side flow channel impeller at the same time are in opposite directions, so that the radial forces of the two cancel each other out and balance the radial forces of the two, greatly reducing the risk of radial runout of the side flow channel pump and improving the operating safety and stability of the multi-stage side flow channel pump. In addition, only the transition section flow channel needs to be added between the secondary side flow channel and the tertiary side flow channel and installed accordingly during assembly. The design of other parts of the original multi-stage side flow channel pump does not need to be modified, the operation is simple, and the overall structure of the multi-stage side flow channel pump is less affected. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the main view of the transition section flow channel of the present invention.

[0015] Figure 2 This is a rear view of the transition section flow channel of the present invention.

[0016] Figure 3 This is a top view of the transition section flow channel of the present invention.

[0017] Figure 4 For the present invention Figure 1 Cross-sectional view in the AA direction.

[0018] Figure 5 For the present invention Figure 1 Cross-sectional view in the BB direction.

[0019] Figure 6 For the present invention Figure 3 Cross-sectional view in CC direction.

[0020] Figure 7 This is a schematic diagram of the assembly of the transition section flow channel, the secondary side flow channel, and the tertiary side flow channel of the present invention. The arrow direction in the figure represents the direction of fluid flow.

[0021] Figure 8 This is a schematic diagram of the fluid domain of the transition section flow channel, the secondary side flow channel, and the tertiary side flow channel of the present invention. The arrow direction in the figure represents the fluid flow direction.

[0022] Figure 9 These are the radial force curves of the impellers at each stage of the three-stage side channel pump when the transition section flow channel is not installed, where (a) is the first-stage centrifugal radial force curve, (b) is the secondary side channel impeller radial force curve, and (c) is the third-stage side channel impeller radial force curve.

[0023] Figure 10 Streamline diagram of the impeller in a side channel pump.

[0024] Figure 11 After installing the transition section flow channel of the present invention, 10m 3 / h flow rate, the radial force curves of the secondary side channel impeller and the third side channel impeller in the x and y directions respectively, where (a) is the radial force curve in the x direction, and (b) is the radial force curve in the y direction.

[0025] In the figure, 1. transition section flow channel, 11. transition section flow channel inlet, 12. transition section flow channel outlet, 13. arc flow channel, 2. secondary side flow channel, 21. secondary side flow channel inlet, 22. secondary side flow channel outlet, 3. tertiary side flow channel, 31. tertiary side flow channel inlet, 4. secondary side flow channel impeller. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below with reference to the specific embodiments of the drawings, but the protection scope of the present invention is not limited thereto.

[0027] The structure for balancing the radial force of the multi-stage side channel pump described in the present invention is a transition section channel 1. The transition section channel 1 is arranged between the secondary side channel 2 and the tertiary side channel 3, and the outer dimensions of the transition section channel 1 match the outer dimensions of the secondary side channel 2 and the tertiary side channel 3. This facilitates the installation of the transition section channel 1 between the secondary side channel 2 and the tertiary side channel 3, while also preventing the installation of the transition section channel 1 from affecting the normal operation of the secondary side channel 2 and the tertiary side channel 3. The transition section channel 1 is provided with a transition section channel inlet 11 and a transition section channel outlet 12 located on both sides, respectively, as well as an arc-shaped channel 13 arranged inside the transition section channel 1 and connecting the transition section channel inlet 11 and the transition section channel outlet 12. The transition section flow channel inlet 11 is positioned directly opposite the secondary-side flow channel outlet 22. It is a circular hole with a diameter equal to the width of the secondary-side flow channel outlet 22. The transition section flow channel outlet 12 is positioned directly opposite the tertiary-side flow channel inlet 31. It is a circular hole with a diameter equal to the width of the tertiary-side flow channel inlet 31. This prevents sudden changes in flow channel size from affecting fluid flow, and suppresses the formation of vortices caused by such changes. The diameter of the transition section flow channel inlet 11 is equal to the width of the end of the arc-shaped flow channel 13 connected to the transition section flow channel inlet 11, and the diameter of the transition section flow channel outlet 12 is equal to the width of the end of the arc-shaped flow channel 13 connected to the transition section flow channel outlet 12. This also avoids the flow of fluid being affected by the sudden change in the flow channel size and suppresses the vortex formed by the sudden change in the flow channel size.

[0028] The arc-shaped flow channel 13 takes the transition section flow channel inlet 11 as the starting point and rotates in the direction of rotation of the pump impeller until it is connected to the transition section flow channel outlet 12, so that the flow direction of the fluid in the arc-shaped flow channel 13 is the same as the rotation direction of the pump impeller. When the fluid flows from the secondary side flow channel 2 to the arc-shaped flow channel 13, the fluid flow direction remains unchanged, avoiding the energy loss caused by the sudden change of the fluid flow direction, and at the same time avoiding the impact on the arc-shaped flow channel 13 and causing damage to the arc-shaped flow channel 13; if the fluid direction changes when flowing into the arc-shaped flow channel 13, it is equivalent to the fluid hitting the inner wall when coming out of the secondary side flow channel outlet 22, forcibly changing the flow direction and flowing in the opposite direction, which will cause impact damage to the arc-shaped flow channel 13, and thus also cause energy loss. The width of the arc-shaped flow channel 13 gradually shrinks / expands from the width of the end connected to the transition section flow channel inlet 11 to the width of the end connected to the transition section flow channel outlet 12; the arc-shaped flow channel 13 is an arc with a variable curvature radius, specifically, the distance from each point on the arc-shaped flow channel 13 to the rotation center of the multi-stage side flow channel pump gradually increases / decreases from the end connected to the transition section flow channel inlet 11 to the end connected to the transition section flow channel outlet 12, so that when the fluid flows in the arc-shaped flow channel 13, the flow of the fluid is avoided from being affected by the sudden change in the flow channel size, and the vortex formed by the sudden change in the flow channel size is suppressed. The axial section of the arc-shaped flow channel 13 is a rectangle. The line connecting the center of the transition section flow channel outlet 12 and the center of the secondary side flow channel inlet 21 is the rotation center line of the multi-stage side flow channel pump, so that after the transition section flow channel 1 is added between the secondary side flow channel 2 and the tertiary side flow channel 3, the circumferential phase difference between the tertiary side flow channel inlet 31 and the secondary side flow channel inlet 21 is 180°, as shown in FIG. Figure 8 As shown in the figure, the green areas on both sides of the rotation center of the multi-stage side channel pump represent the third-stage side channel inlet 31 and the secondary side channel inlet 21 respectively. The phase difference between the two in the circumferential direction is 180°, and the radial force fluctuation periods of the secondary side channel impeller and the third-stage side channel impeller are staggered by 180°, that is, the radial forces acting on the secondary side channel impeller and the third-stage side channel impeller at the same time are in opposite directions, so that the radial forces of the two cancel each other out and balance the radial forces of the two.

[0029] When adding a transition section flow channel 1 between the secondary side flow channel 2 and the tertiary side flow channel 3, it is necessary to ensure that the transition section flow channel inlet 11 is opposite to the secondary side flow channel outlet 22 when the transition section flow channel 1 is installed on the side of the secondary side flow channel 2, and it is necessary to ensure that the tertiary side flow channel inlet 31 is opposite to the transition section flow channel outlet 12 when the tertiary side flow channel 3 is installed on the side of the transition section flow channel 1. Since the center of the transition section flow channel outlet 12 and the center of the secondary side flow channel inlet 21 are connected by a line that is parallel to the rotation center line of the multi-stage side flow channel pump, after assembly, the circumferential phase difference between the tertiary side flow channel inlet 31 and the secondary side flow channel inlet 21 is 180°, so that the radial forces exerted on the secondary side flow channel impeller and the tertiary side flow channel impeller at the same time are in opposite directions, thereby balancing the radial forces of the secondary side flow channel impeller and the tertiary side flow channel impeller when the multi-stage side flow channel pump is working.

[0030] Example 1

[0031] Figure 1-6 The figure shows a specific embodiment of the transition section flow channel 1 described in the present invention. According to the dimensions of the secondary side flow channel 2 and the tertiary side flow channel 3, the inner diameter of the transition section flow channel inlet 11 is designed to be Φ27.5 mm, the inner diameter of the transition section flow channel outlet 12 is designed to be Φ22 mm, and the width of the arc-shaped flow channel 13 gradually decreases from 27.5 mm at the end connected to the transition section flow channel inlet 11 to 22 mm at the end connected to the transition section flow channel outlet 12. The arc-shaped flow channel 13 is an arc with a variable curvature radius, wherein the distance between the center of the transition section flow channel inlet 11 and the rotation center of the multi-stage side flow channel pump is 53.75 mm, and the distance between the center of the transition section flow channel outlet 12 and the rotation center of the multi-stage side flow channel pump is 42.75 mm. The arc-shaped flow channel 13 takes the center of the transition section flow channel inlet 11 as the starting point, rotates 270° clockwise with a variable curvature radius to the center of the transition section flow channel outlet 12, and the center of the transition section flow channel outlet 12 is the end point. Then, the distance from each point on the arc-shaped flow channel 13 to the rotation center of the multi-stage side flow channel pump gradually decreases from 53.75 mm at the starting point to 42.75 mm at the end point.

[0032] like Figure 7 and Figure 8 As shown, when installing the transition section flow channel 1 between the secondary side flow channel 2 and the tertiary side flow channel 3, when installing the transition section flow channel 1 on the side of the secondary side flow channel 2, it is necessary to ensure that the transition section flow channel inlet 11 is facing the secondary side flow channel outlet 22, and when installing the tertiary side flow channel 3 on the side of the transition section flow channel 1, it is necessary to ensure that the tertiary side flow channel inlet 31 is facing the transition section flow channel outlet 12. After installing the transition section flow channel 1, as shown in FIG. Figure 8 The green areas on both sides of the rotation center of the multi-stage side channel pump respectively represent the third-stage side channel inlet 31 and the secondary side channel inlet 21, and the phase difference between the two in the circumferential direction is 180°. Figure 7The middle curve represents the fluid flow path, and the arrow on the curve represents the direction of fluid flow, specifically indicating that the fluid flows from the secondary side channel 2 to the transition section channel 1, and then flows through the arc-shaped channel 13 to the tertiary side channel 3. Figure 8 The arrow in the figure indicates that the fluid flow in this embodiment is clockwise.

[0033] Figure 9 The radial force curve of each stage of the three-stage side channel pump when the transition section flow channel 1 is not installed. Figure 9 (a) shows the first stage centrifugal impeller with a fluid flow rate Q of 4m 3 / h、8m 3 / h、10m 3 / h、12m 3 / h, it can be seen that the maximum radial force does not exceed 7N, that is, the radial force of the first-stage centrifugal impeller is very small. This is because the flow channels of the first-stage centrifugal impeller are the same and periodically distributed, and the radial forces of the fluid acting on the blades cancel each other out. Therefore, the radial force is not large, and the radial force fluctuates periodically, and the period is the same as the number of centrifugal impeller blades. Figure 9 (b) and (c) show the secondary side channel impeller and the third side channel impeller at the fluid flow rate Q of 4m 3 / h、8m 3 / h、10m 3 / h、12m 3 / h, it can be seen that the radial force fluctuation amplitude of the secondary side channel impeller and the third stage side channel impeller is much greater than that of the first stage centrifugal impeller, which is greatly affected by the radial force. Figure 10As shown in the figure, in a side channel pump, the fluid enters from the pump inlet. Under the action of the radial impeller rotation, the fluid acquires a circumferential velocity and is simultaneously driven by centrifugal force to move radially. Since the average velocity in the side channel is lower than the circumferential velocity in the impeller, a centrifugal force difference is formed between the side channel and the impeller. This centrifugal force difference causes the fluid to move tangentially to the side channel at the outer edge of the impeller, and then enter the impeller from the inner diameter of the side channel. This movement is repeated many times. Each time it passes through the impeller, the head is increased until it flows out of the pump outlet. The entire movement trajectory is spiral. In a side channel pump, each time the fluid passes through an impeller, the head is increased and the pressure rises. After multiple pressure increases from the side channel inlet to the outlet, the pressure differential is much larger than that of a centrifugal impeller. The secondary side channel impeller and the third-stage side channel impeller are both side channel pumps. There is a huge pressure difference between the impeller outlet and the impeller inlet, which acts on the blades to form a large radial force. In addition, the flow form of the side channel pump makes it impossible for them to offset each other like a centrifugal impeller, which leads to the phenomenon of high radial force of the side channel pump. Moreover, research has found that when the transition section flow channel 1 is not installed, the radial force of the secondary side channel impeller and the third-stage side channel impeller is almost the same, and the period of their fluctuation is exactly the same. At the same time, the direction of the radial force in the secondary and third-stage side channel impellers is also almost the same, resulting in the superposition of the radial forces in the secondary side channel impeller and the third-stage side channel impeller to produce a larger radial force. Excessive radial force affects the working performance and service life of the multi-stage side channel pump.

[0034] Figure 11 After installing the transition section flow channel 1, the fluid flow rate Q is 10m 3 / h, the radial force component curves of the secondary side channel impeller and the third side channel impeller in the x and y directions, respectively. The radial force components in the x and y directions refer to the decomposition of the radial force acting on the impeller at that moment into the radial force components in the x and y directions. It can be seen that at the flow rate of 10m3 / h, the component F of the secondary side channel impeller and the third side channel impeller on the x axis is x The magnitude and amplitude of the component F on the y-axis y The amplitude is almost the same as the amplitude, and the maximum amplitude exceeds 1000 N. After adding the transition section flow channel 1 between the secondary side flow channel 2 and the tertiary side flow channel 3, the circumferential phase difference between the tertiary side flow channel inlet 31 and the secondary side flow channel inlet 21 is 180°, thereby making the radial forces on the secondary side flow channel impeller and the tertiary side flow channel impeller in opposite directions at the same time, that is, the radial forces on the secondary side flow channel impeller and the tertiary side flow channel impeller are balanced. Figure 10The maximum value of the combined force in the x and y directions shown is less than 100N, far lower than the radial force amplitude of the side channel pump. This indicates that the radial force components in the x and y directions on the secondary and tertiary side channel impellers are effectively balanced, thereby greatly reducing the risk of radial runout in the multi-stage side channel pump and improving the operational safety and stability of the multi-stage side channel pump. In addition, only a transition section flow channel 1 needs to be added between the secondary side channel 2 and the tertiary side channel 3 and installed accordingly during assembly. No modifications are required to the original design of the multi-stage side channel pump, making operation simple and having little impact on the overall structure of the multi-stage side channel pump.

[0035] The examples are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention are within the scope of protection of the present invention.

Claims

1. A structure for balancing the radial force of a multi-stage side channel pump, characterized by: The structure is a transition section flow channel (1), wherein the transition section flow channel (1) is arranged between the secondary side flow channel (2) and the tertiary side flow channel (3); the transition section flow channel (1) is provided with a transition section flow channel inlet (11) and a transition section flow channel outlet (12) located on both sides, respectively, and an arc-shaped flow channel (13) arranged inside the transition section flow channel (1) and connecting the transition section flow channel inlet (11) and the transition section flow channel outlet (12); the transition section flow channel inlet (11) is arranged opposite to the secondary side flow channel outlet (22), and the transition section flow channel outlet (12) is arranged opposite to the The third-stage side flow channel inlet (31) is provided, and the arc-shaped flow channel (13) is rotated with the transition section flow channel inlet (11) as the starting point in the direction of rotation of the pump impeller until it is connected to the transition section flow channel outlet (12), so that the flow direction of the fluid in the arc-shaped flow channel (13) is the same as the direction of rotation of the pump impeller; the line connecting the center of the transition section flow channel outlet (12) and the center of the secondary side flow channel inlet (21) is across the rotation center line of the multi-stage side flow channel pump, so that the circumferential phase difference between the third-stage side flow channel inlet (31) and the secondary side flow channel inlet (21) is 180 degrees; The transition section flow channel inlet (11) and the transition section flow channel outlet (12) are circular holes, the diameter of the transition section flow channel inlet (11) is equal to the width of one end of the arc-shaped flow channel (13) connected to the transition section flow channel inlet (11), and the diameter of the transition section flow channel outlet (12) is equal to the width of one end of the arc-shaped flow channel (13) connected to the transition section flow channel outlet (12); The width of the arc-shaped flow channel (13) gradually shrinks / expands from the width of one end communicating with the transition section flow channel inlet (11) to the width of one end communicating with the transition section flow channel outlet (12); The distance between each point on the arc-shaped flow channel (13) and the rotation center of the multi-stage side flow channel pump gradually increases / decreases from the end connected to the transition section flow channel inlet (11) to the end connected to the transition section flow channel outlet (12); The arc-shaped flow channel (13) has a rectangular axial cross-section.

2. The structure for balancing the radial force of a multi-stage side channel pump according to claim 1 is characterized in that: The outer dimensions of the transition section flow channel (1) match those of the secondary side flow channel (2) and the tertiary side flow channel (3).

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