An axial flow pump variable diameter test and impeller clearance monitoring integrated device and method thereof

Abstract

This invention discloses an integrated device and method for testing the diameter variation of axial flow pumps and monitoring impeller clearance, belonging to the field of axial flow pump technology. It solves the problem in existing technologies where testing the diameter variation and monitoring the impeller clearance of axial flow pumps cannot be performed using only one device. This invention, through switching between two working modes, establishes for the first time a closed-loop testing process of "measurement → optimization → verification." In the first working mode, the main body of the device replaces the impeller chamber and is directly fitted onto the impeller. The eccentricity data of the impeller can be measured under the actual operating conditions of the axial flow pump under test, providing quantitative basis for the optimized design of the impeller clearance. After the optimized impeller chamber is manufactured, the main body of the device switches to the second working mode and is connected in series in the pipeline. The diameter variation performance of the axial flow pump using the optimized impeller chamber is tested to verify the optimization effect, realizing a dual-mode collaborative workflow of "internal dynamic monitoring guiding external design optimization, and external diameter variation testing verifying the optimization effect."

Description

Technical Field

[0001] This invention relates to the field of axial flow pump technology, and specifically to an integrated device and method for axial flow pump diameter testing and impeller clearance monitoring. Background Technology

[0002] As core components of the axial flow pump design and performance verification process, pump performance testing and impeller clearance monitoring are crucial for evaluating their hydraulic performance and operational reliability. Currently, this field treats these two tests as independent processes, relying on separate technical solutions with inherent limitations.

[0003] In pump performance testing, to obtain the external characteristic curves of axial flow pumps under different operating conditions, such as flow rate, head, power, and efficiency, the axial flow pump under test needs to be connected to a test bench with a fixed pipe diameter for testing. However, different specifications of axial flow pumps have different outlet diameters. In order to match the pipes of the test bench with a fixed pipe diameter, a large number of reducers of different diameters must be prepared and frequently replaced. As a result, the variable diameter testing process is not only inefficient, but also requires a lot of storage space due to the multiple reducers, which is not conducive to variable diameter testing.

[0004] In impeller clearance monitoring, existing methods for addressing the dynamic eccentricity of the impeller caused by shaft deflection and hydraulic radial force during operation either rely on costly and complex non-contact sensors that require pump body modifications, or can only be performed offline and statically during shutdown inspections. Neither method can conveniently and cost-effectively obtain the true clearance and offset trajectory of the impeller under operating conditions, and thus cannot conveniently provide a basis for the optimized design of impeller chamber clearance.

[0005] More notably, the two tasks mentioned above currently employ completely separate technical approaches, resulting in a disconnect between the pump's "external characteristic data" and "internal dynamic data": the external characteristic parameters obtained from pump performance tests cannot be directly correlated with internal state parameters such as impeller eccentricity and operating clearance under the same controlled conditions, which restricts in-depth research on the mechanism by which impeller-pump casing clearance affects pump performance and stability.

[0006] Therefore, there is an urgent need for an integrated device that can flexibly serve the above two types of testing needs on a single platform and in different working modes. This device can not only replace a large number of physical reducing tubes to simplify the performance testing process, but also replace the impeller chamber to realize online monitoring of the impeller dynamic clearance, and unify the association between external characteristics and internal dynamic data. Summary of the Invention

[0007] To address the aforementioned shortcomings of the prior art, this invention provides an integrated device and method for testing the diameter variation of axial flow pumps and monitoring impeller clearance, which solves the problem that the testing of the diameter variation of axial flow pumps and monitoring of impeller clearance cannot be performed using only one device in the prior art.

[0008] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: On one hand, an integrated device for testing the diameter change of an axial flow pump and monitoring impeller clearance is provided, comprising a main body, the main body including: a housing with a flow channel inside; an iris diameter change mechanism disposed within the housing and used to change the size of the flow channel in the housing; a monitoring module including three laser triangular displacement sensors arranged in a ring and uniformly disposed on the iris diameter change mechanism; and a control unit including a controller electrically connected to the iris diameter change mechanism and each laser triangular displacement sensor; wherein the main body includes a first working mode for monitoring impeller clearance and a second working mode for testing the diameter change of the axial flow pump; in the first working mode, the housing is fitted onto the impeller of the axial flow pump under test to replace the impeller chamber of the axial flow pump under test; in the second working mode, both ends of the housing are connected to the test pipeline and the axial flow pump under test, respectively.

[0009] On the other hand, a method for providing an integrated device for testing the diameter variation of an axial flow pump and monitoring the impeller clearance includes the following steps: S1. The main body of the device is put into the first working mode, and the casing is installed on the impeller of the axial flow pump to be tested as a temporary impeller chamber. S2. Conduct a flow efficiency curve test on the axial flow pump under test, obtain the optimal flow rate corresponding to the maximum efficiency in the test, and obtain the impeller eccentricity data corresponding to the optimal flow rate through the monitoring module. S3. Determine the impeller clearance of the axial flow pump to be tested based on the impeller eccentricity data, and manufacture an impeller chamber of the corresponding diameter based on the impeller clearance, and replace the main body of the device with the impeller chamber; S4. Implement the second working mode for the main body of the device, connect the housing between the test pipeline and the axial flow pump under test, adjust the flow channel size of the iris diameter reducing mechanism to the target pipe diameter, and conduct a pump performance test at the target pipe diameter.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention, through switching between two working modes, establishes for the first time a closed-loop experimental process of "measurement → optimization → verification". In the first working mode, the main body of the device replaces the impeller chamber and is directly fitted onto the impeller. This allows for the measurement of impeller eccentricity data under the actual operating conditions of the axial flow pump under test, providing quantitative basis for the optimized design of the impeller clearance. After the optimized impeller chamber is manufactured, the main body of the device is switched to the second working mode and connected in series in the pipeline. The axial flow pump using the optimized impeller chamber undergoes variable diameter performance testing to verify the optimization effect. This achieves a dual-mode collaborative workflow of "internal dynamic monitoring guiding external design optimization, and external variable diameter testing verifying the optimization effect". This method organically links the pump's external characteristics with its internal state data, providing experimental results for axial flow pump clearance optimization and performance verification.

[0011] 2. This invention solves two traditional problems simultaneously with a single device. In the field of pump performance testing, when pumps of different diameters are connected to a fixed-diameter test bench, existing methods require frequent replacement of a large number of physical reducers, resulting in low efficiency and poor repeatability. This invention replaces the physical reducer library with an iris-shaped reducer mechanism. By continuously and steplessly adjusting the flow channel diameter, one device can adapt to multiple diameters, significantly improving testing efficiency. In the field of impeller clearance monitoring, existing methods either require installing expensive non-contact sensors on the pump body or can only be performed offline with the pump shut down for inspection. This invention integrates a laser triangular displacement sensor into the iris-shaped reducer mechanism and replaces the impeller chamber, achieving online, non-contact, precise monitoring of impeller dynamic eccentricity. Installation is convenient and cost-effective. Simultaneously, the laser triangular displacement sensor easily obtains the opening size of the iris-shaped reducer mechanism, facilitating the control unit to adjust the iris-shaped reducer mechanism to the target pipe diameter.

[0012] 3. Considering that the existing iris mechanism forms a straight cylindrical opening after the blades close, when applied to fluid pipelines, the flow channel cross-section changes abruptly, the water flow streamlines bend sharply at this point and flow separation occurs, resulting in a significant increase in local head loss and potentially inducing eddies or even cavitation, interfering with the accuracy of performance testing, this invention sets a variable diameter guide groove at the top of the inner wall of each blade near the inlet end of the shell to form a funnel-shaped channel. This pre-directs and guides the water flow near the wall, destroying the conditions for the formation of vortex structures at the inlet edge and effectively suppressing the generation of inlet vortices.

[0013] 4. Considering that existing iris recognition mechanisms typically rely solely on a single pin and involute groove to open and close the blades, the blades have only one constraint point during movement. Under the impact of water flow and pressure pulsation, the blades may rotate slightly or oscillate around the pin, leading to asynchronous movement of the blades, disrupting the roundness of the flow cross-section, and affecting the accuracy of diameter adjustment. This invention adds a constraint block to each blade, which slides with the constraint groove on the fixed ring, forming a "two-point constraint" structure of pin-driven and constraint block-guided movement. The constraint block restricts the rotational freedom of the blades around the pin, ensuring that the blades can still strictly translate along the predetermined radial direction under water flow impact. Simultaneously, the pin bears the driving force, and the constraint block bears the guiding force; the separation of these two force points makes the stress state of the blades more reasonable. This ensures the synchronicity and consistency of the movement of each blade at any opening degree, ensuring that the flow cross-section always maintains high roundness and improving the accuracy and repeatability of pipe diameter adjustment.

[0014] 5. This invention utilizes three uniformly arranged laser triangulation displacement sensors in a ring to establish a polar coordinate system and leverage the geometric relationship between sensor measurements and impeller eccentricity, achieving real-time, non-contact, and accurate calculation of impeller dynamic eccentricity. The method first obtains the optimal estimate of the impeller radius by averaging the distances measured by the three sensors, eliminating random errors from single-point measurements. Then, it uses redundant measurement information to calculate the eccentricity distance and eccentricity phase angle using the least squares method, fully utilizing the data complementarity of the three sensors to improve the accuracy and robustness of the eccentricity calculation. Compared to existing methods that rely on expensive sensors requiring pump modifications or offline shutdown inspections, this method can acquire the impeller's dynamic eccentricity trajectory and minimum operating clearance in real-time during normal pump operation. It requires no pump modification and employs a simple and efficient calculation algorithm, providing reliable data support for online monitoring and subsequent optimization analysis of the internal dynamic state of axial flow pumps.

[0015] 6. This invention employs a feedforward compensation control strategy based on real-time flow rate and real-time pipe diameter feedback. It uses a fluid dynamics model to estimate the hydraulic load acting on the blades of the iris-shaped diameter-changing mechanism in real time, calculates the target output torque of the drive motor for active compensation, and then uses a fuzzy adaptive PID controller to fine-tune the residual error, forming a composite control architecture of "feedforward + feedback". The feedforward model handles the main disturbance torque caused by changes in hydraulic load, significantly reducing the adjustment burden of feedback control and enabling the system to respond quickly and robustly to external hydraulic disturbances. The fuzzy adaptive PID controller self-tunes control parameters online based on pipe diameter deviation, providing fine compensation for model errors, mechanical friction, and unknown disturbances, ensuring the smoothness of the diameter-changing process and high accuracy of pipe diameter positioning. This method eliminates the need for additional pressure sensors, utilizing only the existing flow signal and pipe diameter feedback in the test system to achieve online estimation of hydraulic load. It features low hardware cost, high control accuracy, and provides an efficient and reliable control scheme for automated and intelligent adjustment of diameter-changing conditions in pump performance testing. Attached Figure Description

[0016] Figure 1 A perspective view of an integrated device for testing the diameter variation of an axial flow pump and monitoring impeller clearance; Figure 2 This is a schematic diagram of the iris diameter changing mechanism; Figure 3 A schematic diagram of a single blade; Figure 4 A schematic diagram of the laser sensor installation; Figure 5 This is a schematic diagram of the installation location in the first working mode; Figure 6 This is a schematic diagram of the installation location in the second working mode; The components are as follows: 1. Shell; 2. Rotating ring; 3. Blade; 4. Flange mounting threaded groove; 5. Pin; 6. Drive motor; 7. Worm gear; 8. Constraint block; 9. Pin hole; 10. Sealing cover connection hole; 11. Variable diameter guide groove; 12. Sealing cover; 13. Observation window; 14. Sealing wire harness hole; 15. Laser triangular displacement sensor; 16. First laser sensor; 17. Second laser sensor; 18. Third laser sensor; 19. Controller; 20. Test pipeline; 21. Pump body; 22. Main body of the device; 23. Impeller; 24. Short section. Detailed Implementation

[0017] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0018] Example 1

[0019] refer to Figure 1 This embodiment provides an integrated device for testing the diameter of an axial flow pump and monitoring the impeller clearance, including a device body 22, which includes a housing 1, an iris diameter changing mechanism, a monitoring module, and a control unit.

[0020] Specifically, the housing 1 has a flow channel inside, with openings at both ends of the flow channel, and each opening has a flange mounting thread groove, which is threaded to the connecting flange.

[0021] Specifically, the iris diameter changing mechanism is set inside the housing 1 and is used to change the flow channel size of the housing 1. It includes a fixed ring and a rotating ring 2 that are coaxially rotatable. Multiple blades 3 that change the flow diameter in the housing 1 are arranged between the fixed ring and the rotating ring 2. The rotating ring 2 is connected to the drive motor 6. In this embodiment, the drive motor 6 is connected to the gear on the outside of the rotating ring 2 through the worm wheel on the worm 7.

[0022] To overcome the problems of existing iris recognition mechanisms where the closed blades form a cylindrical opening, and the abrupt change in the flow channel cross-section leads to severe bending of the water flow lines and flow separation when applied to fluid pipelines, resulting in significantly increased local head loss, and easily inducing eddies or even cavitation, thus interfering with the accuracy of performance testing, this solution sets a variable-diameter guide groove 11 on the top of the inner wall of each blade 3 near the inlet end of the shell 1. This makes the variable-diameter channel formed by multiple blades 3 funnel-shaped, with the flow channel cross-sectional area gradually changing along the water flow direction rather than abruptly changing. (Refer to...) Figure 3This design, with its flared variable-diameter channel, allows for a smooth transition of the water flow lines, effectively preventing flow separation and eddy generation, and significantly reducing local hydraulic losses during the diameter change process. The variable-diameter guide channel 11 disrupts the formation conditions of vortex structures at the inlet edge, effectively suppressing the generation of inlet vortices. The two work together to achieve a smooth transition of the entire flow channel from the inlet to the outlet, further reducing hydraulic losses during the diameter change process, improving flow stability and testing accuracy, and ensuring the reliability and accuracy of pump performance test data.

[0023] Among them, reference Figure 2 To enable the rotating ring 2 to drive multiple blades 3 to form a flow channel, multiple constraint grooves and multiple involute grooves are evenly distributed along the circumferential direction on the ring surfaces of the fixed ring and the rotating ring 2, respectively. Each constraint groove and involute groove corresponds one-to-one with a single blade 3. Each blade 3 is equipped with a constraint block 8 for sliding connection with the constraint groove and a pin 5 for insertion into the involute groove. The pin 5 is located in a pin hole 9 within the blade 3. Simultaneously, to avoid swaying and jamming caused by single-point constraint and to ensure the synchronization of the movement of each blade 3, the constraint block 8 and pin 5 on each blade 3 are arranged radially at intervals.

[0024] Compared with the existing technology, this solution adds a constraint block 8 to each blade 3, which slides with the constraint groove on the fixed ring to form a "two-point constraint" structure with the pin shaft 5 driving and the constraint block 8 guiding. Through this setting, the constraint block 8 restricts the rotational freedom of the blade 3 around the pin shaft 5, so that the blade 3 can still strictly translate along the predetermined radial direction when subjected to water flow impact force and pressure pulsation. At the same time, the pin shaft 5 bears the driving force and the constraint block 8 bears the guiding force. The separation of the two force points makes the force state of the blade 3 more reasonable, realizes the synchronicity and consistency of the movement of each blade 3 at any opening, ensures that the flow section always maintains high roundness, and improves the accuracy and repeatability of pipe diameter adjustment.

[0025] Specifically, the monitoring module includes three laser triangular displacement sensors 15 arranged in a ring and evenly distributed on the iris diameter-changing mechanism, for reference. Figure 4 The three laser triangular displacement sensors 15 are the first laser sensor 16, the second laser sensor 17 and the third laser sensor 18, and the central angle of any two of them is 120°.

[0026] Specifically, the control unit includes a controller 19 electrically connected to the drive motor 6 and each laser triangular displacement sensor 15.

[0027] In this embodiment, the main body 22 of the device includes a first working mode for monitoring impeller clearance and a second working mode for testing the diameter change of the axial flow pump. In the first working mode, the iris diameter change mechanism can be extended to its maximum, so that the housing 1 is fitted on the impeller 23 of the axial flow pump under test to replace the impeller chamber of the axial flow pump under test. That is, the two ends of the main body 22 of the device are connected to the pump body 21 and the short section 24 of the axial flow pump under test respectively through connecting flanges. In the second working mode, the two ends of the housing 1 are connected to the test pipeline 20 and the axial flow pump under test respectively.

[0028] As a further embodiment, refer to Figure 3 To install the laser triangulation sensor 15 in the blade 3, a sealed cavity is provided inside the blade 3. A sealing cover 12 is provided at the end of the sealed cavity, and the sealing cover 12 is fixed to the end of the sealed cavity through a sealing cover connection hole 10. The laser triangulation sensor 15 is provided inside the sealed cavity, and an observation window 13 is provided in the sealed cavity in the laser direction of the laser triangulation sensor 15. In this embodiment, a power supply electrically connected to the laser triangulation sensor 15 can be provided inside the sealed cavity. The laser triangulation sensor 15 communicates with the controller 19 via Bluetooth, or a sealing wire harness hole 14 is opened on the sealing cover 12 for the signal line of the laser triangulation sensor 15 to pass through, and the signal line is connected to the external controller 19.

[0029] Example 2

[0030] This embodiment provides a method for an integrated device for testing the diameter variation of an axial flow pump and monitoring the impeller clearance, including the following steps: S1, Reference Figure 5 The device body 22 is put into the first working mode, and the housing 1 is installed as a temporary impeller chamber on the impeller 23 of the axial flow pump to be tested.

[0031] S2. Conduct a flow efficiency curve test on the axial flow pump under test, obtain the optimal flow rate corresponding to the maximum efficiency in the test, and obtain the impeller eccentricity data corresponding to the optimal flow rate through the monitoring module.

[0032] S3. Determine the impeller clearance of the axial flow pump to be tested based on the impeller eccentricity data, and make an impeller chamber of the corresponding diameter according to the impeller clearance, and replace the impeller chamber with the main body 22 of the device.

[0033] S4, Reference Figure 6 The second working mode is executed on the main body 22 of the device. The housing 1 is connected between the test pipeline 20 and the axial flow pump to be tested. The flow channel size of the iris diameter reducing mechanism is adjusted to the target pipe diameter, and the pump performance test is carried out at the target pipe diameter.

[0034] In this embodiment, the impeller eccentricity data includes the eccentricity distance. and eccentric phase angle Methods for obtaining impeller eccentricity data include: S21. Initialize the three laser triangulation sensors 15, and establish a polar coordinate system with the geometric center of the housing 1 as the origin and the measurement direction of one of the laser triangulation sensors 15 as the reference. S22. Calculate the eccentricity of impeller 23 in polar coordinates. and eccentric phase angle Its expression is: ; ; ; in, and The first The distance deviation and installation polar angle of a laser triangular displacement sensor 15; For the first The measurement distance of a laser triangulation sensor 15; The radius of the cross-section of the three laser triangular displacement sensors 15 in housing 1; The impeller radius is 23.

[0035] For ease of understanding, this embodiment provides the eccentricity. and eccentric phase angle The derivation process: For any laser triangulation displacement sensor 15, the measured value is relative to the polar coordinates of the impeller shaft. The following relationship exists: ; This embodiment takes into account that, during normal and stable operation of the axial flow pump under test, the eccentricity of the impeller 23 is much smaller than its own radius. exist Performing a Taylor expansion at this point, we obtain: ; in, Since it is a high-order small quantity, the above formula can be simplified to: ; in, ,definition ,thereby: ; Therefore, the eccentricity can then be calculated using the least squares method. and eccentric phase angle Finally, according to Determine impeller clearance impeller clearance Based on this, the final design inner diameter of the impeller chamber is determined with consideration of safety margins.

[0036] As a further solution in this embodiment, considering that the blades 3 of the iris diameter changing mechanism continuously bear the real-time changing hydraulic load caused by water flow impact when adjusting the flow channel size, if only traditional feedback control is relied upon, it is easy to cause adjustment oscillation or insufficient accuracy due to response lag and load disturbance during diameter change and flow fluctuation, which is difficult to meet the requirements of pump performance test for rapid, stable and accurate pipe diameter positioning. Therefore, this solution adopts a feedforward compensation control strategy based on real-time flow and real-time pipe diameter feedback. The hydraulic load acting on the blades 3 of the iris diameter changing mechanism is estimated in real time through a fluid dynamics model, and the target output torque of the drive motor 6 is calculated for active compensation. On this basis, the fuzzy adaptive PID controller performs feedback fine-tuning on the residual error, forming a "feedforward + feedback" composite control architecture. The feedforward model bears the main disturbance torque caused by the change of hydraulic load, which significantly reduces the adjustment burden of feedback control, making the system have a fast response and strong robustness to external hydraulic disturbances. The fuzzy adaptive PID controller performs fine compensation for model error, mechanical friction and unknown disturbances based on the pipe diameter deviation online self-tuning control parameters, ensuring the smoothness of the diameter change process and the high accuracy of pipe diameter positioning. This solution employs a feedforward torque compensation strategy based on real-time flow rate and real-time pipe diameter feedback. It estimates the hydraulic pressure difference using a fluid dynamics model and calculates the target torque that the drive motor 6 needs to actively output to counteract the main disturbance torque, thereby achieving efficient and precise control of the pipe diameter change process. Specifically, the methods for adjusting the flow channel size of the iris pipe diameter change mechanism include: S31. Obtain the real-time flow rate in the test pipeline 20 and the real-time pipe diameter feedback value of the iris reducing mechanism.

[0037] S32. Based on the real-time flow rate and real-time pipe diameter feedback values, calculate in real-time the target output torque of the drive motor 6 in the iris diameter changing mechanism. .

[0038] S33, according to The output torque of the drive motor 6 is controlled by the controller 19 until the real-time pipe diameter feedback value is equal to the target pipe diameter.

[0039] Specifically, the target output torque The calculation expression is: ; ; ; ; in, The target output torque of the drive motor 6 is the torque at the kth sampling time. This torque is calculated based on the water flow pressure difference and the mechanical model of the structure. It belongs to the feedforward compensation part and its function is to eliminate most of the disturbances before the feedback controller 19 intervenes.

[0040] The total resistance coefficient is a comprehensive dimensionless coefficient used to convert fluid force into equivalent motor end torque. It can be determined in advance through steady-state calibration tests, i.e., by measuring the motor torque required to maintain the opening under known flow rate and opening degree, and then back-calculating it.

[0041] For the fluid pressure difference flowing through the iris reducer at the k-th sampling time, this scheme simplifies the estimation using Bernoulli's principle: first, the real-time head... Subtract the dynamic head to obtain the net pressure head after the flow passes through the reducing mechanism; Multiply by This is converted into pressure. This pressure difference acts directly on the blade wall and is the source of the disturbance torque. For fluid density; It is the acceleration due to gravity; The net pressure head at the k-th sampling time; Let be the real-time head of the axial flow pump under test at the k-th sampling time; This represents the real-time traffic at the k-th sampling time.

[0042] The real-time pipe diameter feedback value at the k-th sampling time is obtained through the laser triangular displacement sensor 15.

[0043] The sign function of the target pipe diameter change rate, with a value of +1 or -1, reflects the direction of the target pipe diameter change, i.e. the direction of the feedforward torque. When changing the diameter, the drive motor 6 needs to overcome the hydraulic resistance. When maintaining the diameter, the feedforward torque is used for static balance.

[0044] The design reference diameter of the iris diameter reducing mechanism is the theoretical throat diameter of blade 3 of the iris diameter reducing mechanism when it is in the design zero position, which serves as the reference value for pipe diameter feedback. This represents the real-time rotation angle of the output shaft of drive motor 6 at the k-th sampling moment; The conversion coefficient from the rotation angle of the rotating ring 2 to the radial displacement of the blade 3 in the iris diameter changing mechanism is determined by the geometric dimensions of the iris diameter changing mechanism. The length of blade 3.

[0045] As a further embodiment, the controller 19 controls the output torque of the drive motor 6 to be... It is the torque command value that the controller 19 finally applies to the drive motor 6, which is generated by the feedforward torque. With feedback compensation torque After addition, the transmission ratio is adjusted. and transmission efficiency The converted expression is as follows: ; in, The feedback compensation torque at the kth sampling time is calculated by the fuzzy adaptive PID control module built into the controller 19 based on the deviation between the real-time pipe diameter feedback value and the target pipe diameter.

[0046] Since the feedforward bears the main load, a fuzzy adaptive PID control module is used to fine-tune the position error. The fuzzy adaptive PID control module calculates the feedback compensation torque to compensate for model errors, friction, and unknown disturbances based on the error between the target pipe diameter and the feedback pipe diameter and the rate of change of the error. Its parameters can be adaptively adjusted online according to the error status. Since the fuzzy adaptive PID control module is existing technology, it will not be described in detail here.

[0047] In summary, the beneficial effects of this plan are as follows: Through an integrated device and its dual operating modes, a closed-loop test process for axial flow pumps was established for the first time, encompassing "internal dynamic eccentricity monitoring → impeller chamber clearance optimization design → variable diameter performance testing and verification." In the first operating mode, the main body 22 of the device directly obtains the eccentricity and phase angle of the impeller 23 under optimal operating conditions online, replacing the impeller chamber, providing a quantitative basis for the scientific customization of the impeller chamber clearance. In the second operating mode, the flow channel diameter is continuously and steplessly adjusted by the iris-shaped variable diameter mechanism, allowing one device to replace a large number of physical variable diameter pipes, significantly saving space and improving testing efficiency. The horn-shaped variable diameter channel and the inlet variable diameter guide groove 11 work together to ensure a smooth transition of the flow channel cross-section, effectively suppressing flow separation and inlet vortex, significantly reducing local hydraulic losses, and ensuring the reliability of performance test data. The two-point constraint structure of the blades 3 ensures that the flow cross-section always maintains high roundness and motion synchronization at each opening degree, improving the accuracy of pipe diameter adjustment. Three laser triangular displacement sensors 15 arranged uniformly in a ring direction, combined with the least squares eccentricity solution method, realize real-time, non-contact, and highly robust measurement of the dynamic eccentricity of the impeller 23. Meanwhile, the composite control architecture, based on feedforward torque compensation combined with fuzzy adaptive PID feedback fine-tuning and real-time flow and pipe diameter feedback, can actively counteract hydraulic load disturbances, achieving rapid response, smooth adjustment, and high-precision positioning during the diameter change process. The overall solution organically unifies the external hydraulic characteristics and internal dynamic clearance data of the axial flow pump, providing a direct basis for the optimized design of the impeller clearance and enabling the verification of optimized pump performance on the same device, significantly improving the overall efficiency and economy of axial flow pump testing.

Claims

1. An integrated device for testing the diameter variation of an axial flow pump and monitoring the impeller clearance, characterized in that, The device includes a main body, which comprises: The shell has flow channels inside; An iris diameter-changing mechanism is disposed within the housing and is used to change the flow channel size of the housing; The monitoring module includes three laser triangular displacement sensors arranged in a ring and evenly distributed on the iris diameter changing mechanism; The control unit includes a controller electrically connected to the iris diameter adjustment mechanism and each of the laser triangulation sensors; The device body includes a first working mode for monitoring impeller clearance and a second working mode for testing the diameter variation of an axial flow pump. In the first working mode, the housing is fitted onto the impeller of the axial flow pump under test to replace the impeller chamber of the axial flow pump under test. In the second working mode, both ends of the housing are connected to the test pipeline and the axial flow pump under test, respectively.

2. The integrated device for testing the diameter variation of an axial flow pump and monitoring the impeller clearance according to claim 1, characterized in that, The iris diameter changing mechanism includes a fixed ring and a rotating ring that are coaxially rotatable. Multiple blades that change the flow diameter in the housing are arranged between the fixed ring and the rotating ring. Each blade has a diameter changing guide groove on its inner wall near the top of the inlet end of the housing to form a trumpet-shaped diameter changing channel. The rotating ring is connected to a drive motor, and the drive motor is electrically connected to the controller.

3. The integrated device for testing the diameter variation of an axial flow pump and monitoring the impeller clearance according to claim 2, characterized in that, The fixed ring and the rotating ring are respectively provided with a plurality of constraint grooves and a plurality of involute grooves evenly spaced along the circumferential direction on their ring surfaces. The plurality of constraint grooves and the plurality of involute grooves are in one-to-one correspondence with a plurality of blades. Each blade is provided with a constraint block for sliding connection with the constraint groove and a pin for insertion into the involute groove.

4. The integrated device for testing the diameter variation of an axial flow pump and monitoring the impeller clearance according to claim 3, characterized in that, The constraint blocks on each blade are arranged radially spaced from the pins.

5. A method for an integrated device for testing the diameter variation of an axial flow pump and monitoring impeller clearance as described in any one of claims 1 to 4, characterized in that, Including the following steps: S1. The main body of the device is put into the first working mode, and the casing is installed on the impeller of the axial flow pump to be tested as a temporary impeller chamber. S2. Conduct a flow efficiency curve test on the axial flow pump under test, obtain the optimal flow rate corresponding to the maximum efficiency in the test, and obtain the impeller eccentricity data corresponding to the optimal flow rate through the monitoring module. S3. Determine the impeller clearance of the axial flow pump to be tested based on the impeller eccentricity data, and manufacture an impeller chamber of the corresponding diameter based on the impeller clearance, and replace the main body of the device with the impeller chamber; S4. Implement the second working mode for the main body of the device, connect the housing between the test pipeline and the axial flow pump under test, adjust the flow channel size of the iris diameter reducing mechanism to the target pipe diameter, and conduct a pump performance test at the target pipe diameter.

6. The method of the integrated device for testing the diameter variation of an axial flow pump and monitoring the impeller clearance according to claim 5, characterized in that, Methods for obtaining impeller eccentricity data include: S21. Establish a polar coordinate system with the geometric center of the shell as the origin and the measurement direction of one of the laser triangular displacement sensors as the reference. S22. Calculate the impeller eccentricity in polar coordinates. and eccentric phase angle Its expression is: ； ； ； in, and The first Distance deviation and installation polar angle of a laser triangulation displacement sensor; For the first The measurement distance of a laser triangulation sensor; Let be the radius of the cross-section of the three laser triangular displacement sensors inside the housing; Where is the impeller radius.

7. The method of the integrated device for testing the diameter variation of an axial flow pump and monitoring the impeller clearance according to claim 6, characterized in that, Methods for adjusting the flow channel size of the iris diameter reducing mechanism include: S31. Obtain the real-time flow rate in the test pipeline and the real-time pipe diameter feedback value of the iris reducing mechanism; S32. Based on the real-time flow rate and real-time pipe diameter feedback values, calculate the target output torque of the drive motor in the iris diameter changing mechanism in real time. ; S33, according to The output torque of the drive motor is controlled by the controller until the real-time pipe diameter feedback value is equal to the target pipe diameter.

8. The method of the integrated device for testing the diameter variation of an axial flow pump and monitoring the impeller clearance according to claim 7, characterized in that, Target output torque The calculation expression is: ； ； ； ； in, The target output torque of the driving motor at the k-th sampling time; This is the total drag coefficient; The fluid pressure difference flowing through the iris diameter reducing mechanism at the k-th sampling time; For fluid density; It is the acceleration due to gravity; The net pressure head at the k-th sampling time; Let be the real-time head of the axial flow pump under test at the k-th sampling time; The real-time traffic at the k-th sampling time; This is the real-time pipe diameter feedback value at the k-th sampling time; The length of the blade; This refers to the transmission ratio from the drive motor to the rotating ring; For transmission efficiency; The sign function of the target pipe diameter change rate; This is the design reference diameter for the iris diameter-changing mechanism; This represents the real-time rotation angle of the drive motor output shaft at the k-th sampling moment; This is the conversion coefficient from the rotation angle of the rotating ring to the radial displacement of the blade in the iris diameter-changing mechanism.

9. The method of the integrated device for testing the diameter variation of an axial flow pump and monitoring the impeller clearance according to claim 8, characterized in that, The controller controls the output torque of the drive motor to be Its calculation expression is: ； in, The feedback compensation torque at the k-th sampling time is calculated by the fuzzy adaptive PID control module built into the controller based on the deviation between the real-time pipe diameter feedback value and the target pipe diameter.

Images