Adaptive anti-cavitation water regulating pump with targeted jet structure and control method thereof

Abstract

The application discloses a self-adaptive anti-cavitation water regulating pump with a targeted jet flow structure and a control method thereof, and the method comprises the following steps: collecting reference state parameters and sensitive signals of the water regulating pump through a signal detection system; extracting pump cavitation characteristic quantities; constructing a basic cavitation risk index; parameterizing the anti-cavitation ability of an impeller structure to obtain impeller structure parameters; calculating a structure anti-cavitation correction coefficient; correcting a basic cavitation critical threshold value and an obvious cavitation basic threshold value to obtain a structure correction threshold value; discriminating the cavitation state of the water regulating pump; generating an anti-cavitation control target and executing a control action; after the execution of the control action, the cavitation state is discriminated again, and an anti-cavitation control target is generated according to the new cavitation state and executed. The application introduces structure parameters corresponding to convergent targeted micro-slots, asymmetric front edge circle blunting, axial drainage ridges and segmented inlet angles into cavitation threshold correction, so that the operation control is matched with the anti-cavitation ability of the impeller body.

Description

Technical Field

[0001] This invention relates to the field of water conservancy regulation technology, and in particular to an adaptive anti-cavitation water pump with a targeted jet structure and its control method. Background Technology

[0002] When large water pumps operate under conditions of low inlet water level, high flow rate regulation, pipeline fluctuation, or deviation from design conditions, local low-pressure areas are easily formed on the suction surface of the blade inlet, which can induce cavitation.

[0003] Among existing anti-cavitation solutions, some rely on external liquid storage tanks, flow pipes, jet holes, or switching mechanisms to form an external jet system, which is complex in structure and has limited coupling with the blade body flow channel; some solutions use surface roughening bands, protrusions, grooves, or additional jet blades to improve local flow, but it is difficult to form a through-flow microjet that compensates for the pressure surface from the suction surface; other solutions use multi-parameter monitoring and conventional threshold judgment to adjust the rotational speed or guide vanes, but their control thresholds usually do not take into account the differences in the anti-cavitation structure of the impeller body.

[0004] Therefore, a cavitation-resistant scheme for water pumps that combines the local anti-cavitation structure of the blade body with the correction of the operation control threshold is needed to improve the inlet flow field, reduce the negative pressure on the back side, and delay the occurrence of cavitation. Summary of the Invention

[0005] To address the aforementioned shortcomings in the prior art, the adaptive anti-cavitation water pump with a targeted jet structure and its control method provided by this invention solve the problem that large water pumps are prone to cavitation under low inlet water level, high flow rate and pipeline fluctuations, and that traditional impeller structures can only passively improve the flow field, while fixed threshold control is difficult to adapt to different impeller anti-cavitation capabilities.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows: an adaptive anti-cavitation water pump with a targeted jet structure, comprising: a pump body, a pump shaft, an impeller, a drive motor, a frequency conversion drive device, a signal detection system, and an intelligent controller; The impeller is mounted on the pump shaft and located in the flow chamber of the pump body; the impeller includes a hub, multiple blades spaced apart circumferentially along the hub, and a cover plate connected to the blades; The signal detection system is used to collect the operating signals of the water pump; The intelligent controller is used to execute cavitation identification and adaptive control programs based on operating signals and output speed commands; The variable frequency drive is used to adjust the speed of the drive motor according to the speed command output by the intelligent controller; The drive motor is used to drive the impeller to rotate; The blades include main blades and diverter blades, which are arranged alternately. The leading edge of the diverter blades and the leading edge of the main blades have a radial gap. The trailing edge of the diverter blades is flush with the trailing edge of the main blades and extends to the radial outer edge of the impeller. The blade inlet area is provided with a composite anti-cavitation structure, which includes an asymmetric rounded blunt structure at the blade inlet leading edge, an axial flow-guiding ridge structure in the blade inlet section, a radial segmented inlet angle structure, and a convergent targeted microgroove that penetrates the pressure surface and suction surface of the blade.

[0007] This invention also provides an intelligent control method for an adaptive anti-cavitation water pump with a targeted jet structure, comprising: The reference state parameters and sensitive signals of the water regulating pump are collected by a signal detection system. The reference state parameters include the inlet pressure, outlet pressure, fluid temperature, pump casing vibration signal, reference inlet pressure fluctuation intensity, reference high-frequency vibration energy, reference differential pressure change rate, and reference net positive suction head (NPSH) under stable operating conditions with no or weak cavitation. The sensitive signals include the inlet pressure, outlet pressure, fluid temperature, pump casing vibration signal, and effective NPSH under normal operating conditions of the water regulating pump. Pump cavitation characteristics are extracted based on baseline state parameters and sensitive signals. These pump cavitation characteristics include inlet pressure fluctuation intensity, inlet and outlet pressure difference, inlet and outlet pressure difference change rate, NPSH margin, and cavitation-sensitive high-frequency vibration energy. Construct basic cavitation risk indicators; The anti-cavitation capability of the impeller structure is parameterized to obtain impeller structure parameters. The impeller structure parameters include the position of the convergent targeted microgroove, the inlet area of ​​the microgroove, the outlet area of ​​the microgroove, the inlet-outlet area ratio of the microgroove, the jet angle at the outlet of the microgroove, the blunt radius of the leading edge of the blade suction side, the blunt radius of the leading edge of the blade pressure side, the ratio of asymmetric blunt radii, the height or arrangement length of the axial flow ridge, and the inlet angle of the hub side, the inlet angle of the middle region, and the inlet angle of the outer edge of the impeller. Calculate the structural cavitation correction coefficient based on the impeller structural parameters; The structural cavitation resistance correction coefficient is used to correct the basic cavitation critical threshold and the obvious cavitation basic threshold to obtain the structural correction threshold; Cavitation status of water pumps is determined based on basic cavitation risk indicators and structural correction thresholds. Based on the cavitation state of the water pump, generate anti-cavitation control targets and execute control actions; After the control action is executed, the cavitation state is re-evaluated, and an anti-cavitation control target is generated and executed based on the new cavitation state.

[0008] The beneficial effects of this invention are as follows: (1) By using an asymmetric leading edge structure with a larger blunt radius on the suction side than on the pressure side, the transition process from the inlet flow to the suction side is extended, which helps to reduce the local low pressure on the suction side of the blade inlet.

[0009] (2) The inlet fluid is pre-guided and distributed by the axial flow ridge, and the inlet flow at different blade height positions is matched by the radial segmented inlet angle, which helps to reduce the concentration of blade inlet velocity, excessive angle of attack and boundary layer separation.

[0010] (3) By using the pressure difference between the two sides of the blade to form a directional microjet through the convergent targeted microgroove that penetrates the pressure surface and suction surface, momentum can be added to the near wall region of the suction surface and the local pressure level can be increased, thereby delaying the initial cavitation and inhibiting the continued development of the cavitation zone.

[0011] (4) By improving the impeller inlet flow and suppressing the formation, development and collapse of cavitation bubbles, pressure pulsation, vibration and noise caused by cavitation can be reduced.

[0012] (5) The composite anti-cavitation structure, combined with the restricted speed control based on the structural correction threshold, can reduce the cavitation risk of large water pumps under low inlet water level, high flow rate and load fluctuation conditions while ensuring water delivery capacity, and reduce the possibility of water hammer and pipeline fluctuation caused by rapid adjustment.

[0013] (6) By reducing the repeated collapse of cavitation bubbles on the blade surface, the cavitation damage trend of the impeller and adjacent flow components can be slowed down, which is conducive to extending the service life of key components.

[0014] (7) By integrating the inlet pressure fluctuation intensity, cavitation-sensitive high-frequency vibration energy, inlet and outlet pressure difference change rate, and and Relationship Construction Basic Cavitation Risk Indicators This can convert pump cavitation sensitive signals into a risk scale suitable for water pumps.

[0015] (8) Anti-cavitation correction coefficient of impeller structure For the base threshold , Make limited corrections to form and This avoids the use of the same cavitation criterion between convergent targeted microgroove impellers and ordinary impellers, highlighting the synergistic relationship between the blade body structure and operation control.

[0016] (9) The targeted microgroove uses the pressure difference on both sides of the blade to drive the jet, eliminating the need for an independent jet pump, air supply device or moving parts, which helps to reduce the structural complexity of the additional jet power supply system and its additional energy consumption.

[0017] (10) By comparing before and after adjustment The changes in inlet pressure fluctuations, differential pressure change rate, and high-frequency vibration energy can be used to evaluate the synergistic suppression effect of the targeted microgroove jet structure and operation regulation, and can be used to update dynamic weights, structural correction coefficients, or control gains. Attached Figure Description

[0018] Figure 1 This is a top view of the impeller structure; Figure 2 This is a schematic diagram of the impeller structure; Figure 3 This is the front view of the impeller structure; Figure 4 A flowchart of an intelligent control method for an adaptive anti-cavitation water pump with a targeted jet structure.

[0019] Among them: 1. Hub; 2. Blade; 21. Main blade; 22. Flow divider blade; 3. Cover plate; 4. Asymmetric rounded passivation structure; 5. Axial flow ridge structure; 6. Converging targeted microgroove; 7. Blade radial segmented inlet angle structure. Detailed Implementation

[0020] 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.

[0021] This invention provides an adaptive anti-cavitation water pump with a targeted jet structure and its control method. The water pump improves the basic flow field through a composite anti-cavitation structure located in the inlet region of blade 2. It identifies cavitation risks remaining after the composite structure's action using multi-source operating signals and corrects the control threshold based on the impeller structure's anti-cavitation capability. When the cavitation risk index reaches the corrected control threshold, the controller generates a target anti-cavitation speed and implements restricted adjustment, thus forming a closed-loop anti-cavitation scheme that combines structural anti-cavitation, risk identification, and operational control.

[0022] At the structural level, the leading edge of blade 2 adopts an asymmetric rounded blunt structure 4 to mitigate the local acceleration of the inflow on the suction side; an axial flow-guiding ridge is provided in the inlet section of blade 2 to guide and distribute the inflow at the impeller inlet; the inlet angle of blade 2 is segmented radially to accommodate the non-uniform inflow on the hub side, the middle blade height region, and the rim side; a convergent targeted microgroove 6, extending from the pressure surface to the suction surface, is provided 10%–25% of the chord length behind the leading edge of blade 2, utilizing the pressure difference on both sides of blade 2 to form a directional microjet that does not require an independent external jet power source. These structures collectively improve the flow state at the impeller inlet, increase the near-wall fluid momentum and local pressure level on the suction surface, suppress boundary layer detachment, and delay cavitation initiation.

[0023] At the identification level, the control system collects multi-source operating signals such as inlet pressure, outlet pressure, fluid temperature, pump casing vibration, and speed. After filtering, frequency domain analysis, and operating condition normalization, it forms net positive suction head (NPSH) risk, inlet pressure fluctuation risk, high-frequency vibration risk, and differential pressure attenuation risk, which are then integrated into the cavitation risk index (CRI). The Cavitation Risk Index is used to convert continuously changing hydraulic and vibration responses into a unified and comparable cavitation risk scale.

[0024] At the control level, the controller incorporates the cavitation resistance correction coefficient obtained from the impeller structure calibration into the cavitation risk classification threshold, ensuring that the control actions reflect both the current operational risk and the actual cavitation resistance of the targeted microgroove and inlet composite structure. When the cavitation risk index reaches the corrected control threshold, the controller generates the cavitation resistance target speed and executes it through the variable frequency drive under speed boundary and rate of change constraints. The executed operating signal re-enters the identification stage, thus forming a closed loop of "real-time perception—state identification—target generation—execution control—feedback correction".

[0025] In one embodiment of the present invention, the adaptive anti-cavitation water pump with a targeted jet structure includes: a pump body, a pump shaft, an impeller, a drive motor, a frequency converter, a signal detection system, and an intelligent controller.

[0026] The impeller is mounted on the pump shaft and located within the flow chamber of the pump body; such as Figure 1 , Figure 2 As shown, the impeller includes a hub 1, multiple blades 2 spaced circumferentially along the hub 1, and a cover plate 3 connected to the blades 2. A signal detection system is used to collect the operating signals of the water pump. An intelligent controller is used to execute cavitation identification and adaptive control programs based on the operating signals and output speed commands. A variable frequency drive is used to adjust the speed of the drive motor according to the speed commands output by the intelligent controller. The drive motor is used to drive the impeller to rotate.

[0027] like Figure 3As shown, the blade 2 includes a main blade 21 and a diverter blade 22, which are arranged alternately. The blade 2 includes a pressure surface (the side of the blade 2 facing the impeller rotation direction, "pushing" the water away), a suction surface (opposite to the pressure surface, located on the back side of the blade 2 in the rotation direction), an inlet leading edge (the edge of the blade 2 that first contacts and cuts the fluid), and an outlet trailing edge (the edge of the blade 2 that last separates from the fluid and throws the water away). The inlet leading edge of the diverter blade 22 has a radial gap with the inlet leading edge of the main blade 21; the outlet trailing edge of the diverter blade 22 is flush with the outlet trailing edge of the main blade 21 and extends to the radial outer edge of the impeller.

[0028] The inlet region of blade 2 is provided with a composite anti-cavitation structure, which includes an asymmetric rounded passivation structure 4 at the leading edge of blade 2 inlet, an axial flow-guiding ridge structure 5 at the inlet section of blade 2, a radially segmented inlet angle structure 7, and a convergent targeted microgroove 6 penetrating both the pressure surface and the suction surface of blade 2. Each structure can be integrally formed with blade 2, or it can be formed by processing or joining under the conditions of meeting the requirements of connection strength, dimensional accuracy, and continuity of the flow surface.

[0029] Specifically, the asymmetric rounded passivation structure 4 at the inlet leading edge of blade 2 is as follows: A rounded transition portion is formed along the thickness direction of blade 2 at the inlet leading edge of the main blade 21, smoothly connecting to both the pressure surface and the suction surface; the rounded passivation dimension on the suction surface side is larger than that on the pressure surface side. This constitutes the asymmetric rounded passivation structure 4. The rounded passivation dimension can be represented by the radius of curvature, equivalent radius of curvature, or other geometric parameters that can characterize the degree of leading edge passivation.

[0030] The suction side uses a larger rounded dimension, which helps to increase the transition length of the incoming flow from the inlet leading edge to the suction side, and reduces the fluid acceleration and pressure drop caused by local curvature abrupt changes. The pressure side uses a relatively smaller rounded dimension, which helps to balance the guiding capacity and hydraulic efficiency of the blade 2 inlet. The rounded transition sections on the pressure side and the suction side are continuously connected to the surfaces of adjacent blades 2 to avoid the formation of new sharp corners, steps, or local vortex sources.

[0031] The axial flow guiding ridge structure 5 at the inlet section of blade 2 specifically comprises: a flow guiding structure extending axially along the pump shaft on the pressure surface side of the inlet section of blade 2, with the front end of the flow guiding structure facing the impeller inlet and the rear end of the flow guiding structure smoothly transitioning to the surface of blade 2. The axial flow guiding ridge extends axially along the pump shaft, or its main extension direction has an axial component, and is arranged in the region where the incoming flow at the inlet of blade 2 first acts, to pre-guide, distribute, and rectify the fluid entering the impeller flow channel.

[0032] The axial flow ridge alters the guiding relationship of the local flow channel at the inlet of blade 2, reducing fluid concentration in the local blade height region, decreasing the non-uniformity of velocity distribution at the inlet section, and mitigating inflow deflection under high flow rates or deviations from design conditions. The height, width, length, and curvature of the axial flow ridge are determined based on the impeller size, inlet flow channel shape, and target operating range. Its surface maintains a continuous transition with the inlet section of blade 2 to minimize additional hydraulic losses.

[0033] The radially segmented inlet angle structure 7 of the blade is specifically as follows: the leading edge of the blade 2 is divided radially into at least two regions, each region having a different local inlet angle, and the regions are connected by a continuous curved surface or a gradual transition. The segmentation can be based on the hub 1 side region, the intermediate blade height region, and the rim side region. The inlet angle of each region is determined according to the incoming flow velocity triangle, axial velocity distribution, and circumferential velocity at the corresponding location.

[0034] The radially segmented inlet angle structure enables the blade inlet geometry to match the non-uniform incoming flow at different blade height positions, reducing the possibility of excessive local angle of attack, flow separation, and backflow. When this structure is combined with the axial flow guide ridge, the axial flow guide ridge first distributes and guides the inlet fluid, and the segmented inlet angle then specifically receives the fluid in different radial regions, thereby jointly improving the impeller inlet velocity distribution.

[0035] A convergent-type targeted microgroove 6, penetrating both the pressure and suction surfaces of blade 2, is positioned at a distance of 10%–25% of the chord length from the leading edge of the blade 2 inlet. The opening on the pressure surface side of blade 2 constitutes the microgroove inlet, and the opening on the suction surface side constitutes the microgroove outlet. The equivalent flow width of the microgroove inlet is greater than the equivalent flow width of the microgroove outlet. The inner wall of the convergent-type targeted microgroove 6 gradually converges from the inlet to the outlet, forming a convergent nozzle-like channel. One convergent-type targeted microgroove 6 can be provided for one blade 2, or multiple convergent-type targeted microgrooves 6 spaced apart along the blade height direction can be provided. Multiple convergent-type targeted microgrooves 6 can use the same or different inlet size, outlet size, and jet direction. The microgroove size is constrained to ensure a stable jet without causing insufficient structural strength or excessive leakage loss in blade 2.

[0036] Under pumping conditions, a pressure difference is formed between the pressure surface and the suction surface of blade 2. This pressure difference drives the fluid on the pressure surface side into the convergent targeted microchannel 6, and as the channel cross-sectional area gradually decreases, it accelerates and exits from the suction surface side outlet, forming a directional microjet directed downstream of the suction surface. The velocity and flow rate of the microjet change accordingly with the pressure difference across blade 2, eliminating the need for a separate jet pump, air supply device, or moving parts.

[0037] The center direction of the targeted micro-groove outlet is oriented downstream of the suction surface, and the micro-jet direction forms an angle of 15°–30° with the mainstream direction corresponding to the suction surface. This angle range allows the jet to have a velocity component in the downstream direction of the suction surface to replenish momentum to the near-wall fluid, while retaining a velocity component pointing towards the flow field outside the suction surface to improve local pressure and mixing. The micro-groove outlet direction and the surface of blade 2 have a smooth transition to reduce the possibility of additional separation at the jet outlet.

[0038] The asymmetric rounded passivation structure 4, the axial flow guiding ridge structure 5, the blade radial segmented inlet angle structure 7, and the convergent targeted microgroove 6 improve the impeller inlet flow from the aspects of low pressure release at the leading edge, inlet flow distribution, radial angle matching, and suction surface near-wall energy replenishment, and together form a composite anti-cavitation effect.

[0039] The aforementioned composite structure reduces the local low pressure at the inlet suction surface of blade 2, slows down inlet velocity concentration, suppresses boundary layer detachment and backflow, and delays cavitation nucleus formation and cavitation zone expansion. The composite impeller structure continuously reduces cavitation susceptibility; when the cavitation risk index reaches the control threshold after structural correction, the intelligent controller generates an anti-cavitation target speed, which is then executed by the variable frequency drive under speed boundary and rate of change constraints.

[0040] Based on the aforementioned anti-cavitation impeller structure, this invention proposes an anti-cavitation operation control method based on impeller structure parameter correction. This method does not simply rely on general operating parameters for conventional closed-loop pump regulation. Instead, it takes the impeller of a water regulating pump equipped with convergent targeted microgrooves 6, an asymmetric rounded passivation structure 4, an axial flow guiding ridge structure 5, and a radially segmented inlet angle structure 7 as the control object, incorporating the impeller's local anti-cavitation structural parameters into the cavitation state criterion and control target generation process.

[0041] In the control method, the blade 2 body first forms a self-driven micro-jet through a convergent targeted micro-groove 6 that runs from the pressure surface to the suction surface, providing momentum compensation for the low-pressure region near the suction surface. The asymmetric leading-edge rounded-off structure, axial flow-guiding ridge, and segmented inlet angle further perform low-pressure slow release, pre-guidance, and zone matching for the inlet flow. Based on this, the control system identifies the remaining cavitation risk based on the cavitation sensitivity signal of the water pump, corrects the cavitation discrimination threshold according to the impeller structure's anti-cavitation capability, and then generates a limited anti-cavitation control target based on the corrected threshold, thus forming a collaborative anti-cavitation method that combines passive structural suppression with active operational adjustment.

[0042] Specifically, such as Figure 4 As shown, the control methods include: S1. Collect the reference status parameters and sensitive signals of the water pump through the signal detection system.

[0043] Under stable operating conditions (baseline state) with no or weak cavitation in the pump, the inlet pressure is collected. Export pressure Fluid temperature T(t) and pump casing vibration signal Establish a benchmark inlet pressure fluctuation intensity Reference high-frequency vibration energy Rate of change of reference pressure difference and baseline net positive suction head The baseline state can be stored by speed and effective flow range for later retrieval under different operating conditions.

[0044]

[0045] in, As a set of baseline parameters, As the reference speed, As the baseline effective flow rate, The inlet average pressure under baseline conditions; when a flow detection unit is present. The actual measured flow rate can be used. If there is no flow detection unit, it can be estimated using the pump station scheduling amount, pump characteristic curve, or operating parameters.

[0046] Acquisition of cavitation-sensitive signals from multi-source pumps: The signal detection system collects the inlet pressure of the water pump under normal operating conditions. Export pressure Fluid temperature and pump casing vibration signal According to temperature Determine saturated vapor pressure The effective net positive suction head (NPSH) of the current unit is calculated by combining the inlet pressure and the average inlet velocity. Its expression is:

[0047] In the formula, For fluid density; This is the acceleration due to gravity.

[0048] The reference state parameters include the inlet pressure, outlet pressure, fluid temperature, pump casing vibration signal, reference inlet pressure fluctuation intensity, reference high-frequency vibration energy, reference differential pressure change rate, and reference net positive suction head (NPSH) of the water pump under stable operating conditions with no or weak cavitation; the sensitive signals include the inlet pressure, outlet pressure, fluid temperature, pump casing vibration signal, and effective NPSH of the water pump under normal operating conditions. S2. Extract pump cavitation characteristics based on baseline state parameters and sensitive signals.

[0049] Extracting inlet pressure fluctuation intensity Inlet and outlet pressure difference Rate of change of inlet and outlet pressure difference NPSH margin and cavitation-sensitive high-frequency vibrational energy .in, It can be obtained from the frequency domain energy of the pump casing vibration signal in the cavitation-sensitive high-frequency band. The cavitation-sensitive frequency band can be determined by comparing the signals of the same type of pump under no cavitation, critical cavitation and obvious cavitation conditions.

[0050]

[0051]

[0052]

[0053] In the formula, This is the lower limit frequency of the cavitation-sensitive high-frequency band; This is the upper limit frequency of the cavitation-sensitive high-frequency band; This indicates that the pump casing vibration signal, after time-frequency transformation, is at time [time value missing]. t ,frequency f The time-frequency amplitude at that location.

[0054] S3. Construct basic cavitation risk indicators.

[0055] Basic cavitation risk indicators Instead of using a simple linear combination of speed, pressure, and temperature, this study incorporates inlet pressure fluctuations, cavitation-sensitive high-frequency vibrations, inlet and outlet pressure difference rates, and NPSH margin into the risk assessment based on the cavitation mechanism of the water pump.

[0056] The basic cavitation risk indicators are as follows:

[0057]

[0058] In the formula, It is a basic cavitation risk indicator; Inlet pressure fluctuation intensity; The reference inlet pressure fluctuation intensity; This refers to cavitation-sensitive high-frequency vibrational energy. The reference high-frequency vibration energy; This represents the rate of change of the pressure difference between the inlet and outlet. The rate of change of the baseline pressure difference; The required net positive suction head (NPSH); This is the effective net positive suction head (NPSH). , , , All weights are dynamic. The larger the value, the higher the risk of cavitation or cavitation development in the pump.

[0059] S4. Parameterize the cavitation resistance of the impeller structure to obtain the impeller structure parameters.

[0060] Read or set the local anti-cavitation structure parameters of the current impeller, including the position of the microslots. Microchannel inlet area Microchannel outlet area Entrance to exit area ratio Microchannel outlet jet angle The radius of the blunt edge of the suction surface side The radius of the blunt edge of the pressure surface side Asymmetric circular passivation radius ratio Axial drainage ridge height or arrangement length and hub-side inlet angle , Middle area entrance angle and the inlet angle of the rim side The impeller structure parameter set is obtained. :

[0061] The above structural parameters are used to represent the anti-cavitation capability of the impeller body formed by the convergent targeted microgroove 6, the asymmetric rounded passivation structure 4, the axial flow ridge structure 5, and the radial segmented inlet angle structure 7 of the blade.

[0062] S5. Calculate the structural cavitation correction coefficient based on the impeller structural parameters. The expression is as follows:

[0063] In the formula, This represents the mapping function used to determine the structural cavitation correction coefficient based on the aforementioned impeller structural parameters. The functional relationship is determined by the calibration results of the impeller structure's cavitation resistance capability.

[0064] S6. The structural cavitation resistance correction coefficient is used to correct the basic cavitation critical threshold and the obvious cavitation basic threshold to obtain the structural correction threshold.

[0065] Specifically:

[0066]

[0067] In the formula, This is the corrected cavitation critical threshold; The corrected obvious cavitation baseline threshold; , All of these are functional relationships determined based on prototype testing, on-site commissioning, or operating data from similar impellers. In the absence of experimental data, specific empirical coefficients are not limited, and the safety protection threshold is not reduced due to increased structural capacity, thus preserving an independent safety boundary. This is the structural cavitation resistance correction factor; It is the critical threshold for basic cavitation; This represents the basic threshold for obvious cavitation.

[0068] S7. Determine the cavitation state of the water pump based on the basic cavitation risk index and structural correction threshold; specifically: when < When, it is determined to be in normal operating condition; when ≤ < When, it is determined to be a cavitation critical state; when ≥ At that time, it was determined to be a clear cavitation state.

[0069] S8. Generate anti-cavitation control targets based on the cavitation state of the water pump and execute control actions.

[0070] The control target is generated based on a structurally modified threshold, rather than being triggered solely by a fixed threshold. < When, maintain the current speed and operating conditions; when ≤ < At that time, while ensuring conveying capacity, a gradual deceleration or operating condition correction target is generated based on risk deviation; when ≥ At that time, stronger speed correction, safety protection, or alarm strategies will be implemented.

[0071] The specific objectives of cavitation control are:

[0072]

[0073] , ≥

[0074] In the formula, The target rotational speed; Rated speed; This is the speed adjustment coefficient; This represents the maximum permissible rate of change in rotational speed of the water pump system.

[0075] S9. After the control action is executed, the cavitation state is re-evaluated, and an anti-cavitation control target is generated and executed based on the new cavitation state.

[0076] The control system compares the values ​​before and after adjustment. Inlet pressure fluctuation intensity Rate of change of inlet and outlet pressure difference and high-frequency vibration energy The synergistic inhibition effect between the convergent targeted microgroove 6 structure and operational regulation was evaluated. If after regulation... and Decline and If the situation tends to stabilize, maintain the current control strength or appropriately reduce the control gain; if the adjustment... , or If it continues to rise, then increase the weight of the vibration characteristics and correct... Or increase the control gain.

[0077] Early solutions mainly employed traditional passive geometric measures such as overall blade inlet angle optimization, increasing leading edge radius, adjusting blade wrap angle, or setting secondary blades. These measures could improve the blade inlet angle of attack and flow around the leading edge near the design operating conditions, but the overall inlet angle was difficult to simultaneously adapt to the non-uniform flow on both the hub side and the rim side. Furthermore, simple rounding was insufficient to continuously improve the low pressure and boundary layer momentum issues downstream of the suction surface.

[0078] Based on the above problems, the research and development focus of this invention has shifted from "overall geometric parameter optimization" to "local flow distribution and regional matching at the impeller inlet". The traditional method is retained as the basic structure, in which the leading edge rounding is further changed to an asymmetric form with different scales on the suction side and the pressure side, so as to more effectively mitigate local acceleration on the suction side.

[0079] An axial flow-guiding ridge is introduced at the inlet section of blade 2, and the inlet angle of blade 2 is divided into multiple regions radially. The axial flow-guiding ridge is used to pre-guide and redistribute the inlet flow of the impeller, and the segmented inlet angle is used to match the local velocity triangles at different blade height positions, thereby improving the problems of uneven velocity distribution at the inlet section of the large pump, excessive local angle of attack, and flow separation on the rim side or hub side.

[0080] The impeller's adaptability to inflows deviating from design conditions has been improved, but its role is still mainly focused on rectification and reception of the inflow as it enters blade 2. For the localized low-pressure zone already formed behind the suction front edge, relying solely on the inlet guiding structure is insufficient to directly replenish the momentum of the near-wall fluid, thus boundary layer detachment and cavitation nucleus development may still occur. Therefore, it is necessary to further develop localized flow control structures that can directly act on the cavitation-prone areas of the suction surface.

[0081] A targeted microgroove is installed at a position 10%–25% of the chord length from the leading edge of blade 2's inlet, penetrating both the pressure and suction surfaces. The microgroove gradually converges from a wider inlet on the pressure surface side to a narrower outlet on the suction surface side. When the water pump is running, the pressure difference across blade 2 drives the fluid on the pressure surface side to accelerate through the microgroove, forming a directional microjet on the suction surface at an angle of 15°–30° to the mainstream direction.

[0082] This improvement eliminates the need for an independent external jet power source, enabling the replenishment of fluid momentum to the near-wall region of the suction surface, increasing local pressure levels, and mitigating boundary layer detachment. Thus, the impeller forms a composite anti-cavitation structure of "leading-edge slow release—inlet rectification—radial matching—targeted energy replenishment." However, the effectiveness of the passive structure is still affected by inlet pressure, flow rate, rotational speed, and pipeline fluctuations. When cavitation risks exceed the structure's coverage, further risk suppression through operational control is necessary.

[0083] Therefore, an anti-cavitation control strategy based on impeller structural parameter correction is introduced. Based on the composite anti-cavitation impeller, an anti-cavitation operation control based on impeller structural parameter correction is introduced. The control system does not simply rely on closed-loop regulation based on general parameters such as speed, pressure, and temperature. Instead, it incorporates the structural parameters of the convergent targeted microgroove 6, the asymmetric circular passivation structure 4, the axial flow guiding ridge structure 5, and the radial segmented inlet angle structure 7 of the blades into the cavitation threshold correction, so that the operation control matches the anti-cavitation capability of the impeller body.

[0084] To avoid using the same cavitation criterion for different impeller structures, this invention calculates the structural anti-cavitation correction coefficient based on the microgroove position, microgroove convergence ratio, jet angle, leading edge asymmetric rounded passivation radius ratio, ridge parameters, and segmented inlet angle. Based on this, the cavitation critical threshold is corrected. and obvious cavitation threshold Therefore, the composite impeller structure first passively reduces the cavitation susceptibility through targeted microgroove jets, leading-edge slow release, inlet rectification, and zone matching. The control system then identifies the remaining cavitation risks beyond the structural capabilities and implements limited regulation.

Claims

1. An adaptive anti-cavitation water pump with a targeted jet structure, characterized in that, include: Pump body, pump shaft, impeller, drive motor, frequency converter, signal detection system and intelligent controller; The signal detection system is used to collect the operating signals of the water pump; The intelligent controller is used to execute cavitation identification and adaptive control programs based on operating signals and output speed commands; The variable frequency drive is used to adjust the speed of the drive motor according to the speed command output by the intelligent controller; The drive motor is used to drive the impeller to rotate; The impeller is mounted on the pump shaft and located in the flow chamber of the pump body; the impeller includes a hub, multiple blades spaced apart circumferentially along the hub, and a cover plate connected to the blades; The blades include main blades and diverter blades, which are arranged alternately. The leading edge of the diverter blades and the leading edge of the main blades have a radial gap. The trailing edge of the diverter blades is flush with the trailing edge of the main blades and extends to the radial outer edge of the impeller. The blade inlet area is provided with a composite anti-cavitation structure, which includes an asymmetric rounded blunt structure at the blade inlet leading edge, an axial flow-guiding ridge structure in the blade inlet section, a radial segmented inlet angle structure, and a convergent targeted microgroove that penetrates the pressure surface and suction surface of the blade.

2. The adaptive anti-cavitation water pump with a targeted jet structure according to claim 1, characterized in that, The asymmetric rounded passivation structure at the leading edge of the blade inlet is specifically defined as follows: a rounded transition section is formed along the thickness direction of the blade inlet leading edge, which is smoothly connected to the pressure surface and the suction surface respectively; wherein the rounded passivation dimension on the suction surface side is larger than that on the pressure surface side.

3. The adaptive anti-cavitation water pump with a targeted jet structure according to claim 1, characterized in that, The axial flow-guiding ridge structure of the blade inlet section is specifically provided as follows: a flow-guiding structure extending axially along the pump shaft is provided on the pressure surface side of the blade inlet section, the front end of the flow-guiding structure faces the impeller inlet, and the rear end of the flow-guiding structure smoothly transitions with the blade surface.

4. The adaptive anti-cavitation water pump with a targeted jet structure according to claim 1, characterized in that, The radially segmented inlet angle structure of the blade is specifically as follows: the leading edge of the blade is divided into at least two regions along the radial direction, each region is provided with a different local inlet angle, and the regions are connected by a continuous curved surface or a gradual transition.

5. The adaptive anti-cavitation water pump with a targeted jet structure according to claim 1, characterized in that, The converging-type targeted microgroove penetrating the pressure surface and suction surface of the blade is positioned at a distance of 10%–25% of the chord length from the leading edge of the blade inlet. The opening on the pressure surface side of the blade constitutes the microgroove inlet, and the opening on the suction surface side constitutes the microgroove outlet. The equivalent flow width of the microgroove inlet is greater than the equivalent flow width of the microgroove outlet. The inner wall of the converging-type targeted microgroove gradually converges from the microgroove inlet to the microgroove outlet, forming a converging nozzle-type channel. One converging-type targeted microgroove can be provided for one blade, or multiple converging-type targeted microgrooves spaced apart from each other can be provided along the blade height direction. Multiple converging-type targeted microgrooves can use the same or different inlet size, outlet size, and jet direction.

6. A smart control method for an anti-cavitation water pump with a targeted jet structure as described in any one of claims 1-5, characterized in that, include: The reference state parameters and sensitive signals of the water regulating pump are collected by a signal detection system. The reference state parameters include the inlet pressure, outlet pressure, fluid temperature, pump casing vibration signal, reference inlet pressure fluctuation intensity, reference high-frequency vibration energy, reference differential pressure change rate, and reference net positive suction head (NPSH) under stable operating conditions with no or weak cavitation. The sensitive signals include the inlet pressure, outlet pressure, fluid temperature, pump casing vibration signal, and effective NPSH under normal operating conditions of the water regulating pump. Pump cavitation characteristics are extracted based on baseline state parameters and sensitive signals. These pump cavitation characteristics include inlet pressure fluctuation intensity, inlet and outlet pressure difference, inlet and outlet pressure difference change rate, NPSH margin, and cavitation-sensitive high-frequency vibration energy. Construct basic cavitation risk indicators; The anti-cavitation capability of the impeller structure is parameterized to obtain impeller structure parameters. The impeller structure parameters include the position of the convergent targeted microgroove, the inlet area of ​​the microgroove, the outlet area of ​​the microgroove, the inlet-outlet area ratio of the microgroove, the jet angle at the outlet of the microgroove, the blunt radius of the leading edge of the blade suction side, the blunt radius of the leading edge of the blade pressure side, the ratio of asymmetric blunt radii, the height or arrangement length of the axial flow ridge, and the inlet angle of the hub side, the inlet angle of the middle region, and the inlet angle of the outer edge of the impeller. Calculate the structural cavitation correction coefficient based on the impeller structural parameters; The structural cavitation resistance correction coefficient is used to correct the basic cavitation critical threshold and the obvious cavitation basic threshold to obtain the structural correction threshold; Cavitation status of water pumps is determined based on basic cavitation risk indicators and structural correction thresholds. Based on the cavitation state of the water pump, generate anti-cavitation control targets and execute control actions; After the control action is executed, the cavitation state is re-evaluated, and an anti-cavitation control target is generated and executed based on the new cavitation state.

7. The method according to claim 6, characterized in that, The basic cavitation risk indicators are as follows: In the formula, It is a basic cavitation risk indicator; Inlet pressure fluctuation intensity; The reference inlet pressure fluctuation intensity; This refers to cavitation-sensitive high-frequency vibrational energy. The reference high-frequency vibration energy; This represents the rate of change of the pressure difference between the inlet and outlet. The rate of change of the baseline pressure difference; The required net positive suction head (NPSH); This is the effective net positive suction head (NPSH). , , , All weights are dynamic.

8. The method according to claim 7, characterized in that, The structural cavitation resistance correction coefficient is used to correct the basic cavitation critical threshold and the obvious cavitation basic threshold, resulting in the structural correction threshold, specifically: In the formula, This is the corrected cavitation critical threshold; The corrected obvious cavitation baseline threshold; All of these are functional relationships determined based on prototype testing, on-site debugging, or operating data of similar impellers; This is the structural cavitation resistance correction factor; It is the critical threshold for basic cavitation; This represents the basic threshold for obvious cavitation.

9. The method according to claim 8, characterized in that, The cavitation state of the water pump is determined based on basic cavitation risk indicators and structural correction thresholds, specifically as follows: when < When, it is determined to be in normal operating condition; when ≤ < When, it is determined to be a cavitation critical state; when ≥ At that time, it was determined to be a clear cavitation state.

10. The method according to claim 8, characterized in that, The specific objectives of cavitation control are: , ≥ In the formula, The target rotational speed; Rated speed; This is the speed adjustment coefficient; This represents the maximum permissible rate of change in rotational speed of the water pump system.

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