Centrifugal pump gas cavitation process simulation visual device, system and control method

Abstract

This invention relates to the field of high-speed centrifugal pump testing technology, and particularly to a device, system, and control method for simulating and visualizing the gas cavitation process in a centrifugal pump. The device integrates dual-function modes: visualization testing of gas cavitation in the pump and observation of bubble dynamics in a transparent tank. Independent operation is achieved through shared gas-liquid pipelines and valve switching. A multi-parameter adaptive algorithm is used to adaptively and precisely adjust gas flow rate, liquid flow rate, and centrifugal pump speed. Its advantages include the ability to intuitively observe the evolution of cavitation within the pump and the bubble behavior in the tank. It is suitable for studying the gas cavitation mechanism and bubble dynamics of high-speed centrifugal pumps, and features adjustable operating conditions, precise control, high visualization, and strong stability.

Description

Technical Field

[0001] This invention relates to the field of high-speed centrifugal pump testing technology, and in particular to a device, system and control method for simulating and visualizing the gas cavitation process of a centrifugal pump. Background Technology

[0002] High-speed centrifugal pumps, as a type of high-efficiency fluid transport equipment, are widely used in many industrial fields such as petrochemicals, aerospace, nuclear power, and water supply and drainage. They play a key role in transporting high-pressure and high-speed fluids, and their reliability and operating efficiency directly determine the stability and economy of the entire transport system.

[0003] In the actual operation of high-speed centrifugal pumps, factors such as the unavoidable mixing of trace amounts of gas in the transported medium, system pressure fluctuations, and sudden increases in local flow velocity due to high impeller speed easily lead to gas-liquid two-phase gas-containing cavitation coupled flow. The combined effect of cavitation and gas content can cause impeller erosion, increased vibration, and decreased efficiency, and in severe cases, structural failure, seriously restricting the service life and operational stability of high-speed centrifugal pumps. Therefore, accurately studying the evolution law of gas-containing cavitation inside high-speed centrifugal pumps under different gas content conditions, and refining the observation of the rising dynamics of bubbles in the liquid medium, including but not limited to bubble rising speed, morphological evolution, bubble coalescence, rupture mechanism, and spatial distribution characteristics, has important engineering application value and theoretical research significance for optimizing the impeller structure design of high-speed centrifugal pumps, improving anti-cavitation performance, increasing propellant delivery efficiency, and ensuring the long-term safe and stable operation of high-speed centrifugal pumps.

[0004] Currently, some research methods and technical solutions related to cavitation and bubble behavior exist in the existing technology. For example, patent CN118070706A discloses a method for predicting the impact strength of cavitation collapse near a near-wall bubble on the wall. This method focuses on the theoretical prediction of the impact strength of a single cavitation collapse near the wall, does not cover the entire process of gas-containing cavitation in a high-speed centrifugal pump, does not involve the study of complex behaviors such as bubble generation and coalescence, and does not consider the actual operating parameters and structural parameters of the high-speed centrifugal pump. It also lacks corresponding experimental equipment support, and the prediction results are out of touch with engineering practice, resulting in weak practicality. Based on this, patent CN119692233B discloses a numerical simulation method for near-wall single cavitation collapse coupled with boundary motion. Although this method optimizes the boundary motion simulation, it is still limited to single cavitation numerical simulation and cannot reflect the real cavitation characteristics of the collaborative evolution of multiple bubbles in a high-speed centrifugal pump. Moreover, the simulation parameters are fixed, the actual physical properties of the propellant are not considered, and it also lacks experimental equipment support, making it impossible to achieve cavitation visualization observation and experimental data calibration. The simulation error is large and it is difficult to adapt to the dynamic operating conditions of a high-speed centrifugal pump.

[0005] In summary, the existing technology has the following main shortcomings: 1. Existing experimental setups typically only allow for individual pump cavitation tests or individual bubble behavior observation tests, making it impossible to conduct both types of tests simultaneously on the same hardware platform under identical operating conditions. Because the operating conditions (such as gas source pressure, liquid flow rate, and gas content) of the two independent setups are difficult to completely match, the experimental data on pump cavitation morphology and external bubble dynamics lack comparability, hindering a deeper understanding of the gas-containing cavitation mechanism.

[0006] 2. Existing methods are mostly limited to numerical simulation or theoretical prediction of single cavitation bubbles, which makes it difficult to reflect the cavitation characteristics of multi-bubble co-evolution and coupling with the actual pump flow field.

[0007] 3. The lack of high-precision, adaptive, and coordinated control methods for multiple parameters such as gas content, pressure, flow rate, and rotation speed makes it difficult to guarantee the stability and repeatability of test conditions under complex working conditions.

[0008] Therefore, this case is brought. Summary of the Invention

[0009] The purpose of this invention is to provide a device, system, and control method for simulating and visualizing the gas cavitation process of a centrifugal pump, so as to achieve precise control of gas content, visualization of the entire gas cavitation process, synchronous measurement of multiple parameters, and dynamic adaptive adjustment, and to support the study of the gas cavitation mechanism and bubble dynamics behavior of high-speed centrifugal pumps.

[0010] To achieve the above objectives, the present invention provides the following technical solution: A simulation and visualization device for the cavitation process of a centrifugal pump includes an air generator, an air storage tank, a flow controller, a transparent storage tank, a gas-liquid mixer, a centrifugal pump, and a water tank, wherein the centrifugal pump has a transparent housing; The air generator's input terminal is used to input air, and its output terminal is connected to the input terminal of the air storage tank. The output terminal of the air storage tank is split into two branches through a flow controller. One branch is connected to the input terminal of the transparent storage tank through a switching valve, and the other branch is connected to the gas phase input terminal of the gas-liquid mixer through a switching valve. The transparent storage tank stores water, and its output terminal is connected to the liquid phase input terminal of the gas-liquid mixer through a switching valve. The output terminal of the gas-liquid mixer is split into two paths. One path is connected to the water tank through a switching valve, and the other path is connected to the input terminal of the centrifugal pump. The output terminal of the centrifugal pump is connected to the water tank through a switching valve. Pressure gauges are installed on the gas storage tank and the transparent storage box, and a flow meter is installed at the output end of the transparent storage box. A flow sensor is installed on the branch line leading to the gas phase input end of the gas-liquid mixer. Pressure sensors are installed at both the input and output ends of the centrifugal pump. Camera units are installed on the outside of the transparent storage box and the outside of the centrifugal pump to collect images of bubbles in the transparent storage box and images of gas-containing cavitation morphology in the centrifugal pump.

[0011] A simulation and visualization system for the gas cavitation process of a centrifugal pump includes: The above-mentioned centrifugal pump gas cavitation process simulation and visualization device; The remote control and data acquisition module includes a data acquisition and analysis unit, a command issuing unit, and a multi-parameter adaptive algorithm unit; The data acquisition and analysis unit is used to acquire the centrifugal pump speed, as well as the data fed back by the camera unit, various pressure gauges, flow meters, pressure sensors, and flow sensors. It calculates the gas content based on the acquired gas flow rate and liquid flow rate, and analyzes the acquired bubble image data to obtain image data of bubble generation, rising, deformation, aggregation, and bursting behavior. It also obtains bubble characteristic data such as bubble diameter, area distribution, and relative frequency. The multi-parameter adaptive algorithm unit is used to calculate parameter deviations based on the current working conditions and the data collected and analyzed, tune PID parameters online, calculate coupling compensation and disturbance compensation, and generate adaptive adjustment commands for pressure, flow rate, speed and gas content during the test. The instruction issuing unit is used to receive strategies or instructions issued by the host computer measurement and control platform, as well as adaptive adjustment instructions generated by the multi-parameter adaptive algorithm unit, to switch or start / stop the test conditions of the centrifugal pump gas cavitation process simulation visualization device, and to regulate the flow controller, centrifugal pump, and various switching valves.

[0012] Furthermore, the remote control and data acquisition module includes a working condition identification unit, which is configured with a set of control strategy parameters for the test working condition. Each set of control strategy parameters for the test working condition includes a target pressure range, a set of control weight coefficients, a pump speed reference, and preset states of the on / off valves. When the host computer control platform issues specific test condition commands, the condition identification unit matches the corresponding test condition control strategy parameter set according to the command, and adjusts the flow controller, centrifugal pump, and various switching valves through the command issuing unit to complete the switching of test conditions.

[0013] A simulation and visualization control method for the gas cavitation process of a centrifugal pump based on the system includes the following steps: Step S1: Complete the assembly of the gas path, liquid path and hardware, establish a communication link, conduct airtightness and pressure resistance tests, and complete the initial configuration of the multi-parameter adaptive algorithm and liquid path venting. Step S2: Select the test condition and issue instructions on the host computer measurement and control platform; Step S3: Based on the selected test conditions, the system automatically matches and loads the corresponding control strategy for the test conditions; Step S4: Real-time acquisition of pressure, flow rate, rotation speed and bubble image data, and analysis to obtain data on gas content, bubble diameter, area distribution and relative frequency; The multi-parameter adaptive algorithm calculates parameter deviations based on the collected and analyzed data, tunes PID parameters online, calculates coupling compensation and disturbance compensation, outputs total control quantity, generates adaptive adjustment commands for pressure, flow rate, speed, and gas content during the test, and performs adaptive adjustment. Step S5: Run stably and save the visualization images and experimental data synchronously; Step S6: The experiment ends, the system automatically resets, archives the data, and completes the experiment loop.

[0014] Furthermore, in step S3, when the selected test condition is the pump-containing air cavitation visualization test mode, the system opens the switch valves from the gas storage tank to the transparent storage tank, the switch valve from the gas storage tank to the gas-liquid mixer, the switch valve between the output end of the transparent storage tank and the gas-liquid mixer, and the switch valve between the output end of the centrifugal pump and the water tank, and closes the switch valve between the output end of the gas-liquid mixer and the water tank.

[0015] Furthermore, in step S3, when the selected test condition is the pump-borne cavitation visualization test mode, the multi-parameter adaptive algorithm triggers a gas content differential control strategy, which includes: The working condition with a gas content not greater than the first preset threshold is defined as a low gas content working condition, the working condition with a gas content between the first preset threshold and the second preset threshold is defined as a medium gas content working condition, and the working condition with a gas content not less than the second preset threshold is defined as a high gas content working condition, wherein the first preset threshold is less than the second preset threshold. When operating under low gas content conditions, based on the online self-tuning of PID parameters and disturbance compensation, coupling compensation between flow rate and speed is triggered to suppress cross-interference between flow rate and speed under low gas content conditions. When operating under medium gas content conditions, based on the online self-tuning and disturbance compensation of PID parameters, the coupling compensation between pressure and flow is triggered to correct the impact of gas tank pressure fluctuations on flow stability under medium gas content conditions. When operating under high gas content conditions, based on the online self-tuning of PID parameters and disturbance compensation, coupling compensation between speed, flow rate and pressure is triggered.

[0016] Furthermore, in step S3, when the selected test condition is the transparent tank cavitation characteristic test mode, the system opens the switch valve between the gas storage tank and the transparent tank, the switch valve between the output end of the transparent tank and the gas-liquid mixer, and the switch valve between the output end of the centrifugal pump and the water tank, and closes the switch valve between the output end of the gas-liquid mixer and the water tank, and the switch valve between the output end of the gas storage tank and the gas phase input end of the gas-liquid mixer.

[0017] Further, it includes a safety interlock protection mechanism. When the system experiences overpressure, underpressure, flow rate exceeding the limit, or equipment failure, it immediately triggers an emergency shutdown and sends a warning signal.

[0018] Further, in step S3, the process of switching test conditions includes the following processes: According to the target condition instruction, adjust the switching valve to complete the switching of the pipeline passage; Linearly and smoothly transition the control weight coefficient of the original condition to the control weight coefficient of the target condition at a set step size, and simultaneously correct the opening instruction of the flow controller and the speed instruction of the centrifugal pump.

[0019] Further, step S1 includes the following processes: Step S11, complete the assembly of the gas circuit, liquid circuit and hardware, and establish a communication link; Step S12, conduct airtightness and pressure resistance tests. Close all switching valves, and fill the gas storage tank with air from the air generator to 1.2 times the design pressure. If the pressure drop value does not exceed 0.02 MPa after maintaining the pressure for 30 minutes, it is qualified; Step S13, inject test water into the water tank and the transparent storage tank. Open the switching valve between the output end of the gas-liquid mixer and the water tank and the switching valve between the output end of the centrifugal pump and the water tank, drive the centrifugal pump to run, and discharge the residual bubbles in the pipeline; Step S​​​​​​​​​​

[0022] 3. This system shares a high-precision flow controller, sensor group and control unit. Compared with two independent devices, it realizes the reuse of hardware resources and the coordination of control logic. Under the same control algorithm, it achieves high-precision and stable control with gas content fluctuation ≤ ±0.5% and speed fluctuation ≤ ±50 rpm, providing consistent and highly stable test conditions for the two test modes.

[0023] 4. This system can independently and collaboratively adjust liquid flow rate, gas flow rate, system back pressure, and pump speed, covering the entire operating range from low to high gas content. It not only meets the wide operating condition requirements for studying the cavitation mechanism of pumps, but also adapts to the fine adjustment requirements for observing the bubble dynamics behavior of transparent tanks, providing an integrated experimental platform for the study of cavitation and bubble dynamics in high-speed centrifugal pumps. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the architecture of the visualization device for simulating the gas cavitation process of a centrifugal pump in the embodiment. Figure 2 This is a schematic diagram of the device architecture when selecting the pump-containing air cavitation visualization test mode in the embodiment. Figure 3 This is a schematic diagram of the device architecture when selecting the transparent tank cavitation characteristic test mode in the embodiment; Figure 4 This is a three-dimensional structural diagram of the centrifugal pump in the embodiment; Figure 5 This is a schematic diagram of the system architecture and control flow for simulating and visualizing the gas cavitation process of a centrifugal pump in the embodiment. Figure 6 This is a flowchart illustrating the multi-parameter adaptive algorithm in the embodiment. Figures 7a to 7d This is a schematic diagram of the gas content / speed / flow rate fluctuations and the stability control effect of the multi-parameter adaptive algorithm when the pump is in the visual test mode of gas cavitation in the embodiment. Figures 8a to 8b This is a schematic diagram showing the statistical distribution of bubble diameters inside the transparent tank during the pump-containing cavitation visualization test mode in the example embodiment. Figures 9a to 9b This is a schematic diagram showing the statistical distribution of bubble diameters inside a transparent tank during the cavitation characteristic test mode in the example.

[0026] Marker description A-1, Transparent storage tank; A-2, Gas-liquid mixer; A-3 / A-5, Pressure sensor; A-9, Flow sensor; A-4, Centrifugal pump; A-6, Air generator; A-7, Air storage tank; A-8, Flow controller; A-10, Water tank; A-11, Remote control and data acquisition module; G-1 / G-2, Pressure gauge; G-3, Flow meter; F-1 / F-2 / F-3 / F-4 / F-5, Switch valve; 101. Motor; 102. Centrifugal pump inlet; 103. Transparent housing of the inducer wheel; 104. Base; 105. Centrifugal pump outlet. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] This embodiment proposes a simulation and visualization device for the gas cavitation process of a centrifugal pump, such as... Figure 1 As shown, it includes an air generator, air tank, flow controller, transparent storage tank, gas-liquid mixer, centrifugal pump, and water tank. (Reference) Figure 4 The centrifugal pump shown is a high-speed centrifugal pump. Its inducer housing is made of a highly transparent and pressure-resistant material, allowing direct observation of the gas-containing cavitation morphology of the inducer and impeller chamber. This centrifugal pump uses a variable frequency drive for closed-loop control, supporting stepless continuous adjustment within a range of 3000~10000 rpm, with a minimum adjustment step of 50 rpm, and is capable of handling a wide range of different experimental conditions. The transparent tank is designed primarily for the visual observation of bubble generation, rise, deformation, and coalescence behavior within the tank, as well as the quantitative measurement of bubble characteristic parameters.

[0029] Continue to refer to Figure 1The air generator's input end is used to input air, and its output end is connected to the input end of the air storage tank. The output end of the air storage tank is divided into branches 1-1 and 1-2 through a flow controller. Branch 1-2 is connected to the input end of the transparent storage tank through a switch valve F-1, and branch 1-1 is connected to the gas phase input end of the gas-liquid mixer through a switch valve F-2. The transparent storage tank stores water, and its output end is connected to the liquid phase input end of the gas-liquid mixer through a switch valve F-3. The pipeline 2-1 of the output end of the gas-liquid mixer is divided into two paths. One path is connected to the water tank through a switch valve F-4, and the other path 2-2 is connected to the input end of the centrifugal pump. The output end of the centrifugal pump is connected to the water tank along branch 3-1 through a switch valve F-5. A pressure gauge G-1 is installed on the gas storage tank, a pressure gauge G-2 is installed on the transparent storage tank, and a flow meter G-3 is installed at the output end of the transparent storage tank. A flow sensor A-9 is installed on branch 1-1, and pressure sensors A-3 and A-5 are installed at the input and output ends of the centrifugal pump, respectively. Camera units are installed outside the transparent storage tank and outside the centrifugal pump to capture images of bubbles inside the transparent storage tank and images of the cavitation morphology of gas inside the centrifugal pump. The camera units are high-speed cameras.

[0030] The aforementioned device integrates two functions—visualized pump cavitation testing and transparent tank bubble characteristic testing—onto a single hardware platform, sharing the same gas source, liquid circuit, and control unit. The two test modes can operate independently under identical gas content, pressure, and flow rate conditions, enabling comparative observation of the pump's internal cavitation morphology and external bubble dynamics. The device allows for rapid switching between the two test modes via a switch valve assembly, eliminating the need for disassembling pipelines, changing media, or re-adjusting hardware. Compared to the traditional method of testing with two separate devices, this significantly reduces the switching time, avoids errors caused by repeated adjustments, and substantially improves testing efficiency, while also reducing the risk of leakage during pipeline disassembly and assembly.

[0031] This device can be remotely controlled through a systematic design, forming a simulation and visualization system for the gas cavitation process of a centrifugal pump. The centrifugal pump gas cavitation process simulation and visualization system includes the aforementioned centrifugal pump gas cavitation process simulation and visualization device and a remote control and data acquisition module. For example... Figure 5 As shown, the remote control and data acquisition module includes a data acquisition and analysis unit, a command issuance unit, a multi-parameter adaptive algorithm unit, and a working condition identification unit.

[0032] The data acquisition and analysis unit is used to acquire the centrifugal pump speed, as well as the data fed back from the camera unit, various pressure gauges, flow meters, pressure sensors, and flow sensors. It calculates the gas content based on the acquired gas flow rate and liquid flow rate, and analyzes the acquired bubble image data to obtain image data of bubble generation, rise, deformation, aggregation, and rupture behavior. It also obtains bubble characteristic data such as bubble diameter, area distribution, and relative frequency.

[0033] The analysis of image data acquired by the high-speed camera in the data acquisition and analysis unit is a mature existing technology and will not be elaborated here.

[0034] The multi-parameter adaptive algorithm unit is used to calculate parameter deviations based on the current operating conditions and the data collected and analyzed, tune PID parameters online, calculate coupling compensation and disturbance compensation, generate adaptive adjustment commands for pressure, flow rate, speed, and gas content during the test, and complete adaptive closed-loop regulation.

[0035] The multi-parameter adaptive algorithm used here is a mature multivariable coupled adaptive PID control algorithm from the industrial measurement and control field. This algorithm is widely used in centrifugal pumps, gas-liquid two-phase flow, and cavitation test systems. It has the capabilities of adaptive operation, online parameter tuning, and multivariable coupling suppression, ensuring high-precision and stable control of pressure, flow rate, speed, and gas content during the test. The core theoretical formula of the multi-parameter adaptive algorithm is as follows: (1) Adaptive PID control The calculation formula is as follows: ; In the formula, The proportional coefficient, integral coefficient, and derivative coefficient are determined online in real time by the algorithm based on the experimental conditions; e(t) is the real-time deviation of the controlled parameter.

[0036] (2) Formula for calculating parameter deviation e(t): ; In the formula, X set X is the setpoint for pressure, flow rate, and speed. mes These are measured values.

[0037] (3) Formula for calculating gas content: ; In the formula, α is the gas content; This refers to the gas flow rate; This represents the liquid volumetric flow rate.

[0038] (4) Total control output ; In the formula, Δu couple(t) is the multi-variable coupling compensation quantity of flow rate - rotational speed - pressure; Δu disturb (t) is the system disturbance compensation quantity, which is used to eliminate external disturbances such as pipeline pressure fluctuations and rotational speed fluctuations.

[0039] The multi-parameter adaptive algorithm can correct the PID parameters in real time according to the deviation, and offset the mutual interference between flow rate - rotational speed - pressure through coupling compensation, so as to achieve high-precision stable control. As Figure 6 shown, it is the flow chart of the multi-parameter adaptive algorithm in this embodiment.

[0040] The instruction issuing unit is used to receive the strategies or instructions issued by the upper computer measurement and control platform, as well as the adaptive adjustment instructions generated by the multi-parameter adaptive algorithm unit, so as to switch or start and stop the test conditions of the centrifugal pump gas cavitation process simulation visualization device, and to control the flow controller, centrifugal pump, and each switching valve.

[0041] The control strategy parameter set of the test conditions is configured in the working condition identification unit. Each set of control strategy parameter sets of the test conditions includes the target pressure range, control weight coefficient set, pump rotational speed reference, and preset states of the switching valves. When the upper computer measurement and control platform issues specific test condition instructions, the working condition identification unit matches the corresponding test condition control strategy parameter set according to the instructions, and controls the flow controller, centrifugal pump, and each switching valve through the instruction issuing unit to complete the switching of the test conditions.

[0042] In this embodiment, the upper computer measurement and control platform and the remote control and data acquisition module can be physically integrated into the same device or separated and deployed.

[0043] Based on the above device and system, this embodiment proposes a centrifugal pump gas cavitation process simulation visualization control method, which specifically includes the following steps.

[0044] Step S11, according to the Figure 1 shown architecture, complete the connection and assembly of the air generator, gas storage tank, flow controller, transparent storage tank, gas-liquid mixer, centrifugal pump, water tank, switching valve, pressure sensor, flow sensor, pressure gauge, and flowmeter; Establish a communication link. In this embodiment, the communication connections between the upper measurement and control platform, remote control and data acquisition module, field flow controller, pressure sensor, flow sensor, pressure gauge, flowmeter, and centrifugal pump controller are established through the Modbus-RTU and TCP / IP industrial Ethernet dual communication protocols.

[0045] Step S12, conduct airtightness and pressure resistance tests. Close all switching valves, fill the gas storage tank with air from the air generator to 0.96 MPa (1.2 times the design pressure), keep the pressure for 30 min, and if the pressure drop value ≤ 0.02 MPa, it is qualified.

[0046] Step S13, Liquid circuit venting and medium injection: Inject test water into the water tank and transparent storage tank, open the switch valves F4 and F5, and drive the centrifugal pump to circulate at low speed to remove residual air bubbles in the pipeline.

[0047] Step S14: After the pressure stabilizes, the multi-parameter adaptive algorithm is initialized and configured. The multi-parameter adaptive algorithm adjusts the PID parameters in real time according to the magnitude and rate of change of the parameter deviation. For large deviations, Kp is increased to speed up the response, Ki is increased to improve accuracy for small deviations, and Kd is increased throughout to suppress fluctuations. At the same time, the coupling compensation matrix is ​​updated online to quantify the mutual interference between liquid flow rate, gas flow rate, and rotation speed, and the compensation amount is calculated to cancel the cross interference and avoid instability of gas content and pressure.

[0048] Step S15: Before the experiment begins, parameter initialization and preset are performed. Basic control parameters are entered into the host computer measurement and control platform, such as gas flow rate ∈ [0,30] L / min, liquid flow rate ∈ [0,50] L / min, centrifugal pump speed ∈ [3000,10000] r / min, flow controller adjustment accuracy (0.25%~1%), pump speed adjustment step size (50 rpm), valve opening range, etc., to achieve linkage and adaptation between the algorithm and hardware.

[0049] Step S2: Select the test condition and issue an instruction on the host computer measurement and control platform, namely, issue the instruction for "pump gas cavitation visualization test mode" or "transparent tank cavitation characteristic test mode".

[0050] Step S3: Based on the selected test conditions, the system automatically matches and loads the corresponding control strategy for the test conditions.

[0051] Step S4: Real-time acquisition of pressure, flow rate, rotation speed and bubble image data, and analysis to obtain data on gas content, bubble diameter, area distribution and relative frequency.

[0052] The multi-parameter adaptive algorithm calculates parameter deviations based on the collected and analyzed data, tunes PID parameters online, calculates coupling compensation and disturbance compensation, outputs total control quantity, generates adaptive adjustment commands for pressure, flow rate, speed, and gas content during the test, and performs adaptive adjustment.

[0053] It is important to note that the pump cavitation test focuses on the synergy of pressure, speed, and gas-liquid flow rate, while the transparent tank bubble test focuses on the fine-tuning of gas flow rate, with real-time adaptive adjustments based on the magnitude and rate of change of parameter deviations. Based on these deviations, the proportional coefficient is increased to accelerate the response during periods of large deviations, and the integral coefficient is increased to improve control accuracy during periods of small steady-state deviations. The coupling compensation matrix quantifies the mutual interference between parameters in real time, calculates the compensation amount, and cancels out the interference, thus avoiding instability in gas content and system pressure caused by the instability of a single parameter.

[0054] This multi-parameter adaptive algorithm requires no additional hardware; it is built into the system through software programming and is deeply adapted to the hardware architecture. It does not change the original experimental operation logic and realizes automated, precise, and adaptive control of pressure, flow rate, speed, and gas content during the test, effectively improving the repeatability of the test conditions and the reliability of the test data.

[0055] Step S5: Run stably and save the visualization images and experimental data synchronously.

[0056] Step S6: The test ends, the system automatically resets, archives data, and completes the test loop. After the test, turn off the air generator and centrifugal pump, slowly depressurize to atmospheric pressure, close all valves, discharge the test medium, and flush the gas and liquid pipelines and core components with clean water to prevent blockage and corrosion. After completion, reset the components and take protective measures.

[0057] The following section details the testing process under the "Pump Air-Containing Cavitation Visualization Test Mode" and the "Transparent Storage Tank Cavitation Characteristics Test Mode".

[0058] like Figure 2 As shown, when the host computer control platform issues the command "Pump-containing air cavitation visualization test mode", the system opens the switch valve F-1 from the air storage tank to the transparent storage tank, the switch valve F-2 from the air storage tank to the gas-liquid mixer, the switch valve F-3 between the output end of the transparent storage tank and the gas-liquid mixer, and the switch valve F-5 between the output end of the centrifugal pump and the water tank, and closes the switch valve F-4 between the output end of the gas-liquid mixer and the water tank. According to the control strategy of the test conditions, the system sends a preset gas phase flow rate to the flow controller, and controls the opening degree of the switch valve group according to the preset liquid phase flow rate. The centrifugal pump controller uses a variable frequency drive to preset the speed.

[0059] Gas enters the storage tank from the air generator, and the pressure in the storage tank is stabilized at 0.6MPa-0.8MPa. When pressure gauge G-1 measures the pressure P1 in the storage tank to be 0.6MPa, the air generator replenishes the storage tank with gas until it reaches 0.8MPa, at which point it stops. Gas from the storage tank, monitored and controlled by a flow controller (gas flow rate adjustment range 0-30L / min), enters branches 1-1 and 1-2. Gas enters a transparent storage tank via branch 1-2, and then a gas-liquid mixer via branch 1-1. A flow meter at the outlet of the transparent storage tank monitors the liquid flow rate, with a liquid flow rate adjustment range of 0-50L / min. Water from the transparent storage tank enters the gas-liquid mixer. The gas-liquid two-phase flow in the gas-liquid mixer flows along a pipeline into a centrifugal pump. The cavitation process within the centrifugal pump can be observed and recorded using a high-speed camera. Finally, the centrifugal pump delivers the gas-liquid two-phase flow into a water tank.

[0060] In this test mode, pressure sensors A-3 and A-5 provide the inlet and outlet pressures of the centrifugal pump, respectively; flow controller A-8 provides the gas phase flow rate; flow meter G-3 provides the liquid phase flow rate; and the controller on the centrifugal pump provides the rotational speed. The gas content is calculated in real time based on the collected gas and liquid phase flow rates. The gas content, along with the pressure and rotational speed, is then fed into a multi-parameter adaptive algorithm unit to calculate parameter deviations and adaptively adjust according to the current test conditions. After the test, the system automatically saves all data, completing the test loop and archiving the data.

[0061] This test uses multi-parameter coordinated adjustment and stable control of pressure, flow rate, speed, and gas content to obtain test data on the entire process of cavitation initiation, development, and collapse of high-speed centrifugal pumps under different operating conditions, ensuring the stability and repeatability of the test data.

[0062] When the selected test condition is the pump-borne cavitation visualization test mode, the multi-parameter adaptive algorithm triggers a gas content differential control strategy, which includes: Operating conditions with a gas content of no more than 5% are defined as low gas content operating conditions, operating conditions with a gas content between 5% and 15% are defined as medium gas content operating conditions, and operating conditions with a gas content of no less than 15% are defined as high gas content operating conditions. When operating under low gas content conditions, based on the online self-tuning of PID parameters and disturbance compensation, coupling compensation between flow rate and speed is triggered to suppress cross-interference between flow rate and speed under low gas content conditions. When operating under medium gas content conditions, based on the online self-tuning and disturbance compensation of PID parameters, the coupling compensation between pressure and flow is triggered to correct the impact of gas tank pressure fluctuations on flow stability under medium gas content conditions. When operating under high gas content conditions, based on the online self-tuning of PID parameters and disturbance compensation, coupling compensation between speed, flow rate and pressure is triggered.

[0063] like Figures 7a to 7d As shown, after differential control by the algorithm, the gas content, speed, and gas-liquid flow rate under all operating conditions converged rapidly and stabilized within the set range in the later stage of the experiment (after 80 seconds). The stable control accuracy fully meets the design requirements of this invention: gas content fluctuation ≤ ±0.5%, centrifugal pump speed fluctuation ≤ ±50 rpm, and gas and liquid flow rate fluctuation ≤ ±1%. This differential control strategy effectively solves the problem of controlling multi-parameter coupled fluctuations in the pump gas cavitation test, and provides core algorithm support for the stability of the test conditions and the reliability of the test data.

[0064] like Figure 3As shown, when the host computer control platform issues the "Transparent Tank Cavitation Characteristic Test Mode" command, the system opens valve F-1 between the gas storage tank and the transparent tank, valve F-3 between the output of the transparent tank and the gas-liquid mixer, and valve F-5 between the output of the centrifugal pump and the water tank. It closes valve F-4 between the output of the gas-liquid mixer and the water tank, and valve F-2 between the output of the gas storage tank and the gas phase input of the gas-liquid mixer. According to the control strategy for the test conditions, the system sends a preset gas phase flow rate to the flow controller, and the centrifugal pump is only used for pressurization and circulation.

[0065] Gas originates from the storage tank and enters the transparent storage tank under the monitoring and control of a flow controller. The pressure in the transparent storage tank is monitored in real time by a pressure gauge G-2. By controlling the gas flow rate and the tank pressure, gas is continuously introduced into the transparent storage tank, generating bubbles. A high-speed camera observes and records the generated bubble image data in real time. The data acquisition and analysis unit obtains image data of bubble generation, rise, deformation, coalescence, and collapse behavior, as well as bubble characteristic data such as bubble diameter, area distribution, and relative frequency. Liquid output from the transparent storage tank enters the water tank via a centrifugal pump.

[0066] During the experiment, the bubble diameter, bubble area distribution, and relative frequency are fed into the multi-parameter adaptive algorithm unit to calculate the parameter deviation, output the total control quantity, and send the control command to the flow controller and valve group. After the experiment, the remote control system automatically saves the entire data, completing the experiment closed loop and data archiving.

[0067] like Figure 8a , Figure 8b and Figure 9a , Figure 9b As shown, the test data for two operating conditions in the transparent tank visualization bubble characteristic test are presented, which demonstrates the system's ability to sensitively capture changes in bubble characteristics under different operating conditions.

[0068] Figure 8a and Figure 8b This is operating condition 1, where the tank pressure is 0 MPa, the gas pressure is 0.6 MPa, and the gas flow rate is 30 L / min. The histogram shows the diameter of air bubbles within the tank. From... Figure 8a and Figure 8b It can be seen that the peak range of particle size distribution corresponds to the medium particle size of the bubbles, and the large particle size range still has a high frequency. The area is proportional to the square of the particle size, and the "area contribution" of large-diameter bubbles is significantly higher than that of small-diameter bubbles. Therefore, the total area of ​​the aggregation region is supported by both large and small bubbles, and the "area proportion" of large-diameter bubbles cannot be ignored.

[0069] Figure 9a and Figure 9bThis is operating condition 2, where the tank pressure is 0.1 MPa, the gas pressure is 0.6 MPa, and the gas flow rate is 30 L / min. The histogram shows the statistical distribution of bubble diameters within the tank. The graph indicates that the peak range of particle size distribution shifts to the right or concentrates on small particles, and the frequency of the small particle size range increases significantly. Although the area contribution of individual small-diameter bubbles is extremely small, their high frequency causes their total area contribution to exceed that of large-diameter bubbles. This suggests that medium-diameter bubbles contribute the most to the area, but the proportion of small-diameter bubbles is high, and the total area of ​​the overall bubble group is still dominated by small and medium-sized bubbles. Figure 8a and Figure 8b This contrasts with the statement that "large particle size makes a significant contribution".

[0070] During the switching between the two operating conditions, the system adopts a parameter gradient smooth transition strategy. First, the valve group is pre-adjusted: according to the target operating condition command, the valves F-1 to F-5 are pre-adjusted to close or open the corresponding gas-liquid branches, completing the pipeline path switching and providing the path conditions for the establishment of the flow field under the new operating condition. Second, the control weight coefficient of the original operating condition is linearly and smoothly transitioned to the control weight coefficient of the target operating condition according to the set step size to avoid abrupt changes in control commands. Finally, according to the new control weight coefficient, the opening command of the flow controller and the speed command of the centrifugal pump are synchronously corrected to ensure that the pressure, flow rate, and gas content parameters transition smoothly without drastic fluctuations, ensuring the stability of the flow field during the switching process and achieving a seamless switching between the two test modes.

[0071] The control weight coefficient described in this embodiment is a dimensionless parameter between 0 and 1. Its value represents the degree of importance the algorithm attaches to different physical quantities during coordinated adjustment. The higher the weight coefficient, the more control resources the algorithm will allocate to suppress the deviation of this parameter. For example, in the pump cavitation test, the gas content control weight is set to 0.9, which is much higher than other parameters, to ensure accurate reproduction of the test conditions. During the transition to the transparent tank test, the weight of gas flow rate increases linearly, while the weight of gas content decreases linearly, so that the control is smoothly transferred.

[0072] In addition, the control method of this embodiment also includes a safety interlock protection mechanism. When the system experiences an emergency such as overvoltage, undervoltage, excessive flow, or equipment failure, it will immediately trigger an emergency shutdown and send a warning signal.

[0073] The above-described implementation method not only covers the complete operational process from pre-experiment preparation to experimental process control and post-experiment processing, but also ensures the accuracy and reliability of the experimental simulation through the coordinated control of key components such as flow controllers and switching valve groups, as well as the real-time acquisition and analysis of experimental process data. In practical applications, operators can flexibly set various parameters such as gas flow rate, liquid flow rate, and system pressure according to different research needs, thereby meticulously observing the dynamic processes of cavitation initiation, development, and collapse of high-speed centrifugal pumps under different gas contents and operating conditions in a controllable experimental environment, as well as the morphological evolution, trajectory, and distribution characteristics of cavitation bubbles in the transparent tank. This highly integrated and controllable implementation method enables the present invention to adapt to the needs of various complex experimental scenarios, providing a powerful experimental platform for in-depth exploration of the intrinsic mechanism of gas-containing cavitation in high-speed centrifugal pumps.

[0074] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. Furthermore, the above embodiments only illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. For those skilled in the art, several modifications and improvements can be made, and these all fall within the protection scope of the present invention.

Claims

1. A device for simulating and visualizing the gas cavitation process of a centrifugal pump, characterized in that, It includes an air generator, an air tank, a flow controller, a transparent storage tank, a gas-liquid mixer, a centrifugal pump, and a water tank, wherein the centrifugal pump has a transparent housing; The air generator's input terminal is used to input air, and its output terminal is connected to the input terminal of the air storage tank. The output terminal of the air storage tank is split into two branches through a flow controller. One branch is connected to the input terminal of the transparent storage tank through a switching valve, and the other branch is connected to the gas phase input terminal of the gas-liquid mixer through a switching valve. The transparent storage tank stores water, and its output terminal is connected to the liquid phase input terminal of the gas-liquid mixer through a switching valve. The output terminal of the gas-liquid mixer is split into two paths. One path is connected to the water tank through a switching valve, and the other path is connected to the input terminal of the centrifugal pump. The output terminal of the centrifugal pump is connected to the water tank through a switching valve. Pressure gauges are installed on the gas storage tank and the transparent storage box, and a flow meter is installed at the output end of the transparent storage box. A flow sensor is installed on the branch line leading to the gas phase input end of the gas-liquid mixer. Pressure sensors are installed at both the input and output ends of the centrifugal pump. Camera units are installed on the outside of the transparent storage box and the outside of the centrifugal pump to collect images of bubbles in the transparent storage box and images of gas-containing cavitation morphology in the centrifugal pump.

2. A simulation and visualization system for the gas cavitation process of a centrifugal pump, characterized in that, include: The centrifugal pump cavitation process simulation and visualization device as described in claim 1; The remote control and data acquisition module includes a data acquisition and analysis unit, a command issuing unit, and a multi-parameter adaptive algorithm unit; The data acquisition and analysis unit is used to acquire the centrifugal pump speed, as well as the data fed back by the camera unit, various pressure gauges, flow meters, pressure sensors, and flow sensors. It calculates the gas content based on the acquired gas flow rate and liquid flow rate, and analyzes the acquired bubble image data to obtain image data of bubble generation, rise, deformation, aggregation, and bursting behavior, and obtains bubble characteristic data such as bubble diameter, area distribution, and relative frequency. The multi-parameter adaptive algorithm unit is used to calculate parameter deviations based on the current working conditions and the data collected and analyzed, tune PID parameters online, calculate coupling compensation and disturbance compensation, and generate adaptive adjustment commands for pressure, flow rate, speed and gas content during the test. The instruction issuing unit is used to receive strategies or instructions issued by the host computer measurement and control platform, as well as adaptive adjustment instructions generated by the multi-parameter adaptive algorithm unit, to switch or start / stop the test conditions of the centrifugal pump gas cavitation process simulation visualization device, and to regulate the flow controller, centrifugal pump, and various switching valves.

3. The centrifugal pump cavitation process simulation and visualization system as described in claim 2, characterized in that, The remote control and data acquisition module includes a working condition identification unit, which is configured with a set of control strategy parameters for the test working condition. Each set of control strategy parameters for the test working condition includes a target pressure range, a set of control weight coefficients, a pump speed reference, and preset states of the switching valves. When the host computer control platform issues specific test condition commands, the condition identification unit matches the corresponding test condition control strategy parameter set according to the command, and adjusts the flow controller, centrifugal pump, and various switching valves through the command issuing unit to complete the switching of test conditions.

4. A method for simulating and visualizing the cavitation process of a centrifugal pump based on the system described in any one of claims 2 to 3, characterized in that, Includes the following steps: Step S1: Complete the assembly of the gas path, liquid path and hardware, establish a communication link, conduct airtightness and pressure resistance tests, and complete the initial configuration of the multi-parameter adaptive algorithm and liquid path venting. Step S2: Select the test condition and issue instructions on the host computer measurement and control platform; Step S3: Based on the selected test conditions, the system automatically matches and loads the corresponding control strategy for the test conditions; Step S4: Real-time acquisition of pressure, flow rate, rotation speed and bubble image data, and analysis to obtain data on gas content, bubble diameter, area distribution and relative frequency; The multi-parameter adaptive algorithm calculates parameter deviations based on the collected and analyzed data, tunes PID parameters online, calculates coupling compensation and disturbance compensation, outputs total control quantity, generates adaptive adjustment commands for pressure, flow rate, speed, and gas content during the test, and performs adaptive adjustment. Step S5: Run stably and save the visualization images and experimental data synchronously; Step S6: The experiment ends, the system automatically resets, archives the data, and completes the experiment loop.

5. The method for simulating and visualizing the cavitation process of a centrifugal pump as described in claim 4, characterized in that, In step S3, when the selected test condition is the pump-containing air cavitation visualization test mode, the system opens the switch valves from the gas storage tank to the transparent storage tank, the switch valve from the gas storage tank to the gas-liquid mixer, the switch valve between the output end of the transparent storage tank and the gas-liquid mixer, and the switch valve between the output end of the centrifugal pump and the water tank, and closes the switch valve between the output end of the gas-liquid mixer and the water tank.

6. The method for simulating and visualizing the cavitation process of a centrifugal pump as described in claim 4, characterized in that, In step S3, when the selected test condition is the pump-borne cavitation visualization test mode, the multi-parameter adaptive algorithm triggers a gas content differential control strategy, which includes: The working condition with a gas content not greater than the first preset threshold is defined as a low gas content working condition, the working condition with a gas content between the first preset threshold and the second preset threshold is defined as a medium gas content working condition, and the working condition with a gas content not less than the second preset threshold is defined as a high gas content working condition, wherein the first preset threshold is less than the second preset threshold. When operating under low gas content conditions, based on the online self-tuning of PID parameters and disturbance compensation, coupling compensation between flow rate and speed is triggered to suppress cross-interference between flow rate and speed under low gas content conditions. When operating under medium gas content conditions, based on the online self-tuning and disturbance compensation of PID parameters, the coupling compensation between pressure and flow is triggered to correct the impact of gas tank pressure fluctuations on flow stability under medium gas content conditions. When operating under high gas content conditions, based on the online self-tuning of PID parameters and disturbance compensation, coupling compensation between speed, flow rate and pressure is triggered.

7. The method for simulating and visualizing the cavitation process of a centrifugal pump as described in claim 4, characterized in that, In step S3, when the selected test condition is the transparent tank cavitation characteristic test mode, the system opens the switch valve between the gas storage tank and the transparent tank, the switch valve between the output end of the transparent tank and the gas-liquid mixer, and the switch valve between the output end of the centrifugal pump and the water tank, and closes the switch valve between the output end of the gas-liquid mixer and the water tank, and the switch valve between the output end of the gas storage tank and the gas phase input end of the gas-liquid mixer.

8. The method for simulating and visualizing the cavitation process of a centrifugal pump as described in claim 4, characterized in that, It includes a safety interlock protection mechanism that immediately triggers an emergency shutdown and sends a warning signal when the system experiences overvoltage, undervoltage, excessive flow, or equipment failure.

9. The method for simulating and visualizing the cavitation process of a centrifugal pump as described in claim 4, characterized in that, In step S3, the test condition switching process includes the following steps: Adjust the switching valve according to the target operating condition command to complete the pipeline path switching; The control weight coefficients of the original operating condition are linearly and smoothly transitioned to the control weight coefficients of the target operating condition according to the set step size, and the opening command of the flow controller and the speed command of the centrifugal pump are corrected simultaneously.

10. The method for simulating and visualizing the cavitation process of a centrifugal pump as described in claim 4, characterized in that, Step S1 includes the following process: Step S11: Complete the gas path, liquid path and hardware assembly, and establish a communication link; Step S12: Perform airtightness and pressure resistance tests. Close all valves and use an air generator to pressurize the air tank to several times the design pressure. If the pressure drop after the pressure holding time is not greater than the preset threshold, it is considered qualified. Step S13: Inject test water into the water tank and the transparent storage tank, open the switch valve between the gas-liquid mixer output end and the water tank and the switch valve between the centrifugal pump output end and the water tank, drive the centrifugal pump to run, and discharge the residual air bubbles in the pipeline. Step S14: After the pressure stabilizes, the multi-parameter adaptive algorithm tunes the PID parameters in real time according to the current deviation magnitude and rate of change, updates the coupling compensation matrix online, quantifies the mutual interference between liquid flow rate, gas flow rate, and rotation speed, and calculates the coupling compensation amount to cancel the cross interference. Step S15: Enter the basic hardware control parameters into the host computer measurement and control platform.

Images