Back pressure regulation method for water tunnel experimental device

Abstract

The present invention relates to the technical field of water tunnel experimental devices, and in particular to a back pressure regulation method for a water tunnel experimental device; an impeller assembly and a pressure sensor are arranged in the water tunnel experimental device, the impeller assembly rotates under the impact of water flow, and converts the kinetic energy of the water flow into mechanical energy, the pressure sensor is connected to a control system signal, and the impeller assembly is arranged in the water tunnel experimental device, and the pressure sensor monitors the back pressure inside the water tunnel experimental device in real time. According to the positive and negative and absolute value of the difference between the target back pressure value and the real-time back pressure value, the control system adjusts the rotation speed of the impeller assembly to achieve stepless regulation of the back pressure, and has a slow response speed. In addition, the back pressure is monitored in real time and the rotation speed of the impeller assembly is adjusted in real time, so that the requirements for dynamic adjustment of experimental parameters can be quickly adapted, and high-precision and stable back pressure regulation can be achieved, thereby ensuring the validity of the experimental process and data.

Description

Technical Field

[0001] The present invention relates to the technical field of water tunnel experimental devices, and in particular to a back pressure regulating method for a water tunnel experimental device. Background Art

[0002] Water tunnels are key experimental equipment for fluid mechanics research. Their energy efficiency and flow field control accuracy directly impact research costs and experimental reliability. Currently, conventional water tunnel facilities face significant technical bottlenecks in energy recovery and backpressure control.

[0003] Existing water tunnel designs generally lack energy recovery devices, leaving the energy contained in the terminal water flow largely unutilized. The terminal water flow often undergoes only simple energy dissipation treatment or is directly discharged, preventing the kinetic energy it carries from being converted into other usable energy forms. This not only results in significant energy waste, but also leads to low overall energy utilization efficiency and high operating costs for water tunnel facilities.

[0004] In addition, current water tunnel facilities have many shortcomings in back pressure regulation, which has become a key factor restricting the effectiveness and efficiency of water tunnel experiments. Specifically, they are manifested in the following aspects:

[0005] (1) Functional deficiencies: Many water tunnel facilities are not equipped with back pressure regulating devices, or even if they are equipped with relevant devices, they cannot achieve stepless back pressure regulation, making it difficult to meet the needs of diversified experiments for flexible back pressure regulation. Some water tunnel facilities use mechanical regulating valves for back pressure regulation, but they only support discrete pressure gear switching and cannot achieve the continuous back pressure regulation required for cavitation experiments.

[0006] (2) Insufficient control accuracy: Existing mechanical regulating valves have the problem of poor pressure control accuracy. Due to factors such as friction between the valve core and the valve seat and pulsation interference of the fluid, it is difficult to accurately adjust to the required back pressure value according to different experimental conditions, which leads to poor cavitation control effect and affects the accuracy and reliability of experimental data. At the same time, the wear of the valve core after long-term use will further aggravate the problem of decreased control accuracy and shorten the service life of the equipment.

[0007] (3) Slow response speed: When the experimental conditions change, the existing back pressure regulating valve responds slowly and cannot quickly adapt to the dynamic adjustment requirements of the experimental parameters, resulting in a significant reduction in experimental efficiency and seriously affecting the effectiveness of the experimental process and data;

[0008] Therefore, it is necessary to develop a method that can effectively prevent cavitation and achieve infinite control of the back pressure of the water tunnel experimental device. Summary of the Invention

[0009] In view of the above-mentioned deficiencies in the prior art, the present invention provides a back pressure regulation method for a water tunnel experimental device capable of achieving stepless regulation.

[0010] The present invention provides a back pressure regulation method for a water tunnel experimental device. The water tunnel experimental device is provided with an impeller assembly and a pressure sensor. The impeller assembly rotates under the impact of water flow to convert the kinetic energy of the water into mechanical energy. The pressure sensor is connected to a control system signal.

[0011] The back pressure adjustment method includes the following steps:

[0012] Get the target backpressure value:

[0013] The control system sets the back pressure value required under different experimental conditions as the target back pressure value P T ;

[0014] Calculate the pressure difference:

[0015] The pressure sensor monitors the real-time back pressure value P of the water tunnel experimental device in real time. i The difference between the target back pressure value and the real-time back pressure value is used as the calculated pressure difference ΔP i :

[0016] ΔP i =P T -P i ;

[0017] Adjust the impeller assembly speed:

[0018] The control system is based on ΔP i The positive and negative as well as the absolute value of the impeller assembly are used to adjust the speed of the impeller assembly: when the real-time back pressure value P i Greater than the target back pressure value P T When the speed of the impeller assembly is increased, the resistance of the impeller assembly to the water flow is reduced. At this time, the real-time back pressure value P i Reduce until the real-time back pressure value is equal to the target back pressure value P T Equal, maintaining the rotation speed of the impeller assembly at this time;

[0019] When the real-time back pressure value P i Less than the target back pressure value P T When the speed of the impeller assembly is reduced, the resistance of the impeller assembly to the water flow increases. At this time, the real-time back pressure value P i Increase until the real-time back pressure value is equal to the target back pressure value P T Equal, maintaining the rotation speed of the impeller assembly at this time;

[0020] The pressure sensor monitors the adjusted back pressure value in real time, feeds it back to the control system, and adjusts the back pressure value in real time, so that the real-time back pressure value is always stable near the target back pressure value.

[0021] This technical solution sets an impeller assembly in the water tunnel experimental device, and the pressure sensor monitors the back pressure inside the water tunnel experimental device in real time. The control system adjusts the rotation speed of the impeller assembly to achieve stepless adjustment of the back pressure. The response speed is slow, and the real-time monitoring of the back pressure and real-time adjustment of the impeller assembly rotation speed can quickly adapt to the dynamic adjustment requirements of the experimental parameters, achieve high-precision and stable adjustment of the back pressure, and ensure the validity of the experimental process and data.

[0022] In some embodiments of the present application, the impeller assembly is connected to the speed regulating device through a transmission shaft, the speed regulating device is connected to the control system signal, the control system controls the speed regulating device, and the speed regulating device adjusts the speed of the impeller assembly through the transmission shaft.

[0023] In some embodiments of the present application, the speed regulating device is a generator, which is arranged on the outside of the end of the water tunnel experimental device. The mechanical energy generated by the rotation of the impeller assembly is converted into electrical energy through the generator. The setting of the generator converts the kinetic energy of the water flow at the end of the water tunnel experimental device into electrical energy, which not only realizes energy recovery, but also can adjust the back pressure of the water tunnel experimental device.

[0024] In some embodiments of the present application, the generator includes a stator, a rotor, and an excitation system. The impeller assembly is connected to the rotor via a transmission shaft. The rotation of the impeller assembly drives the rotor to rotate. The rotation of the rotor cuts the magnetic induction lines generated by the energization of the stator, generating an induced current in the rotor.

[0025] The excitation system is used to adjust the magnitude of the excitation current, adjust the strength of the magnetic field generated by the stator, and further adjust the output power of the generator.

[0026] In some embodiments of the present application, when adjusting the speed of the impeller assembly:

[0027] When the real-time back pressure value P i Greater than the target back pressure value P T When the control system sends a command, the excitation system reduces the excitation current, the magnetic field strength decreases accordingly, the resistance to the rotation of the impeller assembly decreases accordingly, the speed of the impeller assembly increases, the resistance to the water flow generated by the impeller assembly decreases, and the real-time back pressure value P i When the real-time back pressure value decreases to the target back pressure value P T are equal, maintaining the excitation current value of the excitation system at this time;

[0028] When the real-time back pressure value P i Less than the target back pressure value P TWhen the control system sends a command, the excitation system increases the excitation current, the magnetic field strength increases, the resistance to the rotation of the impeller assembly increases, the speed of the impeller assembly decreases, the resistance to the water flow generated by the impeller assembly increases, and the real-time back pressure value P i Increase, when the real-time back pressure value increases to the target back pressure value P T Equal, maintaining the excitation current value of the excitation system at this time.

[0029] In some embodiments of the present application, the pressure sensor monitors the back pressure value of the adjusted water tunnel experimental device in real time, feeds it back to the control system, and adjusts the back pressure value in real time by adjusting the output power of the generator, so that the real-time back pressure value is always stable near the target back pressure value.

[0030] In some embodiments of the present application, the impeller assembly is disposed at the end of the diffusion section of the water tunnel experimental device, and is used to collect kinetic energy at the end of the water tunnel experimental device;

[0031] The pressure sensor is arranged in front of the impeller assembly along the water flow direction. After the control system adjusts the output power of the generator, the pressure sensor can monitor the real-time back pressure value of the adjusted diffusion section in real time.

[0032] In some embodiments of the present application, part of the transmission shaft is located in the diffusion section of the water tunnel experimental device, and the end of the transmission shaft located in the diffusion section is fixed to the impeller assembly; the remaining part of the transmission shaft passes through the pipe wall of the diffusion section and extends axially to the outside, and the end of the transmission shaft located outside the diffusion section is fixed to the generator.

[0033] In some embodiments of the present application, a coupling is provided at the end of the transmission shaft located on the outside, and the coupling is used to connect the transmission shaft and the generator. The coupling is used to transmit the torque of the impeller assembly to the main shaft of the generator. The coupling is also used to compensate for the inter-axial deviation between the transmission shaft and the main shaft of the generator due to installation, and plays a buffering and vibration reduction role during operation to reduce vibration and impact. In addition, the coupling also plays an overload protection function to prevent damage to the equipment after overloading.

[0034] A bearing base is provided on the pipe wall of the diffuser section, and a bearing is provided at a corresponding position of the transmission shaft. The bearing is fixed on the bearing base, so that the transmission shaft can stably transmit when passing through the pipe wall of the diffuser section.

[0035] In some embodiments of the present application, the control system is an industrial computer, which collects pressure data from the pressure sensor, the rotational speed of the impeller assembly, the excitation current data of the excitation system, and the output power data of the generator, calculates the excitation current value required for back pressure regulation through the real-time pressure data fed back by the pressure sensor, and sends control instructions to the excitation system to achieve different power outputs of the generator.

[0036] Based on the above technical solution, an impeller assembly is set in the water tunnel experimental device. The pressure sensor monitors the back pressure inside the water tunnel experimental device in real time. The control system adjusts the speed of the impeller assembly to achieve stepless regulation of the back pressure. The response speed is slow, and the real-time monitoring of back pressure and real-time adjustment of the impeller assembly speed can quickly adapt to the dynamic adjustment requirements of experimental parameters, achieve high-precision and stable adjustment of back pressure, and ensure the validity of the experimental process and data.

[0037] The generator is set up so that the kinetic energy of the water flow is converted into electrical energy by the generator during the back pressure adjustment process, realizing the recycling of the kinetic energy of the water flow, significantly improving the energy utilization efficiency of the water tunnel facility and reducing operating costs;

[0038] Through the linkage control of the pressure sensor's pressure signal and the generator's excitation current, infinitely precise regulation of back pressure is achieved. This not only accurately controls the cavitation number of the fluid in the test section, ensuring the accuracy of experimental data, but also realizes the dual functions of automatic back pressure adjustment and energy recovery through the closed-loop control system. It has the dual advantages of energy saving and environmental protection and efficient experiments, providing an innovative solution for the sustainable development of water tunnel devices.

[0039] This invention not only fills the technical gap in energy recovery and back pressure regulation of existing water tunnel experimental facilities, but also provides a more efficient and reliable experimental platform for underwater equipment research and development, fluid dynamics experiments and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0041] Figure 1 Schematic diagram of the positional relationship between the water tunnel experimental device and the generator according to an embodiment of the present invention;

[0042] In the picture:

[0043] 10. Water tunnel experimental device; 11. Diffuser; 20. Pressure sensor; 30. Impeller assembly; 40. Drive shaft; 50. Industrial computer; 60. Coupling; 70. Generator. DETAILED DESCRIPTION

[0044] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0045] In the description of the present invention, it should be understood that the terms "center", "transverse", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0046] The terms "first," "second," and "third" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or to implicitly specify the quantity of the technical features indicated. Therefore, a feature specified as "first," "second," or "third" may explicitly or implicitly include one or more of such features.

[0047] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0048] As attached Figure 1 As shown, the back pressure regulation method of the water tunnel experimental device of this embodiment is as follows: the end portion of the water tunnel experimental device 10 is a diffuser section 11, a pressure sensor 20 is provided in the diffuser section 11, and an impeller assembly 30 is provided at the end of the diffuser section 11. The impeller assembly 30 is used to collect kinetic energy at the end of the diffuser section 11. The impeller assembly 30 rotates under the impact of the water flow, and converts the kinetic energy of the water at the end of the diffuser section 11 into mechanical energy; the pressure sensor 20 is provided on the inner wall of the diffuser section 11, close to the impeller assembly 30, and the pressure sensor 20 is located in front of the impeller assembly 30 in the direction of water flow. Figure 1 In the figure, the direction of the arrow is the direction of water flow. The water flows through the pressure sensor 20 first and then through the impeller assembly 30. The pressure sensor 20 can accurately monitor the back pressure of the water flow in the diffusion section 11 and feed back the monitored pressure data to the industrial computer 50.

[0049] The impeller assembly 30 is connected to a speed regulating device outside the water tunnel experimental device through a transmission shaft 40. The speed regulating device is connected to an industrial control computer 50 by signal. The industrial control computer can issue instructions to the speed regulating device so that the speed regulating device adjusts the speed of the impeller assembly 30 through the transmission shaft 40.

[0050] In some embodiments, the speed regulating device is a motor, the impeller assembly 30 is fixed to the output shaft of the motor via a transmission shaft 40, and the motor is connected to the industrial computer signal. The speed of the impeller assembly 30 can be adjusted by adjusting the speed of the output shaft of the motor. In this case, the back pressure regulation method includes the following steps:

[0051] Get the target backpressure value:

[0052] The industrial computer 50 sets the back pressure value required under different experimental conditions as the target back pressure value P T ;

[0053] Calculate the pressure difference:

[0054] The pressure sensor 20 monitors the real-time back pressure value P of the diffusion section 11 in real time. i The difference between the target back pressure value and the real-time back pressure value is used as the calculated pressure difference ΔP i :

[0055] ΔP i =P T -P i ;

[0056] Adjust the impeller assembly 30 speed:

[0057] Industrial computer 50 according to ΔP i The positive and negative and absolute value of are used to adjust the speed of the impeller assembly 30, specifically:

[0058] When the real-time back pressure value P i Greater than the target back pressure value P T When ΔP i >0, the industrial computer is based on ΔP i The numerical value of the back pressure is calculated and the speed required to adjust the back pressure is sent to the motor. The output speed of the motor increases, and the speed of the impeller assembly 30 increases accordingly, so that the resistance of the impeller assembly 30 to the water flow decreases, and the real-time back pressure value P i Will decrease, when the real-time back pressure value is equal to the target back pressure value P T Equal, maintain the motor speed at this time;

[0059] When the real-time back pressure value P i Less than the target back pressure value P T When ΔP i <0, industrial computer 50 according to ΔP iThe absolute value of the back pressure is used to calculate the speed required to adjust the back pressure, and the control command is sent to the motor. The output speed of the motor is reduced, and the speed of the impeller assembly 30 is reduced accordingly, so that the resistance of the impeller assembly 30 to the water flow increases, and the real-time back pressure value P i Will increase, when the real-time back pressure value and the target back pressure value P T Equal, maintain the motor speed at this time;

[0060] The pressure sensor 20 monitors the back pressure value of the adjusted diffusion section 11 in real time and feeds it back to the industrial computer 50. When the back pressure value deviates from the target back pressure value, the speed of the output shaft of the motor is adjusted in time to adjust the back pressure value in real time so that the real-time back pressure value is always stable near the target back pressure value.

[0061] In some embodiments, the speed regulating device is a generator 70, such as Figure 1 As shown, the generator 70 is arranged on the outside of the diffusion section 11. The mechanical energy generated by the rotation of the impeller assembly 30 is converted into electrical energy through the generator 70. The setting of the generator 70 converts the kinetic energy of the water flow at the end of the diffusion section 11 of the water tunnel experimental device into electrical energy, thereby realizing energy recovery.

[0062] The generator 70 includes a stator, a rotor and an excitation system. The stator is a fixed coil and the rotor is a rotating coil. The impeller assembly 30 is connected to the rotor through a transmission shaft 40. The rotation of the impeller assembly 30 drives the rotor to rotate. The rotation of the rotor cuts the magnetic induction lines, generating an induced current in the rotor; the stator generates fixed magnetic induction lines through the excitation current. The excitation system is used to adjust the size of the excitation current, adjust the magnetic field strength generated by the stator, and then adjust the output power of the generator.

[0063] Based on the principle of electromagnetic induction, when the rotor cuts through magnetic flux lines, an induced current is generated in the rotor coil, converting mechanical energy into electrical energy. By controlling the magnitude of the stator excitation current, the rotor's speed can be adjusted. This rotor speed influences the speed of the impeller assembly 30, which in turn regulates the water pressure in the terminal diffuser, thereby controlling back pressure.

[0064] In some embodiments, part of the transmission shaft 40 is located in the diffuser section 11, and the end of the transmission shaft located in the diffuser section 11 is fixed to the impeller assembly 30; the remaining part of the transmission shaft 40 passes through the pipe wall at the diffuser section 11 and extends to the outside along the axial direction of the transmission shaft 40, and the end of the transmission shaft 40 located outside the diffuser section 11 is connected to the rotor of the generator 70.

[0065] In order to stably transmit the torque of the impeller assembly 30, a coupling 60 is provided at the end of the outer drive shaft 40. The coupling 60 is used to connect the drive shaft 40 and the rotor of the generator 70. The coupling 60 transmits the torque of the impeller assembly 30 to the rotor of the generator. The coupling 60 can also compensate for the inter-axial deviation between the drive shaft 40 and the generator rotor main shaft caused by installation, and play a buffering and vibration reduction role during operation to reduce vibration and impact. In addition, the coupling 60 also plays an overload protection function to prevent damage to the equipment after overloading.

[0066] A bearing base (not shown) is provided on the pipe wall of the diffuser section 11. A bearing is provided at the corresponding position where the transmission shaft 40 passes through the pipe wall. The bearing is fixed on the bearing base so that the transmission shaft can stably transmit the power when passing through the pipe wall of the diffuser section 11.

[0067] When the speed regulating device is a generator 70, the back pressure of the diffuser section 11 is also regulated by adjusting the speed of the impeller assembly 30, specifically:

[0068] When the real-time back pressure value P i Greater than the target back pressure value P T When ΔP i >0, the industrial computer is based on ΔP i The excitation current required to adjust the back pressure is calculated by numerical value. The industrial computer 50 sends a command, and the excitation system reduces the excitation current to the required excitation current. The magnetic field strength decreases accordingly, and the resistance to the rotation of the rotor decreases, so that the resistance to the rotation of the impeller assembly 30 decreases accordingly. The speed of the impeller assembly 30 increases, and the resistance generated by the impeller assembly to the water flow decreases. The real-time back pressure value P i When the real-time back pressure value decreases to the target back pressure value P T Equal, maintain the excitation current value of the excitation system at this time;

[0069] When the real-time back pressure value P i Less than the target back pressure value P T When ΔP i <0, the industrial computer is based on ΔP i The absolute value of is used to calculate the excitation current required to adjust the back pressure. The industrial computer 50 sends a command, and the excitation system increases the excitation current to the required excitation current. The magnetic field strength increases accordingly, and the resistance to the rotation of the rotor increases. The resistance to the rotation of the impeller assembly 30 also increases accordingly. The speed of the impeller assembly 30 decreases, and the resistance to the water flow generated by the impeller assembly 30 increases. The real-time back pressure value P i Increase, when the real-time back pressure value increases to the target back pressure value P T Equal, maintain the excitation current value of the excitation system at this time.

[0070] The pressure sensor 20 monitors the back pressure value of the adjusted diffusion section in real time and feeds it back to the industrial computer 50. The back pressure value is adjusted in real time by adjusting the magnitude of the excitation current so that the real-time back pressure value is always stable near the target back pressure value.

[0071] The industrial computer 50 of this embodiment collects the pressure data of the pressure sensor 20, the rotational speed of the impeller assembly 30, the excitation current data of the excitation system, and the output power data of the generator. It calculates the excitation current value required for back pressure regulation through the real-time pressure data fed back by the pressure sensor 20, and sends the control instructions to the excitation system to achieve different power outputs of the generator.

[0072] Based on the above technical solution, an impeller assembly is set in the water tunnel experimental device. The pressure sensor monitors the back pressure inside the water tunnel experimental device in real time. The control system adjusts the speed of the impeller assembly to achieve stepless regulation of the back pressure. The response speed is slow, and the real-time monitoring of back pressure and real-time adjustment of the impeller assembly speed can quickly adapt to the dynamic adjustment requirements of experimental parameters, achieve high-precision and stable adjustment of back pressure, and ensure the validity of the experimental process and data.

[0073] The generator is set up so that the kinetic energy of the water flow is converted into electrical energy by the generator during the back pressure adjustment process, realizing the recycling of the kinetic energy of the water flow, significantly improving the energy utilization efficiency of the water tunnel facility and reducing operating costs;

[0074] Through the linkage control of the pressure sensor's pressure signal and the generator's excitation current, infinitely precise regulation of back pressure is achieved. This not only accurately controls the cavitation number of the fluid in the test section, ensuring the accuracy of experimental data, but also realizes the dual functions of automatic back pressure adjustment and energy recovery through the closed-loop control system. It has the dual advantages of energy saving and environmental protection and efficient experiments, providing an innovative solution for the sustainable development of water tunnel devices.

[0075] This invention not only fills the technical gap in energy recovery and back pressure regulation of existing water tunnel experimental facilities, but also provides a more efficient and reliable experimental platform for underwater equipment research and development, fluid dynamics experiments and other fields.

[0076] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0077] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to preferred embodiments, persons skilled in the art should understand that the specific implementation methods of the present invention may still be modified or some technical features may be replaced by equivalents without departing from the spirit of the technical solutions of the present invention, and all of these should fall within the scope of the technical solutions claimed for protection by the present invention.

Claims

1. A back pressure regulation method for a water tunnel experimental device, characterized in that: The water tunnel experimental device is provided with an impeller assembly and a pressure sensor. The impeller assembly rotates under the impact of the water flow, converting the kinetic energy of the water into mechanical energy. The pressure sensor is connected to the control system signal. The impeller assembly is connected to a speed regulating device via a transmission shaft, the speed regulating device is connected to the control system signal, the control system controls the speed regulating device, and the speed regulating device adjusts the speed of the impeller assembly via the transmission shaft; The speed regulating device is a generator, which is arranged outside the end of the water tunnel experimental device. The mechanical energy generated by the rotation of the impeller assembly is converted into electrical energy by the generator. The setting of the generator converts the kinetic energy of the water flow at the end of the water tunnel experimental device into electrical energy, thereby realizing energy recovery and regulating the back pressure of the water tunnel experimental device. The back pressure adjustment method includes the following steps: Get the target backpressure value: The control system sets the back pressure value required under different experimental conditions as the target back pressure value P T ; Calculate the pressure difference: The pressure sensor monitors the real-time back pressure value P of the water tunnel experimental device in real time. i The difference between the target back pressure value and the real-time back pressure value is used as the calculated pressure difference ΔP i : ΔP i =P T -P i ; Adjust the impeller assembly speed: The control system is based on ΔP i The positive and negative as well as the absolute value of the impeller assembly are used to adjust the speed of the impeller assembly: when the real-time back pressure value P i Greater than the target back pressure value P T When the control system sends a command, the excitation system reduces the excitation current, the magnetic field strength decreases accordingly, the resistance to the rotation of the impeller assembly decreases accordingly, the speed of the impeller assembly increases, the resistance to the water flow generated by the impeller assembly decreases, and the real-time back pressure value P i When the real-time back pressure value decreases to the target back pressure value P T are equal, maintaining the excitation current value of the excitation system at this time; When the real-time back pressure value P i Less than the target back pressure value P T When the control system sends a command, the excitation system increases the excitation current, the magnetic field strength increases, the resistance to the rotation of the impeller assembly increases, the speed of the impeller assembly decreases, the resistance to the water flow generated by the impeller assembly increases, and the real-time back pressure value P i Increase, when the real-time back pressure value increases to the target back pressure value P T are equal, maintaining the excitation current value of the excitation system at this time; The pressure sensor monitors the adjusted back pressure value in real time, feeds it back to the control system, and adjusts the back pressure value in real time, so that the real-time back pressure value is always stable near the target back pressure value.

2. The back pressure regulating method of the water tunnel experimental device according to claim 1, characterized in that: The generator includes a stator, a rotor, and the excitation system. The impeller assembly is connected to the rotor via a transmission shaft. The rotation of the impeller assembly drives the rotor to rotate. The rotation of the rotor cuts the magnetic induction lines generated by the electrification of the stator, generating an induced current in the rotor. The excitation system is used to adjust the magnitude of the excitation current, adjust the strength of the magnetic field generated by the stator, and further adjust the output power of the generator.

3. The back pressure regulating method of the water tunnel experimental device according to claim 1, characterized in that: The pressure sensor monitors the adjusted back pressure value of the water tunnel experimental device in real time, feeds it back to the control system, and adjusts the back pressure value in real time by adjusting the output power of the generator, so that the real-time back pressure value is always stable near the target back pressure value.

4. The back pressure regulating method of the water tunnel experimental device according to claim 1, characterized in that: The impeller assembly is arranged at the end of the diffusion section of the water tunnel experimental device, and is used to collect kinetic energy at the end of the water tunnel experimental device; The pressure sensor is arranged in front of the impeller assembly along the water flow direction. After the control system adjusts the output power of the generator, the pressure sensor can monitor the real-time back pressure value of the adjusted diffusion section in real time.

5. The back pressure regulating method of the water tunnel experimental device according to claim 4, characterized in that: Part of the transmission shaft is located in the diffusion section of the water tunnel experimental device, and the end of the transmission shaft located in the diffusion section is fixed to the impeller assembly; the remaining part of the transmission shaft passes through the pipe wall of the diffusion section and extends to the outside along its axial direction, and the end of the transmission shaft located outside the diffusion section is fixed to the generator.

6. The back pressure regulating method of the water tunnel experimental device according to claim 5, characterized in that: A coupling is provided at the end of the transmission shaft located on the outside. The coupling is used to connect the transmission shaft and the generator. The coupling is used to transmit the torque of the impeller assembly to the main shaft of the generator. The coupling is also used to compensate for the inter-axial deviation between the transmission shaft and the main shaft of the generator due to installation, and plays a buffering and vibration reduction role during operation to reduce vibration and impact. In addition, the coupling also plays an overload protection function to prevent damage to the equipment after overloading. A bearing base is provided on the pipe wall of the diffuser section, and a bearing is provided at a corresponding position of the transmission shaft. The bearing is fixed on the bearing base, so that the transmission shaft can stably transmit when passing through the pipe wall of the diffuser section.

7. The back pressure regulating method of the water tunnel experimental device according to claim 2, characterized in that: The control system is an industrial computer, which collects pressure data from the pressure sensor, the rotational speed of the impeller assembly, the excitation current data of the excitation system, and the output power data of the generator. It calculates the excitation current value required for back pressure regulation through the real-time pressure data fed back by the pressure sensor, and sends control instructions to the excitation system to achieve different power outputs of the generator.

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