Vortex elimination method based on underwater jet device

Abstract

The present invention discloses a vortex elimination method based on an underwater jet device. The method is based on an underwater jet device and includes the following steps: step 1, taking a photo of the water surface in a normal state and transmitting it to a central controller; step 2, the central controller performing photo recognition, and returning to step 1 when it is determined that there is no suction vortex; step 3, performing a suction vortex elimination operation when the recognition result is that there is a suction vortex; step 4, the central controller re-performs photo recognition, and so on, for continuous monitoring. The method of the present invention reduces the risk of flow blockage at the water inlet caused by the installation of a solid anti-vortex device, and realizes the function of intelligently eliminating and suppressing the suction vortex existing on the surface of the pump station inlet pool. The method of the present invention can adapt the vortex elimination method based on the underwater jet device to various working conditions, has a high degree of automation, and is simple to operate.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydraulic machinery, and in particular relates to a vortex elimination method based on an underwater jet device. Background Art

[0002] Suction vortexes are a common phenomenon in water conservancy projects. Free surface suction vortices, as a type of suction vortex, often appear in the inlet sump of a pump station. When a free surface suction vortex carries gas into a running pump, it can adversely affect the flow pattern inside the pump, causing the flow pattern to deteriorate and cavitation to occur inside the pump. This can cause vibrations in the pump unit and reduce pump performance, adversely affecting the stable operation of the pump station unit. Pump station suction inlets in the inlet sump generally use either side suction or vertical suction. Different suction inlets require different vortex elimination measures.

[0003] At present, there are more studies on underwater jet devices for vertical suction inlets, but fewer studies on side-suction underwater jet devices. In addition, most underwater jet devices use solid structures or mechanical components to eliminate the suction vortex. When these solid underwater jet devices are used in actual projects, they have certain limitations in terms of geometric customization, installation and operation, as well as performance and maintenance. They cannot monitor the changes in the flow state on the surface of the water inlet pool in real time, and it is difficult to achieve quantitative elimination of the suction vortex formed under different working conditions. Summary of the Invention

[0004] The purpose of the present invention is to provide a vortex elimination method based on an underwater jet device, which solves the limitations of the existing technology, the difficulty in real-time monitoring of changes in the flow state on the surface of the water inlet pool, and the difficulty in quantitatively eliminating the suction vortex formed under different working conditions.

[0005] The technical solution adopted by the present invention is a vortex elimination method based on an underwater jet device, which is implemented according to the following steps:

[0006] Step 1: Take a photo of the water surface in a normal state and transmit it to the central controller;

[0007] Step 2: The central controller performs photo recognition and returns to step 1 if it determines that there is no suction vortex.

[0008] Step 3: If the identification result shows that there is an intake vortex, the intake vortex is eliminated;

[0009] Step 4: The central controller performs photo recognition again, and so on, for continuous monitoring.

[0010] The beneficial effects of the present invention include the following two aspects:

[0011] 1) The vortex elimination method based on the underwater jet device can quickly eliminate the suction vortex formed in the water inlet pool of the side-suction pump station, solving the limitations of the solid anti-vortex device in terms of geometric size, installation and vortex elimination performance, reducing the risk of flow blockage at the water inlet caused by the installation of the solid anti-vortex device, and realizing the function of intelligent elimination and suppression of the suction vortex on the surface of the pump station water inlet pool.

[0012] 2) The quantitative elimination and suppression of the suction vortex based on the inlet flow rate and the submerged depth and the settings made in the step of starting the variable frequency pump can make the vortex elimination method based on the underwater jet device adaptable to various working conditions, with a high degree of automation and simple operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of the structure of the underwater jet device used in the vortex elimination method of the present invention;

[0014] Figure 2 yes Figure 1 A partial enlarged view of the

[0015] Figure 3 It is a schematic flow chart of the vortex elimination method of the present invention.

[0016] In the figure, 1. Nozzle, 2. Camera, 3. Rotor flowmeter, 4. Frequency conversion control pump, 5. Water inlet pipe, 6. Liquid level sensor, 7. Centrifugal pump, 8. Electromagnetic flowmeter, 9. Central controller. DETAILED DESCRIPTION

[0017] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] Reference Figure 1 、 Figure 2 The vortex elimination method of the present invention adopts an underwater jet device, the structure of which is: including a nozzle 1, a frequency conversion control pump 4, a water inlet pipe 5, a centrifugal pump 7 and a central controller 9, the frequency conversion control pump 4 is arranged at the upstream position of the water inlet pool, the water inlet pipe 5 is arranged at the downstream position of the water inlet pool, the nozzle 1 is set on the inner wall of the downstream water inlet pool, and the nozzle 1 is located above the water inlet pipe 5; a camera 2 is arranged above the water surface of the water inlet pool to ensure that the area where the suction vortex often occurs can be photographed; a liquid level sensor 6 is arranged on the outer circumference of the water inlet pipe 5, and the liquid level sensor 6 is at the same height as the center line of the water inlet pipe 5, and is used to monitor the submerged depth of the water inlet pipe 5;

[0019] The inlet end of the frequency conversion control pump 4 is directly connected to the water body upstream of the water inlet pool, and the outlet end of the frequency conversion control pump 4 is connected to the inlet end of the nozzle 1 through the rotor flowmeter 3. The frequency conversion control pump 4 transports the water upstream of the water inlet pool to the nozzle 1 through the rotor flowmeter 3; the outlet end of the water inlet pipe 5 penetrates into the wall surface downstream of the water inlet pool and is connected to the water body downstream of the water inlet pool, and the inlet end of the water inlet pipe 5 is connected to the water body upstream of the water inlet pool through the centrifugal pump 7 and the electromagnetic flowmeter 8;

[0020] The camera 2, rotor flowmeter 3, frequency conversion control pump 4, liquid level sensor 6 and electromagnetic flowmeter 8 are respectively connected to the central controller 9 for signal transmission. The central controller 9 integrates the data from the camera 2, rotor flowmeter 3, liquid level sensor 6 and electromagnetic flowmeter 8, and controls the switch and power of the frequency conversion control pump 4 as needed to adjust the injection flow rate of the nozzle 1.

[0021] See Figure 2 , the diameter of the water inlet pipe 5 is D i , the submerged depth is S i The nozzle 1 is located above the water inlet pipe 5 and is at a 45° angle to the horizontal line. The vertical distance from the center line of the water inlet pipe 5 is h, and the submerged depth is S. j , the diameter of nozzle 1 is d j , preferably d j =0.067D i The distance between the outlet of the water inlet pipe 5 and the inner wall of the water inlet pool is L1, and the distance between the nozzle end face 1 and the inner wall of the water inlet pool is L2, and the ratio of the two is preferably 5:3.

[0022] The vortex elimination principle of the underwater jet device used in the present invention is that the underwater jet generated by the nozzle 1 acts as a point source of external momentum entering the vortex. The existence of the vertical vortex is the result of the conservation of angular momentum. Therefore, applying external momentum to the suction vortex through the underwater jet device can break the angular momentum of the suction vortex area, effectively eliminating the suction vortex formed on the surface of the pump station inlet pool. At the same time, the existence of the underwater jet mechanism will increase local turbulence, and the existence of local turbulence can reduce the vortex momentum and thus effectively suppress the formation of the suction vortex. At the same time, it can be obtained from the numerical simulation results that when the injection direction of the nozzle 1 is 45 degrees to the horizontal line, the underwater jet has the best vortex elimination effect, and at this time, the underwater jet only needs a relatively small flow rate to achieve a good vortex elimination effect.

[0023] Reference Figure 3 The vortex elimination method of the present invention is based on the above-mentioned underwater jet device and is implemented according to the following steps:

[0024] Step 1: Take a photo of the water surface in a normal state and transmit it to the central controller 9.

[0025] The variable frequency controlled pump 4 delivers the water upstream of the water inlet pool to the nozzle 1 through the rotor flowmeter 3. The centrifugal pump 7 delivers the water upstream of the water inlet pool to the water inlet pipe 5 through the electromagnetic flowmeter 8. After the central controller 9 detects that the flow rate measured by the electromagnetic flowmeter 8 is greater than the set critical flow rate or the water level measured by the liquid level sensor 6 is lower than the critical water level, the camera 2 starts to photograph the flow state on the surface of the water inlet pool and transmits the photographed photos to the central controller 9.

[0026] Step 2: The central controller 9 performs photo recognition and returns to step 1 when it determines that there is no suction vortex.

[0027] The central controller 9 recognizes the photo taken by the camera 2 through a preset model based on convolutional neural network training. When the recognition result is that there is no suction vortex, the process ends and the frequency conversion control pump 4 and the centrifugal pump 7 work normally;

[0028] Step 3: If the identification result shows that there is an inhalation vortex, the inhalation vortex is eliminated.

[0029] When the identification result shows that there is a suction vortex, the central controller 9 starts the frequency conversion control pump 4 and adjusts the flow rate Q of the water inlet pipe 5. i and the submerged water depth S of the water inlet pipe 5 i The flow rate of nozzle 1 is regulated and the surface of the water inlet pool is identified in real time by camera 2. If the suction vortex is still detected, the central controller 9 will increase the power of the variable frequency control pump 4 on the basis of the original flow rate of nozzle 1 to increase the flow rate of nozzle 1 until the suction vortex is eliminated by the underwater jet of nozzle 1. After continuing to operate for a time T (i.e., observing for a period of time), the central controller 9 controls the variable frequency control pump 4 to stop working and nozzle 1 stops underwater jetting.

[0030] In step 4, the central controller 9 performs photo recognition again, and so on, for continuous monitoring.

[0031] Camera 2 continuously collects the flow state on the surface of the water inlet pool, and the central controller 9 identifies the collected images. If the identification result is that there is no suction vortex, the process ends; if the identification result is that there is a suction vortex, the cycle of step 3 continues until the underwater jet device is turned off and the suction vortex on the surface of the water inlet pool disappears.

[0032] The flow rate of nozzle 1 is controlled by the following formula:

[0033] The jet velocity at nozzle 1 is:

[0034]

[0035] Among them, q j is the flow rate of nozzle 1, d j is the diameter of nozzle 1;

[0036] The flow rate at the outlet of the water inlet pipe 5 is:

[0037]

[0038] Among them, Q i is the import flow, D i is the diameter of the water inlet pipe 5;

[0039] The expression of the water jet Reynolds number at nozzle 1 is:

[0040]

[0041] where ν is the kinematic viscosity of water,

[0042] The expression of the intake Froude number is:

[0043]

[0044] Where, ɡ=9.8m / s 2 is the acceleration due to gravity

[0045] The functional relationship between the water jet Reynolds number and the intake Froude number is:

[0046]

[0047] Combining the above formulas, we get the flow rate of nozzle 1:

[0048] q j =f(Q i ,D i ,ν,d j ).

[0049] Example 1

[0050] The configuration of the underwater jet device used in the method of the present invention is: the diameter D of the water inlet pipe 5 is i is 5cm, the submerged depth S i The nozzle 1 is at an angle of 45° to the horizontal line, and the vertical distance h from the center line of the water inlet pipe 5 is 3 cm. The submerged depth S j The diameter d of the nozzle 1 is 5 cm. j 0.333cm, d j =0.067D i The distance L1 between the water inlet of the water inlet pipe 5 and the inner wall of the water inlet pool is 5 cm, and the distance L2 between the nozzle end face 1 and the inner wall of the water inlet pool is 2.5 cm, and the ratio of the two is 2:1.

[0051] The process of the embodiment of the method of the present invention is:

[0052] Step 1: The variable frequency controlled pump 4 delivers water from the upstream of the water inlet pool to the nozzle 1 through the rotor flowmeter 3. The centrifugal pump 7 delivers the water from the upstream of the water inlet pool to the water inlet pipe 5 through the electromagnetic flowmeter 8. After the central controller 9 detects that the flow rate measured by the electromagnetic flowmeter 8 is greater than the set critical flow rate or the water level measured by the liquid level sensor 6 is lower than the critical water level, the camera 2 starts to photograph the flow state on the surface of the water inlet pool and transmits the photographed photos to the central controller 9.

[0053] Step 2: The central controller 9 recognizes the photo taken by the camera 2 using a preset model trained based on a convolutional neural network. When the recognition result is that there is no suction vortex, the process ends and the variable frequency control pump 4 and the centrifugal pump 7 operate normally.

[0054] No more suction vortex is found after this, and the steps stop here.

[0055] Example 2

[0056] The configuration of the underwater jet device used in the method of the present invention is: the diameter D of the water inlet pipe 5 is i is 5cm, the submergence depth S i The nozzle 1 is at an angle of 45° to the horizontal line, and the vertical distance h from the center line of the water inlet pipe 5 is 3 cm. The submerged depth S j The diameter d of nozzle 1 is 4 cm. j 0.333cm, d j =0.067D i The distance L1 between the water inlet of the water inlet pipe 5 and the inner wall of the water inlet pool is 5 cm, and the distance L2 between the nozzle end face 1 and the inner wall of the water inlet pool is 3.5 cm, and the ratio of the two is 10:7.

[0057] The process of the embodiment of the method of the present invention is:

[0058] Step 1: The variable frequency controlled pump 4 delivers water from the upstream of the water inlet pool to the nozzle 1 through the rotor flowmeter 3. The centrifugal pump 7 delivers the water from the upstream of the water inlet pool to the water inlet pipe 5 through the electromagnetic flowmeter 8. After the central controller 9 detects that the flow rate measured by the electromagnetic flowmeter 8 is greater than the set critical flow rate or the water level measured by the liquid level sensor 6 is lower than the critical water level, the camera 2 starts to photograph the flow state on the surface of the water inlet pool and transmits the photographed photos to the central controller 9.

[0059] Step 2: The central controller 9 recognizes the photo taken by the camera 2 using a preset model trained based on a convolutional neural network. When the recognition result is that there is no suction vortex, the process ends and the variable frequency control pump 4 and the centrifugal pump 7 operate normally.

[0060] Step 3: When the identification result shows that there is a suction vortex, the central controller 9 starts the variable frequency control pump 4 and adjusts the pump speed according to the inlet flow rate Q. iand the flooding depth S of the water inlet i The flow rate of nozzle 1 is regulated and the surface of the water inlet pool is identified in real time by camera 2. If the suction vortex is still detected, the central controller 9 will increase the power of the variable frequency control pump 4 on the basis of the original flow rate of nozzle 1 to increase the flow rate of nozzle 1 until the suction vortex is eliminated by the underwater jet of nozzle 1. After continuing to operate for a time T, the central controller 9 controls the variable frequency control pump 4 to stop working and nozzle 1 stops underwater jetting.

[0061] In step 4, the camera 2 continuously collects the flow state on the surface of the water inlet pool, and the central controller 9 identifies the collected images. If the identification result is that there is no suction vortex, the process ends; if the identification result is that there is a suction vortex, the cycle of step 3 continues until the suction vortex on the surface of the water inlet pool disappears after the underwater jet device is turned off.

[0062] Example 3

[0063] The configuration of the underwater jet device used in the method of the present invention is: the diameter D of the water inlet pipe 5 is i is 5cm, the submerged depth S i The nozzle 1 is at an angle of 45° to the horizontal line, and the vertical distance h from the center line of the water inlet pipe 5 is 3 cm. The submerged depth S j The diameter d of nozzle 1 is 3 cm. j 0.333cm, d j =0.067D i The distance L1 between the water inlet of the water inlet pipe 5 and the inner wall of the water inlet pool is 5 cm, and the distance L2 between the nozzle end face 1 and the inner wall of the water inlet pool is 3 cm, and the ratio of the two is 5:3.

[0064] The process of the embodiment of the method of the present invention is:

[0065] Step 1: The variable frequency controlled pump 4 delivers water from the upstream of the water inlet pool to the nozzle 1 through the rotor flowmeter 3. The centrifugal pump 7 delivers the water from the upstream of the water inlet pool to the water inlet pipe 5 through the electromagnetic flowmeter 8. After the central controller 9 detects that the flow rate measured by the electromagnetic flowmeter 8 is greater than the set critical flow rate or the water level measured by the liquid level sensor 6 is lower than the critical water level, the camera 2 starts to photograph the flow state on the surface of the water inlet pool and transmits the photographed photos to the central controller 9.

[0066] Step 2: The central controller 9 recognizes the photo taken by the camera 2 using a preset model trained based on a convolutional neural network. When the recognition result is that there is no suction vortex, the process ends and the variable frequency control pump 4 and the centrifugal pump 7 operate normally.

[0067] Step 3: When the identification result shows that there is a suction vortex, the central controller 9 starts the variable frequency control pump 4 and adjusts the pump speed according to the inlet flow rate Q. i and the flooding depth S of the water inleti The flow rate of nozzle 1 is regulated and the surface of the water inlet pool is identified in real time by camera 2. If the suction vortex is still detected, the central controller 9 will increase the power of the variable frequency control pump 4 on the basis of the original flow rate of nozzle 1 to increase the flow rate of nozzle 1 until the suction vortex is eliminated by the underwater jet of nozzle 1. After continuing to operate for a time T, the central controller 9 controls the variable frequency control pump 4 to stop working and nozzle 1 stops underwater jetting.

[0068] In step 4, the camera 2 continuously collects the flow state on the surface of the water inlet pool, and the central controller 9 identifies the collected images. If the identification result is that there is no suction vortex, the process ends; if the identification result is that there is a suction vortex, the cycle of step 3 continues until the suction vortex on the surface of the water inlet pool disappears after the underwater jet device is turned off.

[0069] The present invention is based on a vortex elimination method using an underwater jet device. The inlet flow rate and the submergence depth of the water inlet are used as switches to trigger the underwater jet device. A model trained based on a convolutional neural network is used to determine whether there is a suction vortex on the surface of the water inlet pool, thereby realizing intelligent vortex elimination by controlling the underwater jet device.

Claims

1. A vortex elimination method based on an underwater jet device, characterized in that: Based on an underwater jet device, the structure of the underwater jet device is as follows: a nozzle (1), a variable frequency control pump (4), a water inlet pipe (5), a centrifugal pump (7) and a central controller (9); the variable frequency control pump (4) is arranged at a position upstream of the water inlet pool, the water inlet pipe (5) is arranged at a position downstream of the water inlet pool, the nozzle (1) is arranged on the inner wall downstream of the water inlet pool, and the nozzle (1) is located above the water inlet pipe (5); a camera (2) is arranged above the water surface of the water inlet pool to ensure that the area where the suction vortex often occurs can be photographed; a liquid level sensor (6) is arranged on the outer circumference of the water inlet pipe (5), and the liquid level sensor (6) is at the same height as the center line of the water inlet pipe (5). Follow these steps to implement: Step 1: Take a photo of the water surface in a normal state and transmit it to the central controller (9); Step 2: The central controller (9) performs photo recognition and returns to step 1 when it determines that there is no suction vortex; Step 3: If the identification result shows that there is an intake vortex, the intake vortex is eliminated; In step 4, the central controller (9) performs photo recognition again, and so on, for continuous monitoring.

2. The vortex elimination method based on the underwater jet device according to claim 1, characterized in that: In step 1, the specific process is: The variable frequency controlled pump (4) delivers the water upstream of the water inlet pool to the nozzle (1) through the rotor flow meter (3), and the centrifugal pump (7) delivers the water upstream of the water inlet pool to the water inlet pipe (5) through the electromagnetic flow meter (8). After the central controller (9) detects that the flow rate measured by the electromagnetic flow meter (8) is greater than the set critical flow rate or the water level measured by the liquid level sensor (6) is lower than the critical water level, the camera (2) starts to photograph the flow state on the surface of the water inlet pool and transmits the photographed photos to the central controller (9).

3. The vortex elimination method based on the underwater jet device according to claim 1, characterized in that: In step 2, the specific process is: The central controller (9) recognizes the photo taken by the camera (2) through a preset model based on convolutional neural network training. When the recognition result is that there is no suction vortex, the process ends and the frequency conversion control pump (4) and the centrifugal pump (7) operate normally.

4. The vortex elimination method based on the underwater jet device according to claim 1, characterized in that: In step 3, the specific process is: When the identification result shows that there is a suction vortex, the central controller (9) starts the variable frequency control pump (4) and regulates the flow of the nozzle (1) according to the inlet flow Qi of the water inlet pipe (5) and the submerged water depth Si of the water inlet pipe (5), and identifies the surface of the water inlet pool in real time according to the camera (2); if the suction vortex is still detected, the central controller (9) will increase the power of the variable frequency control pump (4) on the basis of the original nozzle (1) flow to increase the nozzle (1) flow until the nozzle (1) eliminates the suction vortex in the underwater jet, and then continues to run for a time T, and then the central controller (9) controls the variable frequency control pump (4) to stop working, and the nozzle (1) stops underwater jetting.

5. The vortex elimination method based on the underwater jet device according to claim 1, characterized in that: In step 4, the specific process is: The camera (2) continuously collects the flow state on the surface of the water inlet pool, and the central controller (9) identifies the collected images. If the identification result is that there is no suction vortex, the process ends; if the identification result is that there is a suction vortex, the cycle of step 3 is continued until the suction vortex on the surface of the water inlet pool disappears after the underwater jet device is turned off.

6. The vortex elimination method based on the underwater jet device according to claim 1, characterized in that: The inlet end of the variable frequency controlled pump (4) is directly connected to the water body upstream of the water inlet pool, and the outlet end of the variable frequency controlled pump (4) is connected to the inlet end of the nozzle (1) through the rotor flow meter (3). The water upstream of the water inlet pool is transported to the nozzle (1) through the rotor flow meter (3) by the variable frequency controlled pump (4); The outlet end of the water inlet pipe (5) penetrates into the wall surface downstream of the water inlet pool and communicates with the water body downstream of the water inlet pool, and the inlet end of the water inlet pipe (5) communicates with the water body upstream of the water inlet pool through a centrifugal pump (7) and an electromagnetic flowmeter (8); The camera (2), rotor flowmeter (3), frequency conversion control pump (4), liquid level sensor (6) and electromagnetic flowmeter (8) are each connected to the central controller (9) for signal transmission.

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