An adjustable turbine drive pup joint tool

Abstract

This invention belongs to the field of downhole drilling tools in the petroleum development sector, and discloses an adjustable turbine-driven sub. It includes upper and lower drive joints, a power sub assembly, and a hydraulic control assembly. The power sub assembly contains a static valve and a dynamic valve; the dynamic valve has a dynamic valve flow channel, and the static valve has a static valve flow channel. The flow area connecting the dynamic and static valve flow channels changes periodically to generate an axial harmonic pressure wave in the flowing drilling fluid. The hydraulic control assembly contains upper and lower solenoid valves, a directional valve, and a spring. The central fluid channel of the directional valve connects to the channel where the lower spring is located, allowing for the adjustment of the drilling fluid flow channel within the turbine-driven sub. The hydraulic control assembly also includes a plug piston. High-pressure drilling fluid enters the hydraulic cylinder through the directional valve channel, driving the plug piston to block the adjusting nozzle. By changing the flow rate of the drilling fluid flowing into the turbine rotation drive structure, the opening and closing of the hydraulic oscillator is controlled. The purpose of this invention is to provide a turbine-driven short section tool for controlling the operation and shutdown of a hydraulic oscillator, thereby controlling the operation and shutdown of the hydraulic oscillator according to drilling needs, thus improving the service life of the hydraulic oscillator and reducing drilling costs.

Description

Technical Field

[0001] This invention relates to the technical field of downhole drilling tools in the oil development sector, specifically an adjustable turbine-driven short section tool. Background Technology

[0002] With the continuous development of global oil and gas exploration and development technologies, the number of unconventional oil and gas wells being explored is increasing, such as horizontal wells, lateral wells, and extended reach wells. During the drilling process of these unconventional wells, the complex downhole environment and high friction between the drill string and the wellbore make the drill string prone to sticking and other problems. During drilling, one side of the drill string is always in contact with the wellbore. When the friction between the drill string and the wellbore is high, the drill string cannot move, and even with full drilling pressure, it cannot be driven forward, potentially leading to bending or even accidents. In this case, the friction between the drill string and the wellbore is static friction. To solve this problem, extensive research has been conducted both domestically and internationally. A hydraulic oscillator has been developed that reduces drag through vibration, converting static friction into dynamic friction, thus solving the aforementioned problems while improving drilling efficiency and reducing drilling costs.

[0003] Hydraulic oscillators generally consist of a vibrating sub and a power sub. The power sub's drive mechanism is primarily of two types: screw-driven and turbine-driven. When drilling fluid enters the power sub, it drives its rotation. At this time, the mating surfaces of the moving and stationary valve discs of the power sub rotate relative to each other, causing the flow area to change periodically. When the moving and stationary valve discs overlap to their minimum position, the flow area reaches its minimum, and the pressure drop is at its maximum; conversely, when they overlap to their maximum position, the flow area reaches its maximum, and the pressure drop is at its minimum. Pressure is stored in the reeds of the oscillating sub through simple harmonic pressure waves. Energy is stored when the flow area is small and released when the flow area is large. Axial force is transmitted through the reeds, causing axial vibration, converting static friction into dynamic friction, thus improving drilling efficiency.

[0004] Currently used turbine-driven short sections operate at high speeds, resulting in excessively high frequencies and low amplitudes, meaning relatively weak oscillation forces and poor performance in field applications. Furthermore, excessively high operating frequencies reduce the lifespan of the hydraulic oscillator. During drilling, it is sometimes necessary to discontinue the hydraulic oscillator's function and clean the wellbore solely through drilling fluid circulation.

[0005] Therefore, through long-term study of basic knowledge and mastery of professional skills, the inventors have invented an adjustable turbine-driven short section tool, overcoming the shortcomings of existing technologies. Summary of the Invention

[0006] The purpose of this invention is to provide an adjustable turbine-driven short section tool that controls the start and stop of a hydraulic oscillator according to drilling needs, thereby improving the service life of the hydraulic oscillator and reducing drilling costs.

[0007] The objective of this invention is achieved as follows: an adjustable turbine-driven sub-tool includes upper and lower drive joints, a power sub-tool assembly, and a hydraulic control assembly. The upper drive joint is threadedly connected to a hydraulic oscillator vibrating sub-tool, and the lower drive joint is threadedly connected to a drill bit, together forming a hydraulic oscillator tool. The power sub-tool assembly contains a stationary valve and a moving valve. The moving valve has a moving valve flow channel, and the stationary valve has a stationary valve flow channel. The flow area connecting the moving valve flow channel and the stationary valve flow channel changes periodically to generate an axial harmonic pressure wave in the incoming drilling fluid. The hydraulic control assembly contains upper and lower solenoid valves, a directional valve, and a spring. The central fluid channel of the directional valve connects to the drilling fluid fluid channel within the adjustable turbine-driven sub-tool. The upper solenoid valve controls the entry of high-pressure drilling fluid into the directional valve by opening and closing the fluid channel. The central fluid channel is simultaneously pushed downward by the high-pressure drilling fluid to overcome the spring thrust, opening the lower solenoid valve and the lower channel of the directional valve. When the drilling fluid hydraulic pressure cannot overcome the spring thrust, the spring pushes the directional valve upward, thus realizing the function of the directional valve. The hydraulic control assembly is equipped with a plug piston. The high-pressure drilling fluid enters the hydraulic cylinder through the directional valve channel to drive the plug piston, blocking the regulating nozzle. The opening and closing of the hydraulic oscillator is controlled by changing the flow rate of the drilling fluid flowing into the turbine rotation drive structure.

[0008] In a preferred embodiment of the present invention, the upper and lower solenoid valves are installed and fixed at the upper and lower ends of the hydraulic cylinder. The upper solenoid valve is engaged with the side hole of the upper plug of the control valve. The upper plug of the control valve is connected to the rib of the hydraulic cylinder housing by a thread. The opening and closing of the upper solenoid valve realizes the entry of high-pressure drilling fluid into the reversing valve. The lower solenoid valve is directly engaged with the side hole of the rib of the hydraulic cylinder housing. The opening and closing of the lower solenoid valve realizes the connection and closing of the channel where the lower end spring of the reversing valve is located.

[0009] In a preferred embodiment of the present invention, the reversing valve is located in the rib opening of the hydraulic cylinder housing, with its upper end connected to the upper plug of the control valve and its lower end connected to the spring. The reversing valve is cylindrical with a non-penetrating fluid channel in the center and two side holes at the top and bottom for fluid interaction with the inner cavity of the hydraulic cylinder. The spring is located in the fluid channel at the lower end of the reversing valve. When the upper and lower solenoid valves are opened, if the drilling fluid hydraulic pressure cannot overcome the spring's thrust, the spring will push the reversing valve back to the first position.

[0010] In a preferred embodiment of the present invention, the hydraulic cylinder outer shell has three extension ribs, which are joined to the inner surface of the fixed sleeve. The outer surface of the fixed sleeve is joined to the screw outer shell, and two round holes are opened on the side to serve as fluid exchange channels between the hydraulic cylinder and the wellbore. Two round holes are opened on the side of the screw outer shell to serve as fluid exchange channels between the hydraulic cylinder and the wellbore. The inner surface of the hydraulic cylinder is provided with a raised shoulder, which internally connects the plug piston and the piston lower plug.

[0011] In a preferred embodiment of the present invention, the first position state is the working state of the hydraulic oscillator. At this time, the spring pushes the reversing valve to the first position, closes the lower solenoid valve, and the lower space of the reversing valve is closed and cannot be compressed, increasing the hydraulic pressure of the drilling fluid. The drilling fluid enters the upper space of the hydraulic cylinder through the central channel of the reversing valve, pushing the plug piston downward to block the adjusting nozzle until the plug piston engages with the upper end of the lower plug of the piston. The drilling fluid in the lower space of the hydraulic cylinder enters the wellbore space through the annular space and fluid channel of the reversing valve. At this time, all the drilling fluid flows into the rotor drive space, so that the turbine rotor overcomes the frictional force between itself and the turbine stator, driving the hydraulic oscillator to work. The first position state has a corresponding second state, which is the stopped state of the hydraulic oscillator.

[0012] In a preferred embodiment of the present invention, the second state is the hydraulic oscillator stopped state. At this time, the lower solenoid valve is opened, the lower space of the reversing valve is opened, and the high-pressure drilling fluid pushes the reversing valve to move downward against the spring thrust until it reaches the second position. The lower solenoid valve is closed, and the drilling fluid enters the lower space of the hydraulic cylinder, pushing the plug piston to move upward until the upper end of the plug piston engages with the protruding shoulder in the hydraulic cylinder. The drilling fluid in the upper space of the hydraulic cylinder enters the wellbore space through the annular space of the reversing valve and the fluid channel. The regulating nozzle is opened, and a portion of the drilling fluid enters the regulating nozzle. At this time, the flow rate and pressure of the drilling fluid entering the rotor drive space decrease, making it impossible for the turbine rotor to overcome the frictional force between itself and the turbine stator, thus preventing the hydraulic oscillator from working. The hydraulic oscillator stops working. Attached Figure Description

[0013] Figure 1 Schematic diagram of the adjustable turbine-driven short section tool;

[0014] Figure 2 for Figure 1 A magnified view of the central position I, along with the corresponding state diagram of the first position;

[0015] Figure 3 for Figure 1 A magnified view of the central position (I), simultaneously showing the state diagram of the second position;

[0016] Figure 4 A schematic diagram of the bearing outer ring structure for straightening;

[0017] Figure 5 : This is a schematic diagram of a hydraulic cylinder structure;

[0018] Figure 6 : This is a schematic diagram of the reversing valve structure;

[0019] Figure 7 : Schematic diagram of the piston lower plug structure

[0020] In the diagram: 1. Upper drive connector; 2. Screw housing; 3. Hydraulic cylinder; 4. Plug piston; 5. Lower piston plug; 6. Adjusting nozzle; 7. Turbine set nut; 8. Turbine shaft; 9. Adjusting washer; 10. Inner ring of straightening bearing; 11. Outer ring of straightening bearing; 12. Rotor adjusting cylinder; 13. Turbine rotor; 14. Turbine stator; 15. Stator adjusting cylinder; 16. Turbine retaining ring; 17. Thrust ball bearing; 18. Outer ring of adjusting shim; 19. Adjusting shim 20. Inner ring; 21. Thrust bearing; 22. Dynamic valve; 23. Static valve; 24. Lower drive connector; 25. Static valve body; 26. Turbine shaft center channel; 27. Turbine stator and rotor drive channel; 28. Internal fluid channel of turbine tool; 29. ​​Adjusting nozzle center channel; 30. Spring; 31. Directional valve; 32. Lower fluid channel of hydraulic cylinder; 33. Upper fluid channel of hydraulic cylinder; 34. Upper plug of control valve; 35. Central channel of directional valve. Detailed Implementation

[0021] To better illustrate the technical implementation and objective of the present invention, the adjustable turbine drive short section tool will be further described below with reference to the accompanying drawings:

[0022] like Figure 1 , Figure 3 , Figure 5 , Figure 6 , Figure 7As shown, the adjustable turbine-driven short tool, from top to bottom, includes upper and lower drive joints 1 and 23, a hydraulic control assembly, and a power short tool assembly. The upper and lower drive joints 1 and 23 are threaded together via a screw housing 2, forming the housing of the adjustable turbine-driven short tool. A fluid channel hole 103 is provided on the side of the screw housing 2. The hydraulic control assembly includes a hydraulic cylinder 32, a reversing valve 31, a spring 30, an upper control valve plug 34, a plug piston 4, and a lower piston plug 5. The housing of the hydraulic cylinder 32 is provided with three extension ribs 401, upper and lower fixed supports 402 and 403, and upper and lower solenoid valves 351 and 352. One of the extension ribs 401 has a fluid channel 33, 101, or 105 and is engaged with the inner surface of the fixed sleeve 50. The reversing valve 31 is located in the fluid channel 105 of the extension rib 401. Inside the 5th chamber, annular channels 501 and 31, sealing grooves 503 and 502, and fluid channels 106 and 107 are respectively provided at the top and bottom. The upper end of the reversing valve 31 is connected to the upper plug 34 of the control valve, and the lower end is engaged with the spring 30. The spring 30 is located at the bottom end of the fluid channel 105 inside the extension rib 401 and is engaged with the reversing valve 31 at the top. The upper plug 34 of the control valve is threaded to the upper opening 105 of the fluid channel of the extension rib 401, and the side hole is engaged with the upper solenoid valve 351. The plug piston 4 is located inside the hydraulic cylinder 32 and is re-operated under the action of drilling fluid hydraulic pressure to realize the tool function. The lower plug 5 of the piston is threaded to the inner surface of the hydraulic cylinder 32 and is also provided with sealing grooves 504 and 505.

[0023] Furthermore, such as Figure 1 , Figure 4As shown, the power sub-assembly, from top to bottom, includes an adjusting nozzle 6, a turbine set nut 7, a turbine shaft 8, an adjusting washer 9, a centering bearing inner ring 10, a centering bearing outer ring 11, a rotor adjusting cylinder 12, a turbine rotor 13, a turbine stator 14, a stator adjusting cylinder 15, a turbine retaining ring 16, a thrust ball bearing 7, an adjusting shim outer ring 18, an adjusting shim inner ring 19, a thrust bearing 20, a dynamic valve 21, and a static valve 22. The adjusting nozzle 6 is connected to the turbine shaft 8 via an external thread. The adjusting nozzle 6 controls the flow of drilling fluid into the central channel 25 of the turbine shaft. Sometimes it is necessary to change the drilling fluid flow rate in the central channel 25, which can be achieved by replacing the adjusting nozzle 6, i.e., changing the size of the central channel 28 of the adjusting nozzle 6. The turbine set nut 7 is connected to the turbine shaft 8 via an internal thread, and its lower end face engages with the upper end face of the adjusting washer 9. The lower end face of the adjusting washer 9 engages with the inner ring 10 of the centering bearing, serving to fix its position. The outer ring of the centering bearing inner ring 10 engages with the outer ring 11 of the centering bearing, and its lower end face connects to the rotor adjusting cylinder 12. The outer ring 11 of the bearing engages with the screw housing 2 and cooperates with the inner ring 10 of the centering bearing to limit the position of the turbine shaft 8. It also has a circular flow channel 105 for the transmission of fluid between the fluid channels 26 and 27. The turbine rotor 13 and the turbine stator 14 are constrained in the drive ring space by the rotor adjusting cylinder 12 and the stator adjusting cylinder 15 to form a drive assembly. The turbine rotor 13 is fixed to the turbine shaft 8, and the turbine stator 14 is fixed to the screw housing 2. When the drilling fluid flows into the flow channel 26, under the action of pressure difference, the multi-stage turbine rotor 13 rotates relative to the turbine stator 14, and at the same time drives the turbine shaft 8 to rotate.

[0024] Furthermore, such as Figure 1 As shown, the moving valve 21 is connected to the turbine shaft 8 via a thread. The moving valve 21 consists of a moving valve body and a moving valve connecting piece fixed together. The moving valve 21 is connected to the drive assembly by a turbine retaining ring 16, a thrust ball bearing 7, an outer ring of an adjusting shim 18, an inner ring of an adjusting shim 19, and a thrust bearing 20. The stationary valve 22 is externally engaged with the screw housing 2, and its lower end is internally threaded to the drive lower connector 23. The stationary valve 22 includes a stationary valve body 24 and a stationary valve connecting piece fixed together. In specific implementation, the stationary valve 22 is in a stationary state relative to the moving valve 21.

[0025] Furthermore, such as Figure 1 As shown, when the moving valve 21 rotates under the drive of the turbine shaft 8, the moving valve body and the stationary valve body 24 rotate relative to each other. The flow area connecting the moving valve flow channel and the stationary valve flow channel changes periodically, causing the incoming drilling fluid to generate an axial harmonic pressure wave. The harmonic pressure wave can be transmitted to the vibrating sub, which can undergo continuous axial harmonic vibration under its action, and the hydraulic oscillator works.

[0026] Working principle of an adjustable turbine-driven short tool:

[0027] In the first stage, the adjustable turbine-driven short-section tool is in operation, and the hydraulic control assembly is in... Figure 2 State. At this time, the upper and lower solenoid valves 351 and 352 are closed, the hydraulic cylinder fluid passage 105 is closed, the lower end of the plug piston 4 seals the adjusting nozzle 6, and all the drilling fluid in the tool annular flow channel 27 enters the drive switching space 26 through the flow passage 105 of the upper centralizing bearing outer ring. The hydraulic pressure of the drilling fluid drives the turbine rotor 13 to drive the turbine shaft 8 to rotate over the frictional resistance of the turbine shaft 8, and the hydraulic oscillator works. The frictional resistance includes, but is not limited to, the frictional force of the contact surface between the turbine rotor 13 and the turbine stator 14, the frictional force of the contact surface between the turbine shaft 8 and the turbine fixing ring 16, the thrust ball bearing 7 and the inner ring 10 of the centralizing bearing, the frictional force of the contact surface between the moving valve body and the stationary valve body, etc.

[0028] In the second stage, if it is necessary to deactivate the adjustable turbine drive sub-tool, open the upper and lower solenoid valves 351 and 352. The hydraulic cylinder fluid passage 105 opens, and the high-pressure drilling fluid enters the hydraulic cylinder fluid passage 105 through the upper plug 34 of the control valve. Under the push of the high-pressure drilling fluid, the directional valve 31 overcomes the thrust of the spring 30 and moves downward until it reaches the... Figure 3 At the position shown, the spring 30 cannot be compressed. The opening 107 on the lower side of the reversing valve coincides with the inside of the hydraulic cylinder fluid passage 101. The lower solenoid valve 352 is closed. The high-pressure drilling fluid enters the lower part of the hydraulic cylinder through the central passage 35 of the reversing valve, pushing the plug piston 4 to move upward. The liquid in the upper space of the hydraulic cylinder enters the low-pressure wellbore space through the upper fluid passage 33 of the hydraulic cylinder, the annular passage 501 of the reversing valve, the circular hole passage 102 of the fixed sleeve, and the circular hole passage 103 of the screw housing. When the piston plug moves to the upper end and does not coincide with the inside of the hydraulic cylinder... When the shoulder platform 202 is engaged, the movement stops. At this time, the upper solenoid valve 351 is closed, and the adjusting nozzle 6 is fully opened. A portion of the drilling fluid enters the turbine shaft center channel 25 through the center hole of the adjusting nozzle 6. At this time, part of the drilling fluid in the tool annulus flow channel 27 enters the drive switching space 26 through the outer ring flow channel 105 of the upper centering bearing. The hydraulic pressure of the drilling fluid cannot drive the turbine rotor 13 to drive the turbine shaft 8 to overcome the frictional resistance of the turbine shaft 8 and rotate. The hydraulic oscillator stops working and performs some functions, such as cleaning the wellbore.

[0029] In the third stage, it is sometimes necessary to return the tool to the first stage state. At this time, the upper and lower solenoid valves 351 and 352 are opened to reduce the drilling fluid hydraulic pressure. The drilling fluid hydraulic pressure cannot overcome the thrust of spring 30, and the directional valve 31 returns to the first stage state under the push of the spring. Figure 2Position: The opening 106 on the upper side of the reversing valve 31 coincides with the inside of the hydraulic cylinder fluid passage 33. The lower solenoid valve 352 is closed, and the drilling fluid pressure is increased to the normal working pressure. The high-pressure drilling fluid enters the upper part of the hydraulic cylinder through the central passage 35 of the reversing valve, pushing the plug piston 4 to move downward. The liquid in the lower space of the hydraulic cylinder enters the low-pressure wellbore space through the lower fluid passage 101 of the hydraulic cylinder, the annular passage 504 of the reversing valve, the circular hole passage 102 of the fixed sleeve, and the circular hole passage 103 of the screw housing. When the piston plug moves to the lower end and engages with the upper end face of the lower piston plug 5, it stops moving. At this time, the upper solenoid valve 351 is closed, the nozzle 6 is completely blocked, the hydraulic oscillator works, and it returns to the first stage.

Claims

1. An adjustable turbine-driven sub tool, comprising upper and lower drive joints, a power sub assembly, and a hydraulic control assembly; the upper drive joint is threadedly connected to a hydraulic oscillator vibration sub, and the lower drive joint is threadedly connected to a drill bit, together forming a hydraulic oscillator tool; the upper and lower drive joints are threaded together via a screw housing; the power sub assembly contains a stationary valve and a moving valve, the moving valve having a moving valve flow channel, and the stationary valve having a stationary valve flow channel; the flow area connecting the moving valve flow channel and the stationary valve flow channel changes periodically to generate an axial harmonic pressure wave in the incoming drilling fluid; the hydraulic control assembly contains upper and lower solenoid valves, a directional valve, and a spring, the central fluid channel of the directional valve and the channel where the lower spring is located are connected. The adjustable turbine drive sub-tool has a drilling fluid channel. The upper solenoid valve controls the flow of high-pressure drilling fluid into the central fluid channel of the directional valve by opening and closing the fluid channel. At the same time, the high-pressure drilling fluid pushes the directional valve downward against the spring thrust, and the lower solenoid valve opens, opening the lower channel of the directional valve. When the drilling fluid hydraulic pressure cannot overcome the spring thrust, the spring pushes the directional valve upward, thus realizing the function of the directional valve. The hydraulic control assembly is equipped with a plug piston. High-pressure drilling fluid enters the hydraulic cylinder through the directional valve channel to drive the plug piston, blocking the adjusting nozzle. The opening and closing of the hydraulic oscillator is controlled by changing the flow rate of drilling fluid into the drive ring space between the turbine rotor and the turbine stator. The upper and lower solenoid valves are installed and fixed at the upper and lower ends of the hydraulic cylinder. The upper solenoid valve is engaged with the side hole of the upper plug of the control valve. The upper plug of the control valve is connected to the extension rib of the hydraulic cylinder housing through a thread. The opening and closing of the upper solenoid valve realizes the entry of high-pressure drilling fluid into the reversing valve. The lower solenoid valve is directly engaged with the side hole of the extension rib of the hydraulic cylinder housing. The opening and closing of the lower solenoid valve realizes the opening and closing of the channel where the lower end spring of the reversing valve is located. The reversing valve is located in the extension rib opening of the hydraulic cylinder housing. Its upper end is connected to the upper plug of the control valve, and its lower end is connected to the spring. The reversing valve is cylindrical with a non-penetrating fluid channel in the center. It has a side hole at the upper end and a side hole at the lower end for fluid interaction with the inner cavity of the hydraulic cylinder. The spring is located in the fluid channel at the lower end of the reversing valve. When the upper and lower solenoid valves are opened, if the drilling fluid hydraulic pressure cannot overcome the spring's thrust, the spring will push the reversing valve back to the first position.

2. The adjustable turbine drive pup joint tool of claim 1, wherein: The hydraulic cylinder housing has three extension ribs, which are joined to the inner surface of the fixed sleeve. The outer surface of the fixed sleeve is joined to the screw housing. Two round holes are opened on the side as fluid exchange channels between the hydraulic cylinder and the wellbore. Two round holes are opened on the side of the screw housing as fluid exchange channels between the hydraulic cylinder and the wellbore. The inner surface of the hydraulic cylinder is provided with a raised shoulder, which connects the plug piston and the piston lower plug.

3. The adjustable turbine-driven short section tool as described in claim 1, characterized in that: The first position is the working state of the hydraulic oscillator. At this time, the spring pushes the reversing valve to the first position, closes the lower solenoid valve, and the lower space of the reversing valve is closed and cannot be compressed, increasing the hydraulic pressure of the drilling fluid. The drilling fluid enters the upper space of the hydraulic cylinder through the central channel of the reversing valve, pushing the plug piston downward to block the adjusting nozzle until the plug piston engages with the upper end of the lower plug of the piston. The drilling fluid in the lower space of the hydraulic cylinder enters the wellbore space through the annular space and fluid channel of the reversing valve. At this time, all the drilling fluid flows into the rotor drive space, so that the turbine rotor overcomes the friction between itself and the turbine stator, driving the hydraulic oscillator to work. The first position has a corresponding second state, which is the stopped state of the hydraulic oscillator.

4. The adjustable turbine-driven short section tool as described in claim 3, characterized in that: The second state is the hydraulic oscillator stop state. At this time, the lower solenoid valve is open, the lower space of the reversing valve is open, and the high-pressure drilling fluid pushes the reversing valve to move downward against the spring thrust until it reaches the second position. The lower solenoid valve is closed, and the drilling fluid enters the lower space of the hydraulic cylinder, pushing the plug piston to move upward until the upper end of the plug piston engages with the protruding shoulder in the hydraulic cylinder. The drilling fluid in the upper space of the hydraulic cylinder enters the wellbore space through the annular space of the reversing valve and the fluid channel. The regulating nozzle is opened, and a part of the drilling fluid enters the regulating nozzle. At this time, the flow rate and pressure of the drilling fluid entering the rotor drive space decrease, so that the turbine rotor cannot overcome the friction between itself and the turbine stator, and cannot drive the hydraulic oscillator to work. The hydraulic oscillator stops working.

Images