A high-frequency water hammer pressure wave monitor suitable for fracturing

Abstract

The application discloses a high-frequency water hammer pressure wave monitor suitable for fracturing, and relates to the technical field of water hammer pressure monitoring. The inner wall of the shell is sequentially provided with a buffer pad, a communication power supply module, a data acquisition and processing module, a signal adjusting and filtering module and a pressure detection module from top to bottom; the lower side of the inner wall of the shell is fixedly connected with a filter screen; a vibration sensing module and a temperature acquisition module are arranged between the pressure detection module and the signal adjusting and filtering module. The application is provided with the pressure detection module, the signal adjusting and filtering module, the data acquisition and processing module, the communication power supply module, the buffer pad, the vibration sensing module and the temperature acquisition module, a complete pressure acquisition, signal conditioning, data processing and transmission system is constructed, the anti-seismic compensation and temperature correction functions are achieved, the monitoring precision and the system stability are improved, and the application has the characteristics of high practicability and real-time monitoring demand under high-frequency water hammer working conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of water hammer pressure monitoring, and in particular to a high-frequency water hammer pressure wave monitor suitable for fracturing. Background Art

[0002] During the fracturing process of oil and gas wells, high-pressure pumps are often used to inject liquid carrying fracturing sand into the formation to achieve crack expansion and support. During this process, complex fluid conditions such as high-frequency water hammer, pulsating pressure waves, and sand-containing scour frequently occur inside the pipeline. To achieve real-time monitoring and optimized control of the fracturing process, high-sensitivity and high-precision dynamic monitoring of high-frequency pressure fluctuations in the liquid is required.

[0003] Existing Chinese patent publication number CN117846579A discloses a device and method for monitoring high-frequency pressure fluctuations based on the water hammer effect during well shut-in. The device uses a data acquisition module to collect real-time fluctuating pressure data and waveform characteristic data, fully utilizing the software resources of a single-chip microcomputer to clearly identify the changing patterns of wellhead pressure in the initial stage of well shut-in due to the water hammer effect.

[0004] However, this device uses a fixed pressure sensor, which is generally only suitable for low-frequency, steady-state flow fields and cannot effectively capture the instantaneous high-frequency water hammer signals in the fracturing fluid. At the same time, the large amount of high-hardness sand and gravel particles in the fracturing fluid continuously impacts the sensor probe area, which can easily cause structural wear, false alarms, and even sensor failure. In addition, there is significant electromagnetic interference and mechanical vibration at the fracturing site, which often leads to signal instability or reduced monitoring accuracy. This is especially true in applications that require accurate extraction of waveform features and weak fluctuations. The existing technology has obvious shortcomings.

[0005] Therefore, there is an urgent need to design a high-frequency pressure wave monitoring device with stable structure, fast response, impact resistance and shielding of external electromagnetic interference to meet the long-term high-precision real-time detection needs of complex fluid environments under fracturing conditions. Summary of the Invention

[0006] The object of the present invention is to provide a high-frequency water hammer pressure wave monitor suitable for fracturing, so as to solve the problems raised in the above background technology.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: a high-frequency water hammer pressure wave monitor suitable for fracturing, comprising a housing, the inner wall of which is provided with a buffer pad, a communication power supply module, a data acquisition and processing module, a signal conditioning and filtering module, and a pressure detection module in order from top to bottom; a filter is fixedly connected to the lower side of the inner wall of the housing, and a vibration sensing module and a temperature acquisition module are provided between the pressure detection module and the signal conditioning and filtering module;

[0008] The pressure detection module is used to collect pressure information and capture pressure fluctuations;

[0009] The vibration sensing module is used to collect vibration data, and the temperature collection module is used to collect the internal working temperature of the housing;

[0010] The signal conditioning and filtering module is used to perform low-noise amplification, filtering, and normalization on the original pressure signal and output a standard voltage or digital signal;

[0011] The data acquisition and processing module is used for high-speed data sampling, feature extraction, digital signal processing and packet packaging;

[0012] The communication power supply module realizes data communication with the host computer, remote power supply and battery management;

[0013] The buffer pad is used to buffer the communication power supply module, data acquisition and processing module, signal conditioning and filtering module, and pressure detection module on the lower side and to seal and protect the field interface;

[0014] An upper fixing ring and a lower fixing ring are arranged on the upper side of the outer wall of the shell, a balancing mechanism is arranged on the outer sides of the upper fixing ring and the lower fixing ring, and a shielding mechanism is arranged on the outer side of the shell.

[0015] According to the above technical solution, the inner wall of the outer shell is fixedly connected to the outer wall of the buffer pad, and the lower side of the buffer pad contacts the upper side of the communication power supply module, the inner wall of the outer shell is fixedly connected to the outer wall of the pressure detection module, the filter is located on the lower side of the pressure detection module, the upper part of the side wall of the outer shell is fixedly connected to the inner wall of the lower fixing ring by bolts, and the inner wall of the lower fixing ring is fixedly connected to the outer wall of the upper fixing ring by bolts.

[0016] According to the above technical solution, the balancing mechanism includes a fixed disk, which is an annular structure, and a flow channel is provided on the outer ring of the fixed disk, and a spring groove is provided on the inner wall of the fixed disk. A spring is fixedly connected to the inner wall of the spring groove, and the other end of the spring is fixedly connected to the outer wall of the upper fixed ring.

[0017] According to the above technical solution, the upper side of the upper fixing ring and the lower side wall of the lower fixing ring both extend outward, the fixing plate is located between the upper fixing ring and the lower fixing ring, and the housing can only move on a plane relative to the fixing plate.

[0018] According to the above technical solution, the shielding mechanism includes an installation groove, and the installation groove is a groove opened on the side wall of the outer shell. A swivel is provided on the outer side of the outer shell, and an installation ring is provided on the inner wall of the swivel. The installation ring is located inside the installation groove, and a guide groove is opened on the outer wall of the swivel.

[0019] According to the above technical solution, a plurality of guide grooves are provided on the outer wall of the rotating ring. The guide grooves are grooves inclined relative to the rotating ring. The guide grooves are evenly arranged in a ring shape on the outside of the rotating ring, and the middle part of the rotating ring bulges outward.

[0020] According to the above technical solution, a shielding layer is provided inside the rotating ring, and the pressure detection module, temperature acquisition module, vibration sensing module, signal adjustment and filtering module, and data acquisition and processing module are all located inside the shielding layer, and the shielding layer is evenly distributed inside the rotating ring.

[0021] Compared with the existing technology, the present invention has the following beneficial effects: by providing a pressure detection module, a signal conditioning and filtering module, a data acquisition and processing module, a communication power supply module, a buffer pad, a vibration sensing module, and a temperature acquisition module, the present invention constructs a complete pressure acquisition, signal conditioning, data processing and transmission system, has anti-seismic compensation and temperature correction functions, improves monitoring accuracy and system stability, and is suitable for real-time monitoring needs under high-frequency water hammer conditions;

[0022] By providing a balancing mechanism, the housing can slide slightly relative to the fixed plate in the plane, and the spring absorbs the inertial force, effectively buffering the disturbance caused by pipeline vibration, achieving flexible coupling installation between the monitoring device and the pipeline, and improving structural stability and anti-interference ability;

[0023] By setting up a shielding mechanism and using the swivel to drive the shielding layer to rotate, a dynamic and uniform electromagnetic shield is formed under the drive of water flow, which significantly reduces the influence of geomagnetic, motor and high-frequency interference on the pressure signal, ensuring the monitoring accuracy of high-frequency pressure waves;

[0024] The angular momentum generated by the rotation of the swivel ring forms a gyroscopic stabilization effect, which can slow down the shaking tendency of the casing under external vibration impact, realize passive anti-disturbance control, and further enhance the seismic resistance and operational stability of the entire device in the fracturing environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0027] Figure 2 It is a schematic diagram of the split structure of the present invention;

[0028] Figure 3 It is a partial structural schematic diagram of the present invention;

[0029] Figure 4 It is a schematic diagram of the shell structure of the present invention;

[0030] Figure 5 It is a schematic diagram of the internal structure of the housing of the present invention;

[0031] Figure 6 1 is a schematic diagram of the cross-sectional structure of the swivel of the present invention;

[0032] In the figure: 1. Shell; 2. Buffer pad; 3. Communication power supply module; 4. Data acquisition and processing module; 5. Signal conditioning and filtering module; 6. Pressure detection module; 7. Filter; 8. Vibration sensor module; 9. Temperature acquisition module; 10. Upper fixing ring; 11. Lower fixing ring; 12. Balancing mechanism; 13. Shielding mechanism; 201. Fixed plate; 202. Flow channel; 203. Spring groove; 204. Spring; 301. Mounting groove; 302. Rotating ring; 303. Mounting ring; 304. Shielding layer; 305. Guide groove. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] Example 1: Please refer to Figure 1-5 The present invention provides a technical solution: a high-frequency water hammer pressure wave monitor suitable for fracturing, comprising a housing 1, the inner wall of which is provided with a buffer pad 2, a communication power supply module 3, a data acquisition and processing module 4, a signal conditioning and filtering module 5, and a pressure detection module 6 in order from top to bottom; a filter screen 7 is fixedly connected to the lower side of the inner wall of the housing 1, and a vibration sensing module 8 and a temperature acquisition module 9 are provided between the pressure detection module 6 and the signal conditioning and filtering module 5;

[0035] The pressure detection module 6 is used to collect pressure information and capture pressure fluctuations. It is a piezoelectric high-frequency response pressure sensor. Its detection end is arranged along the axis of the housing 1 and is consistent with the liquid flow direction. It is used to capture transient pressure fluctuations with high precision.

[0036] The vibration sensing module 8 is a three-axis MEMS accelerometer used to record the vibration acceleration of the device, assist in determining the source of the error, and collect vibration data. The temperature acquisition module 9 is used to collect the internal working temperature of the housing 1, and is used to record the real-time temperature and realize temperature drift compensation.

[0037] The signal conditioning and filtering module 5 is used to perform low-noise amplification, filtering, and normalization on the original pressure signal and output a standard voltage or digital signal. It has a built-in bandpass filter with a frequency response range of 10–150 kHz to filter out vibration interference and low-frequency water wave signals.

[0038] The data acquisition and processing module 4 integrates a high-speed ADC and a microprocessor, supports a sampling rate of ≥1MSa / s, and performs FFT and time-domain peak feature extraction on the pressure wave data for high-speed data sampling, feature extraction, digital signal processing, and packet packaging;

[0039] The communication power supply module 3 integrates the CAN bus communication interface and the DC-DC voltage regulator module, supports remote power supply and data output, and realizes data communication with the host computer, remote power supply and battery management;

[0040] The cushion 2 is a three-layer cushioning structure made of silicone rubber composite material, which plays a role in shock resistance, sealing and protection. It is used to cushion the communication power supply module 3, data acquisition and processing module 4, signal conditioning and filtering module 5, and pressure detection module 6 on the lower side, and to seal and protect the field interface.

[0041] An upper fixing ring 10 and a lower fixing ring 11 are provided on the upper side of the outer wall of the housing 1. A balancing mechanism 12 is provided on the outer sides of the upper fixing ring 10 and the lower fixing ring 11, and a shielding mechanism 13 is provided on the outer side of the housing 1.

[0042] The inner wall of the housing 1 is fixedly connected to the outer wall of the buffer pad 2, and the lower side of the buffer pad 2 contacts the upper side of the communication power supply module 3. The inner wall of the housing 1 is fixedly connected to the outer wall of the pressure detection module 6. The filter 7 is located on the lower side of the pressure detection module 6. The upper part of the side wall of the housing 1 is fixedly connected to the inner wall of the lower fixing ring 11 by bolts, and the inner wall of the lower fixing ring 11 is fixedly connected to the outer wall of the upper fixing ring 10 by bolts.

[0043] During actual application: the external fracturing fluid passes through the surface of the equipment at high speed, and the filter screen 7 blocks sand and large particles of impurities on the outside of the shell 1 during the flow process to prevent damage to the pressure detection module 6. The pressure detection module 6 contacts the liquid and collects the fluid pressure changes in real time, especially the water hammer pressure fluctuation signal, and outputs the original analog pressure signal. The signal conditioning and filtering module 5 receives the analog signal, performs low-noise amplification, temperature drift compensation, band-pass filtering and normalization processing on it, and generates a standardized analog or digital signal. The data acquisition and processing module 4 performs high-speed sampling and digital processing on the signal, extracts the characteristic value and spectrum of the pressure wave, and the communication power supply module 3 The digital coding package of the completed signal is transmitted to the host computer via wired / wireless means, and stable power supply is provided at the same time. The vibration sensing module 8 and the temperature acquisition module 9 monitor the mechanical vibration and temperature information of the current device environment in real time, and assist the data acquisition and processing module 4 to perform temperature correction or vibration denoising, realizing a complete monitoring process from pressure acquisition to signal processing and data transmission. It can effectively filter out the direct impact of impurities on the sensor and ensure the physical security of the pressure data. Through the synchronous acquisition of temperature and vibration information, the data accuracy and stability of the final pressure signal are improved, supporting high-frequency data transmission and adapting to the high-speed change scenario at the fracturing site.

[0044] Example 2: Please refer to Figure 1-5 Based on the first embodiment, the present invention provides a technical solution: the balancing mechanism 12 includes a fixed disk 201, which is an annular structure. A flow channel 202 is formed on the outer ring of the fixed disk 201, and a spring groove 203 is formed on the inner wall of the fixed disk 201. A spring 204 is fixedly connected to the inner wall of the spring groove 203. The other end of the spring 204 is fixedly connected to the outer wall of the upper fixing ring 10. The upper side of the upper fixing ring 10 and the lower side wall of the lower fixing ring 11 both extend outward. The fixed disk 201 is located between the upper fixing ring 10 and the lower fixing ring 11. The housing 1 can only move on a plane relative to the fixed disk 201.

[0045] After the device is installed, the fixed disk 201 is relatively fixed to the pipeline, so the device will not shake with the water flow due to the impact force of the fluid in the pipeline, and can be fixed at one point for monitoring. When the pipeline is displaced or slightly vibrates due to the impact of the fluid, the shell 1 will lag behind the movement of the fixed disk 201 due to inertia. The spring 204 in the spring groove 203 will absorb and release the displacement energy, so that the shell 1 can slip slightly on the plane where the fixed disk 201 is located, thereby reducing the displacement of the shell 1 during the shaking of the pipeline, thereby enhancing stability, realizing a flexible coupling installation method between the monitor and the fracturing pipeline, and avoiding interference with the signal caused by hard connection.

[0046] Example 3: Please refer to Figure 1-6On the basis of the first and second embodiments, the present invention provides a technical solution: the shielding mechanism 13 includes a mounting groove 301, and the mounting groove 301 is a groove opened on the side wall of the shell 1, a rotating ring 302 is provided on the outer side of the shell 1, and a mounting ring 303 is provided on the inner wall of the rotating ring 302, and the mounting ring 303 is located inside the mounting groove 301, and a guide groove 305 is opened on the outer wall of the rotating ring 302, and a plurality of guide grooves 305 are opened on the outer wall of the rotating ring 302, and the guide grooves 305 are grooves inclined relative to the rotating ring 302, and the plurality of guide grooves 305 are evenly arranged in an annular shape on the outer side of the rotating ring 302, and the middle part of the rotating ring 302 bulges outward, a shielding layer 304 is provided inside the rotating ring 302, and the pressure detection module 6, the temperature acquisition module 9, the vibration sensing module 8, the signal conditioning and filtering module 5, and the data acquisition and processing module 4 are all located inside the shielding layer 304, and the shielding layer 304 is evenly distributed inside the rotating ring 302;

[0047] A stable rotation system is formed by inserting the mounting ring 303 into the mounting groove 301. Since a plurality of guide grooves 305 are provided on the outer wall of the rotating ring 302, and the guide grooves 305 are spirally inclined and the direction is consistent with the tangential direction of the water flow, under the impact of the water flow, the rotating ring 302 is driven by the torque of the guide grooves 305 to rotate around the housing 1, thereby driving the shielding layer 304 to rotate. The shielding layer 304 is composed of a high magnetic permeability metal such as Permalloy and a conductive layer. The shielding layer 304 rotates continuously with the rotating ring 302 to form a dynamic electromagnetic shielding field, which protects the pressure detection module 6, Key components such as the signal conditioning and filtering module 5, the data acquisition and processing module 4, the vibration sensing module 8, and the temperature acquisition module 9 form 360-degree coverage. The guide grooves 305 are distributed in a spiral pattern, ensuring that the water flow stably applies rotational torque, maintaining the uniform rotation of the shielding layer, and effectively suppressing non-contact interference signals such as the external geomagnetic field, motor interference, and cable radiation. In the rotating state, the shielding layer can break the fixed shielding blind spot, making the electromagnetic interference evenly distributed over time, reducing the instantaneous interference peak, and forming a combined shield with the filter circuit to improve the monitoring reliability of high-frequency small signals;

[0048] The swivel 302 is a conical flow-guiding structure with a tapered cylindrical shape that is larger at the top and smaller at the bottom. The structure is aligned with the fluid flow direction. When the fracturing fluid containing sand flows through the structure at high speed, the conical profile guides the circumferential fluid to the center according to the Bernoulli principle, resulting in a local increase in flow velocity and a reunion of flow directions, thereby accelerating the sand-containing fluid through the central axis area.

[0049] During this process, due to the concentration of kinetic energy of sand and gravel particles and the convergence of streamlines, the turbulence in the area of ​​the pressure detection module 6 on the lower side of the device is weakened, and the probability of irregular collision of sand and gravel in this area is significantly reduced, thereby effectively avoiding particle impact damage caused by turbulence or low-speed rotation, and at the same time reducing false vibration signals caused by impact, improving detection accuracy and extending the service life of the device.

[0050] Example 4: Please refer to Figure 1-6 Based on the first, second, and third embodiments, the present invention provides a technical solution: after being subjected to the tangential impact of the high-speed flow of fracturing fluid, the swivel 302 rotates continuously and stably along the axial centerline of the housing 1, and the mass distribution of the swivel 302 is annularly symmetrical. The rotation process will generate stable angular momentum, and the swivel 302 allows it to maintain a low-friction rotation relationship with the housing 1;

[0051] During the fracturing operation, when the pipeline system generates lateral micro-vibration or impact due to instantaneous water hammer or structural stress, the continuous rotation of the swivel 302 will provide a stable gyroscopic effect, so that it maintains the conservation of angular momentum in the direction of the rotation axis, thereby generating a reverse inertial force on the outer shell of the housing 1, reducing its tendency to sudden shaking;

[0052] Since the swivel 302 rotates synchronously with the shielding layer 304, and the shielding layer is a high-density metal multi-layer structure, its total mass further enhances the angular momentum of the rotating assembly. Therefore, the lateral stability of the housing 1 is greatly improved during the operation of the device. Without increasing the external fixed constraint force, this structure forms a passive anti-disturbance structural unit through the angular momentum characteristics of the rotating system itself, effectively weakening the disturbance transmission caused by the fluctuation of the fracturing fluid and the mechanical vibration of the pipeline, and enhancing the anti-interference capability of the overall operation of the device.

[0053] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0054] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A high-frequency water hammer pressure wave monitor suitable for fracturing, comprising a housing (1), characterized in that: The inner wall of the housing (1) is provided with a buffer pad (2), a communication power supply module (3), a data acquisition and processing module (4), a signal adjustment and filtering module (5), and a pressure detection module (6) in order from top to bottom; a filter (7) is fixedly connected to the lower side of the inner wall of the housing (1); a vibration sensing module (8) and a temperature acquisition module (9) are provided between the pressure detection module (6) and the signal adjustment and filtering module (5); The pressure detection module (6) is used to collect pressure information and capture pressure fluctuations; The vibration sensing module (8) is used to collect vibration data, and the temperature collection module (9) is used to collect the internal working temperature of the housing (1); The signal conditioning and filtering module (5) is used to perform low-noise amplification, filtering, and normalization on the original pressure signal, and output a standard voltage or digital signal; The data acquisition and processing module (4) is used for high-speed data sampling, feature extraction, digital signal processing and packet packaging; The communication power supply module (3) realizes data communication with the host computer, remote power supply and battery management; The buffer pad (2) is used to buffer the communication power supply module (3), the data acquisition and processing module (4), the signal adjustment and filtering module (5), and the pressure detection module (6) on the lower side and to provide sealing protection for the on-site interface; An upper fixing ring (10) and a lower fixing ring (11) are provided on the upper side of the outer wall of the housing (1); a balancing mechanism (12) is provided on the outer sides of the upper fixing ring (10) and the lower fixing ring (11); the balancing mechanism (12) comprises a fixing plate (201); the fixing plate (201) is located between the upper fixing ring (10) and the lower fixing ring (11); the housing (1) can only move on a plane relative to the fixing plate (201); A shielding mechanism (13) is provided on the outer side of the housing (1); The shielding mechanism (13) comprises a mounting groove (301), and the mounting groove (301) is a groove opened on the side wall of the housing (1); a rotating ring (302) is provided on the outside of the housing (1); a shielding layer (304) is provided inside the rotating ring (302); a mounting ring (303) is provided on the inner wall of the rotating ring (302); the mounting ring (303) is located inside the mounting groove (301); and a guide groove (305) is opened on the outer wall of the rotating ring (302).

2. The high-frequency water hammer pressure wave monitor suitable for fracturing according to claim 1, characterized in that: The inner wall of the shell (1) is fixedly connected to the outer wall of the buffer pad (2), and the lower side of the buffer pad (2) contacts the upper side of the communication power supply module (3). The inner wall of the shell (1) is fixedly connected to the outer wall of the pressure detection module (6). The filter (7) is located on the lower side of the pressure detection module (6). The upper part of the side wall of the shell (1) is fixedly connected to the inner wall of the lower fixing ring (11) by bolts, and the inner wall of the lower fixing ring (11) is fixedly connected to the outer wall of the upper fixing ring (10) by bolts.

3. The high-frequency water hammer pressure wave monitor suitable for fracturing according to claim 1, characterized in that: The fixed disk (201) is an annular structure, and a flow channel (202) is provided on the outer ring of the fixed disk (201), a spring groove (203) is provided on the inner wall of the fixed disk (201), a spring (204) is fixedly connected to the inner wall of the spring groove (203), and the other end of the spring (204) is fixedly connected to the outer wall of the upper fixed ring (10).

4. The high-frequency water hammer pressure wave monitor suitable for fracturing according to claim 1, characterized in that: The upper side of the upper fixing ring (10) and the lower side wall of the lower fixing ring (11) both extend outward.

5. The high-frequency water hammer pressure wave monitor suitable for fracturing according to claim 1, characterized in that: The outer wall of the rotating ring (302) is provided with a plurality of guide grooves (305), the guide grooves (305) being grooves inclined relative to the rotating ring (302), the plurality of guide grooves (305) being evenly arranged in an annular shape on the outer side of the rotating ring (302), and the middle portion of the rotating ring (302) bulges outwards.

6. The high-frequency water hammer pressure wave monitor suitable for fracturing according to claim 5, characterized in that: The pressure detection module (6), the temperature acquisition module (9), the vibration sensing module (8), the signal adjustment and filtering module (5), and the data acquisition and processing module (4) are all located inside the shielding layer (304), and the shielding layer (304) is evenly distributed inside the rotating ring (302).

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