A structure method and system for intelligently regulating internal oscillation of a low-temperature distribution system

Abstract

The application discloses a structure method and system for intelligently regulating internal oscillation of a low-temperature distribution system, which comprises a liquid supply pipe for conveying low-temperature liquid, a distribution pipe connected with the low-temperature liquid supply pipe, user ends connected with a plurality of distribution branch pipes on the distribution pipe respectively and at room temperature, and an oscillation phase modulation structure installed at the distribution branch pipes, wherein the distribution branch pipes are distributed in a non-linear manner along a pipe axis with respect to temperature, so as to cause pressure oscillation in the pipe. The oscillation phase modulation structure is arranged between the distribution branch pipes to form a double self-excitation coupled oscillator or an external excitation-self-excitation coupled oscillator formed by arranging an external excitation generating device at a single distribution branch pipe, so as to regulate pressure oscillation in the system, realize regulation and control of adverse oscillation in the system, and have the advantages of simple structure, low cost, suitability for a multi-branch pipe system and no influence on the main structure of the distribution system due to the introduction of the phase modulation structure.

Description

Technical Field

[0001] This invention relates to a structural method and system for regulating pressure oscillation in a pipeline, and particularly to a structural method and system for regulating the oscillation state of a cryogenic distribution system. Background Technology

[0002] Cryogenic distribution systems employ various pipeline structures connecting cryogenic fluids to a closed room-temperature end, such as: instrument lines connected to room-temperature feedback pipes, capillary tubes connecting cryogenic baths to room-temperature pressure sensors, pressure relief lines, and closed bayonet connections, etc. When the room-temperature end of a pipeline is closed, or the flow velocity in the pipeline is low, thermoacoustic oscillations can occur in the filling or venting lines of the cryogenic Dewar flask. Because the operating temperature of the cryogenic system is far below room temperature, a significant temperature gradient exists between the room-temperature and cryogenic ends of the pipeline. When this large axial temperature gradient causes the cryogenic gas in the semi-open pipe to heat up and expand rapidly, thermoacoustic oscillations occur. The cryogenic distribution system supplies liquid helium and liquid nitrogen separately to the superconducting radio frequency module and recovers vaporized helium back to the cryogenic system. However, during this distribution and transfer process, a large amount of liquid helium evaporates due to heat leakage caused by thermoacoustic oscillations. The helium level sensor cannot provide reliable liquid helium level readings, leading to overcharging of the cryostat and severely affecting the operation of the radio frequency control and the liquid helium distribution system. Therefore, to ensure stable system operation, it is necessary to adopt effective suppression strategies to reduce thermoacoustic oscillations to an acceptable level. Summary of the Invention

[0003] The purpose of this invention is to provide a structure and method for real-time control of the oscillation state of a cryogenic distribution system. The control structure is simple and easy to control. It adopts an external excitation-self-excited oscillation dual-source coupled oscillator or a dual self-excited acoustic wave coupled oscillator. The self-excited oscillation within the system is controlled by the control system of the coupled oscillator, which can quickly and accurately suppress the thermoacoustic oscillation of the cryogenic distribution system without changing the main structure of the system and at a low cost.

[0004] To achieve the above objectives, this invention proposes a structure for regulating the oscillation state of a cryogenic distribution system, comprising a supply pipe for conveying cryogenic liquid, a distribution pipe connected to the cryogenic supply pipe, a user end at room temperature connected to multiple distribution branches on the distribution pipe, an oscillation phase-tuning structure installed at the distribution branches, and a control system with a coupled oscillator for regulating the system. The temperature of the distribution branches along the pipe axis is nonlinearly distributed, thereby causing pressure oscillation inside the pipe.

[0005] The oscillation phase modulation structure uses an external excitation control element or a self-coupling control element to regulate the self-excited oscillation within the system through the control system of the coupled oscillator.

[0006] The external excitation control element of the oscillation phase modulation structure introduces an external excitation generator at a single branch pipe. The external excitation generator uses an external sound source to form an excitation sound source. The excitation sound source generated by the external excitation generator and the internal self-excited oscillation form an external excitation-self-excited oscillation dual-coupled oscillator. The oscillation state of the external excitation-self-excited oscillation dual-sound source coupled oscillator depends on the external excitation amplitude, external excitation frequency and external excitation phase.

[0007] The self-coupling control element of the oscillation phase modulation structure introduces a regulating tube between two distribution branches with equal lengths and symmetrical temperature distributions that internally induce self-excited oscillations. The regulating tube couples the self-excited waves to form a self-excited double-coupled oscillator. The oscillation state of the self-excited double-coupled oscillator depends on the length, diameter, and connection position of the regulating tube.

[0008] The method for achieving oscillation phase modulation of a cryogenic distribution system according to the present invention includes:

[0009] The external excitation amplitude and phase of the external excitation control element of the oscillation phase modulation structure are small and the driving frequency deviates from the self-excitation frequency, making it easier to suppress the oscillation of the coupled system.

[0010] The external excitation amplitude and phase of the external excitation control element of the oscillation phase modulation structure are small and the driving frequency is close to the self-excitation frequency, which will weaken the oscillation and maintain it at the self-excitation frequency.

[0011] The external excitation amplitude and frequency of the external excitation control element of the oscillation phase modulation structure are large enough to lock the oscillation frequency of the coupling system to the external excitation frequency.

[0012] If the external excitation amplitude and external excitation frequency of the external excitation control element of the oscillation phase modulation structure are too small, the oscillation frequency of the coupled system will be locked at the self-excitation frequency.

[0013] The self-coupled control element of the oscillation phase modulation structure has both ends of the regulating tube connected to the room temperature end, is relatively short in length and has a large tube diameter, making it difficult to achieve the non-oscillating state of the self-excited double-coupled oscillator.

[0014] The two ends of the regulating tube of the self-coupled control element of the oscillation phase modulation structure are connected to the room temperature end and the low temperature end respectively, making it difficult to achieve the non-oscillation state of the self-excited double-coupled oscillator.

[0015] The self-coupling control element of the oscillation phase modulation structure has both ends of the regulating tube connected to the low temperature end, and its long length and small diameter make it easier to achieve the non-oscillation state of the self-excited double-coupled oscillator.

[0016] A data mining-based control system for the oscillation state of a coupled oscillator includes an oscillation parameter monitoring module, a spectrum analysis module, a coupled phase difference solving module, a data mining module, an evaluation feedback module, and an oscillator operation control module.

[0017] The oscillation parameter monitoring module monitors and collects the pressure oscillation sequence and amplitude of the self-excited or externally excited oscillator, and transmits the preprocessed data to the spectrum analysis module. The spectrum analysis module uses Fourier transform to analyze the oscillation frequency of the pressure oscillation sequence of the self-excited or externally excited oscillator, and transmits the analysis results to the data mining module. The coupling phase difference solving module solves for the envelope phase and instantaneous phase of the single oscillator's pressure oscillation, thereby obtaining the dynamic phase difference of the coupled oscillator, and transmits the solution results to the data mining module. The data mining module analyzes the oscillation amplitude, frequency, and phase difference of the coupled oscillator based on Apriori correlation and PCA dimensionality reduction algorithms. The correlation and principal component analysis between parameters and the excitation amplitude, excitation frequency, and excitation phase of the externally excited oscillator, or the length, diameter, and connection position of the phase-tuning tube of the self-excited oscillator, are performed to obtain correlation rules and principal components affecting the oscillation state of the coupled oscillator, and then transmitted to the evaluation feedback module. The evaluation feedback module evaluates the correlation rules based on the oscillation state and determines the range of key control parameters, and feeds back the control strategy to the oscillator operation control module. Based on the feedback control strategy, the oscillator operation control module uses an adaptive controller to control the excitation amplitude, frequency, and phase of the externally excited oscillator, or uses an actuator to control the length, diameter, and connection position of the phase-tuning tube, thereby realizing the control of the oscillation state of the cryogenic system.

[0018] The beneficial effects of this invention are as follows: Since this invention connects one end of the supply pipe for conveying cryogenic liquid to the distribution pipe, and the other ends of multiple distribution branches on the distribution pipe are respectively connected to the user end at room temperature, an oscillation phase-tuning structure for regulating the oscillation state of the system is installed at the distribution branch. The regulation structure is simple and easy to operate, and the introduction of the phase-tuning structure will not affect the main structure of the distribution pipeline of the system. The thermoacoustic oscillation of the cryogenic distribution system is suppressed only through external excitation-self-excited oscillation dual sound source coupling or dual self-excited sound wave coupling. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0020] Figure 2 This is a schematic diagram of the control system of the present invention.

[0021] Figure 3 The oscillation state of the external excitation-self-excited coupling system when the driving frequency deviates from the self-excited frequency.

[0022] Figure 4 The oscillation state of the external excitation-self-excitation coupled system when the driving frequency is close to the self-excitation frequency.

[0023] Figure 5 This represents the oscillation state of a self-excited dual-coupled system.

[0024] Figure 6 This refers to the dynamic change of the phase difference in a self-excited dual-coupled system.

[0025] In the diagram: 1-Liquid supply pipe, 2-Distribution pipe, 3-Distribution branch pipe, 4-User end, 5-Phase adjustment structure, 6-Control system of the coupling oscillator. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to specific embodiments, but this is not intended to limit the present invention.

[0027] Reference Figure 1 The present invention realizes the structure for regulating the oscillation state of a low-temperature distribution system, comprising a low-temperature liquid supply pipe (1), a distribution pipe (2), a distribution branch pipe (3), and an oscillation phase adjustment structure (5). The supply pipe (1) for conveying low-temperature liquid is connected to one end of the distribution pipe (2), and multiple distribution branch pipes (3) on the distribution pipe (2) are respectively connected to a user end (4) at room temperature. The oscillation phase adjustment structure (5) of the system is installed at the distribution branch pipe (3), and a control system (6) of a coupled oscillator is used to regulate the system. The temperature of the distribution branch pipe (3) is nonlinearly distributed along the pipe axis, thereby causing pressure oscillation inside the pipe. The oscillation phase adjustment structure (5) adopts an external excitation control element or a self-coupling control element, and the self-excited oscillation inside the system is regulated by the control system (6) of the coupled oscillator.

[0028] The following specific embodiments will further illustrate the structure and method for controlling the oscillation state of the cryogenic distribution system according to the present invention.

[0029] Example 1

[0030] An external excitation generator is introduced at the ambient temperature end of a distribution branch pipe in a low-temperature distribution system. This external excitation generator uses an external sound source (such as a loudspeaker) to form the excitation sound source. The excitation sound source generated by the external excitation generator, together with the internal self-excited oscillation, forms an externally excited-self-excited oscillator. The ratio of the external excitation amplitude to the self-excited oscillation amplitude is less than 3.6%, and the ratio of the external excitation frequency to the self-excited oscillation frequency is 0.18, which deviates significantly from the self-excited oscillation frequency. The resulting oscillation state of the externally excited-self-excited oscillation dual-coupled oscillator is as follows: Figure 2 As shown, under the action of an external excitation sound source, the oscillation amplitude drops from 150 kPa to less than 0.5 kPa, significantly suppressing system oscillation.

[0031] Example 2

[0032] An external excitation generator is introduced at the ambient temperature end of a distribution branch pipe in a low-temperature distribution system. This external excitation generator uses an external sound source (loudspeaker) to create the excitation sound source. The excitation sound source generated by the external excitation generator, together with the internal self-excited oscillation, forms an externally excited-self-excited oscillator. The ratio of the external excitation amplitude to the self-excited oscillation amplitude is less than 3.6%, and the ratio of the external excitation frequency to the self-excited oscillation frequency is 1.06, close to the self-excited oscillation frequency. The resulting oscillation state of the externally excited-self-excited oscillation dual-coupled oscillator is as follows: Figure 3 As shown, under the action of an external excitation sound source, the oscillation amplitude decreased from 150 kPa to 12.5 kPa. The oscillation weakened but still maintained stable oscillation at the self-excited frequency.

[0033] Example 3

[0034] A regulating tube is introduced between two symmetrically distributed branches that internally induce self-excited oscillations. The regulating tube couples the self-excited waves to form a self-excited double-coupled oscillator. The regulating tube is 1 meter long, has an inner diameter of 0.5 mm, and its two ends are connected to the room temperature end and the low temperature end of the two symmetrically distributed branches, respectively. The resulting oscillation state of the self-excited double-coupled oscillator is as follows: Figure 4 As shown, the oscillation state of the distribution branch pipes, which are completely identical in oscillation state, changes from constant amplitude oscillation to random amplitude oscillation under the coupling effect of the regulating pipe, and as... Figure 5 As shown, the phase difference between the oscillating waves in the two distribution branches can reach up to 65°, and the phase modulation effect is obvious.

[0035] Comparison of results from different control examples shows that the structure and method for controlling the oscillation state of a cryogenic distribution system implemented in this invention can effectively suppress unfavorable pressure oscillations within the cryogenic distribution system. Moreover, the structure is simple, and the control based on the coupled oscillator does not affect the main structure of the distribution tube, resulting in reliable performance.

Claims

1. A structure for regulating the internal oscillation of a cryogenic distribution system, characterized in that, The system includes a supply pipe (1) for conveying cryogenic liquid, a distribution pipe (2) connected to the cryogenic supply pipe (1), a user terminal (4) at room temperature connected to multiple distribution branches (3) on the distribution pipe (2), an oscillation phase-tuning structure (5) installed on the distribution branch (3), and a control system (6) for controlling the system with a coupled oscillator. The temperature of the distribution branch (3) is nonlinearly distributed along the pipe axis, which causes pressure oscillation inside the pipe. The oscillation phase-tuning structure (5) uses an external excitation control element (5.1) or a self-coupling control element (5.2). The self-excited oscillation inside the system is controlled by the control system (6) with a coupled oscillator. In the external excitation control element (5.1) of the oscillation phase modulation structure (5), an external excitation generating device is introduced at the single distribution branch pipe. The external excitation generating device uses an external sound source to form an excitation sound source. The excitation sound source generated by the external excitation generating device and the internal self-excited oscillation form an external excitation-self-excited oscillation double-coupled oscillator. The oscillation state of the external excitation-self-excited oscillation double-coupled oscillator depends on the external excitation amplitude, external excitation frequency and external excitation phase. In the self-coupling control element (5.2) of the oscillation phase modulation structure (5), a regulating tube is introduced between two internally self-excited oscillation distribution branches. The regulating tube couples the two self-excited waves to form a self-coupling oscillator. The oscillation state of the self-coupling oscillator depends on the length, diameter and connection position of the regulating tube. The control system (6) includes: an oscillation parameter monitoring module, a spectrum analysis module, a coupling phase difference solving module, a data mining module, an evaluation feedback module, and an oscillator operation control module; The oscillation parameter monitoring module is used to monitor and collect the pressure oscillation sequence and amplitude of the self-excited or externally excited oscillator, and transmits the preprocessed data to the spectrum analysis module. The spectrum analysis module uses Fourier transform to analyze the oscillation frequency of the pressure oscillation sequence of the self-excited or externally excited oscillator, and transmits the analysis results to the data mining module. The coupling phase difference solving module is used to solve the envelope phase and instantaneous phase of the single oscillator pressure oscillation, thereby obtaining the dynamic phase difference of the coupled oscillator, and transmits the solution results to the data mining module. The data mining module analyzes the oscillation amplitude, frequency, and phase of the coupled oscillator based on Apriori correlation and PCA dimensionality reduction algorithms. The correlation and principal components between the position difference and the excitation amplitude, excitation frequency, and excitation phase of the externally excited oscillator, or with the length, diameter, and connection position of the phase-tuning tube of the self-excited oscillator, are obtained to obtain the correlation rules and the principal components affecting the oscillation state of the coupled oscillator, and are transmitted to the evaluation feedback module. The evaluation feedback module evaluates the correlation rules based on the oscillation state and determines the range of key control parameters, and feeds back the control strategy to the oscillator operation control module. Based on the feedback control strategy, the oscillator operation control module uses an adaptive controller to control the excitation amplitude, frequency, and phase of the externally excited oscillator, or uses an actuator to control the length, diameter, and connection position of the phase-tuning tube, thereby realizing the control of the oscillation state of the cryogenic system.

2. A method for controlling the oscillation of a cryogenic distribution system based on the structure described in claim 1, characterized in that, The following regulatory strategies are included: The external excitation amplitude and external excitation phase of the external excitation control element of the oscillation phase modulation structure (5) are smaller and the driving frequency deviates from the self-excitation frequency, making it easier to suppress the oscillation of the coupled system. The external excitation amplitude and external excitation phase of the external excitation control element of the oscillation phase modulation structure (5) are small and the driving frequency is close to the self-excitation frequency, which will weaken the oscillation and maintain it at the self-excitation frequency. The external excitation amplitude and external excitation frequency of the external excitation control element of the oscillation phase modulation structure (5) are large enough to lock the oscillation frequency of the coupling system to the external excitation frequency. If the external excitation amplitude and external excitation frequency of the external excitation control element of the oscillation phase modulation structure (5) are too small, the oscillation frequency of the coupling system will be locked at the self-excitation frequency. The regulating tubes of the self-coupling control element of the oscillation phase modulation structure (5) are all connected to the room temperature end, are short in length and have a large diameter, making it difficult to achieve the non-oscillation state of the self-coupling oscillator. The regulating tubes of the self-coupling control element of the oscillation phase modulation structure (5) are respectively connected to the room temperature end and the low temperature end, making it difficult to achieve the non-oscillation state of the self-coupling oscillator. The regulating tubes of the self-coupling control element of the oscillation phase modulation structure (5) are all connected to the low temperature end, have a long length and a small diameter, making it easier to achieve the non-oscillation state of the self-coupling oscillator.

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