A pressure fluctuation suppression energy dissipator and fluid-structure interaction optimization method for liquid hydrogen pipelines

Abstract

This invention provides a liquid hydrogen pipeline pressure fluctuation suppression energy dissipator and a fluid-structure interaction optimization method, relating to the field of liquid hydrogen storage and transportation safety technology. The energy dissipator adopts a modular integrated design, including a damping vibration reduction module, a gradient throttling module, and a pressure buffer module. The damping vibration reduction module has a corrugated damping inner wall combining spring damping and bellows; the gradient throttling module consists of multiple throttling plates with gradient-changing orifice parameters; the pressure buffer module is separated by an inert gas chamber and a liquid chamber containing a stored liquid layer by a gas-liquid separation membrane. Simultaneously, this invention proposes a corresponding fluid-structure interaction optimization method. By establishing a fluid-structure interaction model, the physical effects of the energy dissipator are abstracted into flow resistance, flow rate, and flow capacity parameters, solved using the method of characteristics, and the energy dissipation effect is verified by optimizing structural parameters. This invention achieves multi-structure synergistic energy dissipation, reducing liquid hydrogen pressure fluctuation amplitude by more than 40%, and is cryogenically resistant and compact, making it suitable for cryogenic liquid hydrogen transportation systems in the aerospace and energy fields.

Description

Technical Field

[0001] This invention relates to the field of liquid hydrogen storage and transportation safety technology, specifically to a liquid hydrogen pipeline pressure fluctuation suppression energy dissipator and a fluid-structure interaction optimization method. Background Technology

[0002] Liquid hydrogen, as a clean energy carrier with extremely high energy density, continues to see large-scale applications in aerospace propulsion, hydrogen transportation, and large-scale fuel cells. Liquid hydrogen storage relies on specialized storage tanks with cryogenic insulation. After being discharged from the tank outlet, the liquid hydrogen must be transported to downstream equipment via pipelines made of cryogenic alloys. During this process, the pressure stability of the liquid hydrogen within the pipeline directly determines the system's safety and operational efficiency; pressure fluctuations have become a core technological bottleneck for the practical application of the liquid hydrogen industry.

[0003] Existing liquid hydrogen storage tanks typically consist of an inner tank, an outer tank, a vacuum insulation jacket, an outlet assembly, and a transport pipeline. The transport pipeline, as the core channel for liquid hydrogen flow, is subject to multi-factor coupled disturbances to its internal flow field stability, primarily manifested in three key perturbations:

[0004] First, pressure imbalance is caused by flow resistance. When liquid hydrogen flows in a pipeline, it must overcome frictional resistance along the pipe and local resistance: frictional resistance originates from the viscosity between the liquid hydrogen and the pipe wall, causing the pressure to gradually decrease along the delivery direction; local resistance is concentrated at pipe bends, valves, and diameter changes, resulting in sudden drops in local pressure. The superposition of these two types of resistance causes the pressure distribution inside the pipe to exhibit a non-uniform characteristic of "gradual change + sudden change," especially at higher flow velocities, where pressure fluctuations are more pronounced.

[0005] Second, pipeline vibration caused by external excitations. Liquid hydrogen transport pipelines are susceptible to multiple external excitations in actual operation: First, the vibrations from pumps, compressors, and other equipment are transmitted to the pipeline through supports and flanges; second, environmental disturbances such as shock waves from space launch sites and bumps in vehicle systems directly alter the stress state of the pipeline; third, the switching of operating conditions caused by valve opening and closing and sudden changes in downstream hydrogen load leads to instantaneous fluctuations in liquid hydrogen flow velocity, forming an "inertial shock" in the pipeline. These external excitations cause pipeline vibration, further disturbing the flow field inside the pipe and exacerbating pressure fluctuations.

[0006] Third, the endogenous vibrations caused by gas-liquid two-phase flow and fluid-structure interaction. Liquid hydrogen has an extremely low boiling point and is exceptionally sensitive to thermal intrusion. Even minor damage to the pipe insulation or a temperature difference between the pipe wall and the liquid hydrogen can cause the liquid hydrogen near the wall to flash vaporize, forming a gas-liquid two-phase flow. When the gas content is within a specific range, the flow pattern easily transforms into slug flow or slug flow. The high-speed movement and periodic changes of the liquid plugs or bubbles can impact the pipe wall, triggering pressure pulses. Simultaneously, there is a strong fluid-structure interaction effect between the liquid hydrogen flow and the pipe structure: liquid hydrogen pressure fluctuations cause pipe wall deformation and alter the flow channel cross-section, while pipe vibrations disrupt the liquid hydrogen flow boundary layer, creating a vicious cycle of "vibration-flow field disturbance" that significantly exacerbates pressure fluctuations.

[0007] The pressure fluctuations caused by the combination of the above factors pose multidimensional hazards to the liquid hydrogen transportation system: First, they cause fatigue damage to bolts, welds, and other parts connecting the pipeline and the outlet of the storage tank, which can easily lead to sealing failure or pipeline rupture during long-term operation, increasing the risk of liquid hydrogen leakage; second, they cause an imbalance in the hydrogen supply pressure of downstream hydrogen-using equipment, affecting the operating efficiency of the equipment and even causing shutdown failures; third, they may induce the "hydrogen hammer effect," causing impact damage to pipelines, valves, and storage tanks, threatening system safety.

[0008] Currently, there are significant shortcomings in the industry's methods for controlling pressure fluctuations in liquid hydrogen pipelines: pipeline layout optimization can only alleviate some of the effects of flow resistance and cannot eliminate irregular pressure fluctuations caused by vibration; although buffer tanks can achieve pressure buffering, they are large in size, expensive, and have limited effect on suppressing high-frequency pressure fluctuations; pressure regulating valves have a delayed response in low-temperature environments and are difficult to adapt to instantaneous pressure changes during operating condition switching; traditional dampers mostly adopt a single energy dissipation structure, which is not adapted to the two-phase flow characteristics of liquid hydrogen, resulting in low energy dissipation efficiency and easy blockage problems.

[0009] In summary, existing technologies cannot simultaneously meet the requirements of "compact structure, rapid response, and efficient energy dissipation". There is an urgent need to develop a dedicated energy dissipation device for the outflow pipeline of liquid hydrogen storage tanks. Through innovative principles and structural design, pressure fluctuations caused by multi-source disturbances can be suppressed at the source, ensuring the safe and stable operation of the liquid hydrogen transportation system. Summary of the Invention

[0010] The purpose of this invention is to overcome at least one technical problem existing in the prior art and to provide a liquid hydrogen pipeline pressure fluctuation suppression energy dissipator and a fluid-structure interaction optimization method.

[0011] On one hand, this invention provides a pressure fluctuation suppression energy dissipator for liquid hydrogen pipelines. The energy dissipator is connected in series with the liquid hydrogen outflow pipeline. The energy dissipator includes: an energy dissipator shell, a damping and vibration reduction module, a gradient throttling module, and a pressure buffer module. The damping and vibration reduction module, the gradient throttling module, and the pressure buffer module are integrated inside the energy dissipator shell. The energy dissipator shell has inlet and outlet flow channels at both ends adapted to the liquid hydrogen outflow pipeline. The damping and vibration reduction module is a damping inner wall disposed on the inner sidewall of the energy dissipator shell. The damping inner wall adopts a combination of a spring damping structure and a bellows structure, forming an overall shape... The structure is wave-shaped; the gradient throttling module consists of multiple gradient throttling plates arranged inside the energy dissipator along the direction of liquid hydrogen flow. Throttling orifices are formed on the gradient throttling plates, and the orifice diameter and opening ratio of the orifices increase gradually along the direction of liquid hydrogen flow from the inlet / outlet channels to the central liquid cavity. The pressure buffer module includes a gas-liquid separation membrane, an inert gas cavity, and a liquid cavity. The gas-liquid separation membrane divides the interior of the energy dissipator shell into an inert gas cavity and a liquid cavity. The liquid cavity includes a main liquid cavity and a liquid storage layer, which are connected to the liquid storage layer through an opening in the liquid cavity. The inert gas cavity is filled with inert gas.

[0012] Furthermore, the spring damping structure in the damping inner wall consists of a low-temperature resistant elastic spring and an inner wall matrix, and the bellows structure is a metal tube structure with wavy pleats. The damping inner wall is used to dissipate the vibration energy of the pipeline through elastic deformation and damping when the liquid hydrogen flow causes pipeline vibration. The elastic spring absorbs the vibration mechanical energy through elastic expansion and contraction. At the same time, the wavy inner wall increases the friction resistance of liquid hydrogen to hinder the propagation of pressure waves and breaks up the bubbles generated by flash evaporation in the liquid hydrogen, reducing the impact of gas-liquid two-phase flow on pressure fluctuations.

[0013] Furthermore, the gradient throttling plate is used to block the propagation of sudden pressure changes caused by valve opening and closing and load changes through local flow resistance, while reducing the liquid hydrogen flow rate and breaking up bubbles to optimize flow field stability and prevent pressure fluctuations from being transmitted downstream.

[0014] Furthermore, the gas-liquid separator is a flexible component, with the inert gas cavity located on one side of the gas-liquid separator and the liquid cavity located on the other side. The pressure buffer module is used to push the gas-liquid separator towards the inert gas cavity when the liquid hydrogen pressure increases, compressing the inert gas stored inside the inert gas cavity and converting the pressure energy of the liquid hydrogen into the internal energy of the gas for storage. When the liquid hydrogen pressure decreases, the compressed inert gas expands, pushing the gas-liquid separator back to its original position and releasing the stored energy.

[0015] Furthermore, the liquid chamber is used to allow liquid hydrogen to flow into or out of the storage layer through the liquid chamber and the opening of the storage layer when the pressure changes drastically, directly absorbing or replenishing the liquid through volume changes, thus helping to buffer pressure fluctuations.

[0016] Secondly, the present invention provides a fluid-structure interaction optimization method for the above-mentioned energy dissipator, the method comprising: step S1, constructing a fluid-structure interaction physical model of the energy dissipator and the liquid hydrogen pipeline, wherein the fluid domain includes the mainstream liquid cavity, the liquid storage layer and the inlet and outlet channels of the energy dissipator inside the energy dissipator, and the solid domain includes the outer shell of the energy dissipator, the damping inner wall and the gradient throttling plate; step S2, using the lumped parameter equivalent method to equate the throttling and pressure reduction effect of the gradient throttling plate and the friction effect of the damping inner wall to flow resistance; equating the fluid inertial effect of the inlet and outlet channels of the energy dissipator, the mainstream liquid cavity and the liquid storage layer to flow flow; equating the gas compressibility energy storage effect of the inert gas cavity and the volume buffering effect of the mainstream liquid cavity and the liquid storage layer to flow capacity; step S3, using structural mechanics equations to describe the structural vibration characteristics and fluid dynamics control equations to describe the fluid wave characteristics, and through the fluid domain... The pre-set fluid-structure interaction boundary conditions at the connection with the solid domain combine the structural mechanics equations and the fluid dynamics control equations to obtain the fluid-structure interaction control equations; Step S4: The fluid-structure interaction control equations are transformed into ordinary differential equations along the characteristic lines using the characteristic line method; Step S5: A spatiotemporal discrete grid satisfying the CFL stability condition is established; Step S6: The ordinary differential equations obtained along the characteristic lines are discretized using the finite difference method to obtain the liquid hydrogen pressure data corresponding to each discrete grid; Step S7: Based on the liquid hydrogen pressure data corresponding to each discrete grid, the liquid hydrogen pressure fluctuation amplitude reduction rate is used as the energy dissipation effect evaluation index, and based on the influence of flow capacity, flow rate, and flow resistance on the energy dissipation effect, the wave shape parameters of the damping inner wall, the orifice gradient of the gradient throttling plate, the volume of the inert gas cavity, and the travel distance of the mainstream liquid cavity are optimized.

[0017] Furthermore, the mathematical expression for the flow resistance is:

[0018] ;

[0019] The mathematical expression for the flow capacity is:

[0020] ;

[0021] The mathematical expression for influenza is:

[0022] ;

[0023] In the formula, Flow resistance, unit: ; Fluid dynamic viscosity, in units of ; l is the length of the liquid hydrogen outflow pipe, in meters; d is the inner diameter of the liquid hydrogen outflow pipe, in meters; For flow capacity, the unit is 1. A represents the cross-sectional area of ​​the liquid hydrogen outflow pipe, in units of... ; Fluid density, in units of ;a represents the speed of sound, in units of ; It is influenza, and the unit is .

[0024] Furthermore, the fluid dynamics control equations include the fluid momentum equation considering the coupling terms of pipe axial vibration and the fluid continuity equation considering the coupling terms of pipe deformation; the structural mechanics equations include the pipe axial motion equation considering the fluid pressure excitation term and the pipe constitutive equation considering the coupling terms of fluid and structure velocity.

[0025] The fluid momentum equation is:

[0026] ;

[0027] The fluid continuity equation is:

[0028] ;

[0029] The equation for the axial motion of the pipeline is:

[0030] ;

[0031] The constitutive equation of the pipeline is:

[0032] ;

[0033] ;

[0034] ;

[0035] In the formula, the subscript f represents the fluid parameter, the subscript t represents the pipe parameter, and the subscript r represents the difference between the fluid physical quantity and the pipe physical quantity; Let be the acceleration due to gravity, and take . ; and These represent the axial velocities of the fluid and the pipe, respectively. The difference in speed between the two is expressed in m / s. The pressure head of the fluid is expressed in meters (m). This represents the axial stress of the pipe, expressed in Pa. and These are the densities of the fluid and the pipe material, respectively, in units of... ; and These are the cross-sectional areas of the fluid and the pipe, respectively, in units of... K is the bulk modulus of the fluid, measured in Pa. This refers to the elastic modulus of the pipe, expressed in Pa. This is the axial length, in meters (m). Time, in seconds; This is the inner radius of the pipe, in meters (m). The pipe wall thickness is expressed in meters (m). This is the friction resistance factor; Poisson's ratio; The angle between the pipeline axis and the horizontal plane is taken as the positive direction when the pipeline is lifted to a lower height. Pressure wave velocity; Stress wave velocity; For fixed-point acceleration.

[0036] Furthermore, the fluid-structure interaction boundary conditions include displacement compatibility conditions and pressure balance conditions; the displacement compatibility condition is that the radial or axial deformation of the pipe wall is compatible with the resulting change in the flow channel volume; the pressure balance condition is that the pressure pulsation of the fluid is an external excitation acting on the pipe wall structure.

[0037] Furthermore, the wave parameters of the damping inner wall include wave amplitude and wave wavelength. By changing the wave amplitude and wave wavelength, the flow resistance of liquid hydrogen is altered, thus affecting the flow resistance. Increasing the height of the inner wall protrusions / recesses and decreasing the spacing between adjacent protrusions / recesses enhances the disturbance in the liquid hydrogen flow process, resulting in increased flow resistance. The orifice gradient parameter of the gradient throttling plate is the rate of change of orifice diameter along the liquid hydrogen flow direction. Its influence on the energy dissipation effect is achieved by adjusting the flow resistance. The smaller the orifice size and the lower the orifice ratio, the greater the local resistance and the higher the flow resistance. The core parameter of the inert gas cavity is its volume. Its influence on the energy dissipation effect is achieved by adjusting the local flow capacity. The larger the volume, the greater the flow capacity of the gas cavity. The core parameter of the mainstream liquid cavity is its travel distance, which is the length of the flow path of liquid hydrogen from the inlet to the outlet in the liquid cavity. Its influence on the energy dissipation effect is achieved by adjusting the flow rate.

[0038] In another aspect, the present invention also provides a computer-readable storage medium storing one or more instructions for causing a computer to execute the above-described fluid-structure interaction optimization method for an energy dissipator.

[0039] In another aspect, the present invention provides an electronic device, comprising: a memory and a processor; the memory storing at least one program instruction; the processor loading and executing the at least one program instruction to implement the above-described fluid-structure interaction optimization method for energy dissipators.

[0040] Compared with the prior art, the beneficial effects of the present invention are:

[0041] (1) Multi-module coordinated energy dissipation with significant effect: The damping vibration reduction, gradient throttling and pressure buffer modules work together from three dimensions: vibration suppression, pressure blocking and energy absorption. They can reduce the fluctuation amplitude of liquid hydrogen pressure by more than 40%, and the peak hydrogen slugging pressure at valve closure can be reduced from 0.35MPa to 0.174MPa (reduction rate of 50.3%), while the peak hydrogen slugging pressure at valve opening can be reduced from 0.4MPa to 0.207MPa (reduction rate of 48.25%).

[0042] (2) Strong low temperature resistance and adaptability: Each structure uses low temperature resistant materials such as indium steel alloy, titanium alloy, and fluororubber, which meet the stability and compatibility requirements of liquid hydrogen ultra-low temperature (-253℃) environment, and solve the problem of performance failure of traditional energy dissipation devices in low temperature environment.

[0043] (3) Compact structure and wide adaptability: The modular integrated design makes the overall structure of the energy dissipator compact. The inlet and outlet flow channels can be adapted to liquid hydrogen outflow pipes of different specifications. It is convenient to install and maintain and is suitable for various cryogenic liquid hydrogen transportation systems in aerospace, energy and other fields.

[0044] (4) Accurate calculation method and support for optimization: The fluid-structure interaction calculation method realizes the accurate simulation of the interaction between pressure wave propagation and structural vibration through the characteristic line method. The calculation results are in agreement with the experimental data by more than 95%, which can effectively guide the optimization of energy dissipator structural parameters and ensure stable and reliable energy dissipation effect. Attached Figure Description

[0045] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0046] Figure 1 This is a schematic diagram of a liquid hydrogen pipeline pressure fluctuation suppression energy dissipator provided in Embodiment 1 of the present invention.

[0047] Figure 2 This is a schematic diagram of the structure of a liquid hydrogen transport system and the arrangement of the energy dissipator provided in Embodiment 1 of the present invention.

[0048] Figure 3 This is a flowchart of a fluid-structure interaction optimization method for an energy dissipator in Embodiment 1, provided in Embodiment 2 of the present invention.

[0049] Figure 4 This is a schematic diagram of the mesh generated by the fluid-structure interaction calculation method provided in Embodiment 2 of the present invention.

[0050] Figure 5a This is a schematic diagram of a valve-closing hydrogen blast experiment provided in Embodiment 2 of the present invention.

[0051] Figure 5b This is a schematic diagram of a valve-opening hydrogen blast experiment provided in Embodiment 2 of the present invention.

[0052] Figure 6a This is a schematic diagram of fluid pressure fluctuation at a measuring point for hydrogen blasting without an energy dissipator, provided in Embodiment 2 of the present invention.

[0053] Figure 6b This is a schematic diagram of fluid pressure fluctuation at a measuring point when a hydrogen blast occurs with a valve closed, provided in Embodiment 2 of the present invention.

[0054] Figure 6c This is a schematic diagram of the fluid pressure fluctuation at the measuring point when the valve is open for hydrogen blasting without an energy dissipator, provided in Embodiment 2 of the present invention.

[0055] Figure 6d This is a schematic diagram of the fluid pressure fluctuation at the measuring point when a valve is opened for hydrogen blasting, provided in Embodiment 2 of the present invention.

[0056] Figure 7 This is a partial block diagram of the electronic device provided in Embodiment 4 of the present invention.

[0057] The attached figures are labeled as follows:

[0058] 1. Liquid hydrogen storage tank outer shell; 2. Vacuum jacket; 3. Insulation layer; 4. Internal support structure; 5. Inner liner; 6. Hydrogen distribution layer; 7. Liquid hydrogen layer; 8. Liquid hydrogen outflow pipe; 9. Regulating valve; 10. Outflow pipe support; 11. Energy dissipator; 12. External support structure; 13. Energy dissipator inlet and outlet channels; 14. Energy dissipator outer shell; 15. Inert gas chamber; 16. Gas-liquid separation membrane; 17. Liquid chamber and accumulator opening; 18. Accumulator; 19. Damping inner wall (spring damping + bellows); 20. Gradient throttling plate; 21. Main liquid chamber; 22. Pressure measuring point; 23. Valve; 24. Sealing flange. Detailed Implementation

[0059] Before discussing the exemplary embodiments in more detail, it should be noted that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although the flowcharts describe the operations as sequential processes, many of these operations can be performed in parallel, concurrently, or simultaneously. Furthermore, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but may also have additional steps not included in the figures. The process can correspond to a method, function, procedure, subroutine, subroutine, etc.

[0060] It should be understood that although the terms "first," "second," etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are used merely to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, a first unit may be referred to as a second unit, and similarly, a second unit may be referred to as a first unit. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0061] The present invention will now be described in detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0062] Example 1

[0063] To facilitate understanding, the inventive concept is described in its entirety before detailing the embodiments of the invention: The core of the invention lies in the division of labor and cooperation of three modules: Module 1, Damping Vibration Reduction Module (Vibration Control, Gas Control): Structure: A wave-shaped inner wall composed of spring damping and bellows. Functions: Consumes mechanical energy: Utilizes the friction of spring damping and the elastic deformation of the bellows to rapidly attenuate pipeline vibration. Breaks bubbles: The wave-shaped uneven wall shears and breaks bubbles in liquid hydrogen, homogenizing the flow field and reducing pressure pulses caused by gas-liquid two-phase flow from the source. Increases flow resistance: The wave structure increases friction resistance along the flow path, consuming pressure wave energy. Module 2, Gradient Throttling Module (Pressure Control): Structure: Multiple throttling plates with increasing orifice parameters (aperture diameter, orifice ratio). Functions: Staged energy dissipation: Decomposes a large pressure surge into multiple small, stepped pressure drops, avoiding excessive local pressure drops that could trigger new fluctuations. Synergistic gas control: Works in conjunction with the damping inner wall to further break and homogenize bubbles. Provides controllable flow resistance: By designing gradients, the flow resistance distribution inside the energy dissipator is precisely controlled. Module 3, Pressure Buffer Module (Pressure Stabilization): Structure: Gas-liquid separation membrane + inert gas chamber + liquid storage layer. Function: Energy absorption and release: Utilizing the compressibility of inert gas, it compresses and stores energy at high pressures and expands and releases energy at low pressures, smoothing pressure fluctuations like a "breathing lung." Volumetric buffering: The liquid storage layer provides additional volume compensation through the inflow and outflow of liquid, further enhancing the buffering effect. Coordinated process of the three modules: When a pressure wave enters the energy dissipator, it is first "peak-cutting" and decomposed by the gradient throttling plate. Simultaneously, part of the wave energy is consumed as heat by the damping inner wall and breaks up bubbles that may exacerbate the fluctuations. The remaining pressure fluctuation energy is absorbed by the pressure buffer module. The compression and expansion of the gas convert the kinetic / pressure energy of the fluctuations into internal energy, ultimately stabilizing the pressure at the outlet.

[0064] Furthermore, this invention is not only a product but also a design methodology. The fluid-structure interaction (FSI) computational method is a key enabling technology for realizing the above concepts. Specifically, it includes: 1. Precise Modeling: It establishes a mathematical model that accurately reflects the interaction between liquid hydrogen and the energy dissipator structure, overcoming the shortcomings of traditional design software that ignores FSI or oversimplifies it. 2. Physical Abstraction: It abstracts complex physical structures (wave-like shapes, throttling plates, gas cavities) into three basic parameters in a fluid network: flow resistance, flow volume, and flow capacity, providing engineers with an intuitive design language and optimization levers. 3. Directional Optimization: Through this method, it is clearly known that: increasing the wave amplitude of the damping inner wall → increasing flow resistance → enhancing energy dissipation; decreasing the initial opening ratio of the throttling plate → increasing flow resistance → enhancing throttling effect; increasing the gas cavity volume → increasing flow capacity → enhancing buffering capacity; lengthening the liquid cavity flow channel → increasing flow volume → enhancing inertial flow stabilization. 4. Effect Prediction and Verification: By simulating extreme conditions such as "valve shut-off water hammer" on a computer, the optimal structural design parameters can be found on the computer before manufacturing an expensive physical prototype.

[0065] The specific implementation method is as follows:

[0066] like Figure 1 The diagram shown is a schematic of a liquid hydrogen pipeline pressure fluctuation suppression energy dissipator provided by the present invention.

[0067] As an example, the energy dissipator is connected in series with the liquid hydrogen outflow pipe. The energy dissipator comprises: an energy dissipator housing 14, a damping and vibration reduction module, a gradient throttling module, and a pressure buffer module. The damping and vibration reduction module, the gradient throttling module, and the pressure buffer module are integrated inside the energy dissipator housing 14. Both ends of the energy dissipator housing 14 are provided with connections to the liquid hydrogen outflow pipe 8 (connected to...). Figure 2 The energy dissipator inlet and outlet channels 13 are adapted to the energy dissipator; the damping and vibration reduction module is a damping inner wall 19 set on the inner side wall of the energy dissipator shell 14. The damping inner wall 19 adopts a combination of spring damping structure and bellows structure, and the whole is wave-shaped; the gradient throttling module is a number of gradient throttling plates 20 arranged inside the energy dissipator along the liquid hydrogen flow direction. Throttling holes are opened on the gradient throttling plates 20. The aperture and opening ratio of the throttling holes increase in a gradient along the direction of liquid hydrogen flow from the inlet and outlet channels 13 to the middle liquid cavity; the pressure buffer module includes a gas-liquid separation membrane 16, an inert gas cavity 15 and a liquid cavity. The gas-liquid separation membrane 16 divides the inside of the energy dissipator shell 14 into an inert gas cavity 15 and a liquid cavity. The liquid cavity includes a main liquid cavity 21 and a liquid storage layer 18. The main liquid cavity 21 and the liquid storage layer 18 are connected through the liquid cavity and the liquid storage layer opening 17; the inert gas cavity 15 is filled with inert gas.

[0068] Preferably, the spring damping structure in the damping inner wall 19 is composed of a low-temperature resistant elastic spring and an inner wall matrix, and the bellows structure is a metal tube structure with wavy pleats. The damping inner wall 19 is used to consume the vibration energy of the pipeline through elastic deformation and damping when the liquid hydrogen flow causes pipeline vibration. The elastic spring absorbs the vibration mechanical energy through elastic expansion and contraction. At the same time, the wavy inner wall increases the friction resistance of liquid hydrogen to hinder the propagation of pressure waves and breaks up the bubbles generated by flash evaporation in the liquid hydrogen, reducing the influence of gas-liquid two-phase flow on pressure fluctuations. Specifically, the damping and vibration reduction module is a wave-shaped damping inner wall set on the inner side wall of the energy dissipator shell, which is composed of a spring damping structure and a bellows structure; the spring damping structure includes a low-temperature resistant indium steel alloy elastic spring (e.g., wire diameter 0.8-1.2mm, free length 5-8mm, stiffness coefficient 15-25N / mm) and a stainless steel alloy inner wall substrate (e.g., thickness 3-5mm); the bellows is a wave-shaped pleated metal tube made of titanium alloy (e.g., pleat height 3-5mm, pleat spacing 8-12mm, and expansion and contraction up to 5%-8% of its own length). When this module is in operation, if the flow of liquid hydrogen causes pipe vibration, the spring dissipates the vibration energy through its elastic deformation and damping effect. The corrugated structure of the bellows absorbs the mechanical energy generated by the vibration through its elastic expansion and contraction. Simultaneously, the corrugated inner wall increases friction resistance, hindering pressure propagation and reducing pressure transmission during transient water hammer. This effectively attenuates the vibration amplitude of the pipe, reduces the disturbance of the liquid hydrogen flow field, and prevents pressure fluctuations from being exacerbated by vibration. Furthermore, the uneven inner wall can break up and homogenize any bubbles that may exist in the liquid hydrogen, reducing the impact of the gas-liquid two-phase flow on pressure fluctuations.

[0069] Preferably, the gradient throttling plate 20 is used to block the propagation of sudden pressure changes caused by valve opening and closing and load abrupt changes through local flow resistance, while reducing the liquid hydrogen flow rate and secondary breaking up bubbles to optimize flow field stability and prevent pressure fluctuations from being transmitted downstream. Specifically, multiple gradient throttling plates are arranged sequentially along the liquid hydrogen flow direction inside the energy dissipator. The throttling orifice parameters (such as orifice diameter, opening ratio, etc.) on the throttling plate change in a gradient along the liquid hydrogen flow direction. For example, from the two inlets and outlets to the middle liquid cavity opening, the orifice diameter gradually increases and the opening ratio gradually increases. The throttling plate is made of a low-temperature resistant and liquid hydrogen-compatible metal material (such as stainless steel). When liquid hydrogen flows through the gradient throttling plate, the gradient throttling plate acts as a local flow resistance, thereby effectively hindering the pressure propagation caused by sudden changes; at the same time, the multi-stage gradient throttling structure can also break up and homogenize any bubbles that may exist in the liquid hydrogen, reducing the impact of gas-liquid two-phase flow on pressure fluctuations. More specifically, the gradient throttling module consists of multiple stainless steel gradient throttling plates arranged inside the energy dissipator along the liquid hydrogen flow direction. The surface is treated with chrome plating for wear resistance (e.g., chrome plating thickness 5-10 μm, hardness ≥ HV800). The parameters of the throttling orifices on the throttling plates change in a gradient along the direction of "energy dissipator inlet / outlet flow channel → intermediate liquid chamber." Taking a throttling plate adapted to a DN50 pipe as an example, the first throttling plate has an orifice diameter of 5 mm and an opening ratio of 15%, the second has an orifice diameter of 8 mm and an opening ratio of 25%, and the third has an orifice diameter of 12 mm and an opening ratio of 35%. The spacing between adjacent throttling plates is 5-15 mm, gradually increasing along the liquid hydrogen flow direction. This module blocks the propagation of sudden pressure changes caused by valve opening / closing and load mutations through local flow resistance, while simultaneously reducing the liquid hydrogen flow velocity (from 2-3 m / s at the inlet to 0.5-1 m / s in the intermediate liquid chamber), and secondary breaking up of bubbles to optimize flow field stability and prevent pressure fluctuations from being transmitted downstream.

[0070] Preferably, the gas-liquid separator 16 is a flexible component, the inert gas cavity 15 is located on one side of the gas-liquid separator 16, and the liquid cavity is located on the other side of the gas-liquid separator 16; the pressure buffer module is used to push the gas-liquid separator 16 to bulge towards the inert gas cavity 15 when the liquid hydrogen pressure increases, compressing the inert gas stored inside the inert gas cavity 15, and converting the pressure energy of the liquid hydrogen into the internal energy of the gas for storage; when the liquid hydrogen pressure decreases, the compressed inert gas expands, pushing the gas-liquid separator 16 back to its original position, releasing the stored energy.

[0071] Preferably, the internal space of the energy dissipator is divided into an inert gas chamber and a liquid chamber by a gas-liquid separator membrane. The gas-liquid separator membrane is made of a low-temperature resistant, elastic material compatible with liquid hydrogen and inert gases (such as fluororubber membrane), possessing good elasticity and sealing properties. The liquid chamber contains the flowing liquid hydrogen, while the inert gas chamber is filled with an inert gas (such as helium). When the liquid hydrogen pressure fluctuates, the gas-liquid separator membrane undergoes elastic deformation, and the volume of the inert gas chamber changes accordingly. The compressibility of the inert gas absorbs the pressure fluctuation energy, achieving buffering and stabilization of the liquid hydrogen pressure, preventing rapid pressure changes from being transmitted to downstream pipelines. The inert gas chamber is a cavity within the energy dissipator separated by the gas-liquid separator membrane and filled with inert gas. The selection of the inert gas must consider compatibility with the gas-liquid separator membrane and stability in the cryogenic environment of liquid hydrogen; helium is a suitable choice. When liquid hydrogen pressure fluctuates, the inert gas chamber absorbs the energy of the pressure fluctuation through the compression or expansion of the gas, combined with the elastic deformation of the gas-liquid separator, thus acting as a pressure buffer and keeping the liquid hydrogen pressure in the liquid chamber relatively stable. The liquid chamber is the cavity within the energy dissipator used for liquid hydrogen flow. Liquid hydrogen enters the liquid chamber from the inlet, passes through a gradient throttling plate, and contacts the spring-damped inner wall (or bellows), before finally flowing out from the outlet. Within the liquid chamber, the pressure fluctuations of liquid hydrogen are stabilized by multiple factors, including the flow stabilization effect of the gradient throttling plate, the vibration reduction effect of the spring-damped inner wall (or bellows), and the buffering effect of the gas-liquid separator and the inert gas chamber, thereby achieving pressure stability.

[0072] Specifically, the inert gas chamber 15 is filled with helium or nitrogen gas, with an initial filling pressure of 0.3-0.8 MPa, and a pressure compensation port may be provided at the top of the inert gas chamber 15. The volume of the liquid storage layer 18 is 15%-30% of the volume of the main liquid chamber 21, and the flow area between the liquid chamber and the opening 17 of the liquid storage layer is 1-3 times the minimum opening area of ​​the throttling plate.

[0073] Preferred, combined Figure 2As shown, liquid hydrogen is stored in the inner liner 5 of the liquid hydrogen storage tank. The liquid hydrogen layer 7 occupies the lower space of the inner liner 5 and is used to store liquid hydrogen. The hydrogen distribution layer 6 is located in the upper part of the inner liner 5 and retains hydrogen gas. The liquid hydrogen storage tank adopts a composite structure of a liquid hydrogen storage tank shell 1, a vacuum jacket 2, and an insulation layer 3. The vacuum jacket 2 can effectively reduce heat conduction, and the insulation layer 3 further hinders heat transfer, ensuring the ultra-low temperature insulation performance of the storage tank. The internal support structure 4 supports the inner liner 5, while the external support structure 12 ensures the overall stability of the liquid hydrogen storage tank, enabling it to safely withstand the internal liquid hydrogen pressure and the influence of the external environment. Liquid hydrogen flows out through the liquid hydrogen outflow pipe 8. The regulating valve 9 installed on the pipe can accurately control the outflow rate of liquid hydrogen according to the downstream hydrogen demand. The outflow pipe support 10 supports the liquid hydrogen outflow pipe 8 to prevent the pipe from deforming or vibrating due to the gravity and flow impact of liquid hydrogen. The energy dissipator 11 is installed on the liquid hydrogen outflow pipe 8 and is the core device for suppressing liquid hydrogen pressure fluctuations.

[0074] Specifically, the energy dissipator shell adopts a double-layer insulation structure, with the inner layer being a stainless steel alloy (e.g., thickness 4mm, yield strength ≥205MPa) and the outer layer being a 6061 aluminum alloy (e.g., thickness 3mm, thermal conductivity ≤120W / ( The two layers are filled with ultra-fine glass wool insulation material (such as density 40kg / m³, thermal conductivity ≤0.03W / ( Furthermore, the interlayer is evacuated to a vacuum level ≤ It can effectively block the intrusion of external heat and prevent liquid hydrogen from exacerbating pressure fluctuations due to heat absorption and flash evaporation.

[0075] The above embodiments utilize the synergistic effect of a spring-damped inner wall (or bellows), a gradient throttling plate, a gas-liquid separation membrane, and an inert gas chamber to suppress liquid hydrogen pressure fluctuations from multiple aspects, including vibration reduction, flow stabilization, and buffering, resulting in significant energy dissipation. All materials used in each structure have undergone screening for low-temperature resistance and compatibility with liquid hydrogen, ensuring stable operation in ultra-low temperature environments and solving the problem of unstable performance of traditional energy dissipation devices at low temperatures. The high integration of each structure results in a compact overall structure, facilitating installation and maintenance. It can adapt to different specifications of liquid hydrogen outflow pipes, exhibiting wide applicability, while the synergistic operation of each structure ensures the reliability of the energy dissipator.

[0076] Example 2

[0077] Please see Figure 3 This embodiment provides a flowchart of a fluid-structure interaction optimization method for the energy dissipator described in Embodiment 1.

[0078] As an example, the method is applied to the energy dissipator described in Embodiment 1, and the method includes:

[0079] Step S1: Construct a fluid-structure interaction physical model of the energy dissipator and the liquid hydrogen pipeline. The fluid domain includes the main liquid cavity 21, the liquid storage layer 18, and the inlet and outlet channels 13 inside the energy dissipator. The solid domain includes the outer shell 14, the damping inner wall 19, and the gradient throttling plate 20. Step S2: Use the lumped parameter equivalent method to equate the throttling and pressure reduction effect of the gradient throttling plate 20 and the friction effect of the damping inner wall 19 to flow resistance. Equate the fluid inertial effect of the inlet and outlet channels 13, the main liquid cavity 21, and the liquid storage layer 18 to flow flow. Equate the gas compressibility energy storage effect of the inert gas cavity 15 and the volume buffering effect of the main liquid cavity 21 and the liquid storage layer 18 to flow capacity. Step S3: Use structural mechanics equations to describe the structural vibration characteristics and fluid dynamics control equations to describe the fluid wave characteristics. Preset the connection between the fluid domain and the solid domain. The fluid-structure interaction boundary conditions combine the structural mechanics equations and the fluid dynamics control equations to obtain the fluid-structure interaction control equations; Step S4: The fluid-structure interaction control equations are transformed into ordinary differential equations along the characteristic lines using the characteristic line method; Step S5: A spatiotemporal discrete grid that satisfies the CFL stability condition is established; Step S6: The ordinary differential equations obtained along the characteristic lines are discretized using the finite difference method to obtain the liquid hydrogen pressure data corresponding to each discrete grid; Step S7: Based on the liquid hydrogen pressure data corresponding to each discrete grid, the liquid hydrogen pressure fluctuation amplitude reduction rate is used as the energy dissipation effect evaluation index, and based on the influence of flow capacity, flow rate and flow resistance on the energy dissipation effect, the wave shape parameters of the damping inner wall 19, the opening gradient of the gradient throttling plate 20, the volume of the inert gas cavity 15 and the travel distance of the mainstream liquid cavity 21 are optimized.

[0080] Preferably, before explaining the fluid-structure interaction (FSI) optimization method in detail, the significance of this method is briefly explained here: Pipelines are widely used in aerospace, nuclear power, petrochemical, and other fields, often transporting high-pressure or cryogenic fluids. During operation, fluid pulsation, valve switching, and pump start-up and shutdown can all cause pressure and velocity disturbances. These disturbances interact with the structural vibration of the pipeline, generating fluid-structure interaction vibrations. In aerospace propellant pipelines, coupled vibrations can lead to pressure wave amplification, seal failure, and even resonance accidents. Therefore, studying the fluid-structure interaction vibration characteristics of pipelines is of great significance for verifying the energy dissipation effect of energy dissipators. The core objective of this method is to accurately predict and verify the effect of the designed energy dissipator in suppressing pressure fluctuations under real-world operating conditions through computer simulation. It overcomes the limitations of traditional designs that only consider the fluid or only the structure, neglecting the interaction between the two. The reason for employing fluid-structure interaction (FSI) analysis is that in a liquid hydrogen pipeline, there is a strong interaction between the fluid (liquid hydrogen) and the solid (pipeline and energy dissipator structure). This interaction includes: fluid influencing structure: pressure fluctuations in liquid hydrogen act on the pipe walls and internal components (such as throttling plates and damping inner walls), causing deformation or vibration. Structure influencing fluid: vibrations in the pipeline and energy dissipator structure, in turn, alter the shape and volume of the flow channel, affecting the flow state of liquid hydrogen and thus changing the propagation of pressure waves. This interdependent interaction is known as fluid-structure interaction. Ignoring it will lead to calculation results that deviate significantly from reality, making it impossible to accurately assess the performance of the energy dissipator.

[0081] Fluid-structure interaction in pipelines is typically represented by a set of partial differential equations (PDEs): continuity and momentum equations from the fluid, elastic dynamics equations from the pipe wall, and the two coupled through boundary conditions. These equations are often hyperbolic partial differential equations (wave equations), which are difficult to solve directly. Therefore, the method of characteristics (MOC) is often used in numerical calculations for transformation and discretization. The core idea of ​​the method of characteristics is to find paths in the PDEs that degenerate the equations into ordinary differential equations (ODEs). These paths are the characteristic lines. On the characteristic lines, the partial derivative relations are simplified to ordinary differential relations, which can be solved by integration along the characteristic lines. In numerical implementation, it is first necessary to establish a discrete grid that meets the stability conditions in the spatial and temporal domains. Typically, the time step and spatial step are required to satisfy the CFL condition to ensure that the numerical propagation is consistent with the physical wave velocity. Subsequently, the continuity and momentum equations of the fluid within the pipe are integrated along the characteristic lines, transforming the original partial differential forms into ordinary differential relationships. These are then approximated using finite difference methods to discretize the equations into algebraic equations, enabling the recursive calculation of instantaneous values ​​of variables such as pressure and velocity at each intersection of the characteristic lines. For fluid-structure interaction (FSI) cases, the deformation or velocity of the pipe wall is introduced as an additional boundary condition into the fluid equations, while the pressure disturbance of the fluid simultaneously acts on the structural equations as an external excitation. These two types of equations are coupled and solved through interface conditions over time. Ultimately, this method can iteratively advance in the time domain, accurately capturing the propagation, reflection, and interaction processes of fluid pressure waves and structural vibrations within the piping system.

[0082] Preferably, the mathematical expression for the flow resistance is:

[0083] ;

[0084] The mathematical expression for the flow capacity is:

[0085] ;

[0086] The mathematical expression for influenza is:

[0087] ;

[0088] In the formula, Flow resistance, unit: ; Fluid dynamic viscosity, in units of ; l is the length of the liquid hydrogen outflow pipe, in meters; d is the inner diameter of the liquid hydrogen outflow pipe, in meters; For flow capacity, the unit is 1. A represents the cross-sectional area of ​​the liquid hydrogen outflow pipe, in units of... ; Fluid density, in units of ;a represents the speed of sound, in units of ; It is influenza, and the unit is .

[0089] Specifically, before performing detailed calculations, this embodiment employs a clever simplification approach, equating the complex distributed parameter system to a familiar circuit network concept to facilitate rapid analysis and understanding:

[0090] Flow resistance is the energy loss of a fluid due to pressure drop caused by viscous forces. Generally, the pressure drop of a fluid component is related to the flow rate through it, and is usually expressed as volumetric flow rate: ;

[0091] Similar to the definition of resistance, the ratio of the pressure drop across a fluid component to the flow rate through the component under steady flow is defined as flow resistance, i.e.: ;

[0092] In the formula, Pressure loss, unit: Pa; For flow rate, the unit is... K is the characteristic constant of flow resistance; n is the characteristic exponent of flow resistance. The definition of flow resistance in the formula is essentially the steady-state flow resistance under steady flow conditions. Whether it can be directly applied to AC fluid networks needs further discussion and analysis. It can be seen that when n=1, and A linear relationship exists, known as linear flow resistance. In this case, the flow resistance is a constant independent of the flow rate, and its value is equal under both static and dynamic conditions. This can be directly applied to AC fluid networks. Laminar flow circular pipes belong to this category. The flow resistance of a laminar flow circular pipe can be obtained from Poisson's law: ;

[0093] In the formula, Flow resistance, unit: ; Fluid dynamic viscosity, in units of l represents the pipe length in meters (m); d represents the pipe inner diameter in meters (m).

[0094] Because fluids are compressible, an increase in pressure within a container causes an increase in the mass of the fluid, leading to mass accumulation. This is similar to how a capacitor in a circuit accumulates charge, converting potential energy into kinetic energy and storing it. If volumetric flow rate is equivalent to current, the flow capacity is defined as the ratio of the change in fluid volume to the change in pressure that caused it, i.e.: ;

[0095] In the formula, For flow capacity, the unit is 1. V represents the fluid volume, in units of... t represents time, measured in seconds (s).

[0096] For liquids, their compressibility only becomes apparent under relatively high pressures, and is usually represented by the bulk modulus K. It is defined as the ratio of the change in pressure to the relative change in volume, i.e.: ;

[0097] In the formula, K is the bulk modulus, and the unit is Pa.

[0098] According to the above definition, the fluid capacity of a liquid can be described as the ratio between the volume change and the pressure change that causes that change, i.e.: ;

[0099] In liquid pipelines, there is a certain relationship between the bulk modulus of elasticity and the propagation speed of small disturbance waves, i.e., the speed of sound. The speed of sound in a fluid is a crucial parameter in the dynamic analysis of a transport system. It is related not only to the physical properties of the fluid itself but also to the geometry of the pipeline, the mechanical properties of the materials, and the structural support method. In applications, it is treated as a constant and can be obtained through: Calculations show that the fluid capacity of the liquid at this point can also be expressed as: ;

[0100] In the formula, A is the cross-sectional area of ​​the pipe, in units of... ; Fluid density, in units of ;a represents the speed of sound, in units of .

[0101] Under inertia, the acceleration or deceleration of fluid mass causes pressure changes, similar to the self-induced electromotive force generated by inductance in a circuit network, converting potential energy (pressure energy) into kinetic energy and storing it. If the volumetric flow rate is equivalent to current, the flow rate can be defined as the ratio of the pressure change to the rate of change of flow rate across the pipe, i.e.: ;

[0102] In the formula, It is influenza, and the unit is .

[0103] Fluids accelerate or decelerate due to inertia, causing pressure changes. This phenomenon can be described by the relationship between the force causing the fluid's motion and the change in velocity, namely:

[0104] ;

[0105] Then, from the definition of influenza, we obtain the formula for calculating tubal influenza:

[0106] ;

[0107] ;

[0108] In the formula, u is the velocity of the fluid, with units of m / s.

[0109] In the subsequent optimization of the energy dissipator's structural parameters, the optimization was guided by the principles of avoiding excessive flow resistance leading to a sudden drop in local pressure, avoiding excessively small flow volume leading to flow control failure, and avoiding insufficient buffering due to insufficient flow capacity.

[0110] Preferably, the fluid dynamics control equations in step S3 include the fluid momentum equation considering the coupling terms of pipe axial vibration and the fluid continuity equation considering the coupling terms of pipe deformation; the structural mechanics equations include the pipe axial motion equation considering the fluid pressure excitation term and the pipe constitutive equation considering the coupling terms of fluid and structural velocity.

[0111] The fluid momentum equation is:

[0112] ;

[0113] The fluid continuity equation is:

[0114] ;

[0115] The equation for the axial motion of the pipeline is:

[0116] ;

[0117] The constitutive equation of the pipeline is:

[0118] ;

[0119] ;

[0120] ;

[0121] In the formula, the subscript f represents the fluid parameter, the subscript t represents the pipe parameter, and the subscript r represents the difference between the fluid physical quantity and the pipe physical quantity; Let be the acceleration due to gravity, and take . ; and These represent the axial velocities of the fluid and the pipe, respectively. The difference in speed between the two is expressed in m / s. The pressure head of the fluid is expressed in meters (m). This represents the axial stress of the pipe, expressed in Pa. and These are the densities of the fluid and the pipe material, respectively, in units of... ; and These are the cross-sectional areas of the fluid and the pipe, respectively, in units of... K is the bulk modulus of the fluid, measured in Pa. This refers to the elastic modulus of the pipe, expressed in Pa. This is the axial length, in meters (m). Time, in seconds; This is the inner radius of the pipe, in meters (m). The pipe wall thickness is expressed in meters (m). This is the friction resistance factor; Poisson's ratio; The angle between the pipeline axis and the horizontal plane is taken as the positive direction when the pipeline is lifted to a lower height. Pressure wave velocity; Stress wave velocity; For fixed-point acceleration.

[0122] Preferably, since directly solving this complex set of partial differential equations is almost impossible, this embodiment employs the method of characteristics, a powerful mathematical tool for transforming partial differential equations into ordinary differential equations. Therefore, step S4, transforming the fluid-structure interaction control equations into ordinary differential equations along characteristic lines using the method of characteristics, includes: the method of characteristics is a unique method for solving initial-boundary value problems of hyperbolic partial differential equations, possessing high computational accuracy and being the most accurate among various finite difference numerical calculations; solving the equations using the method of characteristics, and rewriting the fluid-structure interaction four-equation model in matrix form:

[0123] ;

[0124] In the formula, and It is a coefficient matrix. , For a 1×4 dimensional vector, its expression is:

[0125] ;

[0126] ;

[0127] ;

[0128] ;

[0129] .

[0130] Characteristic equation There are 4 distinct real roots: the propagation speed of pressure waves and the propagation speed of water hammer waves.

[0131] ;

[0132] ;

[0133] ;

[0134] ;

[0135] in,

[0136] ;

[0137] Using the method of characteristics, the system of equations can be transformed into four ordinary differential equations for solution. Figure 4 feature lines , , , The above compatibility equation holds, as shown below:

[0138] ;

[0139] ;

[0140] ;

[0141] ;

[0142] In the formula, the slope coefficient of the characteristic line ( , , , , , , , ) and margin ( , The corresponding physical quantity expression is:

[0143] ;

[0144] ;

[0145] ;

[0146] ;

[0147] ;

[0148] ;

[0149] ;

[0150] ;

[0151] ;

[0152] .

[0153] Preferably, in the process of numerically solving the compatibility equation, step S5 involves establishing a spatiotemporal discrete grid that satisfies the CFL stability condition; step S6 involves discretizing the ordinary differential equation obtained along the characteristic line using the finite difference method to obtain the liquid hydrogen pressure data corresponding to each discrete grid, including:

[0154] Discretization and Solution: Combination Figure 4 As shown, mesh generation: The pipes and energy dissipators are divided into several small segments (grids) in space and several small steps in time. CFL condition: To ensure computational stability, the time step and spatial step must satisfy the Courant-Friedrich-Lévy condition, that is, the distance the physical wave travels in one time step cannot exceed one spatial step. Finite difference: The compatibility equations obtained on the characteristic lines are discretized using the finite difference method, approximating a set of algebraic equations. Time progression: Starting from the initial state, using these algebraic equations, the fluid pressure (based on H), fluid velocity (V), and pipe stress (H) at each grid point in the next time step can be calculated. The system's dynamic evolution over time can be simulated by iterating through the pipeline velocity (U) and the pipeline speed (U).

[0155] Specifically, based on the definitions and expressions of flow resistance, flow capacity, and flow rate in the above embodiments, by optimizing the wave-shaped parameters of the damping inner wall 19, the orifice gradient of the gradient throttling plate 20, the volume of the inert gas chamber 15, and the travel distance of the mainstream liquid chamber 21, the energy dissipation effect can be adjusted by changing the values ​​of flow resistance, flow capacity, and flow rate. Some of the influencing mechanisms are as follows:

[0156] The damping inner wall 19 is a wave-shaped structure combining spring damping and a bellows. Its core wave-shaped parameters include wave amplitude (maximum height of the inner wall protrusions / recesses) and wave wavelength (distance between adjacent protrusions / recesses). These parameters affect flow resistance by changing the resistance to liquid hydrogen flow. Increased height of the inner wall protrusions / recesses and decreased distance between adjacent protrusions / recesses enhance the disturbance in the liquid hydrogen flow process, directly leading to boundary layer disruption, increased turbulence, and strengthened viscous friction. This increases flow resistance, more effectively hindering pressure wave propagation and consuming the energy of pressure fluctuations.

[0157] The core orifice gradient parameter of the gradient throttling plate 20 refers to the rate of change of orifice diameter along the liquid hydrogen flow direction (the ratio of the difference in orifice diameter from d1 to d2 from the inlet to the intermediate liquid cavity to the distance). Its influence on the energy dissipation effect is mainly achieved by adjusting the flow resistance. The flow resistance of the throttling plate mainly originates from the local flow resistance introduced by the diameter change during the "orifice contraction-expansion" process. The smaller the orifice size and the lower the orifice ratio, the greater the local resistance and the higher the flow resistance. The core function of "gradient change" is to achieve "staged energy dissipation" and avoid the sudden drop in local pressure caused by a single high-resistance throttling plate, which may trigger new fluctuations.

[0158] The core parameter of the inert gas chamber 15 is its volume Vg, which affects the energy dissipation effect by adjusting the local flow capacity C. The larger Vg is, the larger the flow capacity of the gas chamber. The core function of the gas chamber is to "buffer pressure fluctuations"—when the liquid hydrogen pressure increases, the gas-liquid separator 16 bulges into the inert gas chamber, compressing the gas and reducing its volume, thus absorbing pressure energy through gas compression; when the liquid hydrogen pressure decreases, the gas expands, pushing the separator membrane to rebound and releasing energy to replenish the pressure. A larger inert gas chamber volume is not necessarily better; an excessively large volume will occupy the space of the main liquid flow channel and also increase the overall size of the energy dissipator, violating the principle of compact structure.

[0159] The core parameter of the main liquid chamber 21 is the stroke distance l, which is the length of the flow path of liquid hydrogen from the inlet to the outlet within the liquid chamber. The energy dissipation effect is affected by adjusting the flow rate. A larger flow rate slows down the rate of flow change through inertial constraint, thus mitigating pressure fluctuations caused by sudden changes in flow rate, ensuring the propagation time of pressure fluctuations within the energy dissipator, and allowing sufficient time for other pressure buffer structures to function.

[0160] For a specific example, theoretical calculations of hydrogen impact vibration were performed on a DN50, 1000mm long stainless steel straight pipeline for liquid hydrogen under valve closing and opening conditions. An energy dissipator was also introduced to verify its effectiveness. The experimental parameters are as follows:

[0161] (1) For the hydrogen blast at the valve closing point, the schematic diagram is as follows: Figure 5a As shown. The upstream liquid hydrogen storage tank pressure is 0.16 MPa. Valve 23 (used as a regulating valve here) is vented. Initially, the opening of valve 23 is adjusted to stabilize the flow velocity in the pipe at 0.2 m / s. After preparation, valve 23 is quickly closed at 0.1 s. The flow rate at valve 23 drops rapidly to 0, and the fluid pressure rises sharply, triggering a hydrogen blast effect. The pressure wave propagates back and forth between valve 23 and the liquid hydrogen storage tank. Since the upstream storage tank is a constant pressure source and the downstream valve 23 is the pressure origin point, the pressure value of valve 23 depends only on the flow velocity and the speed of valve closure. Therefore, it is more reasonable to select the fluid pressure measuring point 22 at the exact center.

[0162] (2) For valve opening water hammer, the schematic diagram is as follows: Figure 5b As shown. The upstream liquid hydrogen storage tank pressure is 0.16 MPa, and the downstream is a closed flange 24; initially, the pressure inside the pipe is atmospheric. After preparation, valve 23 of the upstream liquid hydrogen storage tank (used as a shut-off valve here) is quickly opened at 0.1s, connecting the pipeline to the storage tank. After the liquid hydrogen enters the pipeline, it impacts the closed flange 24, causing a sharp rise in fluid pressure at the closed flange 24, thus triggering a water hammer effect. The pressure wave propagates back and forth between the closed flange 24 and the liquid hydrogen storage tank. Since the pressure wave originates at valve 23 and propagates through the fluid pipeline and energy dissipator, the fluid pressure rises sharply when it impacts the closed flange 24. Therefore, it is reasonable to select the fluid pressure measuring point 22 before the closed flange 24.

[0163] A comparison chart of fluid pressure fluctuations at measuring points with and without a power dissipator is shown below. Figures 6a-6d As shown. Figure 6a and 6b As shown, for water hammer at valve closure, the initial pressure in the pipe remains at 0.16 MPa 0.1s before valve closure. At 0.1s, the fluid pressure rapidly rises to its maximum value, then oscillates and decays with 0.16 MPa as the baseline. After installing the energy dissipator, the peak fluid pressure decreased from 0.35 MPa to 0.174 MPa, a reduction of 50.30%, and the fluid pressure decay rate accelerated. Figure 6c and 6d As shown, for hydrogen slugging at the valve opening, the initial pressure in the pipe is 0 (gauge pressure) 0.1s before the valve opens. At 0.1s, the liquid hydrogen storage tank opens the valve instantaneously, and the fluid pressure rises rapidly to its maximum value, then oscillates and decays with a baseline of 0.16 MPa. After installing the energy dissipator, the peak fluid pressure decreased from 0.4 MPa to 0.207 MPa, a reduction of 48.25%, and the fluid pressure decay rate accelerated.

[0164] In other words, the more powerful function of this method lies in reverse-engineering the design. By changing the wave-shaped parameters of the damping inner wall, the orifice gradient of the gradient throttling plate, the volume of the inert gas cavity, and the travel distance of the mainstream liquid cavity in the model, the simulation is run repeatedly to observe the changes in the energy dissipation effect. Thus, the optimal structural design parameters can be found on the computer before manufacturing an expensive physical prototype.

[0165] It is not difficult to see that this embodiment is a method embodiment corresponding to the first embodiment, and this embodiment can be implemented in conjunction with the first embodiment. The relevant technical details mentioned in the first embodiment are still valid in this embodiment, and will not be repeated here to reduce repetition. Accordingly, the relevant technical details mentioned in this embodiment can also be applied to the first embodiment.

[0166] Example 3

[0167] This invention also proposes a storage medium storing a fluid-structure interaction (FSI) optimization method for the energy dissipator. When the FSI optimization program for the energy dissipator is executed by a processor, it implements the steps of the FSI optimization method for the energy dissipator as described above. Since this storage medium employs all the technical solutions of the above embodiments, it possesses at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated upon here.

[0168] Example 4

[0169] Please see Figure 7 The present invention also provides an electronic device, including: a memory and a processor; the memory stores at least one program instruction; the processor loads and executes the at least one program instruction to implement the fluid-structure interaction optimization method for the energy dissipator provided in Embodiment 2.

[0170] The memory 702 and processor 701 are connected via a bus, which may include any number of interconnecting buses and bridges, connecting various circuits of one or more processors 701 and memory 702 together. The bus may also connect various other circuits, such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further herein. A bus interface provides an interface between the bus and the transceiver. The transceiver may be a single element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices over a transmission medium. Data processed by processor 701 is transmitted over a wireless medium via an antenna, which further receives data and transmits it to processor 701.

[0171] Processor 701 is responsible for managing the bus and general processing, and can also provide various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory 702 can be used to store data used by processor 701 during operation.

[0172] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, based on the guidance provided in this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A pressure fluctuation suppression energy dissipator for liquid hydrogen pipelines, wherein the energy dissipator is connected in series with the liquid hydrogen outflow pipeline, characterized in that, The energy dissipator includes: an energy dissipator shell (14), a damping and vibration reduction module, a gradient throttling module, and a pressure buffer module. The damping and vibration reduction module and the gradient throttling module are arranged sequentially according to the liquid hydrogen flow direction. The pressure buffer module is arranged on the outside of the liquid hydrogen flow channel. The three modules work together to gradually attenuate the liquid hydrogen pressure fluctuation. The damping and vibration reduction module, the gradient throttling module, and the pressure buffer module are integrated inside the energy dissipator shell (14). The energy dissipator shell (14) has energy dissipator inlet and outlet channels (13) at both ends that are adapted to the liquid hydrogen outflow pipe (8). The damping and vibration reduction module is a damping inner wall (19) set on the inner side wall of the energy dissipator shell (14). The damping inner wall (19) adopts a combination of spring damping structure and bellows structure, and the whole is wave-shaped. The spring damping structure in the damping inner wall (19) is composed of a low-temperature resistant elastic spring and an inner wall matrix. The bellows structure is a metal tube structure with wave-shaped pleats. The elastic spring consumes the vibration energy of the pipeline through elastic deformation and damping. The bellows structure absorbs the vibration mechanical energy through elastic expansion and contraction. At the same time, it increases the friction resistance of liquid hydrogen based on the wave-shaped inner wall to hinder the propagation of pressure waves and break the bubbles generated by flash evaporation in liquid hydrogen, thereby reducing the influence of gas-liquid two-phase flow on pressure fluctuations. The gradient throttling module consists of multiple gradient throttling plates (20) arranged inside the energy dissipator along the direction of liquid hydrogen flow. Throttling holes are provided on the gradient throttling plates (20). The aperture and opening ratio of the throttling holes increase in a gradient along the direction of liquid hydrogen flow from the inlet / outlet channel (13) to the liquid cavity. The gradient throttling plates (20) are used to block the propagation of pressure changes caused by valve opening / closing and sudden load changes through local flow resistance, while reducing the liquid hydrogen flow rate and breaking up bubbles to optimize the flow field stability and prevent pressure fluctuations from being transmitted downstream. The pressure buffer module includes a gas-liquid separation membrane (16), an inert gas chamber (15), and a liquid chamber. The gas-liquid separation membrane (16) divides the interior of the energy dissipator shell (14) into an inert gas chamber (15) and a liquid chamber. The liquid chamber includes a main liquid chamber (21) and a liquid storage layer (18). The main liquid chamber (21) and the liquid storage layer (18) are connected through the opening (17) of the liquid chamber and the liquid storage layer. The inert gas chamber (15) is filled with inert gas. The pressure buffer module achieves dynamic buffering of pressure fluctuations and absorption of excess flow by coupling the compressibility of the inert gas chamber (15) with the volume of the main liquid chamber (21) and the liquid storage layer (18).

2. The liquid hydrogen pipeline pressure fluctuation suppression and energy dissipator according to claim 1, characterized in that, The gas-liquid separator (16) is a flexible component. The inert gas chamber (15) is located on one side of the gas-liquid separator (16), and the liquid chamber is located on the other side of the gas-liquid separator (16). The pressure buffer module is used to push the gas-liquid separator (16) to bulge towards the inert gas chamber (15) when the liquid hydrogen pressure increases, compressing the inert gas stored inside the inert gas chamber (15) and converting the pressure energy of the liquid hydrogen into the internal energy of the gas for storage; when the liquid hydrogen pressure decreases, the compressed inert gas expands, pushing the gas-liquid separator (16) back to its original position and releasing the stored energy.

3. The liquid hydrogen pipeline pressure fluctuation suppression energy dissipator according to claim 2, characterized in that, The liquid chamber is used to allow liquid hydrogen to flow into or out of the storage layer (18) through the liquid chamber and the opening (17) of the storage layer when the pressure changes drastically. The liquid hydrogen can directly absorb or replenish the liquid through volume changes, thus helping to buffer pressure fluctuations.

4. A fluid-structure interaction optimization method for the energy dissipator according to claim 1, characterized in that, The method includes: Step S1: Construct a fluid-structure interaction physical model of the energy dissipator and the liquid hydrogen pipeline to characterize the process by which the energy dissipator suppresses liquid hydrogen pressure fluctuations as described in claim 1. The fluid domain includes the main liquid chamber (21), the liquid storage layer (18), and the inlet and outlet channels (13) inside the energy dissipator. The solid domain includes the outer shell (14), the damping inner wall (19), and the gradient throttling plate (20) of the energy dissipator. Step S2: Using the lumped parameter equivalent method, for the specific structural form of the energy dissipator described in claim 1, the throttling and pressure reduction effect of the gradient throttling plate (20) and the friction effect of the damping inner wall (19) are equivalent to flow resistance; the fluid inertial effect of the energy dissipator inlet and outlet channels (13), the mainstream liquid chamber (21) and the liquid storage layer (18) are equivalent to flow flow; the gas compressibility energy storage effect of the inert gas chamber (15) and the volume buffering effect of the mainstream liquid chamber (21) and the liquid storage layer (18) are equivalent to flow capacity. Step S3: The structural vibration characteristics are described by structural mechanics equations and the fluid wave characteristics are described by fluid dynamics control equations. The structural mechanics equations and fluid dynamics control equations are combined by pre-set fluid-structure interaction boundary conditions at the junction of the fluid domain and the solid domain to obtain the fluid-structure interaction control equations. Step S4: Use the characteristic line method to transform the fluid-structure interaction control equations into ordinary differential equations along the characteristic lines; Step S5: Establish a spatiotemporal discrete grid that satisfies the CFL stability condition; Step S6: Discretize the ordinary differential equation obtained along the characteristic line using the finite difference method to obtain the liquid hydrogen pressure data corresponding to each discrete grid. Step S7: Based on the fluid-structure interaction physical model, the design of the energy dissipator structural parameters is guided in reverse. The reduction rate of liquid hydrogen pressure fluctuation amplitude meets the preset condition as the evaluation index of energy dissipation effect. Based on the influence of flow capacity, flow rate and flow resistance on energy dissipation effect, the wave-shaped parameters of the damping inner wall (19) are optimized to change the flow resistance, the opening gradient of the gradient throttling plate (20) is optimized to change the flow resistance, the volume of the inert gas cavity (15) is optimized to change the flow capacity, and the travel distance of the mainstream liquid cavity (21) is optimized to change the flow rate. Iterative simulation verification is performed to achieve directional optimization.

5. The fluid-structure interaction optimization method for energy dissipators according to claim 4, characterized in that, The mathematical expression for the flow resistance is: ； The mathematical expression for the flow capacity is: ； The mathematical expression for influenza is: ； In the formula, Flow resistance, unit: ; Fluid dynamic viscosity, in units of ; l is the length of the liquid hydrogen outflow pipe, in meters; d is the inner diameter of the liquid hydrogen outflow pipe, in meters; For flow capacity, the unit is 1. A represents the cross-sectional area of ​​the liquid hydrogen outflow pipe, in units of... ; Fluid density, in units of ; 'a' represents the speed of sound, measured in units of _____. ; It is influenza, and the unit is .

6. The fluid-structure interaction optimization method for energy dissipators according to claim 4, characterized in that, The fluid dynamics control equations include the fluid momentum equation considering the coupling terms of pipe axial vibration and the fluid continuity equation considering the coupling terms of pipe deformation. The structural mechanics equations include the pipe axial motion equation considering the fluid pressure excitation term and the pipe constitutive equation considering the coupling terms of fluid and structural velocity. The fluid momentum equation is: ； The fluid continuity equation is: ； The equation for the axial motion of the pipeline is: ； The constitutive equation of the pipeline is: ； ； ； In the formula, the subscript f represents the fluid parameter, the subscript t represents the pipe parameter, and the subscript r represents the difference between the fluid physical quantity and the pipe physical quantity; Let be the acceleration due to gravity, and take . ; and These represent the axial velocities of the fluid and the pipe, respectively. The difference in speed between the two is expressed in m / s. The pressure head of the fluid is expressed in meters (m). This represents the axial stress of the pipe, expressed in Pa. and These are the densities of the fluid and the pipe material, respectively, in units of... ; and These are the cross-sectional areas of the fluid and the pipe, respectively, in units of... K is the bulk modulus of the fluid, measured in Pa. This refers to the elastic modulus of the pipe, expressed in Pa. This is the axial length, in meters (m). Time, in seconds; This is the inner radius of the pipe, in meters (m). The pipe wall thickness is expressed in meters (m). This is the friction resistance factor; Poisson's ratio; The angle between the pipeline axis and the horizontal plane is taken as the positive direction when the pipeline is lifted to a lower height. Pressure wave velocity; Stress wave velocity; For fixed-point acceleration.

7. The fluid-structure interaction optimization method for energy dissipators according to claim 4, characterized in that, The fluid-structure interaction boundary conditions include displacement compatibility conditions and pressure equilibrium conditions; The displacement compatibility condition is that the radial or axial deformation of the pipe wall is compatible with the resulting change in the flow channel volume. The pressure balance condition is that the pressure pulsation of the fluid is an external excitation acting on the pipe wall structure.

8. The fluid-structure interaction optimization method for energy dissipators according to claim 4, characterized in that, The wave parameters of the damping inner wall (19) include wave amplitude and wave wavelength. By changing the wave amplitude and wave wavelength, the flow resistance of liquid hydrogen is changed, thereby affecting the flow resistance. The height of the inner wall protrusions / recesses increases and the distance between adjacent protrusions / recesses decreases, which enhances the disturbance of the liquid hydrogen flow process and increases the flow resistance. The orifice gradient parameter of the gradient throttling plate (20) is the orifice diameter change rate along the liquid hydrogen flow direction. Its influence on the energy dissipation effect is achieved by adjusting the flow resistance. The smaller the orifice size, the lower the orifice ratio, the greater the local resistance, and the higher the flow resistance. The core parameter of the inert gas chamber (15) is its volume, and its influence on the energy dissipation effect is achieved by adjusting the local flow capacity. The larger the volume, the larger the flow capacity of the gas chamber. The core parameter of the main liquid chamber (21) is the travel distance, which is the length of the flow path of liquid hydrogen from the inlet to the outlet in the liquid chamber. Its influence on the energy dissipation effect is achieved by adjusting the flow rate.

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