Liquid hydrogen pipeline pressure fluctuation suppression energy dissipater and fluid-solid coupling optimization method

Abstract

The invention provides a liquid hydrogen pipeline pressure fluctuation suppression energy dissipater and a fluid-solid coupling optimization method, and relates to the technical field of liquid hydrogen storage and transportation safety. The energy dissipater adopts a modular integrated design and comprises a damping vibration attenuation module, a gradient throttling module and a pressure buffering module. The damping vibration attenuation module is a wavy damping inner wall formed by combining a spring damper and a corrugated pipe; the gradient throttling module is composed of a plurality of throttling plates with hole opening parameters changing in a gradient mode. The pressure buffer module is divided into an inert gas cavity and a liquid cavity containing a liquid storage layer through a gas-liquid separation membrane. Meanwhile, the invention provides a corresponding fluid-structure interaction optimization method, the physical effect of the energy dissipater is abstracted into flow resistance, flu and flow capacity parameters by establishing a fluid-structure interaction model, a characteristic line method is adopted for solving, and the energy dissipation effect is verified by optimizing structural parameters. Multi-structure cooperative energy dissipation is achieved, the liquid hydrogen pressure fluctuation range can be reduced by 40% or above, and the low-temperature liquid hydrogen conveying system is resistant to low temperature, compact in structure and suitable for the aerospace and energy field.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of liquid hydrogen storage and transportation safety, and particularly relates to a liquid hydrogen pipeline pressure fluctuation suppression energy absorber and a fluid-structure coupling optimization method. BACKGROUND

[0002] As a clean energy carrier with extremely high energy density, liquid hydrogen continues to promote the large-scale application in the fields of aerospace propulsion, hydrogen energy transportation, large fuel cells, etc. Liquid hydrogen storage relies on special storage tanks with ultra-low temperature insulation performance. After the liquid hydrogen is discharged from the outflow port of the storage tank, it needs to be transported to the downstream equipment through the transportation pipeline made of low-temperature alloy material. In this process, the pressure stability of the liquid hydrogen in the pipeline directly determines the system safety and operation efficiency, and the pressure fluctuation has become a core technical bottleneck for the landing of the liquid hydrogen industry. The existing liquid hydrogen storage tank is usually composed of an inner tank, an outer tank, a vacuum insulation layer, an outflow port assembly and a transportation pipeline. The transportation pipeline is the core channel for the flow of liquid hydrogen, and the internal flow field stability is disturbed by multiple factors. The main manifestations are three key disturbances: First, the pressure imbalance caused by flow resistance. When liquid hydrogen flows in the pipeline, it needs to overcome the frictional resistance and local resistance along the way: the frictional resistance is caused by the viscous action of liquid hydrogen and the pipe wall, which causes the pressure to gradually decrease along the transportation direction; the local resistance is concentrated in the pipe bends, valves, variable diameter sections and other parts, forming a local pressure drop. The superposition of the two types of resistance makes the pressure distribution in the pipeline present a non-uniform characteristic of "gradual change + sudden change", especially when the flow rate is high, the pressure fluctuation is more obvious. Second, the pipeline vibration caused by external excitation. The liquid hydrogen transportation pipeline is easily affected by multiple external excitations in actual working conditions: first, the operation vibration of pumps, compressors and other equipment is transmitted to the pipeline through supports and flanges; second, environmental disturbances such as shock waves in space launch sites, bumps in vehicle systems and the like directly change the stress state of the pipeline; third, the working condition switching caused by valve opening and closing and sudden change of downstream hydrogen load causes instantaneous fluctuation of liquid hydrogen flow rate, forming pipeline "inertia impact". These external excitations cause the pipeline to vibrate, further disturb the pipeline flow field, and exacerbate the pressure fluctuation. Third, the endogenous vibration caused by gas-liquid two-phase flow and fluid-structure coupling. Liquid hydrogen has a very low boiling point and is extremely sensitive to heat invasion. Even if there is a small damage to the pipeline insulation layer or a temperature difference exists between the pipe wall and the liquid hydrogen, the liquid hydrogen near the wall will flash and vaporize, forming gas-liquid two-phase flow. When the gas content rate is in a certain range, the flow pattern is easily changed to plug flow or drop flow, and the high-speed movement and periodic change of liquid plugs or bubbles will impact the pipe wall, causing pressure pulses. At the same time, there is a strong fluid-structure coupling effect between the liquid hydrogen flow and the pipeline structure: the pressure fluctuation of the liquid hydrogen causes the deformation of the pipe wall and changes the flow passage section, while the pipeline vibration destroys the liquid hydrogen flow boundary layer, forming a vicious cycle of "vibration-flow field disturbance", which greatly exacerbates the pressure fluctuation. The superimposed pressure fluctuation caused by the above factors causes multi-dimensional harm to the liquid hydrogen conveying system: first, it causes fatigue damage to the bolt, weld and other parts connected between the pipeline and the outlet of the storage tank, and long-term operation may cause sealing failure or pipeline rupture, increasing the risk of liquid hydrogen leakage; second, it causes imbalance of hydrogen supply pressure of downstream hydrogen equipment, affecting the operation efficiency of the equipment, and even causing shutdown failure; third, it may induce "hydrogen hammer effect", causing impact damage to the pipeline, valve and storage tank, threatening the safety of the system. Currently, the control means for liquid hydrogen pipeline pressure fluctuation in the industry has obvious shortcomings: pipeline layout optimization can only alleviate the influence of part of the flow resistance, and cannot eliminate irregular pressure fluctuations caused by vibration; although the buffer tank can achieve pressure buffering, it has large volume and high cost, and the effect of suppressing high-frequency pressure fluctuations is limited; the pressure regulating valve responds slowly in a low-temperature environment, and is difficult to adapt to the instantaneous pressure change of the working condition switching; the traditional damper mainly uses a single energy dissipation structure, which is not suitable for the characteristics of liquid hydrogen gas-liquid two-phase flow, and has low energy dissipation efficiency and is prone to blockage. In summary, the existing technology cannot meet the needs of "compact structure, rapid response and high-efficiency energy dissipation" at the same time, and it is urgent to develop a special energy dissipation device for the liquid hydrogen storage tank outlet pipeline to suppress the pressure fluctuation caused by multi-source disturbance from the root and ensure the safe and stable operation of the liquid hydrogen conveying system. SUMMARY

[0003] The purpose of the present application is to overcome at least one technical problem in the prior art, and to provide a liquid hydrogen pipeline pressure fluctuation suppression energy dissipator and a fluid-structure coupling optimization method.

[0004] In one aspect, the present application provides a liquid hydrogen pipeline pressure fluctuation suppression energy dissipator, which is connected in series to the liquid hydrogen outlet pipeline. The energy dissipator comprises an energy dissipator shell, a damping vibration reduction module, a gradient throttling module and a pressure buffering module. The damping vibration reduction module, the gradient throttling module and the pressure buffering module are integrated inside the energy dissipator shell. The energy dissipator shell is provided with energy dissipator inlet and outlet flow channels adapted to the liquid hydrogen outlet pipeline at both ends. The damping vibration reduction module is a damping inner wall provided on the inner side wall of the energy dissipator shell. The damping inner wall adopts a combination of spring damping structure and bellows structure, and has a whole wave shape. The gradient throttling module is a plurality of gradient throttling plates arranged inside the energy dissipator along the liquid hydrogen flow direction. Throttling holes are formed on the gradient throttling plates. The hole diameter and the opening rate of the throttling holes increase in the direction of liquid hydrogen flowing from the inlet and outlet flow channels to the middle liquid chamber. The pressure buffering module comprises a gas-liquid separation membrane, an inert gas chamber and a liquid chamber. The gas-liquid separation membrane separates the inside of the energy dissipator shell into the inert gas chamber and the liquid chamber. The liquid chamber comprises a main flow liquid chamber and a liquid storage layer. The main flow liquid chamber and the liquid storage layer are connected through a liquid chamber and liquid storage layer opening. The inert gas chamber is filled with inert gas.

[0005] Further, the spring damping structure in the damping inner wall is composed of a low-temperature-resistant elastic spring and an inner wall base body, and the bellows structure is a metal tube structure with wave-shaped folds; when the liquid hydrogen flow causes pipeline vibration, the elastic spring consumes the pipeline vibration energy through elastic deformation and damping effect, and the bellows structure absorbs vibration mechanical energy through elastic expansion and contraction, and at the same time, based on the wave-shaped inner wall, increases the resistance of the liquid hydrogen along the pipeline to hinder the propagation of pressure waves, and breaks the bubbles generated in the liquid hydrogen due to flashing, thereby reducing the influence of gas-liquid two-phase flow on pressure fluctuation.

[0006] Further, the gradient throttle plate is used to block the propagation of pressure sudden change caused by valve opening and closing and load mutation through local flow resistance effect, and at the same time, reduce the liquid hydrogen flow rate, and break bubbles again to optimize the stability of the flow field and avoid the transmission of pressure fluctuation to the downstream.

[0007] Further, the gas-liquid separation membrane is a flexible component, the inert gas cavity is located on one side of the gas-liquid separation membrane, and the liquid cavity is located on the other side of the gas-liquid separation membrane; the pressure buffer module is used to push the gas-liquid separation membrane to protrude towards the inert gas cavity when the liquid hydrogen pressure rises, compress the inert gas stored in the inert gas cavity, and convert the pressure energy of the liquid hydrogen into the internal energy of the gas storage; when the liquid hydrogen pressure decreases, the compressed inert gas expands and pushes the gas-liquid separation membrane back to its original position, thereby releasing the stored energy.

[0008] Further, the liquid cavity is used to flow into or out of the liquid storage layer through the liquid cavity and the liquid storage layer opening when the pressure changes sharply, thereby directly absorbing or supplementing the liquid through volume change to assist in buffering the pressure fluctuation.

[0009] In a second aspect, the present application provides a fluid-structure coupling optimization method for the energy absorber, the method comprising: step S1, constructing a fluid-structure coupling physical model of the energy absorber and the liquid hydrogen pipeline, wherein the fluid domain comprises a main flow liquid cavity inside the energy absorber, a liquid storage layer, and an inlet and outlet flow passage of the energy absorber, and the solid domain comprises an energy absorber shell, a damping inner wall, and a gradient throttle plate; step S2, using a lumped parameter equivalent method to equivalently convert the throttling pressure reduction effect of the gradient throttle plate and the friction effect of the damping inner wall into flow resistance; equivalently converting the fluid inertia effect of the inlet and outlet flow passage of the energy absorber, the main flow liquid cavity, and the liquid storage layer into flow inductance; and equivalently converting the gas compressibility energy storage effect of the inert gas cavity and the volume buffering effect of the main flow liquid cavity and the liquid storage layer into flow capacity; step S3, using a structural mechanics equation to describe the structural vibration characteristics, using a fluid mechanics control equation to describe the fluid wave characteristics, and combining the structural mechanics equation and the fluid mechanics control equation through a preset fluid-structure coupling boundary condition at the connection between the fluid domain and the solid domain to obtain a fluid-structure coupling control equation; step S4, using a characteristic line method to convert the fluid-structure coupling control equation into an ordinary differential equation along a characteristic line; step S5, establishing a time-space discrete grid that satisfies a CFL stability condition; step S6, using a finite difference method to discretize the ordinary differential equation along the characteristic line to obtain liquid hydrogen pressure data corresponding to each discrete grid; and step S7, based on the liquid hydrogen pressure data corresponding to each discrete grid, taking a liquid hydrogen pressure fluctuation amplitude reduction rate satisfying a preset condition as an energy absorption effect evaluation index, and based on the influence of the flow capacity, the flow inductance, and the flow resistance on the energy absorption effect, optimizing the wave-shaped parameters of the damping inner wall, the opening gradient of the gradient throttle plate, the volume of the inert gas cavity, and the stroke distance of the main flow liquid cavity.

[0010] Further, the flow resistance mathematical expression is: ; The flow capacity mathematical expression is: ; The flow inductance mathematical expression is: ; In the formula, is the volume flow resistance, and the unit is ; is the fluid dynamic viscosity, and the unit is ; l is the length of the liquid hydrogen outflow pipeline, and the unit is m; d is the inner diameter of the liquid hydrogen outflow pipeline, and the unit is m; is the volume flow capacity, and the unit is ; A is the cross-sectional area of the liquid hydrogen outflow pipeline, and the unit is ; is the fluid density, and the unit is ; a is the sound speed, and the unit is ; is the volume flow inductance, and the unit is .

[0011] Further, the fluid mechanics control equations include a fluid momentum equation considering a pipeline axial vibration coupling term and a fluid continuity equation considering a pipeline deformation coupling term, and the structural mechanics equations include a pipeline axial motion equation considering a fluid pressure excitation term and a pipeline constitutive equation considering a fluid, structure velocity coupling term; The fluid momentum equation is: ; The fluid continuity equation is: ; The pipeline axial motion equation is: ; The pipeline constitutive equation is: ; ; ; In the formula, the subscript f represents a fluid parameter, the subscript t represents a pipeline parameter, and the subscript r represents a difference between a fluid physical quantity and a pipeline physical quantity; is a gravitational acceleration, and is taken as ; and are axial motion velocities of a fluid and a pipeline respectively, is a difference between the velocities, and has a unit of m / s; is a fluid pressure head, and has a unit of m; is an axial stress of the pipeline, and has a unit of Pa; and are densities of fluid and pipeline materials respectively, and have a unit of ; and are areas of fluid and pipeline sections respectively, and have a unit of ; K is a fluid bulk modulus, and has a unit of Pa; is a pipeline elastic modulus, and has a unit of Pa; is an axial length, and has a unit of m; is time, and has a unit of s; is a pipeline inner radius, and has a unit of m; is a pipeline wall thickness, and has a unit of m; is a friction resistance factor; is a Poisson ratio; is an angle between a pipeline axis and a horizontal plane, and is taken as a positive direction of pipeline lifting height reduction; is a pressure wave velocity; is a stress wave velocity; To fix the point acceleration.

[0012] Further, the fluid-structure coupling boundary condition comprises a displacement compatibility condition and a pressure balance condition; the displacement compatibility condition is that the radial or axial deformation of the pipe wall is compatible with the volume change of the flow passage caused thereby; and the pressure balance condition is that the pressure pulsation of the fluid acts on the pipe wall structure as an external excitation.

[0013] Further, the wave shape parameters of the damping inner wall include wave amplitude and wave length, and the flow resistance of liquid hydrogen is changed by changing the wave amplitude and wave length, so as to affect the flow resistance, the height of the protrusion / recess of the inner wall is increased, the distance between adjacent protrusions / recesses is reduced, the disturbance of the liquid hydrogen flow process is enhanced, and the flow resistance is increased; the opening gradient parameter of the gradient throttle plate is the aperture change rate along the liquid hydrogen flow direction, the influence of the energy dissipation effect is realized by adjusting the flow resistance, the smaller the opening size, the lower the opening rate, the greater the local resistance, and the higher the flow resistance; the core parameter of the inert gas cavity is the volume, and the influence of the energy dissipation effect is realized by adjusting the local flow capacity; and the core parameter of the main flow liquid cavity is the stroke distance, the stroke distance is the flow path length of liquid hydrogen in the liquid cavity from the inlet to the outlet, and the influence of the energy dissipation effect is realized by adjusting the flow sense.

[0014] In another aspect, the application also provides a computer readable storage medium, wherein one or more instructions are stored in the computer readable storage medium, and the computer instructions are used to make the computer execute the above-mentioned fluid-structure coupling optimization method for the energy absorber.

[0015] In another aspect, the application provides an electronic device, comprising a memory and a processor; at least one program instruction is stored in the memory; and the processor loads and executes the at least one program instruction to realize the above-mentioned fluid-structure coupling optimization method for the energy absorber.

[0016] Compared with the prior art, the application has the following advantages: (1) Multi-module collaborative energy dissipation, significant effect: damping vibration reduction, gradient throttling, pressure buffering module collaborates from three dimensions of vibration suppression, pressure blocking and energy absorption, which can reduce the liquid hydrogen pressure fluctuation amplitude by more than 40%, the valve-closing hydrogen impact pressure peak value can be reduced from 0.35 MPa to 0.174 MPa (reduction rate 50.3%), and the valve-opening hydrogen impact pressure peak value can be reduced from 0.4 MPa to 0.207 MPa (reduction rate 48.25%).

[0017] (2) Strong low-temperature adaptability: each structure adopts low-temperature resistant materials such as indium steel alloy, titanium alloy and fluorine rubber, and meets the stability and compatibility in the liquid hydrogen ultra-low temperature (-253℃) environment, solving the performance failure problem of traditional energy dissipation devices in low-temperature environment.

[0018] (3) Compact structure, wide adaptability: The modular integrated design makes the overall structure of the energy absorber compact, the inlet and outlet flow channels can be adapted to different specifications of liquid hydrogen outlet pipelines, and the installation and maintenance are convenient, which is suitable for various low-temperature liquid hydrogen conveying systems in the fields of aerospace and energy.

[0019] (4) Accurate calculation method, supporting optimization: The fluid-structure coupling calculation method realizes accurate simulation of the interaction between pressure wave propagation and structure vibration through the method of characteristic line, and the calculation result is highly consistent with the experimental data, with a consistency of more than 95%, which can effectively guide the optimization of the structure parameters of the energy absorber and ensure the stable and reliable energy absorption effect. BRIEF DESCRIPTION OF DRAWINGS

[0020] The application will be further described below in combination with the drawings and examples.

[0021] Figure 1 is a liquid hydrogen pipeline pressure fluctuation suppression energy absorber structure provided by embodiment 1 of the application.

[0022] Figure 2 is a liquid hydrogen conveying system structure and energy absorber arrangement provided by embodiment 1 of the application.

[0023] Figure 3 is a fluid-structure coupling optimization method flowchart provided by embodiment 2 of the application for the energy absorber of embodiment 1.

[0024] Figure 4 is a mesh diagram divided by the fluid-structure coupling calculation method provided by embodiment 2 of the application.

[0025] Figure 5a is a valve closing hydrogen impact experiment diagram provided by embodiment 2 of the application.

[0026] Figure 5b is a valve opening hydrogen impact experiment diagram provided by embodiment 2 of the application.

[0027] Figure 6a is a fluid pressure fluctuation diagram of a measurement point of valve closing hydrogen impact without an energy absorber provided by embodiment 2 of the application.

[0028] Figure 6b is a fluid pressure fluctuation diagram of a measurement point of valve closing hydrogen impact with an energy absorber provided by embodiment 2 of the application.

[0029] Figure 6c is a fluid pressure fluctuation diagram of a measurement point of valve opening hydrogen impact without an energy absorber provided by embodiment 2 of the application.

[0030] Figure 6dis a schematic diagram of the fluid pressure fluctuation of a hydrogen valve opening with an energy absorber according to the embodiment 2 of the present application.

[0031] Figure 7 is a partial block diagram of an electronic device according to the embodiment 4 of the present application.

[0032] Reference signs are as follows: Liquid hydrogen tank shell 1, vacuum jacket 2, thermal insulation layer 3, internal support structure 4, inner container 5, hydrogen distribution layer 6, liquid hydrogen layer 7, liquid hydrogen outflow pipe 8, regulating valve 9, outflow pipe support 10, energy absorber 11, external support structure 12; energy absorber inlet and outlet flow channel 13, energy absorber shell 14, inert gas cavity 15, gas-liquid separation membrane 16, liquid cavity and liquid storage layer opening 17, liquid storage layer 18, damping inner wall (spring damping + bellows) 19, gradient throttle plate 20, main flow liquid cavity 21, pressure measuring point 22, valve 23, closed flange 24. DETAILED DESCRIPTION

[0033] Before any examples embodiments are described in further detail, it should be noted that some example embodiments are described as processes or methods depicted as flowcharts. Although the processes are described in a particular sequential order, many of the processes can be performed in parallel, concurrently or in any order. In addition, the order of the processes can be re-arranged. The processes can be terminated when their operations are completed, but the processes can also have additional steps not included in the figure, which can likewise be performed after the processes are terminated. The processes can correspond to methods, functions, procedures, subroutines, subprograms, etc.

[0034] It is to be understood that the terms "first", "second", etc. can be used herein to describe various elements, but the elements should not be limited by these terms. The terms are only used to identify one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of example embodiments. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0035] The application will now be described in detail based on the drawings. The figure is a simplified schematic diagram, and only schematically illustrates the basic structure of the application, and thus only shows the components related to the application.

[0036] Embodiment 1 For the sake of understanding, before the detailed description of the embodiments of the present application, the overall concept of the present application is set forth: the core of the present application lies in the division and cooperation of three modules: module one, damping vibration module (vibration control, gas control): structure: spring damping + corrugated pipe composed of wave-shaped inner wall. Function: consume mechanical energy: use the friction of spring damping and the elastic deformation of corrugated pipe to quickly attenuate pipeline vibration. Break bubbles: the uneven wall surface of the wave shape shears and breaks the bubbles in liquid hydrogen, homogenizes the flow field, and reduces the pressure pulse caused by gas-liquid two-phase flow from the source. Increase flow resistance: the wave structure increases the resistance along the way, and consumes pressure wave energy. Module two, gradient throttling module (pressure control): structure: multiple blocks of opening parameters (pore size, opening rate) gradient increased throttle plate. Function: energy dissipation: decompose the large pressure surge into multiple small, stepped pressure drops, avoid local pressure drop too large to cause new fluctuations. Synergistic gas control: work together with the damping inner wall to further break and homogenize the bubbles. Provide controllable flow resistance: by designing the gradient, accurately control the flow resistance distribution inside the energy absorber. Module three, pressure buffer module (pressure stabilization): structure: gas-liquid separation membrane + inert gas cavity + liquid storage layer. Function: energy throughput: take advantage of the compressibility of inert gas to store energy when the pressure is high and release energy when the pressure is low, like a "breathing lung" to smooth the pressure fluctuations. Volume buffer: the liquid storage layer provides additional volume compensation by inflow and outflow of liquid, further enhancing the buffering effect. The synergistic process of the three modules: when a pressure wave enters the energy absorber, it is first "peak cut" by the gradient throttle plate, at the same time, part of the wave energy is consumed by the damping inner wall in the form of heat, and the bubbles that may exacerbate the fluctuations are broken, the remaining pressure fluctuation energy is absorbed by the pressure buffer module, the compression and expansion of the gas converts the fluctuating kinetic energy / pressure energy into internal energy, and finally the pressure at the outlet tends to be stable.

[0037] In addition, the present application is not only a product, but also a design method. The fluid-structure interaction calculation method is the key enabling technology to realize the above concept. Specifically, it includes: 1. Accurate modeling: it establishes a mathematical model that can truly reflect the interaction between liquid hydrogen and the structure of the energy absorber, overcoming the defects of traditional design software that ignores fluid-structure interaction or simplifies it too much. 2. Physical abstraction: abstract the complex physical structure (wave shape, throttle plate, gas cavity) into three basic parameters of flow resistance, flow sense, and flow capacity in the fluid network, providing engineers with an intuitive design language and optimization lever. 3. Directional optimization: through this method, it can be clearly known that: increasing the wave amplitude of the damping inner wall → increasing the flow resistance → enhancing energy consumption. Reducing the initial opening rate of the throttle plate → increasing the flow resistance → enhancing the throttling effect. Increasing the volume of the gas cavity → increasing the flow capacity → enhancing the buffering capacity. Increasing the liquid cavity flow path → increasing the flow sense → enhancing the inertial flow stabilization effect. 4. Effect prediction and verification: by simulating extreme conditions such as "valve water hammer" on the computer, the optimal structural design parameters can be found on the computer before manufacturing the expensive physical prototype.

[0038] The specific implementation is as follows: As Figure 1 shown, a liquid hydrogen pipeline pressure fluctuation suppression energy absorber structure schematic diagram provided by the application.

[0039] As an example, the energy absorber is connected in series on the liquid hydrogen outflow pipeline, characterized in that the energy absorber comprises an energy absorber shell 14, a damping vibration reduction module, a gradient throttling module and a pressure buffer module, the damping vibration reduction module, the gradient throttling module and the pressure buffer module are integrated inside the energy absorber shell 14, and the energy absorber shell 14 is provided with energy absorber inlet and outlet flow channels 13 adapted to the liquid hydrogen outflow pipeline 8 (combined Figure 2 shown) at both ends; the damping vibration reduction module is a damping inner wall 19 arranged on the inner wall of the energy absorber shell 14, the damping inner wall 19 adopts a combination of spring damping structure and bellows structure, and the whole is in a wave shape; the gradient throttling module is a plurality of gradient throttling plates 20 arranged inside the energy absorber along the liquid hydrogen flow direction, the gradient throttling plates 20 are provided with throttling holes, and the hole diameter and the opening rate of the throttling holes increase in the direction of the liquid hydrogen flowing from the inlet and outlet flow channels 13 to the middle liquid cavity; the pressure buffer module comprises a gas-liquid separation membrane 16, an inert gas cavity 15 and a liquid cavity, the gas-liquid separation membrane 16 separates the inside of the energy absorber shell 14 into the inert gas cavity 15 and the liquid cavity, the liquid cavity comprises a main flow liquid cavity 21 and a liquid storage layer 18, the main flow liquid cavity 21 and the liquid storage layer 18 are communicated through a liquid cavity and liquid storage layer opening 17, and the inert gas cavity 15 is filled with inert gas.

[0040] Preferably, the spring damping structure in the damping inner wall 19 is composed of low-temperature-resistant elastic springs and an inner wall base body, and the bellows structure is a metal tube structure with wavy folds; when the liquid hydrogen flow causes pipeline vibration, the elastic springs consume the pipeline vibration energy through elastic deformation and damping effect, and the bellows structure absorbs the vibration mechanical energy through elastic expansion and contraction, while the wavy inner wall increases the liquid hydrogen resistance to hinder the propagation of pressure waves and break the bubbles generated in the liquid hydrogen due to flashing, thereby reducing the influence of gas-liquid two-phase flow on pressure fluctuations. Specifically, the damping vibration reduction module is a wavy damping inner wall arranged on the inner side wall of the energy absorber shell, which is composed of a spring damping structure and a bellows structure; the spring damping structure includes low-temperature-resistant indium steel alloy elastic springs (such as wire diameter 0.8-1.2mm, free length 5-8mm, stiffness coefficient 15-25N / mm) and a stainless steel alloy inner wall base body (such as thickness 3-5mm); the bellows is a wavy fold metal tube made of titanium alloy (such as fold height 3-5mm, fold spacing 8-12mm, and expansion amount up to 5%-8% of the length of the tube itself). When the module works, when the liquid hydrogen flow causes pipeline vibration, the springs consume vibration energy through their elastic deformation and damping effect; the wavy structure of the bellows can absorb the mechanical energy generated by vibration through its elastic expansion and contraction, and the wavy inner wall can also increase the resistance to hinder the propagation of pressure waves and dissipate the pressure conduction when transient flow surge occurs, thereby effectively attenuating the vibration amplitude of the pipeline, reducing the disturbance of the liquid hydrogen flow field, and avoiding the intensification of pressure fluctuations due to vibration. At the same time, the uneven inner wall can also break and homogenize the bubbles that may exist in the liquid hydrogen, thereby reducing the influence of gas-liquid two-phase flow on pressure fluctuations.

[0041] Preferably, the gradient throttle plate 20 is used to block the propagation of pressure shock caused by valve opening and load mutation by local flow resistance, while reducing the flow rate of liquid hydrogen, secondary crushing bubbles to optimize the stability of the flow field, and avoid the transmission of pressure fluctuation downstream. Specifically, the energy absorber is provided with multiple gradient throttle plates arranged in sequence along the liquid hydrogen flow direction. The throttle hole parameters (such as hole diameter, opening rate, etc.) on the throttle plate change in gradient along the liquid hydrogen flow direction, for example, from both sides of the inlet and outlet to the middle liquid cavity opening, the hole diameter of the throttle hole gradually increases, and the opening rate gradually improves. The throttle plate is made of low-temperature resistant and liquid hydrogen compatible metal material (such as stainless steel). When the liquid hydrogen flows through the gradient throttle plate, the gradient throttle plate plays a role of local flow resistance, thereby effectively hindering the pressure propagation caused by mutation; at the same time, the multi-stage gradient throttle structure can also crush and homogenize the bubbles that may exist in the liquid hydrogen, reducing the influence of gas-liquid two-phase flow on pressure fluctuation. More specifically, the gradient throttle module is a plurality of stainless steel gradient throttle plates arranged in the energy absorber along the liquid hydrogen flow direction, and the surface is treated by chrome plating for wear resistance (such as chrome plating layer thickness 5-10 μm, hardness ≥HV800); The throttle hole parameters on the throttle plate change in gradient along the direction of "energy absorber inlet and outlet flow channel → middle liquid cavity", for example, taking the throttle plate suitable for DN50 pipeline as an example, the first block has a hole diameter of 5 mm and an opening rate of 15%, the second block has a hole diameter of 8 mm and an opening rate of 25%, and the third block has a hole diameter of 12 mm and an opening rate of 35%; The distance between adjacent throttle plates is 5-15 mm and gradually increases along the liquid hydrogen flow direction. This module blocks the propagation of pressure shock caused by valve opening and load mutation by local flow resistance, while reducing the flow rate of liquid hydrogen (from 2-3 m / s at the inlet to 0.5-1 m / s in the middle liquid cavity), secondary crushing bubbles to optimize the stability of the flow field, and avoid the transmission of pressure fluctuation downstream.

[0042] Preferably, the gas-liquid separation membrane 16 is a flexible component, the inert gas cavity 15 is located on one side of the gas-liquid separation membrane 16, and the liquid cavity is located on the other side of the gas-liquid separation membrane 16; the pressure buffer module is used to push the gas-liquid separation membrane 16 to protrude towards the inert gas cavity 15 when the pressure of liquid hydrogen rises, compress the inert gas stored in the inert gas cavity 15, and convert the pressure energy of liquid hydrogen into internal energy storage of gas; when the pressure of liquid hydrogen decreases, the compressed inert gas expands and pushes the gas-liquid separation membrane 16 back to its original position, releasing the stored energy.

[0043] Preferably, the energy absorber is divided into a inert gas cavity and a liquid cavity by a gas-liquid separation membrane. The gas-liquid separation membrane is made of a low-temperature-resistant and liquid-hydrogen-and-inert-gas-compatible elastic material (such as a fluororubber membrane), has good elasticity and sealing performance, and is used for containing the flowing liquid hydrogen. The inert gas cavity is filled with inert gas (such as helium). When the liquid hydrogen pressure fluctuates, the gas-liquid separation membrane elastically deforms, the volume of the inert gas cavity changes accordingly, and the compressibility of the inert gas is used to absorb the pressure fluctuation energy, so as to buffer and stabilize the liquid hydrogen pressure and avoid the transmission of sharp pressure changes to the downstream pipeline. The inert gas cavity is a cavity in the energy absorber separated by the gas-liquid separation membrane, and is filled with inert gas. The selection of the inert gas needs to consider the compatibility with the gas-liquid separation membrane and the stability in the liquid hydrogen ultra-low temperature environment, and helium is a relatively suitable choice. When the liquid hydrogen pressure fluctuates, the inert gas cavity absorbs the energy of the pressure fluctuation through the compression or expansion of the gas, cooperates with the elastic deformation of the gas-liquid separation membrane, plays a role of pressure buffering, and makes the pressure of the liquid hydrogen in the liquid cavity relatively stable. The liquid cavity is a cavity in the energy absorber for the flow of liquid hydrogen. The liquid hydrogen enters the liquid cavity from the inlet, sequentially passes through the gradient throttle plate, contacts the spring damping inner wall (or the corrugated pipe), and finally flows out from the outlet. In the liquid cavity, the pressure fluctuation of the liquid hydrogen is subjected to multiple effects of the pressure stabilization of the gradient throttle plate, the vibration reduction of the spring damping inner wall (or the corrugated pipe), and the buffering of the gas-liquid separation membrane and the inert gas cavity, so as to realize the stabilization of the pressure.

[0044] Specifically, the inert gas filled in the inert gas cavity 15 is helium or nitrogen, the initial filling pressure is 0.3-0.8 MPa, and the inert gas cavity 15 can be provided with a pressure compensation interface. The volume of the liquid storage layer 18 is 15%-30% of the volume of the main flow liquid cavity 21, and the flow area of the liquid cavity and the liquid storage layer opening 17 is 1-3 times the minimum opening area of the throttle plate.

[0045] Preferably, in combination with Figure 2As shown, liquid hydrogen is stored in the inner container 5 of the liquid hydrogen storage tank, the liquid hydrogen layer 7 occupies the lower space of the inner container 5 for storing liquid hydrogen, and the hydrogen distribution layer 6 is located in the upper part of the inner container 5 to retain hydrogen. The liquid hydrogen storage tank adopts a composite structure of a liquid hydrogen storage tank shell 1, a vacuum jacket 2 and an insulating layer 3, wherein the vacuum jacket 2 can effectively reduce heat conduction, and the insulating layer 3 further hinders heat transfer to ensure the ultra-low temperature insulation performance of the storage tank; the internal support structure 4 supports the inner container 5, and the external support structure 12 ensures the stability of the liquid hydrogen storage tank as a whole, so that it can safely withstand the pressure of the internal liquid hydrogen and the influence of the external environment. The liquid hydrogen flows out through the liquid hydrogen outflow pipeline 8, and the regulating valve 9 arranged on the pipeline can accurately control the outflow of the liquid hydrogen according to the downstream hydrogen demand; the outflow pipeline support 10 supports the liquid hydrogen outflow pipeline 8 to prevent the pipeline from deforming or vibrating due to the gravity and flow impact force of the liquid hydrogen, and the energy absorber 11 installed on the liquid hydrogen outflow pipeline 8 is the core device for suppressing the pressure fluctuation of the liquid hydrogen.

[0046] Specifically, the energy absorber shell adopts a double-layer insulation structure, the inner layer is a stainless steel alloy (such as 4mm in thickness and ≥205MPa in yield strength), the outer layer is a 6061 aluminum alloy (such as 3mm in thickness and ≤120W / (m·K) in thermal conductivity), and the space between the two layers is filled with superfine glass wool insulation material (such as 40kg / m³ in density and ≤0.03W / (m·K) in thermal conductivity), and the space is vacuumized to a vacuum degree ≤ ) to effectively block the invasion of external heat and prevent the liquid hydrogen from flashing due to heat absorption and aggravating pressure fluctuation. The above-mentioned embodiments are based on the synergistic effect of spring-damping inner wall (or bellows), gradient throttle plate, gas-liquid separation membrane and inert gas cavity to suppress the pressure fluctuation of liquid hydrogen from multiple aspects such as vibration reduction, flow stabilization and buffering, and the energy absorption effect is remarkable. The materials used in each structure are selected for low-temperature resistance and compatibility with liquid hydrogen to ensure stable operation in the ultra-low temperature environment of liquid hydrogen, solving the problem of unstable performance of traditional energy absorption devices in low-temperature environment. Each structure has high integration and compact overall structure, which is convenient for installation and maintenance, can adapt to liquid hydrogen outflow pipelines of different specifications, has wide applicability, and the synergistic work of each structure ensures the reliability of the energy absorber.

[0047] The above-mentioned embodiments are based on the synergistic effect of spring-damping inner wall (or bellows), gradient throttle plate, gas-liquid separation membrane and inert gas cavity to suppress the pressure fluctuation of liquid hydrogen from multiple aspects such as vibration reduction, flow stabilization and buffering, and the energy absorption effect is remarkable. The materials used in each structure are selected for low-temperature resistance and compatibility with liquid hydrogen to ensure stable operation in the ultra-low temperature environment of liquid hydrogen, solving the problem of unstable performance of traditional energy absorption devices in low-temperature environment. Each structure has high integration and compact overall structure, which is convenient for installation and maintenance, can adapt to liquid hydrogen outflow pipelines of different specifications, has wide applicability, and the synergistic work of each structure ensures the reliability of the energy absorber.

[0048] Embodiment 2 Please refer to Figure 3 The embodiment provides a fluid-structure coupling optimization method flowchart for the energy absorber of embodiment 1.

[0049] As an example, the method is applied to the energy absorber of embodiment 1, and the method comprises: ​Step S1, a fluid-structure coupling physical model of the energy absorber and the liquid hydrogen pipeline is constructed, wherein the fluid domain includes the main flow liquid cavity 21 inside the energy absorber, the liquid storage layer 18 and the inlet and outlet flow passages 13 of the energy absorber, and the solid domain includes the energy absorber shell 14, the damping inner wall 19 and the gradient throttle plate 20; Step S2, the throttling pressure reduction effect of the gradient throttle plate 20 and the friction effect of the damping inner wall 19 are equivalent to flow resistance by using the lumped parameter equivalent method; the fluid inertia effects of the energy absorber inlet and outlet flow passages 13, the main flow liquid cavity 21 and the liquid storage layer 18 are equivalent to flow sensitivity; the gas compressibility energy storage effect of the inert gas cavity 15 and the volume buffer effect of the main flow liquid cavity 21 and the liquid storage layer 18 are equivalent to flow capacity; Step S3, the structural vibration characteristics are described by using the structural mechanics equation, the fluid wave characteristics are described by using the fluid mechanics control equation, and the fluid-structure coupling control equation is obtained by combining the structural mechanics equation and the fluid mechanics control equation through the preset fluid-structure coupling boundary conditions at the connection between the fluid domain and the solid domain; Step S4, the fluid-structure coupling control equation is converted into an ordinary differential equation along the characteristic line by using the characteristic line method; Step S5, a time-space discrete grid satisfying the CFL stability condition is established; Step S6, the ordinary differential equation obtained along the characteristic line is discretized by using the finite difference method, and the liquid hydrogen pressure data corresponding to each discrete grid is obtained; Step S7, based on the liquid hydrogen pressure data corresponding to each discrete grid, the liquid hydrogen pressure fluctuation amplitude reduction rate is taken as an energy absorption effect evaluation index when the liquid hydrogen pressure fluctuation amplitude reduction rate satisfies a preset condition, and based on the influence of the flow capacity, the flow sensitivity and the flow resistance on the energy absorption effect, the wave shape parameter of the damping inner wall 19, the opening gradient of the gradient throttle plate 20, the volume of the inert gas cavity 15 and the stroke distance of the main flow liquid cavity 21 are optimized.

[0050] Preferably, before explaining the fluid-structure coupling optimization method in detail, the significance of the fluid-structure coupling optimization method set here is explained: flow pipe is widely used in aerospace, nuclear power, petrochemical and other fields, and internal high pressure or low temperature fluid is often transported. In the process of operation, the pulsation of fluid, valve switching, start and stop of pump, etc. will cause disturbance of pressure and flow rate. These disturbances will interact with the structural vibration of the pipe, producing fluid-structure coupling vibration. In the pipeline of space propulsion agent, the coupling vibration may cause pressure wave amplification, sealing failure and even resonance accident. Therefore, it is of great significance to study the fluid-structure coupling vibration characteristics of flow pipe for verifying the energy dissipation effect of energy absorber. The core purpose of the method is to accurately predict and verify the effect of the designed energy absorber in inhibiting pressure fluctuation under real working conditions through computer simulation. It solves the limitation of traditional design which only considers fluid or structure and ignores the interaction between the two. The reason for using fluid-structure coupling analysis is that in the liquid hydrogen pipeline, there is a strong interaction between fluid (liquid hydrogen) and solid (pipe and energy absorber structure), including: fluid affecting structure: the pressure fluctuation of liquid hydrogen will act on the pipe wall and internal components (such as throttle plate, damping inner wall), causing deformation or vibration. Structure affects fluid: the vibration of pipe and energy absorber structure will in turn change the shape and volume of flow passage, affecting the flow state of liquid hydrogen, and thus changing the propagation of pressure wave. This "you have me, I have you" interaction is fluid-structure coupling. Ignoring it will cause the calculation result to deviate seriously from the reality, and the performance of energy absorber cannot be accurately evaluated.

[0051] The fluid-structure interaction of a fluid conveying pipe is usually represented by a set of partial differential equations (PDEs): continuity and momentum equations from the fluid, and elastic dynamics equations from the pipe wall, which are coupled through boundary conditions. These equations are often hyperbolic PDEs (wave equation type), which are difficult to solve directly, so in numerical calculation, the method of characteristics (MOC) is often used for transformation and discretization. The core idea of the method of characteristics is to find a path in the PDE that can make the equation degenerate into an ordinary differential equation (ODE). These paths are called characteristics. On the characteristic line, the partial derivative relationship is simplified to an ordinary differential relationship, which can be integrated along the characteristic line to solve. In the process of numerical implementation, first, a discrete grid that meets the stability condition in the space and time domain needs to be established, and the time step and space step are usually required to satisfy the CFL condition to ensure that the numerical propagation is consistent with the physical wave speed. Subsequently, the continuity and momentum equations of the fluid in the pipe are integrated on the characteristic line, so that the original partial differential form is transformed into an ordinary differential relationship, which is then discretized into algebraic equations by combining the finite difference approximation, so that the instantaneous values of variables such as pressure and flow rate can be recursively calculated at each intersection of the characteristic line. For the fluid-structure interaction case, the deformation or velocity of the pipe wall needs to be taken as an additional boundary condition into the fluid equation, and the pressure disturbance of the fluid simultaneously acts on the structure equation as an external excitation, and the two types of equations are coupled and solved through the interface condition in the time advancing process. Finally, this method can iteratively advance in the time domain, accurately capturing the propagation, reflection, and interaction process of fluid pressure waves and structure vibrations in the pipe system.

[0052] Preferably, the flow resistance mathematical expression is: ; The flow capacity mathematical expression is: ; The flow sensitivity mathematical expression is: ; In the formula, is the volume flow resistance, with the unit of ; is the fluid dynamic viscosity, with the unit of ; l is the length of the liquid hydrogen outflow pipe, with the unit of m; d is the inner diameter of the liquid hydrogen outflow pipe, with the unit of m; is the volume flow capacity, with the unit of ; A is the cross-sectional area of the liquid hydrogen outflow pipe, with the unit of ; is the fluid density, with the unit of ; a is the sound speed, with the unit of ; is the volume flow sensitivity, with the unit of .

[0053] Specifically, before making detailed calculations, the embodiment adopts a clever simplification approach to equivalent complex distributed parameter system to familiar circuit network concept, so as to facilitate quick analysis and understanding: The flow resistance is the energy loss of the fluid due to the pressure drop caused by the viscous force. Generally, the pressure drop of the fluid component and the flow rate through it have the following relationship, which is usually expressed in terms of volumetric flow rate: ; Similar to the definition of resistance, the ratio of the pressure drop across the fluid component to the flow rate through the component under steady flow is defined as the flow resistance, that is, R = ΔP / Q, then: ; In the formula, The pressure loss is in Pa; The flow rate is in ; K is the characteristic constant of the flow resistance; n is the characteristic index of the flow resistance. The definition of flow resistance in the formula is essentially the steady-state flow resistance under steady flow, whether it can be directly used in alternating fluid networks needs to be discussed and analyzed. It can be seen that when n = 1, and are in a linear relationship, which is called linear flow resistance. In this case, the flow resistance is a constant independent of the flow rate, and the resistance value is equal in static and dynamic, which can be directly used in alternating fluid networks. The laminar flow type of circular pipe belongs to this case, and the volumetric flow resistance of the laminar flow type of circular pipe can be obtained from the Poiseuille law: ; In the formula, The volumetric flow resistance is in ; The dynamic viscosity of the fluid is in ; l is the length of the pipe, in m; d is the inner diameter of the pipe, in m.

[0054] Due to the compressibility of the fluid, when the pressure in the container increases, the mass of the fluid in it will increase, resulting in mass accumulation, which is similar to the way the capacitor in the circuit accumulates electric charge, converting potential energy into kinetic energy and storing it. If the volumetric flow rate is equivalent to the electric current, the flow capacity is defined as the ratio of the change in fluid volume to the change in pressure that causes it, that is: ; In the formula, The volumetric flow capacity is in ; V is the volume of the fluid, in ; t is the time, in s.

[0055] For liquids, their compressibility can only be manifested at high pressures, and the bulk modulus of elasticity K is usually used to represent it. It is defined as the ratio of the change in pressure to the relative change in volume, that is: ; In the formula, K is the bulk modulus, in Pa.

[0056] According to the above definition, the flow capacity of the liquid can be described as the ratio between the volume change and the pressure change that causes the change, that is: ; For the liquid pipeline, there is a certain relationship between the bulk modulus and the propagation speed of small disturbance wave, i.e. the sound speed. The fluid sound speed is an extremely important parameter in the dynamic analysis of the conveying system. It is not only related to the physical properties of the fluid itself, but also related to the geometric size of the pipeline, the mechanical properties of the material, and the structural support method. In the application, it is regarded as a constant and can be calculated by: At this time, the flow capacity of the liquid can also be represented as: ; In the formula, A is the cross-sectional area of the pipeline, and the unit is ; ρ is the fluid density, and the unit is ; a is the sound speed, and the unit is .

[0057] Under the action of inertia, the acceleration or deceleration of the fluid mass will cause a change in pressure, which is similar to the self-induced potential in the circuit network, i.e. the conversion of potential energy (pressure energy) into kinetic energy storage. If the volume flow rate is equivalent to the current, the flow inductance can be defined as the ratio of the pressure change at both ends of the pipeline to the flow rate change rate, i.e.: ; In the formula, is the volume flow inductance, and the unit is .

[0058] The acceleration or deceleration of the fluid mass due to inertia will cause a change in pressure. This phenomenon can be described according to the relationship between the force causing the fluid motion state and the speed change, i.e.: ; The calculation formula of the pipeline flow inductance is obtained from the definition of the flow inductance: ; ; In the formula, u is the speed of the fluid, and the unit is m / s.

[0059] In the subsequent process of optimizing the structural parameters of the energy absorber, in order to avoid excessive flow resistance leading to local pressure drop, avoid excessive flow inductance leading to flow rate out of control, and avoid excessive flow capacity leading to insufficient buffering, the structural parameters are optimized.

[0060] Preferably, the fluid mechanics control equation in step S3 includes a fluid momentum equation considering a pipeline axial vibration coupling term and a fluid continuity equation considering a pipeline deformation coupling term, and the structural mechanics equation includes a pipeline axial motion equation considering a fluid pressure excitation term and a pipeline constitutive equation considering a fluid and structure speed coupling term. The fluid momentum equation is: ; The fluid continuity equation is: ; The pipe axial motion equation is: ; The pipe constitutive equation is: ; ; ; wherein subscript f represents fluid parameters, subscript t represents pipe parameters, and subscript r represents the difference between fluid physical quantities and pipe physical quantities; is the gravitational acceleration, taken as ; and are the axial motion velocities of the fluid and the pipe, respectively, is the difference between the two velocities, with a unit of m / s; is the fluid pressure head, with a unit of m; is the axial stress of the pipe, with a unit of Pa; and are the densities of the fluid and the pipe material, respectively, with a unit of ; and are the cross-sectional areas of the fluid and the pipe, respectively, with a unit of ; K is the bulk modulus of the fluid, with a unit of Pa; is the elastic modulus of the pipe, with a unit of Pa; is the axial length, with a unit of m; is the time, with a unit of s; is the inner radius of the pipe, with a unit of m; is the pipe wall thickness, with a unit of m; is the friction resistance factor; is the Poisson ratio; is the angle between the pipe axis and the horizontal plane, taken as positive in the direction of the pipe lifting height reduction; is the pressure wave velocity; is the stress wave velocity; is the fixed point acceleration.

[0061] Preferably, since it is almost impossible to directly solve this set of complex partial differential equations, the present embodiment adopts the method of characteristics, which is a powerful mathematical tool for converting partial differential equations into ordinary differential equations. Therefore, step S4 of converting the fluid-structure coupling control equation into an ordinary differential equation along a characteristic line by using the method of characteristics comprises: the method of characteristics is a special method for solving the initial boundary value problem of hyperbolic partial differential equations, has high calculation accuracy, and is the most accurate among various finite difference numerical calculations; the equation is solved by using the method of characteristics, and the fluid-structure coupling four-equation model is written in matrix form: ; wherein, and are coefficient matrices, , is a 1x4-dimensional vector, and its expression is: ; ; ; ; .

[0062] characteristic equation has four different real roots, i.e. the pressure wave propagation speed and the water hammer wave propagation speed: ; ; ; ; wherein, ;

[0063] By using the method of characteristics, the equation set can be converted into four ordinary differential equations for solving. In the characteristic line Figure 4 , , , , , there are compatible equations, and the compatible equations are as follows: ; ; ; ; wherein, the characteristic line slope coefficient ( , , , 、 、 、 、 )and the residual ( 、 )corresponding physical quantity expression: ; ; ; ; ; ; ; ; ; .

[0064] Preferably, in the process of numerically solving the compatible equations, step S5, a space-time discrete grid satisfying the CFL stability condition is established; step S6, the ordinary differential equation obtained along the characteristic line is discretized using the finite difference method to obtain the liquid hydrogen pressure data corresponding to each discrete grid, including: Discretization and solution: as shown in Figure 4 , grid division: the pipeline and energy absorber are divided into small segments (grids) in space and small steps in time. CFL condition: to ensure calculation stability, the time step and space step must satisfy the Courant-Friedrichs-Lewy condition, that is, the distance of physical wave propagation in one time step cannot exceed one space step. Finite difference: the compatible equation obtained on the characteristic line is discretized by finite difference method, which is approximated as a set of algebraic equations. Time marching: starting from the initial state, the fluid pressure (based on H), fluid velocity (V), pipeline stress (P) and pipeline velocity (U) at each grid point in the next time step can be calculated using these algebraic equations. Such a cycle iteration can simulate the dynamic evolution of the entire system over time.

[0065] Specifically, combined with the definitions and expressions of flow resistance, flow capacity and flow sensitivity in the above embodiments, the damping inner wall 19 wave shape parameters, the gradient throttle plate 20 opening gradient, the inert gas cavity 15 volume, and the main flow liquid cavity 21 stroke distance can be optimized to adjust the energy absorption effect by changing the numerical value of flow resistance, flow capacity and flow sensitivity. Some of the influencing mechanisms are as follows: ​The damping inner wall 19 is a wave structure of spring damping and bellows combination, and the core wave parameters include wave amplitude (the maximum height of the inner wall protrusion / recess) and wave length (the distance between adjacent protrusions / recesses). These parameters affect the flow resistance by changing the liquid hydrogen flow resistance. The increase of the inner wall protrusion / recess height and the decrease of the distance between adjacent protrusions / recesses enhance the disturbance of the liquid hydrogen flow process, directly leading to the destruction of the boundary layer, the increase of the turbulence degree, the strengthening of the viscous friction, the increase of the flow resistance, and the more effective hindering of the pressure wave propagation and the consumption of the pressure fluctuation energy.

[0066] The core opening gradient parameter of the gradient throttle plate 20 refers to the change rate of the hole diameter along the liquid hydrogen flow direction (the ratio of the difference between the hole diameters d1 and d2 to the distance from the inlet to the middle liquid chamber). The effect of the parameter on the energy dissipation is mainly realized by adjusting the flow resistance. The flow resistance of the throttle plate mainly comes from the local flow resistance introduced by the diameter change in the "orifice contraction-expansion" process. The smaller the opening size and the lower the opening rate, the greater the local resistance and the higher the flow resistance. The core function of the "gradient change" is to realize "graded energy dissipation" to avoid the sudden pressure drop caused by a single high resistance throttle plate, which may trigger new fluctuations.

[0067] The core parameter of the inert gas chamber 15 is the volume Vg, and the effect of the parameter on the energy dissipation is realized by adjusting the local flow capacity C. The greater the Vg, the greater the flow capacity of the gas chamber. The core function of the gas chamber is to "buffer pressure fluctuations". When the liquid hydrogen pressure rises, the gas-liquid separation membrane 16 protrudes into the inert gas chamber, compresses the gas, and reduces the volume of the gas to absorb pressure energy through gas compression. When the liquid hydrogen pressure decreases, the gas expands to push the separation membrane back, releasing energy to supplement the pressure. The volume of the inert gas chamber is not the larger the better. Too large a volume will occupy the space of the main liquid flow channel and increase the overall volume of the energy absorber, which violates the principle of compact structure.

[0068] The core parameter of the main liquid chamber 21 is the travel distance l, which is the flow path length of the liquid hydrogen from the inlet to the outlet in the liquid chamber. A greater flow path length slows down the flow rate change through inertia, reduces the pressure fluctuations caused by sudden changes in flow rate, ensures the propagation time of pressure fluctuations in the energy absorber, and gives other pressure buffering structures sufficient time to act.

[0069] Specific examples, DN50, 1000mm long liquid hydrogen stainless steel straight pipeline valve closing and opening valve hydrogen shock vibration theory calculation, and the introduction of energy absorber to verify the effect of energy absorber. The experimental conditions are as follows: (1) For the valve closing hydrogen shock, the schematic diagram is as Figure 5aThe upstream liquid hydrogen tank pressure is 0.16 MPa, and the regulating valve 23 is vented outside; at the initial moment, the opening of the regulating valve 23 is adjusted so that the flow rate in the pipe is stabilized at 0.2 m / s. After preparation, the regulating valve 23 is quickly closed at 0.1 s, the flow rate at the valve 23 is rapidly reduced to 0, and the fluid pressure is sharply increased, thereby causing the hydrogen shock effect, and the pressure wave propagates back and forth between the regulating valve 23 and the liquid hydrogen tank. Since the upstream tank is a constant pressure source, and the downstream valve 23 is a pressure source point, the pressure value of the valve 23 only depends on the flow rate and the speed of closing the valve, and therefore it is more reasonable to select the fluid pressure measuring point 22 at the middle.

[0070] (2) For the opening valve water hammer, the schematic diagram is as shown in Figure 5b The upstream liquid hydrogen tank pressure is 0.16 MPa, and the downstream is a closed flange 24; at the initial moment, the pipe is at atmospheric pressure. After preparation, the upstream liquid hydrogen tank stop valve 23 is quickly opened at 0.1 s, the pipe is connected with the tank, and the liquid hydrogen enters the pipe to impact the closed flange 24, the fluid pressure at the closed flange 24 is sharply increased, thereby causing the water hammer effect, and the pressure wave propagates back and forth between the closed flange 24 and the liquid hydrogen tank. Since the pressure wave source point is at the stop valve 23, and the fluid propagates through the pipe and the energy absorber, the fluid pressure is sharply increased when impacting the closed flange 24, and therefore it is more reasonable to select the fluid pressure measuring point 22 in front of the closed flange 24.

[0071] The comparison diagram of the fluid pressure fluctuation of the valve-closing hydrogen shock, the valve-opening hydrogen shock, and the presence or absence of the energy absorber is as shown in Figure 6a-6d As shown in Figure 6a and 6b For the valve-closing water hammer, the initial pressure in the pipe before 0.1 s is maintained at 0.16 MPa, the valve is closed at 0.1 s, the fluid pressure is quickly increased to the maximum value, and then oscillates and attenuates with 0.16 MPa as the baseline. After installation of the energy absorber, the fluid pressure peak value is reduced from 0.35 MPa to 0.174 MPa, the peak value is reduced by 50.30%, and the fluid pressure attenuation speed is accelerated. Figure 6c and 6d For the valve-opening hydrogen shock, the initial pressure in the pipe before 0.1 s is 0 (gauge pressure), the liquid hydrogen tank is instantaneously opened at 0.1 s, the fluid pressure is quickly increased to the maximum value, and then oscillates and attenuates with 0.16 MPa as the baseline. After installation of the energy absorber, the fluid pressure peak value is reduced from 0.4 MPa to 0.207 MPa, the peak value is reduced by 48.25%, and the fluid pressure attenuation speed is accelerated.

[0072] That is, the method is more powerful in the reverse direction of the design. By changing the wave-shaped parameters of the damping inner wall in the model, the opening gradient of the gradient throttle plate, the volume of the inert gas cavity and the stroke distance of the main flow liquid cavity, repeatedly running the simulation, observing the change of the energy dissipation effect, so as to find the optimal structure design parameters on the computer before manufacturing the expensive physical prototype.

[0073] It can be found that the present embodiment is a method embodiment corresponding to the first embodiment, and the present embodiment can be implemented in cooperation with the first embodiment. The related technical details mentioned in the first embodiment are still valid in the present embodiment. In order to reduce repetition, they will not be described here. Correspondingly, the related technical details mentioned in the present embodiment can also be applied in the first embodiment.

[0074] Embodiment 3 The present embodiment also proposes a storage medium, which stores the fluid-solid coupling optimization method for the energy dissipater. The fluid-solid coupling optimization program for the energy dissipater is executed by the processor to realize the steps of the fluid-solid coupling optimization method for the energy dissipater as described above. Since the present storage medium adopts all the technical solutions of the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described here one by one.

[0075] Embodiment 4 Please refer to Figure 7 The present embodiment also provides an electronic device, which includes 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 realize the fluid-solid coupling optimization method for the energy dissipater provided in embodiment 2.

[0076] The memory 702 and the processor 701 are connected by bus. The bus can include any number of interconnected buses and bridges. The bus connects one or more processors 701 and various circuits of the memory 702 together. The bus can also connect various other circuits such as peripheral devices, voltage stabilizers and power management circuits together, which are well known in the art, and therefore will not be further described herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be one element or multiple elements such as multiple receivers and transmitters, which provide a unit for communicating with various other devices on the transmission medium. The data processed by the processor 701 is transmitted on the wireless medium through the antenna, and further, the antenna also receives data and transmits the data to the processor 701.

[0077] The 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. The memory 702 can be used to store data used by the processor 701 in performing operations.

[0078] The above is only an embodiment of the present application, and the common knowledge of the specific structure and characteristics in the scheme is not described in detail. The ordinary skilled person in the art knows all the ordinary technical knowledge in the field of the present application before the application date or the priority date, can know all the prior art in the field, and has the ability to apply conventional experimental means before that date. The ordinary skilled person in the art can perfect and implement the present scheme based on the disclosure given in the present application, and the ability of the ordinary skilled person in the art should not be an obstacle to the implementation of the present application. It should be noted that for those skilled in the art, without departing from the structure of the present application, a number of modifications and improvements can be made, which should be considered as the protection scope of the present application. The scope of protection of the present application should be subject to the content of its claims, and the specific implementation mode in the specification can be used to explain the content of the claims.

Claims

1. A liquid hydrogen pipeline pressure fluctuation suppression energy dissipator, said dissipator being in series with a liquid hydrogen outflow pipeline, characterized by, The energy absorber comprises an energy absorber shell (14), a damping vibration module, a gradient throttling module and a pressure buffer module, the damping vibration module, the gradient throttling module and the pressure buffer module are integrated inside the energy absorber shell (14), and the energy absorber shell (14) is provided with an energy absorber inlet and outlet flow channel (13) matched with the liquid hydrogen outlet pipeline (8) at both ends. The damping vibration module is a damping inner wall (19) arranged on the inner wall of the energy absorber shell (14), the damping inner wall (19) adopts a combined form of spring damping structure and bellows structure, and the whole is in a wave shape. The gradient throttling module is a plurality of gradient throttling plates (20) arranged inside the energy absorber along the liquid hydrogen flow direction, the gradient throttling plate (20) is provided with a throttling hole, and the hole diameter and the opening rate of the throttling hole increase in a gradient along the direction of the liquid hydrogen flowing from the inlet and outlet flow channel (13) to the middle liquid chamber. The pressure buffer module comprises a gas-liquid separation membrane (16), an inert gas chamber (15) and a liquid chamber, the gas-liquid separation membrane (16) divides the inside of the energy absorber shell (14) into the inert gas chamber (15) and the liquid chamber, the liquid chamber comprises a main flow liquid chamber (21) and a liquid storage layer (18), the main flow liquid chamber (21) and the liquid storage layer (18) are communicated through a liquid chamber and liquid storage layer opening (17), and the inert gas chamber (15) is filled with inert gas.

2. The liquid hydrogen pipeline pressure surge mitigation damper of claim 1, wherein, The spring damping structure in the damping inner wall (19) is composed of a low-temperature resistant elastic spring and an inner wall base, and the bellows structure is a metal pipe structure with wave-shaped corrugations. The damping inner wall (19) is used for consuming the pipeline vibration energy when the liquid hydrogen flow causes pipeline vibration, the elastic spring consumes the pipeline vibration energy through elastic deformation and damping effect, the bellows structure absorbs the vibration mechanical energy through elastic expansion and contraction, and the wave-shaped inner wall is used for increasing the resistance of the liquid hydrogen along the pipeline to hinder the propagation of the pressure wave, breaking the gas bubbles generated in the liquid hydrogen due to flashing, and reducing the influence of the gas-liquid two-phase flow on the pressure fluctuation.

3. The liquid hydrogen pipeline pressure surge mitigation damper of claim 1, wherein, The gradient throttling plate (20) is used for blocking the propagation of the pressure sudden change caused by the opening and closing of the valve and the load mutation through local flow resistance, reducing the liquid hydrogen flow rate, and breaking the gas bubbles again to optimize the flow field stability and avoid the transmission of the pressure fluctuation to the downstream.

4. The liquid hydrogen pipeline pressure surge mitigation damper of claim 1, wherein, The gas-liquid separation membrane (16) is a flexible component, the inert gas chamber (15) is located on one side of the gas-liquid separation membrane (16), and the liquid chamber is located on the other side of the gas-liquid separation membrane (16). The pressure buffer module is used for pushing the gas-liquid separation membrane (16) to protrude towards the inert gas chamber (15) when the liquid hydrogen pressure rises, compressing the inert gas stored in 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, pushes the gas-liquid separation membrane (16) back to the original position, and releases the stored energy.

5. The liquid hydrogen pipeline pressure surge mitigation damper of claim 4, wherein, The liquid chamber is used for flowing the liquid hydrogen into or out of the liquid storage layer (18) through the liquid chamber and liquid storage layer opening (17) when the pressure changes sharply, directly absorbing or supplementing the liquid through volume change, and assisting in buffering the pressure fluctuation.

6. A method of fluid-structure coupling optimization for the energy absorber of claim 1, characterized by, The method comprises: Step S1, a fluid-structure coupling physical model of the energy absorber and the liquid hydrogen pipeline is constructed, wherein the fluid domain includes a main flow liquid cavity (21) inside the energy absorber, a liquid storage layer (18) and an energy absorber inlet and outlet flow channel (13), and the solid domain includes an energy absorber shell (14), a damping inner wall (19) and a gradient throttle plate (20); Step S2, the throttling pressure reduction effect of the gradient throttle plate (20) and the friction effect of the damping inner wall (19) are equivalent to flow resistance by using the lumped parameter equivalent method; the fluid inertia effects of the energy absorber inlet and outlet flow channel (13), the main flow liquid cavity (21) and the liquid storage layer (18) are equivalent to flow sensitivity; and the gas compressibility energy storage effect of the inert gas cavity (15) and the volume buffer effect of the main flow liquid cavity (21) and the liquid storage layer (18) are equivalent to flow capacity; Step S3, the structural vibration characteristics are described by using a structural mechanics equation, the fluid wave characteristics are described by using a fluid mechanics control equation, and the fluid-structure coupling control equation is obtained by combining the structural mechanics equation and the fluid mechanics control equation through the preset fluid-structure coupling boundary conditions at the connection between the fluid domain and the solid domain; Step S4, the fluid-structure coupling control equation is converted into a constant differential equation along a characteristic line by using a characteristic line method; Step S5, a time-space discrete grid satisfying a CFL stability condition is established; Step S6, the constant differential equation obtained along the characteristic line is discretized by using a finite difference method, and liquid hydrogen pressure data corresponding to each discrete grid are obtained; Step S7, based on the liquid hydrogen pressure data corresponding to each discrete grid, the liquid hydrogen pressure fluctuation amplitude reduction rate is taken as an energy absorption effect evaluation index when a preset condition is satisfied, and based on the influences of the flow capacity, the flow sensitivity and the flow resistance on the energy absorption effect, the wave shape parameters of the damping inner wall (19), the opening gradient of the gradient throttle plate (20), the volume of the inert gas cavity (15) and the stroke distance of the main flow liquid cavity (21) are optimized.

7. The method of fluid-structure coupling optimization of an energy dissipater according to claim 6, wherein, The flow resistance mathematical expression is: ； The flow capacity mathematical expression is: ； The flow sensitivity mathematical expression is: ； wherein is the volumetric flow resistance, with units of ; is the hydrodynamic viscosity, with units of ; l is the length of the liquid hydrogen outflow pipe, with units of m; d is the inner diameter of the liquid hydrogen outflow pipe, with units of m; is the volumetric flow capacity, with units of ; A is the cross-sectional area of the liquid hydrogen outflow pipe, with units of ; is the fluid density, with units of ; a is the speed of sound, in units of ; is the volumetric flow sense, in units of .

8. The method of fluid-structure coupling optimization of an energy dissipater according to claim 6, wherein, The fluid mechanics control equation includes a fluid momentum equation considering a pipeline axial vibration coupling term and a fluid continuity equation considering a pipeline deformation coupling term, and the structural mechanics equation includes a pipeline axial motion equation considering a fluid pressure excitation term and a pipeline constitutive equation considering a fluid and structure velocity coupling term; The fluid momentum equation is: ； The fluid continuity equation is: ； The pipeline axial motion equation is: ； The pipeline constitutive equation is: ； ； ； where subscript f represents fluid parameters, subscript t represents pipe parameters, and subscript r represents the difference between fluid physical quantities and pipe physical quantities; is the gravitational acceleration, taken as ; and are the axial movement velocities of the fluid and the pipe, respectively, is the difference between the two velocities, in units of m / s; is the fluid pressure head, in units of m; is the axial stress of the pipe, in units of Pa; and are the densities of the fluid and the pipe material, respectively, in units of ; and are the cross-sectional areas of the fluid and the pipe, respectively, in units of ; K is the bulk modulus of the fluid, in units of Pa; is the elastic modulus of the pipe, in units of Pa; is the axial length, in units of m; is the time, in units of s; is the inner radius of the pipe, in units of m; is the pipe wall thickness, in units of m; is the friction resistance factor; is the Poisson ratio; is the angle between the pipe axis and the horizontal plane, taken as positive in the direction of the pipe lifting height reduction; is the pressure wave velocity; is the stress wave velocity; is the fixed point acceleration.

9. The method for fluid-structure coupling optimization of an energy dissipater according to claim 6, wherein, The fluid-structure coupling boundary conditions include a displacement compatibility condition and a pressure balance condition; The displacement compatibility condition is that the radial or axial deformation of the pipe wall is compatible with the volume change of the flow channel caused thereby; The pressure balance condition is that the pressure pulsation of the fluid acts on the pipe wall structure as an external excitation.

10. The method of fluid-structure coupling optimization of an energy dissipater according to claim 6, wherein, The wave shape parameters of the damping inner wall (19) include a wave amplitude and a wave length, the liquid hydrogen flow resistance is changed by changing the wave amplitude and the wave length, the liquid hydrogen flow resistance is increased by increasing the height of the inner wall protrusion / recess and reducing the distance between adjacent protrusions / recesses, and the disturbance of the liquid hydrogen flow process is enhanced, so that the flow resistance is increased. The opening gradient parameter of the gradient throttle plate (20) is the aperture variation rate along the liquid hydrogen flow direction, and the influence of the opening gradient parameter on the energy dissipation effect is realized by adjusting the flow resistance, the smaller the opening size, the lower the opening rate, the greater the local resistance, and the higher the flow resistance; The core parameter of the inert gas cavity (15) is the volume, and the influence of the volume on the energy dissipation effect is realized by adjusting the local flow capacity, and the greater the volume, the greater the flow capacity of the gas cavity; The core parameter of the main flow liquid cavity (21) is the stroke distance, and the stroke distance is the flow path length of liquid hydrogen in the liquid cavity from the inlet to the outlet, and the influence of the stroke distance on the energy dissipation effect is realized by adjusting the flow feeling.

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