Design method of pressure pulsation attenuator

Abstract

The invention discloses a pressure pulsation attenuator design method, and relates to the field of fluid medium pipeline vibration noise control, and the method comprises the steps: determining the characteristic frequency of a fluid conveying pipeline system under a target working condition, and initializing the design parameters of a pressure pulsation attenuator; constructing an attenuator model, and fitting by using a numerical simulation method to obtain fluid characteristic parameters of the attenuator model; based on the kinetic equation of the energy absorption disc model and the inlet and outlet flow conservation equation of the attenuator model, an energy absorption disc state-space equation is established in combination with the fluid characteristic parameters; solving the state-space equation of the energy absorption disc to obtain an inherent frequency calculation value of the pressure pulsation attenuator; and adjusting design parameters until the design requirements are met, and designing to obtain the pressure pulsation attenuator. The design parameters are optimized through combination of numerical simulation and theoretical analysis, and the performance and the effect of the pressure pulsation attenuator are effectively improved.

Description

Technical Field

[0001] The present application relates to the field of vibration and noise control of fluid medium pipelines, and particularly to a design method for a pressure pulsation attenuator. Background Art

[0002] The fluid conveyance pipeline system realizes functions such as fluid medium supply and energy transfer through pump-like devices. Among them, primary excitation sources such as hydraulic motors and hydraulic pumps, secondary excitation sources such as valves and elbows, and the circuit of the pipeline system will all generate pressure pulsations during the process of fluid medium transmission. The periodic pressure pulsations will disrupt the flow characteristics of the fluid in the pipe, induce non-uniform flow of the fluid in the pipe, deteriorate the operation quality of the pipeline system, and cause structural vibration and radiated noise of the pipeline and its accessories. The vibration and noise generated by the fluid conveyance pipeline system will not only reduce the service life and operation performance of the accessories, but also affect the living environment of the surrounding personnel.

[0003] Currently, installing a pressure pulsation attenuator is widely used to suppress the vibration and noise of the fluid conveyance pipeline system. By reasonably designing the structure of the pressure pulsation attenuator, the effect of reducing fluid pressure pulsations can be achieved. Therefore, the design and evaluation of the pressure pulsation attenuator for the fluid conveyance pipeline are of great significance.

[0004] The design of traditional pressure pulsation attenuators mainly manually adjusts the design parameters of the pressure pulsation attenuator based on human experience. The unreasonable design parameters are likely to introduce additional errors, making it difficult to ensure the performance and effect of the pressure pulsation attenuator in suppressing pressure pulsations, and the efficiency is low. Especially when applied to complex fluid environments, the stability and robustness are not ideal. Summary of the Invention

[0005] In view of the above problems and technical requirements, the present application proposes a design method for a pressure pulsation attenuator, and the technical solution of the present application is as follows:

[0006] A design method for a pressure pulsation attenuator includes the following steps:

[0007] Determine the characteristic frequency of the fluid conveyance pipeline system under the target working condition and initialize the design parameters of the pressure pulsation attenuator;

[0008] Construct an attenuator model according to the design parameters of the pressure pulsation attenuator, and use numerical simulation methods to fit and obtain the fluid characteristic parameters of the attenuator model operating under the target working condition; the attenuator model includes an energy absorption disc model, and the pressure pulsation energy of the fluid conveyance pipeline system is transferred and dissipated through the movement of the energy absorption disc model; the fluid characteristic parameters indicate the fluid characteristics of the attenuator model when the energy absorption disc model is in different positions;

[0009] Based on the dynamic equation of the energy absorbing disk model and the conservation equation of the inlet and outlet flow of the attenuator model, the state space equation of the energy absorbing disk is established in combination with the fluid characteristic parameters; the natural frequency calculation value of the pressure pulsation attenuator is obtained by solving the state space equation of the energy absorbing disk;

[0010] The design parameters of the pressure pulsation attenuator are adjusted until the deviation between the calculated value of the natural frequency and the characteristic frequency of the fluid delivery pipeline system meets the design requirements, and the pressure pulsation attenuator is designed.

[0011] A further technical solution is that the energy absorbing disk state space equation is related to the displacement x(t), velocity v(t) of the energy absorbing disk model and the inlet pressure p of the attenuator model. in (t) is related to; the calculated value of the natural frequency of the pressure pulsation attenuator obtained by solving includes:

[0012] Calculate the energy absorbing disk state space equation for the displacement x(t), velocity v(t) of the energy absorbing disk model and the inlet pressure p of the attenuator model in The partial derivative of (t) is used to obtain the Jacobian matrix of the state space equation of the energy absorbing disk;

[0013] Determine the displacement x(t), velocity v(t) of the energy absorbing disk model and the inlet pressure p of the attenuator model in (t) When the first-order derivative of time t is 0, the energy absorbing disk model is in equilibrium, and the displacement x(t), velocity v(t) of the energy absorbing disk model and the inlet pressure p of the attenuator model when the energy absorbing disk model is in equilibrium in (t) Substitute the Jacobian matrix into the Jacobian matrix and calculate the value of each element of the Jacobian matrix;

[0014] Solve the eigenvalue of the Jacobian matrix and obtain the calculated value of the natural frequency of the pressure pulsation attenuator.

[0015] A further technical solution is that the energy absorbing disk state space equation includes a first state variable expression y1, a second state variable expression y2 and a third state variable expression y3; establishing the energy absorbing disk state space equation includes:

[0016] Based on the dynamic equation of the energy absorbing disk model and combined with the fluid characteristic parameters, the first state variable expression y1 and the second state variable expression y2 of the energy absorbing disk state space equation are determined; based on the dynamic equation of the energy absorbing disk model and the inlet and outlet flow conservation equation of the attenuator model and combined with the fluid characteristic parameters, the third state variable expression y3 of the energy absorbing disk state space equation is determined;

[0017] The first state variable expression y1, the second state variable expression y2 and the third state variable expression y3 are combined to obtain the energy absorption disk state space equation [y1, y2, y3] T .

[0018] A further technical solution is that the fluid characteristic parameter includes the fluid excitation force F fluid (t) received by the energy absorption disc model; the dynamic equation of the energy absorption disc model is:

[0019]

[0020] Determine the expression of the first state variable of the energy absorption disc state space equation according to the dynamic equation of the energy absorption disc model

[0021] According to the dynamic equation of the energy absorption disc model and combined with the fluid excitation force F fluid (t), determine the expression of the second state variable of the energy absorption disc state space equation

[0022] where m is the mass of the energy absorption disc, c is the damping coefficient, k is the spring stiffness, x(t) is the displacement of the energy absorption disc model, v(t) is the velocity of the energy absorption disc model, is the first derivative of x(t), is the second derivative of x(t), A s is the force-bearing area of the energy absorption disc model, p in (t) is the inlet pressure of the attenuator model, p out (t) is the outlet pressure of the attenuator model; the fluid excitation force F fluid (t) is related to the inlet pressure p in (t) of the attenuator model.

[0023] A further technical solution is that the fluid characteristic parameter includes the flow coefficient C e (t); the inlet and outlet flow conservation equation of the attenuator model is:

[0024]

[0025] Determine the expression of the third state variable of the energy absorption disc state space equation according to the dynamic equation of the energy absorption disc model and the inlet and outlet flow conservation equation of the attenuator model

[0026]

[0027] where E is the bulk modulus of elasticity of the fluid, V is the energy absorption cavity volume of the attenuator model, q in (t) is the inlet flow rate of the attenuator model, q out (t) is the outlet flow rate of the attenuator model, ρ is the fluid density, F fluid (t) is the fluid excitation force, A s is the force-bearing area of the energy absorption disc model, p in (t) is the inlet pressure of the attenuator model, p out(t) is the outlet pressure of the attenuator model, indicating the inlet pressure p of the attenuator model in The first derivative of (t), the flow coefficient C e (t) is related to the inlet pressure p of the attenuator model in (t).

[0028] Its further technical solution is that the design parameters include the mass m of the energy-absorbing disc, the spring stiffness k, and the damping coefficient c. The design parameters for adjusting the pressure pulsation attenuator include:

[0029] When the deviation between the calculated value of the natural frequency and the characteristic frequency of the fluid-conveying pipeline system does not meet the design requirements, and the calculated value of the natural frequency is lower than the characteristic frequency of the fluid-conveying pipeline system, according to the natural frequency of the pressure pulsation attenuator it is determined to increase the spring stiffness k, or decrease the mass m of the energy-absorbing disc; according to the adjusted mass m of the energy-absorbing disc and the spring stiffness k, and combined with the damping ratio of the pressure pulsation attenuator under the condition within the predetermined damping ratio range, adjust the damping coefficient c;

[0030] When the deviation between the calculated value of the natural frequency and the characteristic frequency of the fluid-conveying pipeline system does not meet the design requirements, and the calculated value of the natural frequency is higher than the characteristic frequency of the fluid-conveying pipeline system, according to the natural frequency of the pressure pulsation attenuator it is determined to decrease the spring stiffness k, or increase the mass m of the energy-absorbing disc; according to the adjusted mass m of the energy-absorbing disc and the spring stiffness k, and combined with the damping ratio of the pressure pulsation attenuator under the condition within the predetermined damping ratio range, adjust the damping coefficient c.

[0031] Its further technical solution is that the design parameters include the shape of the energy-absorbing disc; initializing the shape of the energy-absorbing disc includes:

[0032] Determine the shape of the energy-absorbing disc according to the pressure pulsation amplitude of the fluid-conveying pipeline system under the target working condition;

[0033] When the pressure pulsation amplitude is less than the predetermined threshold, initialize the shape of the energy-absorbing disc as conical, otherwise, initialize the shape of the energy-absorbing disc as disc-shaped.

[0034] Its further technical solution is that the pressure pulsation attenuator further includes an energy-absorbing cavity, a mass-spring-damper, and an adjusting end cover. One end of the mass-spring-damper is fixed on the energy-absorbing disc, and the other end is fixed on the adjusting end cover. The adjusting end cover is arranged on the side wall of the energy-absorbing cavity; by moving the position of the adjusting end cover, change the volume of the energy-absorbing cavity to adapt to different target working conditions.

[0035] Its further technical solution is that the design method of the pressure pulsation attenuator includes:

[0036] When the deviation between the calculated value of the natural frequency and the characteristic frequency of the fluid-conveying pipeline system is within the predetermined error range, it is determined that the design requirements are met.

[0037] The beneficial technical effects of this application are as follows:

[0038] A design method of a pressure pulsation attenuator proposed in this application calculates the natural frequency of the attenuator model by constructing an attenuator model and using a method combining numerical simulation and theoretical analysis, fully combining the high efficiency and convenience of the numerical simulation method and the interpretability and accuracy of the theoretical analysis method. The method of this application can efficiently handle the complex boundary conditions and fluid-structure coupling problems of the fluid-conveying pipeline system, breaking through the limitations of traditional analytical methods. Through the theoretical analysis of the working process of the pressure pulsation attenuator, the natural frequency of the pressure pulsation attenuator can be accurately calculated and the design parameters can be automatically iteratively optimized, effectively improving the efficiency of the design process. Compared with the method of manually adjusting the design parameters, the design cycle is greatly shortened while ensuring the stability and accuracy of the designed pressure pulsation attenuator.

[0039] This application designs a pressure pulsation attenuator with an adjustable energy-absorbing cavity volume. Compared with the traditional pressure pulsation attenuator with a fixed structure, the pressure pulsation attenuator designed in this application changes the volume of the energy-absorbing cavity by moving the position of the adjusting end cover to adapt to the pressure pulsation generated by the fluid in the fluid-conveying pipeline under different working conditions. The design of the movable adjusting end cover expands the range of characteristic frequencies of the fluid-conveying pipeline system that the pressure pulsation attenuator can absorb, achieving the effect of suppressing pressure pulsation in a wide frequency band in a structurally compact fluid-conveying pipeline system, and significantly improving the performance of the pressure pulsation attenuator. Description of the Drawings

[0040] Figure 1 is the flow chart of the design method of the pressure pulsation attenuator.

[0041] Figure 2 is the structural schematic diagram of the pressure pulsation attenuator of an embodiment.

[0042] Figure 3 is the schematic diagram of the shape of the energy-absorbing disc of an embodiment.

[0043] Reference Signs: 1. Inlet connecting pipe, 2. Energy-absorbing cavity, 3. Energy-absorbing disc, 4. Damper, 5. Spring, 6. Adjusting end cover, 7. Outlet connecting pipe. Detailed Embodiments

[0044] The following further describes the detailed embodiments of this application with reference to the drawings.

[0045] A design method of a pressure pulsation attenuator proposed in this application, please refer to Figure 1 the flow chart shown, and the specific steps are as follows:

[0046] Step 1: Determine the characteristic frequency of the fluid-conveying pipeline system under the target working condition and initialize the design parameters of the pressure pulsation attenuator.

[0047] The essence of the vibration and noise generation of the fluid-conveying pipeline system is the fluid-structure interaction problem of the fluid-conveying pipeline system, that is, the dynamic transfer of wave energy between the fluid medium and the pipeline mechanical structure. Therefore, by installing a pressure pulsation attenuator on the fluid-conveying pipeline system, the pressure pulsation energy generated by the fluid fluctuation in the fluid-conveying pipeline is transferred to external mechanical structures such as mass-spring-damper for dissipation, thereby suppressing the pressure pulsation inside the fluid-conveying pipeline. The principle of the pressure pulsation attenuator to suppress pressure pulsation is to use the natural frequency of the pressure pulsation attenuator to match the characteristic frequency of the fluid-conveying pipeline system to absorb the characteristic frequency of the fluid-conveying pipeline system, thereby suppressing the vibration and noise caused by pressure pulsation.

[0048] Therefore, first, it is necessary to determine the characteristic frequency of the fluid-conveying pipeline system under the target working condition. The characteristic frequency of the fluid-conveying pipeline system includes the typical characteristic frequencies composed of the frequencies of excitation sources such as pump equipment and the natural frequency of the fluid-conveying pipeline itself. The frequency of the excitation source refers to the relevant frequency when the excitation source operates to transport the fluid medium, such as the rotation frequency of pump rotating equipment. The natural frequency of the fluid-conveying pipeline itself characterizes the characteristics of the fluid-conveying pipeline and has nothing to do with whether there is a fluid medium. For example, the acoustic cavity frequency of the fluid-conveying pipeline can be determined by the pipe diameter and pipe length of the fluid-conveying pipeline. The specific value of the characteristic frequency of the fluid-conveying pipeline system can be determined by theoretical calculation or experimental measurement methods.

[0049] Estimate and initialize the design parameters of the pressure pulsation attenuator according to the characteristic frequency, pressure pulsation amplitude of the fluid-conveying pipeline system under the target working condition, and the pipeline size parameters. Among them, the pressure pulsation amplitude is determined according to the corresponding relationship between the pressure pulsation amplitude and the characteristic frequency. The characteristic frequency and pressure pulsation amplitude of the fluid-conveying pipeline system can be directly calculated through theoretical calculation, or the pressure pulsation amplitude at the corresponding characteristic frequency can be obtained through experimental measurement methods. The specific design parameters are related to the structure of the pressure pulsation attenuator. In this application, the traditional resonance-type pulsation attenuator is improved, and a pressure pulsation attenuator with an adjustable energy absorption cavity volume is designed. The specific structure is as Figure 2 shown. The pressure pulsation attenuator includes an energy absorption cavity 2, and an inlet connecting pipe 1 and an outlet connecting pipe 7 for connecting the fluid-conveying pipeline are respectively arranged on both sides of the energy absorption cavity. An energy absorption disc 3 and two mass-spring-dampers symmetrically distributed along the fluid-conveying pipeline are arranged inside the energy absorption cavity 2. The mass-spring-damper includes a damper 4 and a spring 5. One end of the mass-spring-damper is fixed on the energy absorption disc 3, and the other end is fixed on the adjusting end cover 6, and the adjusting end cover 6 is arranged on the side wall of the energy absorption cavity 2. The connection between the adjusting end cover 6 and the energy absorption cavity 2 can adopt a spiral type or a push-pull type, and the specific method is not limited in this application, as long as it is ensured that the adjusting end cover 6 is hermetically connected to the energy absorption cavity.

[0050] Based on Figure 2 the pressure pulsation attenuator shown, the design parameters include the volume of the energy absorption cavity, the shape of the energy absorption disk, the mass of the energy absorption disk, the spring stiffness, and the damping coefficient. Among them, the volume of the energy absorption cavity is comprehensively set according to the pressure pulsation amplitude and the flow rate passing through the pressure pulsation attenuator under the target working condition. The energy absorption cavity needs to adapt to the size requirements of the pipeline layout for fluid transportation and be able to accommodate the flow rate passing through the pressure pulsation attenuator under the target working condition. The shape of the energy absorption disk can be determined according to the pressure pulsation amplitude of the pipeline system for fluid transportation under the target working condition, Figure 2 the conical energy absorption disk shown is only for illustration, and the specific shape selection needs to be determined according to the pressure pulsation amplitude.

[0051] In one embodiment, the specific method for determining the shape of the energy absorption disk is as follows: when the pressure pulsation amplitude is less than a predetermined threshold, the shape of the energy absorption disk is initialized as conical; otherwise, the shape of the energy absorption disk is initialized as disk-shaped. The two shapes of the energy absorption disk are as Figure 3 shown, Figure 3 (a) is a side view of the conical energy absorption disk, Figure 3 (b) is a side view of the disk-shaped energy absorption disk. The predetermined threshold of the pressure pulsation amplitude can be set according to the actual application situation. In this application, the predetermined threshold is set to 1000 pa. The shape of the energy absorption disk depends on the magnitude of the pressure pulsation amplitude. For a larger amplitude of pressure pulsation, a disk-shaped energy absorption disk needs to be set to move back and forth better in the fluid medium flowing into the energy absorption cavity; for a smaller amplitude of pressure pulsation, a conical energy absorption disk can be set to move back and forth well in the fluid medium flowing into the energy absorption cavity.

[0052] Furthermore, the shape of the energy absorption disk also includes the bottom diameter of the energy absorption disk and the cone angle of the energy absorption disk. The bottom diameter of the energy absorption disk is determined according to the size of the energy absorption cavity to ensure that the energy absorption disk can move normally in the energy absorption cavity. For the conical energy absorption disk, the cone angle of the energy absorption disk also needs to be set. The cone angle of the energy absorption disk is determined according to the resistance characteristics of the pipeline for fluid transportation. The resistance characteristics refer to the change law of fluid resistance caused by factors such as the change of the geometric shape of the pipeline (diameter change, elbows, valves, etc.), surface roughness, and flow velocity when the fluid flows in the pipeline for fluid transportation.

[0053] The mass of the energy absorption disk, the spring stiffness, and the damping coefficient are comprehensively selected according to the characteristic frequency of the pipeline system for fluid transportation, the pressure pulsation amplitude, and the shape of the energy absorption disk. The approximate ranges of the mass of the energy absorption cavity and the spring stiffness can be determined according to the pressure pulsation amplitude. For a smaller amplitude of pressure pulsation, a smaller mass of the energy absorption cavity and a softer spring stiffness can be used; for a larger amplitude of pressure pulsation, a larger mass of the energy absorption cavity and a harder spring stiffness can be used. Further, according to the relationship between the values of the mass of the energy absorption cavity and the spring stiffness, the natural frequency calculation formula of the pressure pulsation attenuator is satisfied Combined with the matching relationship between the natural frequency of the pressure pulsation attenuator and the characteristic frequency of the fluid conveying pipeline system, the initial values of the energy absorption cavity mass and the spring stiffness are set. Then, according to the energy absorption disc mass m and the spring stiffness k, and combined with the damping ratio calculation formula of the pressure pulsation attenuator Determine the initial value of the damping coefficient c. Among them, the damping ratio is a predetermined value, which is customarily set according to actual application requirements. In this application, it is set to 0.7.

[0054] Step 2: Construct an attenuator model based on the design parameters of the pressure pulsation attenuator, and use the numerical simulation method to fit and obtain the fluid characteristic parameters of the attenuator model operating under the target working conditions. The attenuator model includes an energy absorption disc model, and the pressure pulsation energy of the fluid conveying pipeline system is transferred and dissipated through the movement of the energy absorption disc model. The fluid characteristic parameters indicate the fluid characteristics of the attenuator model when the energy absorption disc model is in different positions.

[0055] Based on the initialized design parameters, use CFD simulation software to construct a three-dimensional model of the pressure pulsation attenuator, and perform basic numerical simulation processes such as flow field grid division, selection of turbulence models and near-wall functions, and grid independence verification. Then use the CFD solver to obtain the fluid characteristics of the energy absorption disc model at different positions. Finally, through regression analysis, fit and obtain the fluid characteristic parameters. Since the energy absorption disc model corresponds to different inlet pressures p of the pressure pulsation attenuator at different positions in Therefore, the fitted fluid characteristic parameters are the functional relationship of the fluid characteristics with respect to the inlet pressure p in .

[0056] CFD simulation belongs to the prior art, and the specific process thereof will not be elaborated in this application. It should be noted that since the result of the flow field grid division has a great influence on the convergence and accuracy of the subsequent numerical simulation, this application considers the different requirements of different turbulence models and near-wall functions for the height of the first layer of grids during the simulation, and encrypts the grids in the boundary layer region near the wall surface.

[0057] Step 3: Based on the dynamic equation of the energy absorption disc model and the inlet and outlet flow conservation equations of the attenuator model, and combined with the fluid characteristic parameters, establish the state space equation of the energy absorption disc; solve the state space equation of the energy absorption disc to obtain the calculated value of the natural frequency of the pressure pulsation attenuator.

[0058] The pressure pulsation energy is transferred to the mass-spring-damper and dissipated through the movement of the energy absorption disc model. Therefore, the motion state of the energy absorption disc model represents the characteristics of the attenuator model. Through theoretical analysis of the motion process of the energy absorption disc model, the inherent characteristics of the attenuator model are quantitatively analyzed. Since the flow rate flowing into the attenuator model is equal to the flow rate flowing out of the attenuator model when the energy absorption disc model is in the equilibrium state, the energy absorption disc can characterize the inherent characteristics of the attenuator model at this time.

[0059] The motion state of the energy absorption disc model in the fluid is closely related to the displacement x(t), velocity v(t) of the energy absorption disc model, and the inlet pressure p in (t) of the attenuator model. Therefore, the state space equation of the energy absorption disc is a functional equation related to the displacement x(t), velocity v(t) of the energy absorption disc model, and the inlet pressure p in (t) of the attenuator model. In one embodiment, the specific method for solving the state space equation of the energy absorption disc to obtain the calculated value of the natural frequency of the pressure pulsation attenuator is as follows:

[0060] (1) Calculate the partial derivatives of the state space equation of the energy absorption disc with respect to the displacement x(t), velocity v(t) of the energy absorption disc model, and the inlet pressure p in (t) of the attenuator model to obtain the Jacobian matrix of the state space equation of the energy absorption disc;

[0061] (2) Determine that the energy absorption disc model is in an equilibrium state when the first-order derivatives of the displacement x(t), velocity v(t) of the energy absorption disc model, and the inlet pressure p in (t) of the attenuator model with respect to time t are 0, and substitute the displacement x(t), velocity v(t) of the energy absorption disc model, and the inlet pressure p in (t) of the attenuator model when the energy absorption disc model is in an equilibrium state into the Jacobian matrix to calculate the values of each element of the Jacobian matrix;

[0062] (3) Solve the eigenvalues of the Jacobian matrix to obtain the calculated value of the natural frequency of the pressure pulsation attenuator.

[0063] When the energy absorption disc model moves in the energy absorption cavity of the attenuator model, considering the action of the fluid on the energy absorption disc model and the fact that the flow rate flowing into and out of the attenuator model follows the principle of flow conservation. Therefore, the state space equation of the energy absorption disc is established based on the dynamic equation of the energy absorption disc model and the inlet and outlet flow conservation equation of the attenuator model. In one embodiment, the state space equation of the energy absorption disc includes a first state variable expression y1, a second state variable expression y2, and a third state variable expression y3. The specific method for establishing the state space equation of the energy absorption disc is as follows:

[0064] Based on the dynamic equation of the energy absorption disc model and combined with the fluid characteristic parameters, determine the first state variable expression y1 and the second state variable expression y2 of the state space equation of the energy absorption disc; based on the dynamic equation of the energy absorption disc model and the inlet and outlet flow conservation equation of the attenuator model and combined with the fluid characteristic parameters, determine the third state variable expression y3 of the state space equation of the energy absorption disc.

[0065] The fluid characteristic parameters include the fluid excitation force F fluid (t) received by the energy absorption disc model. The specific method for determining the first state variable expression y1 and the second state variable expression y2 of the state space equation of the energy absorption disc is as follows:

[0066] The dynamic equation of the energy absorption disc model is as follows:

[0067]

[0068] Determine the expression of the first state variable of the energy absorption disc state space equation according to the dynamic equation of the energy absorption disc model

[0069] According to the dynamic equation of the energy absorption disc model and combined with the fluid excitation force F fluid (t), determine the expression of the second state variable of the energy absorption disc state space equation

[0070] Where m is the mass of the energy absorption disc, c is the damping coefficient, k is the spring stiffness, x(t) is the displacement of the energy absorption disc model, v(t) is the velocity of the energy absorption disc model, is the first derivative of x(t), is the second derivative of x(t), A s is the force-bearing area of the energy absorption disc model, p in is the inlet pressure of the attenuator model, p out is the outlet pressure of the attenuator model; the fluid excitation force F fluid (t) is related to the inlet pressure p in of the attenuator model.

[0071] The fluid characteristic parameters also include the flow coefficient C e (t), the specific method to determine the expression of the third state variable y3 of the energy absorption disc state space equation is:

[0072] The inlet and outlet flow conservation equation of the attenuator model is:

[0073]

[0074] According to the dynamic equation of the energy absorption disc model and the inlet and outlet flow conservation equation of the attenuator model and combined with the flow coefficient C e (t), determine the expression of the third state variable of the energy absorption disc state space equation

[0075]

[0076] Where E is the bulk modulus of elasticity of the fluid, V is the energy absorption cavity volume of the attenuator model, q in (t) is the inlet flow rate of the attenuator model, q out (t) is the outlet flow rate of the attenuator model, ρ is the fluid density, F fluid (t) is the fluid excitation force, A s is the force-bearing area of the energy absorption disc model, p in(t) is the inlet pressure of the attenuator model, p out (t) is the outlet pressure of the attenuator model, represents the inlet pressure p of the attenuator model in The first derivative of (t), the flow coefficient C e (t) and the inlet pressure p of the attenuator model in (t). Among them, the fluid excitation force F fluid (t) and flow coefficient C e (t) is the fluid property when the energy absorbing disk model is at different positions, so the fluid excitation force F fluid (t) and flow coefficient C e (t) is based on the inlet pressure p in (t) is the functional relationship of the independent variable, which is obtained through the numerical simulation process in step 2.

[0077] The first state variable expression y1, the second state variable expression y2 and the third state variable expression y3 are combined to obtain the energy absorption disk state space equation [y1, y2, y3] T , [] T Represents matrix transpose.

[0078] The state space equation of the energy absorbing disk established is [y1,y2,y3] T The expression is:

[0079]

[0080] Due to the fluid excitation force F fluid (t) and flow coefficient C e (t) is based on the inlet pressure p in (t) is the function relationship of the independent variable. The energy absorbing disk state space equation is about the displacement x(t), velocity v(t) of the energy absorbing disk model and the inlet pressure p of the attenuator model. in (t). Therefore, the state space equation of the energy absorbing disk can be solved for displacement x(t), velocity v(t) and inlet pressure p in The Jacobian matrix at the equilibrium point is obtained by taking the partial derivative of (t), and then the Jacobian matrix is used as a linearization tool for the nonlinear system of the attenuator model at the equilibrium point, so as to obtain the equilibrium state of the attenuator model.

[0081] For the energy absorbing disk state space equation with three state variable expressions [y1,y2,y3] T , the calculated Jacobian matrix A is:

[0082]

[0083] Among them, the 0 in the lower right corner of the Jacobian matrix A represents the Jacobian matrix at the equilibrium point. At the equilibrium point, the displacement velocity of the energy absorption disc model and the inlet pressure of the attenuator model. The energy absorption disc model is in an equilibrium state. Specifically, substituting the displacement x(t), velocity v(t), and inlet pressure p in (t) of the energy absorption disc model in the equilibrium state into the Jacobian matrix A can obtain the specific values of each matrix element, and then the eigenvalues of the Jacobian matrix A can be solved, and the calculated value of the natural frequency of the attenuator model can be calculated.

[0084] Step 4: Adjust the design parameters of the pressure pulsation attenuator until the deviation between the calculated value of the natural frequency and the characteristic frequency of the fluid conveying pipeline system meets the design requirements, and then design the pressure pulsation attenuator.

[0085] In one embodiment, when the deviation between the calculated value of the natural frequency and the characteristic frequency of the fluid conveying pipeline system is within a predetermined error range, it is determined that the design requirements are met, and the pressure pulsation attenuator under the target working conditions can be designed according to the determined design parameters. The predetermined error range is custom-set according to the actual application situation. In this application, the predetermined error range is set to 5% of the characteristic frequency of the fluid conveying pipeline system.

[0086] When the deviation between the calculated value of the natural frequency and the characteristic frequency of the fluid conveying pipeline system does not meet the design requirements, the calculated value of the natural frequency of the attenuator model obtained in step 3 is used to adjust the design parameters and then the simulation calculation process of step 3 is carried out again.

[0087] In one embodiment, adjusting the design parameters of the pressure pulsation attenuator includes:

[0088] When the deviation between the calculated value of the natural frequency and the characteristic frequency of the fluid conveying pipeline system does not meet the design requirements, and the calculated value of the natural frequency is lower than the characteristic frequency of the fluid conveying pipeline system, according to the natural frequency of the pressure pulsation attenuator, it is determined to increase the spring stiffness k, or decrease the mass m of the energy absorption disc; according to the adjusted mass m of the energy absorption disc and the spring stiffness k, and combined with the damping ratio of the pressure pulsation attenuator within the predetermined damping ratio range, the damping coefficient c is adjusted; by adjusting the spring stiffness k, the mass m of the energy absorption disc, and the damping coefficient c, the effect of increasing the natural frequency of the pressure pulsation attenuator to match the characteristic frequency of the fluid conveying pipeline system is achieved.

[0089] When the deviation between the calculated value of the natural frequency and the characteristic frequency of the fluid conveying pipeline system does not meet the design requirements, and the calculated value of the natural frequency is higher than the characteristic frequency of the fluid conveying pipeline system, according to the natural frequency Determine to reduce the spring stiffness k, or increase the mass m of the energy absorbing disk; according to the adjusted mass m of the energy absorbing disk and the spring stiffness k, combined with the damping ratio of the pressure pulsation attenuator Under the condition of the predetermined damping ratio range, the damping coefficient c is adjusted; by adjusting the spring stiffness k, the mass m of the energy absorbing disk and the damping coefficient c, the natural frequency of the pressure pulsation attenuator is reduced to match the characteristic frequency of the fluid delivery pipeline system.

[0090] Since the damping ratio affects the response bandwidth of the entire system and the attenuation effect of the pressure pulsation attenuator, it is necessary to adjust the damping coefficient c to ensure that the damping ratio ζ is within a reasonable range. The predetermined damping ratio range of the damping ratio ζ can be customized according to the actual application.

[0091] The pressure pulsation attenuator designed in the present application can also be applied to different target working conditions. In one embodiment, the volume of the energy absorption cavity is changed by moving the position of the adjustment end cap to adapt to different target working conditions, and then the design parameters of the pressure pulsation attenuator are continuously adjusted using the method of the present application until the new target working conditions are met. The moving range of the adjustment end cap corresponds to the axial length of the adjustment end cap, and the specific value can be customized according to the actual application requirements.

[0092] The above is only a preferred embodiment of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the scope of protection of the present application.

Claims

1. A method for designing a pressure pulsation attenuator, characterized in that The design method of the pressure pulsation attenuator includes: Determine the characteristic frequency of the fluid conveying pipeline system under the target working condition and initialize the design parameters of the pressure pulsation attenuator; Construct an attenuator model according to the design parameters of the pressure pulsation attenuator, and use numerical simulation methods to fit and obtain the fluid characteristic parameters of the attenuator model operating under the target working condition; the attenuator model includes an energy absorption disc model, and the pressure pulsation energy of the fluid conveying pipeline system is transferred and dissipated through the movement of the energy absorption disc model; the fluid characteristic parameters indicate the fluid characteristics of the attenuator model when the energy absorption disc model is in different positions; Based on the dynamic equation of the energy absorption disc model and the inlet and outlet flow conservation equations of the attenuator model, and combined with the fluid characteristic parameters, establish the state space equation of the energy absorption disc; solve the state space equation of the energy absorption disc to obtain the calculated value of the natural frequency of the pressure pulsation attenuator; Adjust the design parameters of the pressure pulsation attenuator until the deviation between the calculated value of the natural frequency and the characteristic frequency of the fluid conveying pipeline system meets the design requirements, and then design the pressure pulsation attenuator.

2. The pressure pulsation attenuator design method according to claim 1, characterized in that, The state space equation of the energy absorption disc is related to the displacement x(t), velocity v(t) of the energy absorption disc model, and the inlet pressure p in (t) of the attenuator model; the calculated value of the natural frequency of the pressure pulsation attenuator obtained by solving includes: Calculate the partial derivatives of the energy-absorbing disc state-space equation with respect to the displacement x(t), velocity v(t) of the energy-absorbing disc model, and the inlet pressure p in (t) of the attenuator model to obtain the Jacobian matrix of the energy-absorbing disc state-space equation; Determine the displacement \(x(t)\), velocity \(v(t)\) of the energy-absorbing disc model and the first-order derivative of the inlet pressure \(p(t)\) of the attenuator model with respect to time \(t\) to be 0 when the energy-absorbing disc model is in an equilibrium state, and substitute the displacement \(x(t)\), velocity \(v(t)\) of the energy-absorbing disc model and the inlet pressure \(p(t)\) of the attenuator model when the energy-absorbing disc model is in an equilibrium state into the Jacobian matrix to calculate the values of the elements of the Jacobian matrix; in (t) When the first-order derivative with respect to time \(t\) is 0, the energy-absorbing disc model is in an equilibrium state, and substitute the displacement \(x(t)\), velocity \(v(t)\) of the energy-absorbing disc model and the inlet pressure \(p(t)\) of the attenuator model when the energy-absorbing disc model is in an equilibrium state in (t) into the Jacobian matrix to calculate the values of the respective elements of the Jacobian matrix; Solve the eigenvalues of the Jacobian matrix to obtain the calculated value of the natural frequency of the pressure pulsation attenuator.

3. The pressure pulsation attenuator design method according to claim 2, characterized in that The state space equation of the energy absorption disc includes the first state variable expression y1, the second state variable expression y2, and the third state variable expression y3; Establishing the state space equation of the energy absorption disc includes: Based on the dynamic equation of the energy absorption disc model and combined with the fluid characteristic parameters, determine the first state variable expression y1 and the second state variable expression y2 of the state space equation of the energy absorption disc; based on the dynamic equation of the energy absorption disc model and the inlet and outlet flow conservation equations of the attenuator model and combined with the fluid characteristic parameters, determine the third state variable expression y3 of the state space equation of the energy absorption disc; The first state variable expression y1, the second state variable expression y2 and the third state variable expression y3 are combined to obtain the energy absorption disk state space equation [y1, y2, y3] T .

4. The pressure pulsation attenuator design method according to claim 3, characterized in that, The fluid characteristic parameters include the fluid excitation force F fluid (t) received by the energy absorption disc model; the dynamic equation of the energy absorption disc model is: Determine the expression of the first state variable of the energy-absorbing disk state space equation according to the kinetic equation of the energy-absorbing disk model According to the dynamic equation of the energy absorption disc model and combined with the fluid excitation force F fluid (t), determine the expression of the second state variable of the state space equation of the energy absorption disc where m is the mass of the energy-absorbing disc, c is the damping coefficient, k is the spring stiffness, x(t) is the displacement of the energy-absorbing disc model, v(t) is the velocity of the energy-absorbing disc model, is the first derivative of x(t), is the second derivative of x(t), A s is the force-bearing area of the energy-absorbing disc model, p in (t) is the inlet pressure of the attenuator model, p out (t) is the outlet pressure of the attenuator model; the fluid excitation force F fluid (t) is related to the inlet pressure p in (t) of the attenuator model.

5. The pressure pulsation attenuator design method according to claim 4, characterized in that, The fluid characteristic parameters include the flow coefficient C e (t); the inlet and outlet flow conservation equation of the attenuator model is: Determine the third state variable expression of the state space equation of the energy absorption disc according to the dynamic equation of the energy absorption disc model and the inlet and outlet flow conservation equations of the attenuator model where E is the bulk modulus of elasticity of the fluid, V is the volume of the energy absorption cavity of the attenuator model, q in (t) is the inlet flow rate of the attenuator model, q out (t) is the outlet flow rate of the attenuator model, ρ is the fluid density, F fluid (t) is the fluid excitation force, A s is the force-bearing area of the energy absorption disc model, p in (t) is the inlet pressure of the attenuator model, p out (t) is the outlet pressure of the attenuator model, denotes the first derivative of the inlet pressure p in (t) of the attenuator model, and the flow coefficient C e (t) is related to the inlet pressure p in (t) of the attenuator model.

6. The pressure pulsation attenuator design method according to claim 1, wherein The design parameters include the mass m of the energy absorption disc, the spring stiffness k, and the damping coefficient c. Adjusting the design parameters of the pressure pulsation attenuator includes: When the deviation between the calculated natural frequency and the characteristic frequency of the fluid-conveying pipeline system does not meet the design requirements, and the calculated natural frequency is lower than the characteristic frequency of the fluid-conveying pipeline system, according to the natural frequency of the pressure pulsation attenuator it is determined to increase the spring stiffness k, or decrease the mass m of the energy-absorbing disc; according to the adjusted mass m of the energy-absorbing disc and the spring stiffness k, and combined with the damping ratio of the pressure pulsation attenuator under the condition within the predetermined damping ratio range, adjust the damping coefficient c; When the deviation between the calculated natural frequency and the characteristic frequency of the fluid-conveying pipeline system does not meet the design requirements, and the calculated natural frequency is higher than the characteristic frequency of the fluid-conveying pipeline system, according to the natural frequency of the pressure pulsation attenuator it is determined to reduce the spring stiffness k, or increase the mass m of the energy-absorbing disc; according to the adjusted mass m of the energy-absorbing disc and the spring stiffness k, and combined with the damping ratio of the pressure pulsation attenuator under the condition within the predetermined damping ratio range, the damping coefficient c is adjusted.

7. The pressure pulsation attenuator design method according to claim 1, wherein The design parameters include the shape of the energy absorption disc; Initializing the shape of the energy absorption disc includes: Determine the shape of the energy absorption disc according to the pressure pulsation amplitude of the fluid conveying pipeline system under the target working condition; When the pressure pulsation amplitude is less than a predetermined threshold, initialize the shape of the energy absorption disc as conical, otherwise, initialize the shape of the energy absorption disc as disc-shaped.

8. The pressure pulsation attenuator design method according to claim 1, characterized in that, The pressure pulsation attenuator further includes an energy absorption cavity, a mass-spring-damper, and an adjustment end cover. One end of the mass-spring-damper is fixed on the energy absorption disc, and the other end is fixed on the adjustment end cover. The adjustment end cover is arranged on the side wall of the energy absorption cavity; by moving the position of the adjustment end cover, the volume of the energy absorption cavity is changed to adapt to different target working conditions.

9. The pressure pulsation attenuator design method according to claim 1, wherein The design method of the pressure pulsation attenuator includes: When the deviation between the calculated value of the natural frequency and the characteristic frequency of the fluid conveying pipeline system is within a predetermined error range, it is determined that the design requirements are met.

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