Method and device for determining liquid rocket sloshing load and electronic equipment

Abstract

The application discloses a liquid rocket shaking load determination method and device and electronic equipment, wherein the determination method comprises the following steps: obtaining the shaking characteristic parameters of each tank, and obtaining the shaking force of each tank according to the shaking characteristic parameters; obtaining a first simulation input parameter; performing rigidity characteristic simulation and mass characteristic simulation based on the first simulation input parameter, and obtaining rigidity characteristic data and mass characteristic data of a cabin section; performing rocket body dynamic characteristic simulation of the liquid rocket based on the rigidity characteristic data and the mass characteristic data, obtaining rocket body modal parameters, and obtaining a unit pulse response function according to the rocket body modal parameters; and determining the shaking load of the rocket body based on a first-order vibration mode, the unit pulse response function, the shaking force action position and the shaking force of each tank, mass stations and a first-order modal circular frequency. The method can improve the calculation precision of the shaking load.

Description

Technical Field

[0001] This application relates to the field of liquid rocket technology, and in particular to a method, apparatus and electronic equipment for determining the sloshing load of a liquid rocket. Background Technology

[0002] During the flight of a liquid rocket, external stimuli such as engine start / stop, thrust adjustment, wind shear, gusts, and attitude adjustments can all cause periodic sloshing of the propellant inside the propellant tank. Because the first-order frequency of liquid sloshing is relatively low, and the larger the tank diameter, the lower the sloshing frequency becomes, approaching the rigid body cutoff frequency, it may couple with the control system, affecting flight attitude stability. Simultaneously, the sloshing propellant generates periodic sloshing forces on the tank walls, exciting a low-frequency response in the rocket body and generating sloshing loads. Traditional static load handling methods have certain limitations. Reusable rockets, to improve reusability design performance, such as the number of reuses and maintainability, require refined load design. This necessitates high-precision load prediction, and ensuring the accuracy of sloshing load calculations is a fundamental prerequisite.

[0003] One current method for calculating sway load is to apply the sway force amplitude of different tanks as a static concentrated force to the rocket body, and to obtain the maximum load value of each section by combining different positive and negative concentrated forces of different tanks. However, this method has the problem of the load calculation result being too small. On the other hand, the method of using a safety factor for envelope is contrary to the refined load design. Summary of the Invention

[0004] This invention provides a method, apparatus, and electronic device for determining the sloshing load of a liquid rocket, in order to solve or partially solve the technical problem that the current calculation methods for sloshing loads of liquid rockets result in underestimating the load.

[0005] Firstly, according to an embodiment of the present invention, the following technical solution is provided:

[0006] A method for determining the sloshing load of a liquid rocket, the liquid rocket comprising two or more propellant tanks, the method comprising:

[0007] Obtain the sloshing characteristic parameters of each tank, and obtain the sloshing force of each tank based on the sloshing characteristic parameters; the sloshing characteristic parameters include the sloshing mass of the liquid in the tank, the sloshing frequency, the sloshing displacement amplitude, the sloshing damping, and the location of the sloshing force.

[0008] Obtain the first simulation input parameters; the first simulation input parameters include the liquid rocket body model, section material stiffness, section material density, section mass, section center of mass, section moment of inertia, rocket body mass, rocket body center of mass, rocket body moment of inertia, propellant mass, propellant center of mass, and propellant moment of inertia;

[0009] Based on the first simulation input parameters, stiffness characteristic simulation and mass characteristic simulation are performed to obtain stiffness characteristic data and mass characteristic data of the compartment. The stiffness characteristic data includes the cross-sectional diameter, equivalent thickness, elastic modulus and Poisson's ratio of each beam element in the compartment; the mass characteristic data includes the mass fraction and moment of inertia of the structural compartment and the propellant compartment.

[0010] Based on the stiffness characteristic data and the mass characteristic data, the dynamic characteristics of the liquid rocket body are simulated to obtain the body modal parameters, and the unit impulse response function is obtained according to the body modal parameters; the body modal parameters include the first-order modal circular frequency, the first-order generalized mass, the first-order damping ratio, and the first-order mode shape;

[0011] Based on the first-order vibration mode, the unit impulse response function, the location and force of the swaying force of each tank, the mass station, and the first-order modal circular frequency, the swaying load of the rocket body is determined; the swaying load includes the first-order response shear force and the first-order response bending moment.

[0012] Optionally, obtaining the sway characteristic parameters of each tank includes:

[0013] Obtain the second simulation input parameters, which include the tank size of each tank, the initial velocity excitation of the propellant, the propellant density, the flight axial overload, the size of the anti-sway plate, and the position information of the anti-sway plate;

[0014] Based on the second simulation input parameters, Euler multiphase flow simulation is performed to obtain the time-domain data of the swaying force of each tank in the initial velocity excitation direction and the time-domain data of the swaying torque perpendicular to the initial velocity excitation plane.

[0015] Based on the time-domain data of the swaying force and the time-domain data of the swaying torque, the swaying characteristic parameters of each tank are determined.

[0016] Optionally, determining the sway load of the rocket body based on the first-order vibration mode, the unit impulse response function, the location and force of the swaying force of each tank, the mass station, and the first-order modal circular frequency includes:

[0017] Based on the first-order mode shape, the unit impulse response function, the location and force of the swaying force of each tank, the first-order generalized displacement time-domain response data of the rocket body are determined.

[0018] Based on the mass substation, the first-order modal circular frequency, and the first-order generalized displacement time-domain response data, the sway load of the rocket body is determined; the sway load includes the first-order response shear force and the first-order response bending moment.

[0019] Optionally, determining the first-order generalized displacement time-domain response data of the rocket body based on the first-order mode shape, the unit impulse response function, the location and force of the swaying force of each tank includes:

[0020] Based on the first-order vibration mode, the location and force of the swaying force of each tank, the time-domain data of the first-order generalized force of the rocket body are determined.

[0021] Based on the unit impulse response function and the first-order generalized force time-domain data, the first-order generalized displacement time-domain response data of the rocket body is determined.

[0022] Optionally, determining the time-domain data of the first-order generalized force of the rocket body based on the first-order vibration mode, the location of the swaying force of each tank, and the swaying force includes:

[0023] Based on the first-order vibration mode value of each tank at the location where the swaying force is applied, the positive and negative information of the swaying force of each tank is determined.

[0024] The first-order generalized force time-domain data of the rocket body is obtained by weighted summation based on the first-order vibration mode, the swaying force of all tanks and the corresponding positive and negative information.

[0025] Optionally, determining the first-order generalized displacement time-domain response data of the rocket body based on the unit impulse response function and the first-order generalized force time-domain data includes:

[0026] Based on the unit impulse response function and the first-order generalized force time-domain data, the first-order generalized displacement time-domain response data of the rocket body is obtained by performing Duhamel integration.

[0027] Optionally, determining the sway load of the rocket body based on the mass substation, the first-order modal circular frequency, and the first-order generalized displacement time-domain response data includes:

[0028] Based on the mass substation and the first-order modal circular frequency, the modal shear force and modal bending moment of the rocket body under the first-order modal response are determined;

[0029] The maximum value of the generalized displacement is obtained based on the first-order generalized displacement time-domain response data;

[0030] Based on the maximum value of the generalized displacement and the modal shear force under the first-order modal response, the first-order response shear force of the rocket body is determined;

[0031] Based on the maximum value of the generalized displacement and the modal bending moment under the first-order modal response, the first-order response bending moment of the rocket body is determined.

[0032] Secondly, according to an embodiment of the present invention, the following technical solution is provided:

[0033] A device for determining the sloshing load of a liquid rocket, the liquid rocket comprising two or more tanks, the device comprising:

[0034] The acquisition module is used to obtain the sloshing characteristic parameters and the first simulation input parameters of each tank, and to obtain the sloshing force of each tank based on the sloshing characteristic parameters; the sloshing characteristic parameters include the sloshing mass, sloshing frequency, sloshing displacement amplitude, sloshing damping, and the location of the sloshing force of the liquid in the tank; the first simulation input parameters include the rocket body model, section material stiffness, section material density, section mass, section center of mass, section moment of inertia, rocket body mass, rocket body center of mass, rocket body moment of inertia, propellant mass, propellant center of mass, and propellant moment of inertia;

[0035] The first simulation module is used to perform stiffness characteristic simulation and mass characteristic simulation based on the first simulation input parameters to obtain stiffness characteristic data and mass characteristic data of the compartment. The stiffness characteristic data includes the cross-sectional diameter, equivalent thickness, elastic modulus and Poisson's ratio of each beam element in the compartment. The mass characteristic data includes the mass fraction and moment of inertia of the structural compartment and the propellant compartment.

[0036] The second simulation module is used to simulate the dynamic characteristics of the liquid rocket body based on the stiffness characteristic data and the mass characteristic data, obtain the body modal parameters, and obtain the unit impulse response function based on the body modal parameters; the body modal parameters include the first-order modal circular frequency, the first-order generalized mass, the first-order damping ratio, and the first-order mode shape;

[0037] The determination module is used to determine the sway load of the rocket body based on the first-order vibration mode, the unit impulse response function, the swaying force application location and swaying force of each tank, the mass station and the first-order modal circular frequency; the sway load includes the first-order response shear force and the first-order response bending moment.

[0038] Thirdly, according to an embodiment of the present invention, the following technical solution is provided:

[0039] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the steps of any of the methods provided in the first aspect.

[0040] Fourthly, according to an embodiment of the present invention, the following technical solution is provided:

[0041] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any of the methods provided in the first aspect.

[0042] Through one or more technical solutions of the present invention, the present invention has the following beneficial effects or advantages:

[0043] This application provides a method for determining the sloshing load of a liquid rocket. By performing stiffness and mass characteristic simulations based on first simulated input parameters, stiffness and mass characteristic data characterizing the elastic state of the liquid rocket section are obtained. Then, dynamic characteristic simulation is performed based on these data to obtain modal parameters reflecting the rocket body under elastic influence. Finally, the sloshing load of the rocket body is calculated based on the first-order mode shape, the location and force of the sloshing force for each propellant tank, the unit impulse response function obtained from the modal parameters, the mass substation, and the first-order modal angular frequency. Because the influence of rocket body elasticity is considered during the dynamic characteristic simulation, the calculated sloshing load of the liquid rocket obtained by this method is greater than that of traditional methods and more closely approximates the actual state of the liquid rocket during flight, resulting in higher accuracy in the calculated sloshing load.

[0044] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0045] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0046] In the attached diagram:

[0047] Figure 1 A flowchart illustrating a method for determining the sloshing load of a liquid rocket according to an embodiment of the present invention is shown.

[0048] Figure 2 The positional relationship and positive / negative values ​​of the first mode shape and sloshing force of a liquid rocket with a four-tank configuration according to an embodiment of the present invention are shown.

[0049] Figure 3 A graph of time-domain data of a first-order generalized force provided according to an embodiment of the present invention is shown;

[0050] Figure 4 A graph of time-domain data of first-order generalized displacement provided according to an embodiment of the present invention is shown;

[0051] Figure 5The comparison of the sway load calculated by the present application's solution according to an embodiment of the invention with that of a conventional solution is shown;

[0052] Figure 6 A schematic diagram of a device for determining the sloshing load of a liquid rocket according to an embodiment of the present invention is shown;

[0053] Figure 7 A schematic diagram of an electronic device provided according to an embodiment of the present invention is shown;

[0054] Figure 8 A schematic diagram of a storage medium provided according to an embodiment of the present invention is shown. Detailed Implementation

[0055] To enable those skilled in the art to more clearly understand this application, the technical solution of this application is described in detail below with reference to the accompanying drawings and specific embodiments. Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art. In case of any conflict, this specification takes precedence. Unless otherwise specified, all devices, etc., used in this invention can be purchased commercially or prepared by existing methods.

[0056] Studies have shown that the traditional method for calculating sway loads—applying different tank sway amplitudes as static concentrated forces to the rocket body and combining these forces with varying positive and negative values ​​to determine the maximum load at each cross-section—results in underestimating the load because it only considers the rigid body characteristics of the rocket. Current research in the field of swaying mainly focuses on sway models and the identification of sway characteristic parameters. However, there is currently a lack of literature supporting the low-frequency dynamic loads of the rocket body caused by swaying. Therefore, there is a need for a rapid iterative method to calculate sway loads given the acquired sway characteristic parameters.

[0057] Based on the above research, in a first aspect, in an optional embodiment, such as Figure 1 As shown, a method for determining the sloshing load of a liquid rocket is provided, wherein the liquid rocket is a multi-tank liquid rocket, including two or more tanks, specifically at least one oxidizer tank and at least one propellant tank. The determination method includes steps S101 to S106, as follows:

[0058] S101: Obtain the sloshing characteristic parameters of each tank, and obtain the sloshing force of each tank based on the sloshing characteristic parameters; the sloshing characteristic parameters include the sloshing mass of the liquid in the tank, the sloshing frequency, the sloshing displacement amplitude, the sloshing damping, and the location of the sloshing force.

[0059] Specifically, the sloshing characteristic parameters are the characteristic parameters of each tank in the first-order sloshing equivalent mechanical model. Let the number of tanks be n (typically n=4), and the liquid in the tanks be a propellant or oxidant. Then, the sloshing characteristic parameters of a tank include the sloshing mass m of the liquid in that tank. hk Shaking frequency ω hk , Sway displacement amplitude x hk , Sway Damping hk and the position of the swaying force h k , where k represents the k-th storage tank out of n storage tanks.

[0060] One method to obtain sloshing characteristic parameters is through volumetric flow (VOF) simulation, with Euler multiphase flow simulation being a commonly used approach, as detailed below:

[0061] A second simulation input parameter is obtained, which includes the tank size of each tank, the initial velocity excitation of the propellant, the propellant density, the flight axial overload, the size of the anti-sway plate, and the anti-sway plate position information. Based on the second simulation input parameter, Euler multiphase flow simulation is performed to obtain the time-domain data of the swaying force of each tank in the initial velocity excitation direction and the time-domain data of the swaying torque perpendicular to the initial velocity excitation plane. Based on the time-domain data of the swaying force and the time-domain data of the swaying torque, the swaying characteristic parameters of each tank are determined.

[0062] Specifically, the second simulation input parameter is the input parameter used during VOF simulation. In practice, fluid-structure interaction simulation software, such as starccm+ or other similar software, can be used to simulate the propellant sloshing process using the VOF method, outputting time-domain data of the sloshing force acting on the wall (along the excitation direction) and the time-domain data of the sloshing torque acting on the bottom of the tank (perpendicular to the excitation plane).

[0063] Next, the nonlinear least squares fitting method can be used for data processing. Based on the time-domain data of swaying force and the time-domain data of swaying torque, the characteristic parameters of the first-order swaying equivalent mechanical model of each tank can be identified as swaying characteristic parameters.

[0064] Considering that the swaying force changes exponentially under the initial wave height excitation, after obtaining the swaying characteristic parameters, the corresponding swaying force F of each tank is... k for:

[0065]

[0066] In the above formula, t represents time.

[0067] S102: Obtain the first simulation input parameters; the first simulation input parameters include the liquid rocket body model, section material stiffness, section material density, section mass, section center of mass, section moment of inertia, rocket body mass, rocket body center of mass, rocket body moment of inertia, propellant mass, propellant center of mass, and propellant moment of inertia.

[0068] S103: Based on the first simulation input parameters, perform stiffness characteristic simulation and mass characteristic simulation to obtain stiffness characteristic data and mass characteristic data of the compartment. The stiffness characteristic data includes the cross-sectional diameter, equivalent thickness, elastic modulus, and Poisson's ratio of each beam element in the compartment. The mass characteristic data includes the mass stations and moments of inertia of the structural compartment and the propellant compartment. Wherein, the mass station m... i This refers to the process of discretizing the mass of a continuous rocket body to obtain a concentrated mass at a set interval. The value of the concentrated mass and its corresponding position constitute the mass substation information.

[0069] S104: Based on the stiffness characteristic data and the mass characteristic data, perform dynamic characteristic simulation of the liquid rocket body to obtain the body modal parameters, and obtain the unit impulse response function according to the body modal parameters; the body modal parameters include the first-order modal circular frequency, the first-order generalized mass, the first-order damping ratio, and the first-order mode shape.

[0070] Specifically, S102–S104 simulate the dynamic characteristics of the liquid rocket body. The first simulation input parameters are used for simulating stiffness and mass characteristics. While identifying the swaying characteristic parameters, a simulation model is established in the finite element method (FEM) software. Based on the first simulation input parameters, the stiffness and mass characteristics of the sections are simulated using lumped mass elements and beam elements in the FEM software. The main sections of the liquid rocket body are simulated using beam elements, and the mass characteristics of the beam elements are simulated using lumped mass simulation; the propellant mass characteristics are simulated using coupled mass simulation. By establishing the dynamic characteristic model of the rocket body, modal analysis simulation is performed to extract the modal parameters of the rocket body.

[0071] Finite element simulation software such as Partran / Nastran, commonly used in the aerospace field, can be employed. Taking this as an example, in practical implementation, the stiffness characteristics of beam elements depend on their material and cross-sectional properties (including cross-sectional area, moment of inertia, and polar moment of inertia). When defining the cross-sectional properties of CBEAM elements in Partran / Nastran, this can be achieved using either PBEAML or PBEAM cards. The mass characteristics of the rocket body structure include the translational mass and rotational inertia of each section. The simulation method involves establishing a series of lumped mass elements (CONM2 elements) along the rocket body. When performing dynamic finite element modeling of liquid propellants, only their mass characteristics are considered, and the propellant model is established using coupled mass elements (CONM1 elements) in Partran / Nastran.

[0072] Next, using stiffness and mass characteristic data as input, modal analysis simulation of the rocket's dynamic characteristics is performed. A real eigenvalue solver provided by finite element software (such as Nastran's SOL103) can be used for modal analysis (normal modes), outputting the rocket's modal parameters, including: first-order modal circular frequency ω1, first-order generalized mass M1, first-order damping ratio ζ1, and first-order mode shape. Based on the modal parameters of the rocket body, the unit impulse response function h(t) of the single-degree-of-freedom system of the rocket body in the first-order modal space is obtained, and its expression is as follows:

[0073]

[0074] In the above formula, ω d For the natural frequency, the expression is as follows:

[0075]

[0076] Through steps S102 to S104, the calculation of the swaying load of the liquid rocket is transformed into a problem of solving the first-order generalized displacement h(t) in modal space with the first-order modal parameters of the rocket as the input of a single-degree-of-freedom system, which is beneficial to improving the calculation accuracy of the swaying load.

[0077] Next:

[0078] S105: Based on the first-order vibration mode, the unit impulse response function, the location and force of the swaying force of each tank, the mass station, and the first-order modal circular frequency, determine the swaying load of the rocket body; the swaying load includes the first-order response shear force and the first-order response bending moment.

[0079] Specifically, the first-order generalized displacement time-domain response data of the rocket body can be determined based on the first-order mode shape, the unit impulse response function, the location of the swaying force of each tank, and the swaying force.

[0080] Specifically, it can be based on the first-order vibration mode. and the position h of the swaying force of each tank k and swaying force F k The first-order generalized force time-domain data of the rocket body with a multi-tank structure can be determined. Then, based on the unit impulse response function and the first-order generalized force time-domain data, the first-order generalized displacement time-domain response data of the rocket body can be determined.

[0081] Considering that the load calculation is based on the principle of maximum load, in order to calculate the maximum first-order generalized force, the positive and negative information of the swaying force of each tank can be determined based on the first-order mode shape value of each tank at the location of the swaying force. Based on the first-order mode shape, the swaying force of all tanks and the corresponding positive and negative information, the weighted summation is performed to obtain the time-domain data of the first-order generalized force of the rocket body.

[0082] Specifically, based on the positive and negative information or relationship between the first-order vibration mode and the swaying force, the positive and negative arrangement of the swaying force is determined, thereby identifying the signed swaying force F of all the tanks. hk The column vector {F} is formed, and then the first-order generalized force time-domain data f1(t) is obtained by using the modal weighted accumulation method, which is expressed as:

[0083]

[0084] In the above formula is the transpose matrix of the first-order mode shape.

[0085] Next, based on the first-order generalized force time-domain data f1(t) obtained from equation (4) and the unit impulse response function h(t) obtained from equation (2), the first-order generalized displacement time-domain response data q1(t) of the rocket body is obtained based on the Duhamel integral. The essence of the Duhamel integral is a convolution process based on the unit impulse response function h(t), and its mathematical expression is as follows:

[0086]

[0087] In the above formula, τ is the integration variable.

[0088] Considering that the form of the first-order generalized force is unknown, there is no specific theoretical solution for equation (5), and its algorithm can be implemented by the lsim function under the MATLAB platform.

[0089] After obtaining the first-order generalized displacement time-domain response data q1(t), the sway load of the rocket body is determined based on the mass substation, the first-order modal circular frequency, and the first-order generalized displacement time-domain response data; the sway load includes the first-order response shear force and the first-order response bending moment.

[0090] First, based on the mass of the rocket body, station m i The first-order modal circular frequency ω1 and the first-order mode shape at the mass station The modal shear force Q1(x) of the rocket body under the first-order modal response can be determined. n ) and modal bending moment M1(x n The details are as follows:

[0091]

[0092]

[0093] In the above formula, x n and x i Indicates quality substation m i The position coordinates are the coordinates of the cross section used for load calculation.

[0094] Next, the maximum value q is obtained from the first-order generalized displacement time-domain data q1(t) obtained by equation (5). 1max One option is to perform probability statistics on the first-order generalized displacement time domain q1(t) to obtain the maximum value with a 99% probability; another option is to use the method of finding the extrema of the function to solve for the maximum value of q1(t).

[0095] Then, based on the generalized displacement maximum value q 1max and the modal shear force Q1(x) under the first-order modal response n The first-order response shear force Q(x) of the arrow body is determined as follows:

[0096] Q(x) = Q1(x) n )·q 1max (8)

[0097] Based on the maximum value of the generalized displacement q 1max and the modal bending moment M1(x) under the first-order modal response n The first-order response bending moment M(x) of the arrow body is determined as follows:

[0098] M(x)=M1(x n )·q 1max (9)

[0099] The first-order response shear force Q(x) and first-order response bending moment M(x) of the rocket body are the sloshing loads of the liquid rocket sought in this application.

[0100] This embodiment provides a method for determining the sloshing load of a liquid rocket. By performing stiffness and mass characteristic simulations based on first simulated input parameters, stiffness and mass characteristic data characterizing the elastic state of the liquid rocket section are obtained. Then, dynamic characteristic simulation is performed based on these data to obtain modal parameters reflecting the rocket body under elastic influence. Finally, the sloshing load of the rocket body is calculated based on the first-order mode shape, the location and force of the sloshing force for each propellant tank, the unit impulse response function obtained from the modal parameters, the mass substation, and the first-order modal angular frequency. Because the influence of rocket body elasticity is considered during the dynamic characteristic simulation, the calculated sloshing load of the liquid rocket obtained by this method is greater than that of traditional methods and more closely approximates the actual state of the liquid rocket during flight, resulting in higher accuracy in the calculated sloshing load.

[0101] In the following embodiments, for the sake of clarity, the above scheme will be further explained in conjunction with specific implementation data:

[0102] Taking a liquid rocket with a four-tank structure as an example, the nonlinear problems caused by the anti-sloshing plate design and the non-flat bottom of the tanks are first modeled based on the Euler multiphase flow VOF method. The simulation platform is starccm+, the tank walls are treated as rigid walls, and the fluid computational domain is drawn as a hexahedral mesh. The flow state is set as laminar, the time discretization format is second-order, the time step is 0.01s, and the number of iteration steps in each time step is set according to the convergence of the sloshing force. The simulation input uses the initial velocity excitation of the propellant, and the output is the time-domain data of the sloshing force along the excitation direction and the time-domain data of the sloshing torque perpendicular to the excitation plane. Then, through data processing, the sloshing characteristic parameters of the liquid in each tank are identified, including: sloshing mass m. hk Shaking frequency ω hk , Sway displacement amplitude x hk , Sway Damping hk and the position of the swaying force h k And obtain the swaying force F based on the swaying characteristic parameters. k .

[0103] The stiffness and mass characteristics of the rocket section were simulated using lumped mass elements and beam elements. Propellant mass characteristics were simulated using coupled mass simulation, neglecting the propellant's stiffness characteristics. A dynamic characteristic model of the rocket body was established, and modal analysis simulations were performed. The simulation platform used MSC.Patran / Nastran software. The former served as the pre-processing software for finite element analysis, used to establish the finite element model, while the latter served as the dynamic characteristic analysis software. Its SOL103 (real eigenvalue solver) was used for modal analysis calculations to extract the rocket body's modal parameters, including: first-order modal circular frequency ω1, first-order generalized mass M1, first-order damping ratio ζ1, and first-order mode shape. Based on the modal parameters of the rocket body and equation (2), the unit impulse response function h(t) of the single-degree-of-freedom system of the rocket body in the first-order modal space is obtained.

[0104] To obtain a larger value for the generalized force, considering the characteristics of the first-order vibration mode, the swaying force F k The sign should correspond to the position h where the swaying force is applied. k The first-order mode shape values ​​at each location retain the same sign. In this embodiment, please refer to... Figure 2 If the value of the first mode shape at the secondary methane tank is positive, then the sloshing force of the secondary methane tank is positive; similarly, the sloshing forces of the secondary oxygen tank and the primary methane tank are positive, and the sloshing force of the primary oxygen tank is negative; based on equation (4), the time-domain data of the first-order generalized force of the single-degree-of-freedom system, f1(t), is obtained by weighted summation of mode shapes. The curve of f1(t) can be found in the figure. Figure 3 .

[0105] The lsim function, based on the MATLAB platform, can calculate the output of a linear time-invariant model under arbitrary inputs. Specifically, the modal parameters of the rocket body serve as the input to the lsim function, enabling the solution of the generalized displacement time-domain data q1(t) under generalized force and extracting the maximum value q of the generalized displacement. 1max For a schematic diagram of the generalized displacement time-domain data q1(t), please refer to [reference needed]. Figure 4 .

[0106] Modal shear force and bending moment can be calculated using theoretical formulas (6) and (7), or extracted from the modal analysis results. Next, based on the maximum value of the generalized displacement q... 1max Modal shear force Q1(x) under first-order modal response n ) and bending moment M1(x n The final sway load is obtained by using equations (8) and (9).

[0107] Figure 5 The diagram illustrates a comparison between the calculation method proposed in this embodiment and the traditional method: "Applying different tank sway amplitudes as static concentrated forces to the rocket body, and combining different positive and negative concentrated forces from different tanks to obtain the maximum load value for each section." The diagram shows a comparison of the sway loads calculated using the method described in this embodiment and the traditional method: "...using different tank sway amplitudes as static concentrated forces applied to the rocket body, and combining different positive and negative concentrated forces from different tanks to obtain the maximum load value for each section." The horizontal axis represents the mass distribution station, and the vertical axis represents the first-order response bending moment, with units of 10. 5 N·m. It can be seen that the sway load obtained by the calculation method provided in this embodiment is larger and closer to the actual working conditions during the flight of a liquid rocket.

[0108] In summary, this embodiment provides a rapid method for calculating the sloshing load of multi-tank liquid rockets, given the relevant sloshing characteristic parameters. This method achieves the goal of refined load design while meeting the needs of rapid iterative demonstration in projects.

[0109] Secondly, based on the same inventive concept, please refer to Figure 6 A device for determining the sloshing load of a liquid rocket is provided, comprising:

[0110] The acquisition module 610 is used to obtain the sloshing characteristic parameters and the first simulation input parameters of each tank, and to obtain the sloshing force of each tank based on the sloshing characteristic parameters; the sloshing characteristic parameters include the sloshing mass, sloshing frequency, sloshing displacement amplitude, sloshing damping, and the location of the sloshing force of the liquid in the tank; the first simulation input parameters include the rocket body model, section material stiffness, section material density, section mass, section center of mass, section moment of inertia, rocket body mass, rocket body center of mass, rocket body moment of inertia, propellant mass, propellant center of mass, and propellant moment of inertia;

[0111] The first simulation module 620 is used to perform stiffness characteristic simulation and mass characteristic simulation based on the first simulation input parameters to obtain stiffness characteristic data and mass characteristic data of the compartment. The stiffness characteristic data includes the cross-sectional diameter, equivalent thickness, elastic modulus and Poisson's ratio of each beam element in the compartment. The mass characteristic data includes the mass fraction and moment of inertia of the structural compartment and the propellant compartment.

[0112] The second simulation module 630 is used to simulate the dynamic characteristics of the liquid rocket body based on the stiffness characteristic data and the mass characteristic data, obtain the modal parameters of the rocket body, and obtain the unit impulse response function based on the modal parameters of the rocket body; the modal parameters of the rocket body include the first-order modal circular frequency, the first-order generalized mass, the first-order damping ratio, and the first-order mode shape;

[0113] The determination module 640 is used to determine the sway load of the rocket body based on the first-order vibration mode, the unit impulse response function, the swaying force application location and swaying force of each tank, the mass station and the first-order modal circular frequency; the sway load includes the first-order response shear force and the first-order response bending moment.

[0114] Optionally, the acquisition module 610 is used for:

[0115] Obtain the second simulation input parameters, which include the tank size of each tank, the initial velocity excitation of the propellant, the propellant density, the flight axial overload, the size of the anti-sway plate, and the position information of the anti-sway plate;

[0116] Based on the second simulation input parameters, Euler multiphase flow simulation is performed to obtain the time-domain data of the swaying force of each tank in the initial velocity excitation direction and the time-domain data of the swaying torque perpendicular to the initial velocity excitation plane.

[0117] Based on the time-domain data of the swaying force and the time-domain data of the swaying torque, the swaying characteristic parameters of each tank are determined.

[0118] Optionally, the determining module 640 is used for:

[0119] Based on the first-order mode shape, the unit impulse response function, the location and force of the swaying force of each tank, the first-order generalized displacement time-domain response data of the rocket body are determined.

[0120] Based on the mass substation, the first-order modal circular frequency, and the first-order generalized displacement time-domain response data, the sway load of the rocket body is determined; the sway load includes the first-order response shear force and the first-order response bending moment.

[0121] Furthermore, the determining module 640 is used for:

[0122] Based on the first-order vibration mode, the location and force of the swaying force of each tank, the time-domain data of the first-order generalized force of the rocket body are determined.

[0123] Based on the unit impulse response function and the first-order generalized force time-domain data, the first-order generalized displacement time-domain response data of the rocket body is determined.

[0124] Furthermore, the determining module 640 is used for:

[0125] Based on the first-order vibration mode value of each tank at the location where the swaying force is applied, the positive and negative information of the swaying force of each tank is determined.

[0126] The first-order generalized force time-domain data of the rocket body is obtained by weighted summation based on the first-order vibration mode, the swaying force of all tanks and the corresponding positive and negative information.

[0127] Furthermore, the determining module 640 is used for:

[0128] Based on the unit impulse response function and the first-order generalized force time-domain data, the first-order generalized displacement time-domain response data of the rocket body is obtained by performing Duhamel integration.

[0129] Furthermore, the determining module 640 is used for:

[0130] Based on the mass substation and the first-order modal circular frequency, the modal shear force and modal bending moment of the rocket body under the first-order modal response are determined;

[0131] The maximum value of the generalized displacement is obtained based on the first-order generalized displacement time-domain response data;

[0132] Based on the maximum value of the generalized displacement and the modal shear force under the first-order modal response, the first-order response shear force of the rocket body is determined;

[0133] Based on the maximum value of the generalized displacement and the modal bending moment under the first-order modal response, the first-order response bending moment of the rocket body is determined.

[0134] Thirdly, based on the same inventive concept as the foregoing embodiments, in yet another optional embodiment, such as Figure 7 As shown, an electronic device 700 is provided, including a processor 720 and a memory 710. The memory 710 is coupled to the processor 720 and stores a computer program 711. When the computer program 711 is executed by the processor 720, the electronic device 700 performs the steps of the determination method provided in the first aspect embodiment.

[0135] Fourthly, based on the same inventive concept as the foregoing embodiments, in yet another optional embodiment, such as Figure 8 As shown, a computer-readable storage medium 800 is provided, on which a computer program 811 is stored, which, when executed by a processor, implements the steps of the determination method provided in the first aspect embodiment.

[0136] Through one or more embodiments of the present invention, the present invention has the following beneficial effects or advantages:

[0137] This embodiment provides a method, apparatus, electronic device, and storage medium for determining the sloshing load of a liquid rocket. By performing stiffness and mass characteristic simulations based on first simulated input parameters, stiffness and mass characteristic data characterizing the elastic state of the liquid rocket section are obtained. Then, dynamic characteristic simulation is performed based on the stiffness and mass characteristic data to obtain the rocket body modal parameters reflecting the elastic influence. Finally, the sloshing load of the rocket body is calculated based on the first-order vibration mode, the location and force of the sloshing force for each propellant tank, the unit impulse response function obtained from the rocket body modal parameters, the mass substation, and the first-order modal circular frequency. Because the influence of rocket body elasticity is considered in the dynamic characteristic simulation, the calculated sloshing load of the liquid rocket obtained by this method is greater than that of traditional methods and is closer to the actual state of the liquid rocket during flight, resulting in higher accuracy in the sloshing load calculation.

[0138] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0139] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for determining the sloshing load of a liquid rocket, characterized in that, The liquid rocket includes two or more propellant tanks, and the method includes: Obtain the sloshing characteristic parameters of each tank, and obtain the sloshing force of each tank based on the sloshing characteristic parameters; the sloshing characteristic parameters include the sloshing mass of the liquid in the tank, the sloshing frequency, the sloshing displacement amplitude, the sloshing damping, and the location of the sloshing force. Obtain the first simulation input parameters; the first simulation input parameters include the liquid rocket body model, section material stiffness, section material density, section mass, section center of mass, section moment of inertia, rocket body mass, rocket body center of mass, rocket body moment of inertia, propellant mass, propellant center of mass, and propellant moment of inertia; Based on the first simulation input parameters, stiffness characteristic simulation and mass characteristic simulation are performed to obtain stiffness characteristic data and mass characteristic data of the compartment. The stiffness characteristic data includes the cross-sectional diameter, equivalent thickness, elastic modulus and Poisson's ratio of each beam element in the compartment; the mass characteristic data includes the mass fraction and moment of inertia of the structural compartment and the propellant compartment. Based on the stiffness characteristic data and the mass characteristic data, the dynamic characteristics of the liquid rocket body are simulated to obtain the body modal parameters, and the unit impulse response function is obtained according to the body modal parameters; the body modal parameters include the first-order modal circular frequency, the first-order generalized mass, the first-order damping ratio, and the first-order mode shape; Based on the first-order vibration mode, the unit impulse response function, the location and force of the swaying force of each tank, the mass station, and the first-order modal circular frequency, the swaying load of the rocket body is determined; the swaying load includes the first-order response shear force and the first-order response bending moment.

2. The method as described in claim 1, characterized in that, The process of obtaining the sway characteristic parameters of each tank includes: Obtain the second simulation input parameters, which include the tank size of each tank, the initial velocity excitation of the propellant, the propellant density, the flight axial overload, the size of the anti-sway plate, and the position information of the anti-sway plate; Based on the second simulation input parameters, Euler multiphase flow simulation is performed to obtain the time-domain data of the swaying force of each tank in the initial velocity excitation direction and the time-domain data of the swaying torque perpendicular to the initial velocity excitation plane. Based on the time-domain data of the swaying force and the time-domain data of the swaying torque, the swaying characteristic parameters of each tank are determined.

3. The method as described in claim 1, characterized in that, The determination of the sway load of the rocket body based on the first-order vibration mode, the unit impulse response function, the location and force of the swaying force of each tank, the mass station, and the first-order modal circular frequency includes: Based on the first-order mode shape, the unit impulse response function, the location and force of the swaying force of each tank, the first-order generalized displacement time-domain response data of the rocket body are determined. Based on the mass substation, the first-order modal circular frequency, and the first-order generalized displacement time-domain response data, the sway load of the rocket body is determined; the sway load includes the first-order response shear force and the first-order response bending moment.

4. The method as described in claim 3, characterized in that, The determination of the first-order generalized displacement time-domain response data of the rocket body based on the first-order mode shape, the unit impulse response function, the location and force of the swaying force of each tank, includes: Based on the first-order vibration mode, the location and force of the swaying force of each tank, the time-domain data of the first-order generalized force of the rocket body are determined. Based on the unit impulse response function and the first-order generalized force time-domain data, the first-order generalized displacement time-domain response data of the rocket body is determined.

5. The method as described in claim 4, characterized in that, The determination of the first-order generalized force time-domain data of the rocket body based on the first-order vibration mode, the location of the swaying force of each tank, and the swaying force includes: Based on the first-order vibration mode value of each tank at the location where the swaying force is applied, the positive and negative information of the swaying force of each tank is determined. The first-order generalized force time-domain data of the rocket body is obtained by weighted summation based on the first-order vibration mode, the swaying force of all tanks and the corresponding positive and negative information.

6. The method as described in claim 4, characterized in that, The determination of the first-order generalized displacement time-domain response data of the rocket body based on the unit impulse response function and the first-order generalized force time-domain data includes: Based on the unit impulse response function and the first-order generalized force time-domain data, the first-order generalized displacement time-domain response data of the rocket body is obtained by performing Duhamel integration.

7. The method as described in claim 3, characterized in that, The determination of the sway load of the rocket body based on the mass substation, the first-order modal circular frequency, and the first-order generalized displacement time-domain response data includes: Based on the mass substation and the first-order modal circular frequency, the modal shear force and modal bending moment of the rocket body under the first-order modal response are determined; The maximum value of the generalized displacement is obtained based on the first-order generalized displacement time-domain response data; Based on the maximum value of the generalized displacement and the modal shear force under the first-order modal response, the first-order response shear force of the rocket body is determined; Based on the maximum value of the generalized displacement and the modal bending moment under the first-order modal response, the first-order response bending moment of the rocket body is determined.

8. A device for determining the sloshing load of a liquid rocket, characterized in that, The liquid rocket includes two or more propellant tanks, and the device includes: The acquisition module is used to obtain the sloshing characteristic parameters and the first simulation input parameters of each tank, and to obtain the sloshing force of each tank based on the sloshing characteristic parameters; the sloshing characteristic parameters include the sloshing mass, sloshing frequency, sloshing displacement amplitude, sloshing damping, and the location of the sloshing force of the liquid in the tank; the first simulation input parameters include the rocket body model, section material stiffness, section material density, section mass, section center of mass, section moment of inertia, rocket body mass, rocket body center of mass, rocket body moment of inertia, propellant mass, propellant center of mass, and propellant moment of inertia; The first simulation module is used to perform stiffness characteristic simulation and mass characteristic simulation based on the first simulation input parameters to obtain stiffness characteristic data and mass characteristic data of the compartment. The stiffness characteristic data includes the cross-sectional diameter, equivalent thickness, elastic modulus and Poisson's ratio of each beam element in the compartment. The mass characteristic data includes the mass fraction and moment of inertia of the structural compartment and the propellant compartment. The second simulation module is used to simulate the dynamic characteristics of the liquid rocket body based on the stiffness characteristic data and the mass characteristic data, obtain the body modal parameters, and obtain the unit impulse response function based on the body modal parameters; the body modal parameters include the first-order modal circular frequency, the first-order generalized mass, the first-order damping ratio, and the first-order mode shape; The determination module is used to determine the sway load of the rocket body based on the first-order vibration mode, the unit impulse response function, the swaying force application location and swaying force of each tank, the mass station and the first-order modal circular frequency; the sway load includes the first-order response shear force and the first-order response bending moment.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

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