Method for constructing fluid-structure thermal coupling dynamics model of thin film evaporator and related device

Abstract

The embodiment of the application relates to the technical field of lyocell fiber equipment, and provides a thin film evaporator fluid-thermal coupling dynamics model construction method and related devices, the method comprises the following steps: a scraper force model under multiple working conditions is established; a nonlinear normal contact force model of a thrust self-aligning roller bearing is established; a flexible body model of a main shaft and a scraper plate is established; a flexible body model of a cylinder is established; the scraper force model, the nonlinear normal contact force model, the flexible body model of the main shaft and the scraper plate and the flexible body model of the cylinder are integrated into a multi-body dynamics simulation platform to construct a thin film evaporator fluid-thermal coupling dynamics model of a complete machine, and the method can ensure key deformation precision while greatly reducing calculation load in the process of large-scale thin film evaporator dynamics modeling.

Description

Technical Field

[0001] This application relates to the field of lyocell fiber equipment technology, specifically to a method for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator and related devices. Background Technology

[0002] Lyocell fiber is a new type of green and environmentally friendly cellulose fiber. With its renewable raw materials, pollution-free production process, and biodegradable products, it has become an important direction for the transformation and upgrading of the global textile industry, leading to continuously increasing demand for its production capacity. Lyocell fiber production, as a typical process industry, involves numerous production steps, low levels of automation, weak equipment health management capabilities, and a high risk of unplanned downtime. The high-value core equipment limiting its production capacity—the thin-film evaporator—faces the dual challenges of large-scale production and continuous stable operation. Researching kinetic modeling methods for lyocell thin-film evaporators and analyzing the kinetic coupling mechanism is an effective way to accelerate the development of large-scale thin-film evaporators and an efficient way to achieve predictive maintenance, possessing significant scientific research and industry application value.

[0003] A typical large-scale lyocell thin-film evaporator system includes a motor, reducer, feeder, cylinder, main shaft, bearings, scraper, and blade. In the context of lyocell fiber production, existing research on the dynamic modeling of large-scale thin-film evaporators directly uses finite element modeling and simulation to study the coupling characteristics of liquid film fluid and temperature. This results in a large amount of computation and a long computation time, making it difficult to apply to the development of intelligent operation and maintenance technologies that urgently require a large amount of data. Summary of the Invention

[0004] This application provides a method and related apparatus for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator, which can significantly reduce the computational load and improve efficiency while ensuring the accuracy of key deformations during the dynamics modeling of large-scale thin-film evaporators.

[0005] A first aspect of this application provides a method for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator, the method comprising:

[0006] Establish a scraper force model under multiple working conditions;

[0007] A nonlinear normal contact force model for a thrust self-aligning roller bearing is established.

[0008] Establish flexible body models for the main shaft and scraper;

[0009] Establish a flexible body model of the cylinder;

[0010] The scraper force model, the nonlinear normal contact force model, the flexible body model of the main shaft and scraper, and the flexible body model of the cylinder are integrated into a multibody dynamics simulation platform to construct a fluid-structure-thermal coupling dynamics model of the entire thin-film evaporator.

[0011] In one possible implementation, establishing the scraper force model under multiple working conditions includes:

[0012] The forces acting on the scraper are projected onto the tangential and normal directions of the scraper's circular motion, and the first scraper normal force calculation model and the first scraper tangential force calculation model are constructed after the projection of the normal force and tangential force.

[0013] The finite element method is used to model a long cylindrical section containing several scrapers, and the unknown component force parameters in the calculation models of the normal force and the tangential force of the first scraper are solved.

[0014] Identify the key operating parameters that affect the stress on the scraper;

[0015] Based on the key operating parameters, multiple sets of simulation operating conditions are planned using experimental design methods to obtain a simulation test scheme.

[0016] For each set of working conditions in the simulation test scheme, a finite element model is run for simulation. The component force parameters are extracted from the simulation results and substituted into the first scraper normal force calculation model and the first scraper tangential force calculation model to calculate the normal force and tangential force under the corresponding working conditions.

[0017] Using the key working parameters under each working condition and the calculated normal and tangential forces as sample data, a data-driven method is used for regression fitting to establish a parameterized scraper force model with the key working parameters as input and the normal and tangential forces as output.

[0018] In one possible implementation, the force model of the scraper is expressed by the following formula:

[0019]

[0020]

[0021] In the formula, Main spindle speed The temperature inside the cylinder. The thickness is the liquid film thickness.

[0022] In one possible implementation, establishing the nonlinear normal contact force model of the thrust self-aligning roller bearing includes:

[0023] Analyze the contact geometry characteristics between the rolling elements and the inner and outer rings in a thrust self-aligning roller bearing to determine the contact form between the rolling elements and the inner and outer rings;

[0024] Based on the contact pattern between the rolling element and the inner and outer rings, the Hunt-Crossley contact model is used as the basic calculation framework for the normal contact force.

[0025] Based on the contact geometry characteristics, a Caishan-Ke contact force model applicable to pin-surface contact is introduced to determine the equivalent Hertz contact stiffness.

[0026] The equivalent Hertz contact stiffness is substituted into the restoring force term in the Hunt-Crossley model framework to replace the original Hertz contact stiffness. Combined with the damping term in the basic calculation framework, a nonlinear normal contact force model suitable for thrust self-aligning roller bearings is constructed.

[0027] In one possible implementation, determining the equivalent Hertz contact stiffness by introducing a Caishan-Ke contact force model suitable for pin-to-surface contact based on the contact geometry features includes:

[0028] A Caishan-Ke contact force model applicable to pin-surface contact is introduced as the basic mechanical model describing the contact force between the rolling element and the inner and outer rings.

[0029] Analyze the contact geometry parameters between the rolling element and the inner and outer rings to determine the difference between the average radius of the rolling element and the radius of curvature of the contact surface, as well as the range of values ​​for the contact deformation.

[0030] Based on the engineering approximation condition that the contact deformation is much smaller than the difference in the radius of curvature of the surface, the Caishan-Ke contact force model is simplified by ignoring the δ term in the denominator and approximately expressed as a power-law function of the contact deformation δ.

[0031] The coefficients are extracted from the simplified power-law function to determine the equivalent Hertz contact stiffness.

[0032] In one possible implementation, establishing the flexible body model of the spindle and scraper includes:

[0033] Based on the structural features of the main shaft and scraper, the three-dimensional geometric model of the main shaft and scraper is simplified to obtain a simplified three-dimensional geometric model of the main shaft and scraper.

[0034] The simplified three-dimensional geometric model of the spindle and scraper is meshed and discretized into finite element elements of the spindle and scraper;

[0035] Define the material properties and modal analysis parameters for the flexible body model;

[0036] Modal solving was performed to obtain flexible body models of the spindle and scraper for multibody dynamics simulation.

[0037] In one possible implementation, establishing the flexible body model of the cylinder includes:

[0038] The cylinder is divided into sections along the axial direction at the bolt connection points, and each section is constructed as a rigid cylinder;

[0039] Massless beam elements are used to connect adjacent rigid cylinder sections to construct a discrete flexible connection structure;

[0040] Assign cross-sectional properties to the beam elements to obtain a flexible body model of the cylinder.

[0041] A second aspect of this application provides a device for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator, the device comprising:

[0042] The first module is used to establish the scraper force model under multiple working conditions;

[0043] The second module is used to establish a nonlinear normal contact force model for thrust self-aligning roller bearings;

[0044] The third module is used to create a flexible body model of the main shaft and scraper;

[0045] The fourth module is used to create a flexible body model of the cylinder;

[0046] The fifth module is used to integrate the scraper force model, the nonlinear normal contact force model, the flexible body model of the main shaft and scraper, and the flexible body model of the cylinder into the multibody dynamics simulation platform to construct the fluid-structure-thermal coupling dynamics model of the whole thin film evaporator.

[0047] A third aspect of this application provides a terminal including a processor, an input device, an output device, and a memory, wherein the processor, input device, output device, and memory are interconnected, wherein the memory is used to store a computer program, the computer program including program instructions, and the processor is configured to invoke the program instructions to execute the steps described in the method for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator in the first aspect of this application.

[0048] A fourth aspect of this application provides a computer-readable storage medium storing a computer program for electronic data interchange, wherein the computer program causes a computer to perform some or all of the steps described in the method for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator in the first aspect of this application.

[0049] A fifth aspect of this application provides a computer program product, wherein the computer program product includes a non-transitory computer-readable storage medium storing a computer program operable to cause a computer to perform some or all of the steps described in the method for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator in the first aspect of this application. The computer program product may be a software installation package.

[0050] The beneficial effects of this example include:

[0051] 1. This example abandons the traditional single-scale or local modeling approach and proposes a multi-scale modeling framework that combines "breaking down the whole into parts" and "combining the parts into a whole". This framework refines the local flow-thermal coupling problem through the finite element method, establishes an efficient surrogate model through a data-driven method, and finally achieves system-level integration on a multibody dynamics platform, providing a generalizable paradigm for the whole-machine dynamics modeling of similar complex industrial equipment.

[0052] 2. This example addresses the challenge of balancing accuracy and efficiency in large-scale thin-film evaporators by proposing a practical hybrid modeling technique. For the scraper forces under the coupled effects of non-Newtonian fluid and temperature, a parametric model based on CFD simulation and response surface methodology is established, enabling rapid calculation of complex loads. For the unique contact geometry of thrust self-aligning roller bearings, the classic Hunt-Crossley contact force model is improved to enhance the fidelity of contact simulation. For slender structures and segmented cylinders, a rigid-flexible coupling and discrete flexible connection method is employed, significantly reducing the computational load while ensuring the accuracy of key deformations.

[0053] 3. This example addresses the lack of dynamic models supporting overall system performance prediction and intelligent operation and maintenance by constructing a fluid-solid-thermal coupled dynamic model for a large-scale lyocell fiber thin-film evaporator suitable for equipment operation status assessment and predictive maintenance. This model integrates multiphysics mechanisms, enabling it to simulate complex operating conditions and typical faults. It provides high-quality simulation data for overall system performance prediction and intelligent operation and maintenance algorithm development, thus bridging the gap between mechanistic models and R&D design and intelligent operation and maintenance applications. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 This application provides a schematic diagram of the overall process for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator.

[0056] Figure 2 This application provides a schematic diagram of the scraper force in a method for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator.

[0057] Figure 3 This application provides a fluid volume fraction cloud map of the film scraping process in a method for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator.

[0058] Figure 4 A schematic diagram of a thrust self-aligning roller bearing structure is provided for a method of constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator according to an embodiment of this application.

[0059] Figure 5 This application provides a schematic diagram of the main shaft and scraper structure for a method of constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator.

[0060] Figure 6 The present application provides a flexible body cloud diagram of the main axis and scraper for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator.

[0061] Figure 7 A schematic diagram showing the test and simulation values ​​of the vibration velocity of the bearing housing of a large thin-film evaporator made of lyocell fiber, which provides a method for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator according to an embodiment of this application;

[0062] Figure 8 A schematic diagram showing the test and simulation values ​​of the spindle torque of a large lyocell fiber thin-film evaporator, which provides a method for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator according to an embodiment of this application;

[0063] Figure 9 This application provides a schematic diagram of the bearing outer ring fault modeling process in a method for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator.

[0064] Figure 10 A schematic diagram of the bearing outer ring vibration response provided in this application embodiment for a method of constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator;

[0065] Figure 11 This application provides a schematic diagram of the overall structure of a device for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator.

[0066] Figure 12 This application provides a schematic diagram of the structure of a terminal.

[0067] Figure label:

[0068] Module 1-1, Module 2-2, Module 3-3, Module 4-4, Module 5-5. Detailed Implementation

[0069] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0070] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0071] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0072] To better understand the method for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator provided in this application embodiment, the following is a brief introduction to the scenarios in which this method is applied. Currently, modeling and analysis of lyocell fiber thin-film evaporators mainly focus on scaled-down models or small-scale thin-film evaporators, and there is a lack of effective and feasible modeling methods for large-scale thin-film evaporators. Existing technologies directly study the coupling characteristics of liquid film fluid and temperature through finite element modeling and simulation, which involves large computational loads and long computation times, making it difficult to apply to the development of intelligent operation and maintenance technologies that urgently require large amounts of data.

[0073] The method for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator is applied to a device for constructing such a model. Figure 1 A schematic diagram of the overall process for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator is shown. Figure 1 As shown, it includes:

[0074] S1. Establish the scraper force model under multiple working conditions.

[0075] One of the challenges in modeling the fluid-solid-thermal coupling dynamics of a lyocell fiber thin-film evaporator is accurately simulating the interaction between the scraper, liquid film, and cylinder during dynamic operation. The liquid film, composed of a mixture of cellulose and NMMO solution, is a viscous liquid. During the rotation of the main shaft, the liquid film adheres to the cylinder wall and exerts resistance on the scraper. This resistance is transmitted to the main shaft after passing through the scraper, scraper blade, and scraper support frame. The magnitude of this resistance is closely related to the fluid characteristics constituting the liquid film. This fluid is a non-Newtonian fluid, exhibiting shear-thinning characteristics, so the scraper film speed has a non-linear effect on the resistance. Furthermore, the liquid viscosity and flow velocity differ at different temperatures, resulting in varying resistance magnitudes. Additionally, rotor eccentricity or main shaft deformation can lead to variations in liquid film thickness and resistance magnitude. The research employs a modeling approach of first breaking down the problem into smaller parts and then integrating them back into a whole. First, focusing on the scraper as the research object, the influence of the flow field and temperature field is considered, and modeling and analysis are performed based on finite element theory. Then, based on the stress characteristics of the scraper under different operating conditions, a multi-condition scraper stress model was established using data-driven modeling methods. Finally, the multi-condition scraper stress model was incorporated into the overall multibody dynamics model of the thin-film evaporator to form a stress model of the scraper array, thus considering the influence of multiple structural fields on the scraper stress.

[0076] Step S1 includes the following steps:

[0077] S101. Project the force on the scraper onto the tangential and normal directions of the scraper's circular motion, and construct the first scraper normal force calculation model and the first scraper tangential force calculation model after projection of normal force and tangential force.

[0078] in, Figure 2 This diagram illustrates the forces acting on a scraper in a fluid-structure-thermal coupling kinetic model construction method for a thin-film evaporator. The top of the scraper is immersed in the liquid film and subjected to forces from the liquid, such as... Figure 2 As shown on the left, Figure 2 The image on the left shows a complete scraper with four blades. The image on the right shows the force analysis of the second blade. The other three blades are subjected to similar forces. , , , , , , , , Its function.

[0079] Furthermore, the force acting on the scraper is projected onto the tangential and normal directions of the scraper's circular motion, such as... Figure 2 As shown on the right, according to Figure 2 Based on the geometry and stress conditions of the scraper shown, a calculation model for the normal force of the first scraper after projection is obtained. And the calculation model of the first scraper tangential force The calculation formula is as follows:

[0080] (1)

[0081] (2)

[0082] In the formula, , , , , The normal force on the plane of action, for The angle with the vertical direction, for Angle with the vertical direction, footnote It represents 1, 2, 3, and 4.

[0083] Furthermore, in order to calculate and You need to obtain it first. , , , , .

[0084] In this example, Ansys software is used. First, finite element modeling is performed, then fluid simulation is conducted, and the fluid dynamics are extracted from the simulation results. , , , , The simulation process is a standard procedure for fluid simulation using Ansys software. The key to fluid modeling and simulation is setting up a reasonable non-Newtonian fluid dynamics model.

[0085] Common non-Newtonian fluid dynamics models include the Ostwald-De Wale model, the Carreau-Yasuda model, and the Cross model. Among them, the Ostwald-De Wale model is applicable to pseudoplastic or dilatant fluids under a wide range of shear deformation rates and is the most widely used non-Newtonian fluid model in engineering applications.

[0086] This model has been widely used in the simulation of Lyocell fiber solutions. The equations of the Ostwald-De Wale model are as follows:

[0087] (3)

[0088] In the formula, Shear viscosity, This is the fluid consistency index. Shear strain rate This is the power-law exponent.

[0089] when When the model reflects the characteristics of shear-thickened dilatant fluids (such as starch solutions, sucrose solutions, paint solutions, etc.); when When the model reflects the properties of shear-thinned pseudoplastic fluids (such as lyocell fiber solutions, tomato sauce, etc.); when At this time, the model reflects the properties of Newtonian fluids. However, the Ostwald-De Wale model does not directly consider the effect of temperature on the fluid. Therefore, the Arrhenius equation is introduced to consider the effect of temperature on the rheological properties of the solution, as follows:

[0090] (4)

[0091] In the formula, These are characteristic constants. For activation energy, The gas constant is... The absolute temperature is used. The models shown in equations (3) and (4) are used in the simulation to realize the non-Newtonian fluid setting that takes into account temperature changes.

[0092] S102. The long cylindrical section containing several scrapers is modeled using the finite element method, and the unknown component force parameters in the calculation models of the normal force and the tangential force of the first scraper are solved.

[0093] The scraper has an axial dimension of 400 mm in the cylinder. Therefore, to accelerate the fluid simulation and simulate the scraping action of a complete scraper as closely as possible, a fluid domain within 500 mm of the cylinder's axial direction is modeled. Four complete scrapers operate simultaneously in this domain, distributed radially. The fluid flow near the scrapers is complex. To ensure the accuracy of the fluid simulation while reducing computational requirements, the finite element mesh size is set smaller near the scrapers and larger further away.

[0094] Figure 3 This application provides a fluid volume fraction cloud map of the film scraping process in a method for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator. Figure 3 (a) in this application provides a method for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator, where the fluid volume fraction cloud represents the film scraping process. Figure 1 , Figure 3 (b) in this embodiment of the application provides a method for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator, which includes a fluid volume fraction cloud during the film scraping process. Figure 2 When performing fluid simulation, the volume fraction distribution of liquids and gases is as follows: Figure 3 As shown in (a) in the figure. Figure 3 As shown in (b), the red trace represents the liquid phase, the blue trace represents the gas phase, and the other colors represent the gas-liquid mixture.

[0095] S103. Determine the key operating parameters that affect the force on the scraper.

[0096] Based on the actual production conditions of the thin-film evaporator, the key operating parameters affecting the force on the scraper include at least the spindle speed ω, the temperature inside the cylinder T, and the liquid film thickness D.

[0097] S104. Based on the key operating parameters, multiple sets of simulation operating conditions are planned using experimental design methods to obtain a simulation test scheme.

[0098] Among these factors, different production needs will lead to variations in the spindle speed and internal temperature of the thin-film evaporator, while component installation errors, structural deformation, and structural vibrations will cause changes in the liquid film thickness.

[0099] The operating conditions of the scraper also change accordingly. The force model of the scraper under multiple operating conditions is shown below:

[0100] (5)

[0101] (6)

[0102] (7)

[0103] (8)

[0104] (9)

[0105] In the formula, Main spindle speed For temperature, For liquid film thickness, footnote It represents 1, 2, 3, and 4.

[0106] For example: FA2 indicates that the tip of the second scraper is subjected to force, see Figure 2 (Left), and so on.

[0107] Combining equations (1)~(2) and (5)~(9), the models for normal and tangential forces under multiple working conditions can be further derived as follows:

[0108] (10)

[0109] (11)

[0110] In actual production Since the range of values ​​is known, a data-driven approach can be used to obtain [the value]. and The expression is given. For data modeling of three influencing factors, response surface methodology is one of the better methods. This example uses the commonly used central composite design method to design a simulation experiment, and then obtains the results through regression analysis of the simulation data. and The expression is given. Based on the operating conditions of the equipment, a factor level table of influencing factors for the central composite design method is designed. Subsequently, an experimental orthogonal array is further designed. Simulations are performed according to the experiments determined by the experimental orthogonal array, and the simulation results are extracted. The results are then calculated according to equations (1) and (2) for each operating condition. and The value of .

[0111] S105. For each set of working conditions in the simulation test scheme, run the finite element model to perform simulation, extract each component force parameter from the simulation results, and substitute it into the first scraper normal force calculation model and the first scraper tangential force calculation model to calculate the normal force and tangential force under the corresponding working condition.

[0112] Among them, response surface regression analysis in Minitab software was used to obtain and The expression.

[0113] S106. Using the key working parameters under each working condition and the calculated normal force and tangential force as sample data, a data-driven method is used to perform regression fitting to establish a parameterized scraper force model with the key working parameters as input and the normal force and tangential force as output.

[0114] Ultimately, we obtained and The mathematical model is as follows:

[0115] (12)

[0116] (13)

[0117] In the formula, , , , , , , , , , , , , All are constant coefficients, directly generated from response surface analysis.

[0118] Will and Substituting into Equations 10 and 11 yields the parameterized force model of the scraper.

[0119] S2. Establish a nonlinear normal contact force model for thrust self-aligning roller bearings.

[0120] Multibody dynamics theory has been widely applied, and numerous well-known dynamic modeling and analysis software programs have been developed based on this theory, with ADAMS being one of them. This example uses ADAMS, and the modeling process focuses on how to accurately simulate the coupled dynamic responses of the bearings, main shaft, scrapers, blades, and cylinder of a large-scale Lyocell fiber thin-film evaporator under various operating conditions.

[0121] Step S2 includes the following steps:

[0122] S201. Analyze the contact geometry characteristics between the rolling elements and the inner and outer rings in a thrust self-aligning roller bearing, and determine the contact form between the rolling elements and the inner and outer rings.

[0123] Figure 4 A schematic diagram of a thrust self-aligning roller bearing structure is shown in a method for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator. Figure 4 As shown, the upper end of the main shaft of the equipment adopts a thrust self-aligning roller bearing. In this example, the contact form between the rolling element and the inner and outer rings is determined by decomposing the contact force into contact normal force and contact tangential force. The tangential contact force can be calculated using the Coulomb friction force model.

[0124] S202. Based on the contact form between the rolling element and the inner and outer rings, the Hunt-Crossley contact model is used as the basic calculation framework for the normal contact force.

[0125] The Hunt-Crossley contact model, which ensures the continuity of the contact force model and the advantage of closed hysteresis loops, has gained widespread recognition and further research. The theoretical model of the Hunt-Crossley contact model is as follows:

[0126] (14)

[0127] (15)

[0128] In the formula, For Hertz contact stiffness, For contact deformation, Energy index The impact coefficient, It is the hysteresis damping factor. Relative to the initial collision velocity, The coefficient of restitution is given. The first term in equation (14) represents the restoring force due to the elasticity of the material, and the second term represents the energy loss caused by the damping effect during the contact process. In this example, a reasonable normal contact force model is constructed based on the Hunt-Crossley contact model, taking into account the geometric characteristics of the contact body of the thrust self-aligning roller bearing. The rolling elements of the thrust self-aligning roller bearing are spherical rolling elements, and the contact surfaces between the inner and outer rings and the rollers are approximately conical surfaces. The contact between the rolling elements and the inner and outer rings is similar to the contact between a pin and a curved surface, and the contact surface is approximately a slender rectangle, such as... Figure 4 As shown.

[0129] Furthermore, from the perspective of the geometric characteristics of the contacting bodies, the traditional Hertz two-ball contact model is not well applicable to the contact force modeling in thrust self-aligning roller bearings.

[0130] S203. Based on the contact geometry characteristics, introduce the Caishan-Ke contact force model applicable to pin-surface contact to determine the equivalent Hertz contact stiffness.

[0131] Step S203 includes the following steps:

[0132] S2031. Introduce the Caishan-Ke contact force model, which is applicable to pin-curved surface contact, as the basic mechanical model for describing the contact force between the rolling element and the inner and outer rings.

[0133] The contact force model between the Caishan-Ke cylindrical pin and the curved surface is introduced:

[0134] (16)

[0135] S2032. Analyze the contact geometry parameters between the rolling elements and the inner and outer rings, determine the difference between the average radius of the rolling elements and the radius of curvature of the contact surface, and the range of values ​​for the contact deformation.

[0136] Formula 17 is introduced here, and Formula 17 is shown below:

[0137] (17)

[0138] In the formula, This is the difference between the average radius of the rolling element and the radius of curvature of the contact surface. and These are the Young's moduli of the two contact bodies, respectively.

[0139] S2033. Based on the engineering approximation condition that the contact deformation is much smaller than the difference in the radius of curvature of the surface, the Caishan-Ke contact force model is simplified by ignoring the δ term in the denominator and approximately expressed as a power-law function of the contact deformation δ.

[0140] In order to reasonably integrate the Hunt-Crossley contact model and the Caishan-Ke contact model, the Caishan-Ke contact model needs to be expressed as follows: The power-law term and the equivalent Hertz contact stiffness Multiplication form:

[0141] (18)

[0142] In the formula, For equivalent Hertz contact stiffness, This represents the amount of contact deformation.

[0143] It is a constant, calculated according to equation (16).

[0144] Obviously, equation (16) cannot be precisely expressed in the form of equation (18).

[0145] Therefore, considering the structural characteristics of large-scale thin-film evaporators, a limiting approximation method is adopted for processing.

[0146] Measurements showed that in the contact model between the rolling element and the outer ring, The value is 341.12 mm; in the contact model between the rolling element and the inner ring, The value is 313.12 mm. During the contact process, The range of variation is relatively small, generally not exceeding [0, 0.5]. Therefore, ,but Equation (16) simplifies to:

[0147] (19)

[0148] In the formula, , E is the difference between the average radius of the rolling element and the radius of curvature of the contact surface, and E is Young's modulus.

[0149] S2034. Extract the coefficients from the simplified power-law function to determine the equivalent Hertz contact stiffness.

[0150] The equivalent Hertz contact stiffness was obtained from this. .

[0151] S204. Substitute the equivalent Hertz contact stiffness into the restoring force term in the Hunt-Crossley model framework, replacing the original Hertz contact stiffness, and combine it with the damping term in the basic calculation framework to construct a nonlinear normal contact force model suitable for thrust self-aligning roller bearings.

[0152] The normal contact force model suitable for dynamic modeling of thrust self-aligning roller bearings in large thin-film evaporators is as follows:

[0153] (20)

[0154] (twenty one)

[0155] In the formula, For equivalent Hertz contact stiffness, For contact deformation, Energy index The impact coefficient, It is the hysteresis damping factor. The relative collision velocity, Relative to the initial collision velocity, The coefficient of recovery.

[0156] S3. Establish flexible body models of the main shaft and scraper.

[0157] Step S3 includes the following steps:

[0158] S301. Based on the structural characteristics of the main shaft and scraper, the three-dimensional geometric model of the main shaft and scraper is simplified to obtain a simplified three-dimensional geometric model of the main shaft and scraper.

[0159] in, Figure 5 A schematic diagram of the spindle and scraper structure is shown in a method for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator. Figure 5 As shown, the main shaft is a hollow cylinder with a length-to-diameter ratio of 36, and the scraper is a C-shaped steel with a length-to-section side length of 253. The main shaft and scraper are prone to deformation during equipment operation. The designed thickness of the liquid film is 5mm, meaning the designed distance between the scraper connected to the scraper and the inner wall of the cylinder is 5mm. Under normal operating conditions, the allowable deformation of the main shaft and scraper is minimal.

[0160] Furthermore, during the modeling process, the main shaft and scraper were established as flexible bodies. The analysis examined whether the deformation of the main shaft and scraper would cause the liquid film thickness to exceed a reasonable range, and whether the deformation would cause the main shaft to jam. During normal operation, the allowable radial deformation of the main shaft and scraper within the cylinder is less than 5mm, which is far less than the axial dimensions of the main shaft and scraper, and can be considered to be within the linear elastic range. Therefore, a linear flexibility method was used to model the main shaft and scraper as flexible bodies.

[0161] S302. Mesh the simplified three-dimensional geometric model of the spindle and scraper, and discretize it into finite element elements of the spindle and scraper.

[0162] In this embodiment, a suitable element type is selected for mesh generation based on the geometric characteristics of the main shaft (hollow cylinder) and the scraper (C-shaped steel). This approach employs a hybrid mesh generation strategy, using hexahedral elements as the primary element and tetrahedral elements as the secondary element, to control the number of elements while ensuring computational accuracy.

[0163] Furthermore, in areas of stress concentration or areas of significant deformation (such as the connection between the scraper and the blade, or the mating point between the spindle and the bearing), the local mesh is refined with a unit size of 5mm to 10mm; in other non-critical areas, a relatively sparse mesh is used with a unit size of 20mm to 30mm to balance computational accuracy and efficiency.

[0164] After mesh generation, perform mesh quality checks to ensure there are no distorted elements (e.g., Jacobian determinant > 0.7, warpage < 5°) and generate a high-quality finite element mesh model.

[0165] S303. Define the material properties and modal analysis parameters of the flexible body model.

[0166] The material property parameters for the main shaft and scraper are set, including: density ρ = 7850 kg / m³. 3 Young's modulus E = 2.06 × 10⁻⁶ 11 Pa, Poisson's ratio μ = 0.3.

[0167] Furthermore, boundary conditions are set based on the constraints of the spindle and scraper in actual assembly. In this embodiment, an elastic support constraint is applied at the connection between the spindle and the bearing to simulate the support stiffness of the bearing; a fixed constraint is applied at the connection between the scraper and the scraper blade to simulate the rigid connection of the bolted connection; and a rotational degree of freedom constraint is applied at the top of the spindle to simulate the connection relationship of the drive end.

[0168] Furthermore, modal analysis parameters are set, including the modal order or frequency range to be extracted. In this embodiment, the extraction frequency range is set to all modes within 0~10000Hz.

[0169] S304. Perform modal solving to obtain flexible body models of the main shaft and scraper for multibody dynamics simulation.

[0170] Among them, the modal solution is run to calculate and extract the natural frequencies and corresponding mode shapes of the structure.

[0171] Figure 6 The present application provides a flexible body cloud diagram of the main axis and scraper for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator. Figure 6 (a) in this application is a contour map of the main axis and the flexible body mode of the scraper in a method for constructing a fluid-structure-thermal coupling dynamics model of a thin film evaporator provided in an embodiment of this application; Figure 6(b) in this embodiment of the present application provides a method for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator, which includes a deformation displacement cloud diagram of the main axis and the flexible body of the scraper. Figure 6 (a) shows the first and third free modes of the main shaft and scraper. Figure 6 (b) shows the displacement contour diagram of the spindle and scraper assembly under a certain operating condition.

[0172] Furthermore, based on the rotational speed range of the thin-film evaporator and the vibration frequencies to be analyzed, a modal cutoff frequency is set. In this embodiment, the operating rotational speed range of the thin-film evaporator spindle is 60 rpm to 90 rpm, corresponding to a fundamental frequency range of 1 Hz to 1.5 Hz. The vibration frequencies to be analyzed are mainly low-frequency vibrations in the range of 0 to 500 Hz. To simultaneously ensure the accuracy of structural vibration displacement calculation and reduce computational requirements, the modal cutoff frequency is set to 10000 Hz, retaining all modes with frequencies below this threshold and ignoring higher-order modes that contribute little to the structural dynamic response.

[0173] Furthermore, the obtained modal information (including nodal coordinates, element information, natural frequencies, and mode shapes) is written into a flexible body model file, such as an MNF (Modal Neutral File) format file.

[0174] Finally, the generated flexible body model file is imported into a multibody dynamics simulation platform (such as ADAMS) for subsequent whole-machine rigid-flexible coupling dynamics simulation analysis. This flexible body model can accurately simulate the elastic deformation of the spindle and scraper during operation, and is used to analyze whether the deformation will cause the liquid film thickness to exceed the reasonable range (design thickness 5mm) and whether the deformation will cause the spindle to jam.

[0175] S4. Establish a flexible body model of the cylinder.

[0176] Radial vibration of the cylinder is a key aspect of the dynamic modeling and analysis of the thin-film evaporator. In this embodiment, the cylinder is divided into five sections, which are connected by bolts. To conserve computational resources while still simulating the dynamic response of each section, a discrete flexible connection method is used to establish a flexible cylinder.

[0177] Step S4 includes the following steps:

[0178] S401. Divide the cylinder into sections along the axial direction at the bolt connection points, and construct each section as a rigid cylinder.

[0179] In this embodiment, the cylinder is segmented at the bolted connection points based on its actual structure. The cylinder is divided into five sections, with segmentation points set at the flange connections at both ends of each section, thus constructing each section as an independent rigid body. The rigid body assumption means that the elastic deformation of each section is not considered during the simulation; only its rigid body motion (including translation and rotation) is taken into account, which significantly reduces computational complexity.

[0180] S402. Massless beam elements are used to connect adjacent rigid cylinder sections to construct a discrete flexible connection structure.

[0181] In this process, massless beam elements are established between corresponding connection points of two adjacent rigid cylinder sections. "Massless" means that the beam elements only provide connection stiffness and do not contribute inertial mass; their mass properties are already reflected in the rigid cylinder.

[0182] Furthermore, to simulate multiple bolt connections evenly distributed on the circumference of the cylinder, multiple massless beam elements are evenly arranged along the circumferential direction between every two adjacent rigid cylinders. In this embodiment, based on the actual number and distribution of bolt connections, 12 beam elements are evenly arranged on the circumference, with each beam element corresponding to a bolt connection position, collectively simulating the mechanical characteristics of flange bolt connections.

[0183] S403. Assign cross-sectional properties to the beam element to obtain the flexible body model of the cylinder.

[0184] In this design, each beam element is assigned annular section properties to simulate the radial, tangential, and axial stiffness of the bolted connection. The section properties of the beam element include parameters such as cross-sectional area and moment of inertia, which are calculated and determined based on the actual geometry and material properties of the bolts.

[0185] In this embodiment, the cross-sectional properties of the beam element are set as follows: the cross-sectional shape is circular, and the diameter is set to 30mm based on the actual bolt diameter; the material properties are consistent with the bolt material, and the Young's modulus E = 2.06 × 10⁻⁶. 11 Pa, Poisson's ratio μ=0.3, density set to 0 (reflecting massless characteristics); the length of the beam element is equal to the connection distance between the two rigid cylinder sections.

[0186] Through the above setup, the rigid cylinder sections are connected into a whole by beam elements. This preserves the rigid body motion characteristics of each section while simulating the elastic stiffness of the bolted connection using beam elements. This effectively reflects the overall dynamic response of the cylinder, including the relative displacement and vibration transmission characteristics between sections. This modeling method ensures computational accuracy while avoiding the enormous computational overhead of building the entire cylinder as a complex flexible body.

[0187] S5. Integrate the scraper force model, the nonlinear normal contact force model, the flexible body model of the main shaft and scraper, and the flexible body model of the cylinder into a multibody dynamics simulation platform to construct a fluid-structure-thermal coupling dynamics model of the whole thin film evaporator.

[0188] Step S5 includes the following steps:

[0189] S501. Establish the complete assembly model in the multibody dynamics simulation platform.

[0190] In this embodiment, ADAMS multibody dynamics simulation software is used as the integration platform. First, the flexible body models of the main shaft and scraper (MNF files) established in S3, the flexible body model of the cylinder (composed of rigid segments and beam elements) established in S4, and the three-dimensional geometric models of other components in the equipment are imported.

[0191] Furthermore, based on the actual assembly relationship of the thin-film evaporator, the connection methods between each component are defined:

[0192] The feeder and scraper support frame are equivalent to rigid bodies and are connected to the main shaft through a fixed pair based on their actual welded connection relationship with the main shaft.

[0193] The scrapers are connected to the scraper via fixed pairs according to their installation positions on the scraper, forming a spatial scraper array consisting of 80 scrapers;

[0194] Based on the spatial position of the scraper, four liquid film rigid body dynamic models corresponding to the four cylindrical regions are established, and the initial depth of the scraper embedded in the liquid film is set to 5 mm, which is the initial design thickness of the liquid film.

[0195] A rotating pair is established between the spindle and the bearing, and a nonlinear normal contact force model of the thrust self-aligning roller bearing is established by S2.

[0196] 502. The scraper force model is embedded into the contact force model library through secondary development.

[0197] In this embodiment, the parameterized scraper force model established in S106 is added to the software's normal contact force and tangential contact force model library through the secondary development function of ADAMS software (such as subroutine interface or user-defined function) to form a custom contact force model.

[0198] Furthermore, the custom contact force model can dynamically calculate the normal and tangential forces acting on the scraper based on the spindle speed ω, cylinder temperature T, and local liquid film thickness D determined in real time by simulation.

[0199] S503 defines the contact force for each scraper in the scraper array.

[0200] The custom contact force model established by S502 is invoked to establish the contact force between each scraper in the scraper array and the corresponding liquid film. Specifically, this includes:

[0201] Determine the region of the cylinder where each scraper is located, and then associate it with the corresponding liquid film model;

[0202] Set up a contact pair, defining the scraper as the contact body and the liquid film as the target body;

[0203] Assign a custom contact force model established by S502 to each contact pair;

[0204] Set contact parameters, including contact stiffness, damping coefficient, and friction coefficient.

[0205] Through the above settings, a force model of the scraper array consisting of 80 scraping contact forces is finally formed, which can simulate the different loads borne by each scraper due to differences in spatial position, operating conditions and structural deformation.

[0206] S504 defines the contact force for thrust self-aligning roller bearings.

[0207] Specifically, the nonlinear normal contact force model of the thrust self-aligning roller bearing established in S2 is applied to the contact pairs between each rolling element and the inner and outer rings in the bearing model. This includes:

[0208] In the bearing model, multiple rolling elements are created, and each rolling element establishes a contact pair with the inner ring and the outer ring, respectively.

[0209] A nonlinear normal contact force model established by S205 is applied to each contact pair;

[0210] Set contact parameters, including equivalent Hertz contact stiffness, damping coefficient, and restitution coefficient.

[0211] S505, Set the drive and load to complete the construction of the whole machine model.

[0212] Set the spindle drive to apply rotational motion, with a speed range of 60rpm~90rpm, corresponding to actual production conditions. Set the internal temperature field of the cylinder, which can be set to a constant temperature within the range of 80℃~110℃ or a temperature curve that changes over time, depending on the simulation requirements.

[0213] After completing all the above settings, a complete fluid-structure-thermal coupling kinetic model of the thin-film evaporator is obtained.

[0214] Furthermore, based on the aforementioned research, a fluid-solid-thermal coupled dynamic model of a large-scale Lyocell fiber thin-film evaporator was established. Figure 7 A schematic diagram showing the test and simulation values ​​of the vibration velocity of the bearing housing of a large thin-film evaporator made of lyocell fiber, which provides a method for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator according to an embodiment of this application; Figure 7 (a) in the figure is a measured time-domain diagram of bearing housing vibration velocity of a method for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator provided in an embodiment of this application; Figure 7 (b) is a time-domain simulation diagram of bearing housing vibration velocity of a method for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator provided in an embodiment of this application; Figure 8 A schematic diagram showing the test and simulation values ​​of the spindle torque of a large lyocell fiber thin-film evaporator, which provides a method for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator according to an embodiment of this application; Figure 8 (a) in this application is a time-domain diagram of the measured spindle torque of a method for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator provided in an embodiment of this application; Figure 8 (b) is a time-domain diagram of the spindle torque simulation of a method for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator provided in this application embodiment; the established coupling dynamics model is verified by collecting the vibration response and spindle torque response of the device through the built-in sensor of the large thin-film evaporator made of Lyocell fiber. Figure 7 (a) Figure 7 (b) Figure 8 (a) and Figure 8 Figure (b) shows the vertical vibration velocity and spindle torque of the thin-film evaporator bearing housing at a spindle speed of 88 r / min and an internal temperature of 92°C. The effective values ​​of the vibration velocity collected by the sensors are as follows: Figure 7 As shown in (a) above, the vibration velocities extracted through the coupled dynamics model are as follows: Figure 7 As shown in (b) above. For a more intuitive comparison, regarding... Figure 7 The average value of the data in (a) is calculated for... Figure 7 Calculate the valid values ​​for the data in (b) and fill them into Table 1. Figure 8 As shown in (a), the measured spindle torque value mainly varies within the range of [4225, 4450], while the spindle torque value extracted through the coupled dynamics model mainly varies within the range of [3600, 4200]. Although there is a difference in the response range between the measured data and the simulated data, the values ​​are quite close. Regarding... Figure 8 Calculate the valid values ​​of the data in (b) and fill them into Table 1. As shown in Table 1, based on the statistical characteristics of the test data and simulation data, the response accuracy of the coupled dynamics model exceeds 88.9%, and its dynamic simulation calculation results have high reliability. It can be used to evaluate the dynamic response of equipment in the early stage of R&D, and can also simulate faults and generate valid fault data in the development stage of intelligent operation and maintenance system of equipment.

[0215] The comparison between the test data and simulation data in Table 1 is as follows:

[0216]

[0217] In summary, typical failures of thin-film evaporators include main shaft bearing damage, scraper wear, main shaft or scraper deformation, and main shaft fatigue cracking. The proposed fluid-structure-thermal coupled dynamic modeling method for large-scale thin-film evaporators relies on a three-dimensional model of the equipment. Therefore, by expressing typical failures in the three-dimensional model or parameter settings, the dynamic response of the equipment under failure conditions can be simulated. Here, we take the simulation of bearing outer ring wear failure as an example to conduct fault twin modeling and analysis. Figure 9 This application provides a schematic diagram of the bearing outer ring fault modeling process in a method for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator. Figure 9 (a) is a schematic diagram of the bearing outer ring fault in a method for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator provided in an embodiment of this application; Figure 9 (b) is a schematic diagram of bearing outer ring fault modeling in a method for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator provided in this application embodiment; the bearing outer ring wear fault phenomenon is as follows: Figure 9 As shown in (a), a semi-circular groove is created in the 3D model of the outer ring of the spindle bearing to simulate an outer ring failure, as shown in (a). Figure 9 As shown in (b) of the figure. Referring to the requirements of normal production, the internal temperature of the cylinder is set to 90℃ and the spindle speed is set to 90r / min. First, a fault-free simulation is performed, and then the depth of the fault groove on the outer ring is set to 0.5mm for fault simulation. Figure 10 A schematic diagram of the bearing outer ring vibration response provided in this application embodiment for a method of constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator; Figure 10 Image (a) in this application provides a time-domain diagram of the bearing outer ring vibration response under fault conditions, based on an embodiment of the fluid-structure-thermal coupling dynamics model construction method for a thin-film evaporator. The time-domain vibration response of the bearing outer ring under different health conditions is obtained, as shown in image (a). Figure 10 As shown in (a) above. A commonly used model for calculating the characteristic frequency of bearing failures is:

[0218] (twenty two)

[0219] (twenty three)

[0220] (twenty four)

[0221] (25)

[0222] In the formula, The characteristic frequency of inner ring faults, The characteristic frequency of the outer ring fault. The characteristic frequency of rolling element failure, To determine the characteristic frequency of cage failure, For the number of rolling elements, The diameter of the rolling element, For the bearing diameter, The relative rotational frequency between the inner and outer rings. This is the radial contact angle.

[0223] According to equation (17), the characteristic frequency of the outer ring fault of the thin film evaporator is calculated to be 25 Hz.

[0224] Figure 10 Image (b) in this application provides a frequency domain analysis diagram of the bearing outer ring fault vibration response using a method for constructing a fluid-structure-thermal coupling dynamics model of a thin-film evaporator. Time-frequency transformation is performed on the bearing outer ring vibration time-domain data to obtain the corresponding spectrum, as shown below. Figure 10 The fast Fourier transform curve is shown in (b) of the figure.

[0225] As can be seen from the Fast Fourier Transform curve, a new frequency peak appears when there is a fault in the outer ring.

[0226] To more clearly visualize the newly emerging frequency peaks, a Gaussian filter function is used to filter out the frequency peaks other than those related to the bearing outer race fault. A one-dimensional Gaussian filtering function is employed:

[0227] (26)

[0228] In the formula, This is the spectrum after Gaussian filtering. The original spectrum, The standard deviation of the Gaussian kernel. The frequency point number in the filter window. This is the center frequency number of the current filter window. , These are discrete frequency sampling points in the spectrum. The filtering window is half-width. During the filtering process, it is necessary to retain the fault characteristic frequencies and their harmonics. Therefore, a harmonic preservation mechanism is introduced based on Gaussian filtering. The modified filtering function is as follows:

[0229] (27)

[0230] In the formula, To preserve the filtered spectrum of fault characteristic harmonics, The fundamental frequency of the bearing fault characteristic frequency. It is a multiple of the frequency. To retain the maximum harmonic number, Reserve bandwidth for frequency doubling.

[0231] This selective Gaussian filtering method effectively reduces interference in the frequency domain signal without introducing phase distortion, while maintaining the amplitude and spectral integrity of the bearing fault characteristic frequency and its harmonic components.

[0232] The spectrum after Gaussian filtering is as follows Figure 10 The Gaussian filtered curve in (b) is shown. This demonstrates that the established coupled dynamics model of the thin-film evaporator can simulate the fault characteristic signal when the depth of the fault groove in the outer ring of the main shaft bearing is 0.5 mm. However, from... Judging from the amplitude of its harmonics, the characteristic frequency is not particularly obvious. To further prove that the established coupled model can effectively simulate the characteristics of faults of different degrees, the same temperature and spindle speed settings as the aforementioned fault simulation were used, and the depth of the outer ring fault groove was set to 1 mm for fault simulation.

[0233] The established coupled dynamics model of the thin-film evaporator is proven to effectively simulate the fault characteristic signal when the depth of the fault groove in the outer ring of the spindle bearing is 1 mm, and the amplitude of the characteristic signal is significantly higher than that when the depth of the fault groove is 0.5 mm.

[0234] The simulation results above show that the established fluid-solid-thermal coupled dynamic model of the large-scale Lyocell fiber thin film evaporator can effectively simulate the fault characteristics of the bearing outer ring and can reflect different characteristic signals under different fault degrees.

[0235] This coupled dynamics model can simulate faults during the development phase of an intelligent operation and maintenance system, quickly generate a large number of fault samples, and promote the research and development of intelligent operation and maintenance systems.

[0236] This example includes at least the following beneficial effects:

[0237] 1. This example abandons the traditional single-scale or local modeling approach and proposes a multi-scale modeling framework that combines "breaking down the whole into parts" and "combining the parts into a whole". This framework refines the local flow-thermal coupling problem through the finite element method, establishes an efficient surrogate model through a data-driven method, and finally achieves system-level integration on a multibody dynamics platform, providing a generalizable paradigm for the whole-machine dynamics modeling of similar complex industrial equipment.

[0238] 2. This example addresses the challenge of balancing accuracy and efficiency in large-scale thin-film evaporators by proposing a practical hybrid modeling technique. For the scraper forces under the coupled effects of non-Newtonian fluid and temperature, a parametric model based on CFD simulation and response surface methodology is established, enabling rapid calculation of complex loads. For the unique contact geometry of thrust self-aligning roller bearings, the classic Hunt-Crossley contact force model is improved to enhance the fidelity of contact simulation. For slender structures and segmented cylinders, a rigid-flexible coupling and discrete flexible connection method is employed, significantly reducing the computational load while ensuring the accuracy of key deformations.

[0239] 3. This example addresses the lack of dynamic models supporting overall system performance prediction and intelligent operation and maintenance by constructing a fluid-solid-thermal coupled dynamic model for a large-scale lyocell fiber thin-film evaporator suitable for equipment operation status assessment and predictive maintenance. This model integrates multiphysics mechanisms, enabling it to simulate complex operating conditions and typical faults. It provides high-quality simulation data for overall system performance prediction and intelligent operation and maintenance algorithm development, thus bridging the gap between mechanistic models and R&D design and intelligent operation and maintenance applications.

[0240] For those consistent with the above, please refer to Figure 11 , Figure 11 This application provides a schematic diagram of a device for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator. (See attached diagram.) Figure 11 As shown, the device includes:

[0241] Module 1 is used to establish the scraper force model under multiple working conditions.

[0242] Module 2 is used to establish a nonlinear normal contact force model for thrust self-aligning roller bearings.

[0243] Module 3 is used to create a flexible body model of the spindle and scraper.

[0244] Module 4 is used to create a flexible body model of the cylinder.

[0245] Module 5 is used to integrate the scraper force model, the nonlinear normal contact force model, the flexible body model of the main shaft and scraper, and the flexible body model of the cylinder into the multibody dynamics simulation platform to construct the fluid-structure-thermal coupling dynamics model of the whole thin film evaporator.

[0246] For examples consistent with the above embodiments, please refer to... Figure 12 , Figure 12 A schematic diagram of a terminal structure provided in an embodiment of this application is shown in the figure. It includes a processor, an input device, an output device, and a memory. The processor, input device, output device, and memory are interconnected. The memory is used to store a computer program, which includes program instructions. The processor is configured to call the program instructions. The program includes instructions for performing the following steps.

[0247] Establish a scraper force model under multiple working conditions;

[0248] A nonlinear normal contact force model for a thrust self-aligning roller bearing is established.

[0249] Establish flexible body models for the main shaft and scraper;

[0250] Establish a flexible body model of the cylinder;

[0251] The scraper force model, the nonlinear normal contact force model, the flexible body model of the main shaft and scraper, and the flexible body model of the cylinder are integrated into a multibody dynamics simulation platform to construct a fluid-structure-thermal coupling dynamics model of the entire thin-film evaporator.

[0252] The above mainly describes the solutions of the embodiments of this application from the perspective of the method execution process. It is understood that, in order to achieve the above functions, the terminal includes the corresponding hardware structure and / or software modules for executing each function. Those skilled in the art should readily recognize that, in conjunction with the units and algorithm steps of the various examples described in the embodiments provided herein, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0253] This application embodiment can divide the terminal into functional units according to the above method example. For example, each function can be divided into a separate functional unit, or two or more functions can be integrated into one processing unit. The integrated unit can be implemented in hardware or as a software functional unit. It should be noted that the unit division in this application embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0254] This application also provides a computer storage medium storing a computer program for electronic data exchange, which causes a computer to perform some or all of the steps of any of the methods described in the above-described method embodiments for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator.

[0255] This application also provides a computer program product, which includes a non-transitory computer-readable storage medium storing a computer program that causes a computer to perform some or all of the steps of any of the methods described in the above method embodiments for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator.

[0256] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0257] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0258] In the several embodiments provided in this application, it should be understood that the disclosed apparatus can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical or other forms.

[0259] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0260] Furthermore, the functional units in the various embodiments of the application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software program module.

[0261] If the integrated unit is implemented as a software program module and sold or used as an independent product, it can be stored in a computer-readable storage device (CMD). Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a memory and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned memory includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0262] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage device, which may include: a flash drive, a read-only memory, a random access memory, a magnetic disk, or an optical disk, etc.

[0263] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator, characterized in that, include: Establish a scraper force model under multiple working conditions; A nonlinear normal contact force model for a thrust self-aligning roller bearing is established. Establish flexible body models for the main shaft and scraper; Establish a flexible body model of the cylinder; The scraper force model, the nonlinear normal contact force model, the flexible body model of the main shaft and scraper, and the flexible body model of the cylinder are integrated into a multibody dynamics simulation platform to construct a fluid-structure-thermal coupling dynamics model of the whole thin film evaporator. The establishment of the nonlinear normal contact force model for the thrust self-aligning roller bearing includes: Analyze the contact geometry characteristics between the rolling elements and the inner and outer rings in a thrust self-aligning roller bearing to determine the contact form between the rolling elements and the inner and outer rings; Based on the contact pattern between the rolling element and the inner and outer rings, the Hunt-Crossley contact model is used as the basic calculation framework for the normal contact force. Based on the contact geometry characteristics, a Caishan-Ke contact force model applicable to pin-surface contact is introduced to determine the equivalent Hertz contact stiffness. The equivalent Hertz contact stiffness is substituted into the restoring force term in the Hunt-Crossley model framework to replace the original Hertz contact stiffness. Combined with the damping term in the basic calculation framework, a nonlinear normal contact force model suitable for thrust self-aligning roller bearings is constructed.

2. The method for constructing a fluid-structure-thermal coupling kinetic model for a thin-film evaporator according to claim 1, characterized in that, The establishment of the scraper force model under multiple working conditions includes: The forces acting on the scraper are projected onto the tangential and normal directions of the scraper's circular motion, and the first scraper normal force calculation model and the first scraper tangential force calculation model are constructed after the projection of the normal force and tangential force. The finite element method is used to model a long cylindrical section containing several scrapers, and the unknown component force parameters in the calculation models of the normal force and the tangential force of the first scraper are solved. Identify the key operating parameters that affect the stress on the scraper; Based on the key operating parameters, multiple sets of simulation operating conditions are planned using experimental design methods to obtain a simulation test scheme. For each set of working conditions in the simulation test scheme, a finite element model is run for simulation. The component force parameters are extracted from the simulation results and substituted into the first scraper normal force calculation model and the first scraper tangential force calculation model to calculate the normal force and tangential force under the corresponding working conditions. Using the key working parameters under each working condition and the calculated normal and tangential forces as sample data, a data-driven method is used for regression fitting to establish a parameterized scraper force model with the key working parameters as input and the normal and tangential forces as output.

3. The method for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator according to claim 1, characterized in that, The formula for expressing the force model of the scraper is as follows: In the formula, Main spindle speed The temperature inside the cylinder. The thickness is the liquid film thickness.

4. The method for constructing a fluid-structure-thermal coupling kinetic model for a thin-film evaporator according to claim 1, characterized in that, Based on the contact geometry characteristics, the Caishan-Ke contact force model applicable to pin-surface contact is introduced to determine the equivalent Hertz contact stiffness, including: A Caishan-Ke contact force model applicable to pin-surface contact is introduced as the basic mechanical model describing the contact force between the rolling element and the inner and outer rings. Analyze the contact geometry parameters between the rolling element and the inner and outer rings to determine the difference between the average radius of the rolling element and the radius of curvature of the contact surface, as well as the range of values ​​for the contact deformation. Based on the engineering approximation condition that the contact deformation is much smaller than the difference in the radius of curvature of the surface, the Caishan-Ke contact force model is simplified by ignoring the δ term in the denominator and approximately expressed as a power-law function of the contact deformation δ. The coefficients are extracted from the simplified power-law function to determine the equivalent Hertz contact stiffness.

5. The method for constructing a fluid-structure-thermal coupling kinetic model for a thin-film evaporator according to claim 1, characterized in that, The process of establishing the flexible body model of the main shaft and scraper includes: Based on the structural features of the main shaft and scraper, the three-dimensional geometric model of the main shaft and scraper is simplified to obtain a simplified three-dimensional geometric model of the main shaft and scraper. The simplified three-dimensional geometric model of the spindle and scraper is meshed and discretized into finite element elements of the spindle and scraper. Define the material properties and modal analysis parameters for the flexible body model; Modal solving was performed to obtain flexible body models of the spindle and scraper for multibody dynamics simulation.

6. The method for constructing a fluid-structure-thermal coupling kinetic model for a thin-film evaporator according to claim 1, characterized in that, The establishment of the flexible body model of the cylinder includes: The cylinder is divided into sections along the axial direction at the bolt connection points, and each section is constructed as a rigid cylinder; Massless beam elements are used to connect adjacent rigid cylinder sections to construct a discrete flexible connection structure; Assign cross-sectional properties to the beam element to obtain a flexible body model of the cylinder.

7. A system for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator, characterized in that, include: The first module is used to establish the scraper force model under multiple working conditions; The second module is used to establish a nonlinear normal contact force model for thrust self-aligning roller bearings; The third module is used to create a flexible body model of the main shaft and scraper; The fourth module is used to create a flexible body model of the cylinder; The fifth module is used to integrate the scraper force model, the nonlinear normal contact force model, the flexible body model of the main shaft and scraper, and the flexible body model of the cylinder into the multibody dynamics simulation platform to construct the fluid-structure-thermal coupling dynamics model of the whole thin film evaporator. The establishment of the nonlinear normal contact force model for the thrust self-aligning roller bearing includes: Analyze the contact geometry characteristics between the rolling elements and the inner and outer rings in a thrust self-aligning roller bearing to determine the contact form between the rolling elements and the inner and outer rings; Based on the contact pattern between the rolling element and the inner and outer rings, the Hunt-Crossley contact model is used as the basic calculation framework for the normal contact force. Based on the contact geometry characteristics, a Caishan-Ke contact force model applicable to pin-surface contact is introduced to determine the equivalent Hertz contact stiffness. The equivalent Hertz contact stiffness is substituted into the restoring force term in the Hunt-Crossley model framework to replace the original Hertz contact stiffness. Combined with the damping term in the basic calculation framework, a nonlinear normal contact force model suitable for thrust self-aligning roller bearings is constructed.

8. A terminal, characterized in that, The device includes a processor, an input device, an output device, and a memory, which are interconnected. The memory is used to store a computer program, which includes program instructions. The processor is configured to call the program instructions to execute the method for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, the computer program including program instructions, which, when executed by a processor, cause the processor to perform the method for constructing a fluid-structure-thermal coupling kinetic model of a thin-film evaporator as described in any one of claims 1-6.

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