Method for determining vapor-liquid interphase interaction force coefficient model in reactor rod beam channel

Abstract

The embodiment of the invention relates to the technical field of computer aided design, in particular to a method for determining a vapor-liquid interphase interaction force coefficient model in a reactor rod beam flow channel, and the method comprises the steps: S10, determining a numerical model of a turbulent flow field of bubbles in the reactor rod beam flow channel; s20, according to the numerical model, determining a numerical model of a fluid volume method of vapor-liquid two-phase flow of the reactor rod beam flow channel; s30, according to the model determined in the step S20, determining a bubble dynamics multi-physics field of a near-wall area of the rod beam flow channel; and S40: according to the bubble dynamics multi-physical field, determining a vapor-liquid interphase interaction force coefficient model. Compared with a vapor-liquid interphase interaction force coefficient model obtained through experimental data fitting, the method for determining the vapor-liquid interphase interaction force coefficient model has the advantages that parameter measurement errors can be avoided, the model precision can be improved, and therefore more accurate microscopic characteristics of vapor-liquid two-phase flow in a reactor rod beam flow channel can be obtained; and the interphase acting force of vapor-liquid two-phase flow is accurately simulated.

Description

Technical Field

[0001] The embodiments of this application relate to the field of computer-aided design technology, specifically to a method for determining the gas-liquid phase interaction force coefficient model in a reactor rod bundle channel. Background Technology

[0002] The statements herein are provided merely as background information in connection with this application and do not necessarily constitute prior art.

[0003] Supercooled boiling is a boiling heat transfer phenomenon that occurs when the overall temperature of the liquid is lower than the saturation temperature at the current pressure. During reactor operation, compared to the typical single-phase flow in the fuel rod bundle channel, supercooled boiling offers higher heat transfer efficiency. However, if allowed to develop excessively, it can lead to changes in the boiling pattern, causing overheating or even damage to the fuel rod bundle. In supercooled boiling, the distribution of void fraction is a crucial parameter affecting heat transfer efficiency. It is influenced by the interphase forces of the vapor-liquid two-phase flow in the fuel rod bundle channel. Therefore, simulating the interphase forces in the vapor-liquid two-phase flow in the fuel rod bundle channel helps to accurately predict the void fraction distribution, improve the prediction accuracy of the development stage of supercooled boiling, and thus ensure the safety and stability of the reactor.

[0004] Simulating the interphase interaction forces in a vapor-liquid two-phase flow requires determining an accurate model of the vapor-liquid interphase interaction force coefficients. Currently, the accuracy of the vapor-liquid interphase interaction force coefficient models determined using existing technologies is still insufficient. Summary of the Invention

[0005] A brief overview of this application is provided below to offer a basic understanding of certain aspects thereof. It should be understood that this overview is not an exhaustive summary of the application. It is not intended to identify key or essential parts of the application, nor is it intended to limit its scope. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.

[0006] The embodiments of this application provide a method for determining the gas-liquid interphase interaction force coefficient model in a reactor rod bundle channel, which includes the following steps: S10: determining a numerical model of the turbulence field of bubbles in the reactor rod bundle channel; S20: determining a numerical model of the gas-liquid two-phase flow of the reactor rod bundle channel using the fluid volume method based on the numerical model; S30: determining the bubble dynamics multiphysics field of the near-wall region of the rod bundle channel based on the numerical model determined in step S20; S40: determining the gas-liquid interphase interaction force coefficient model based on the bubble dynamics multiphysics field.

[0007] The method for determining the gas-liquid interphase interaction force coefficient model in the reactor rod bundle flow channel provided in the embodiments of this application determines the numerical model of the turbulence field of bubbles in the reactor rod bundle flow channel, and then determines the numerical model of the gas-liquid two-phase flow of the reactor rod bundle flow channel by the fluid volume method based on this numerical model. Then, based on the numerical model, the bubble dynamics multiphysics field of the near-wall region of the reactor rod bundle flow channel is determined to accurately describe the bubble dynamic characteristics of the near-wall region of the rod bundle flow channel, which is convenient for accurately simulating the force and motion state of bubbles in the rod bundle flow channel. Based on the bubble dynamics multiphysics field, the gas-liquid interphase interaction force coefficient model is determined. Compared with the gas-liquid interphase interaction force coefficient model obtained by fitting experimental data, it can avoid parameter measurement errors and improve model accuracy. Thus, it can obtain more accurate microscopic characteristics of the gas-liquid two-phase flow in the reactor rod bundle flow channel, accurately simulate the interphase interaction force of the gas-liquid two-phase flow, and thus facilitate the accurate prediction of the cavitation fraction distribution in the supercooled boiling phenomenon, improve the prediction accuracy of the development stage of the supercooled boiling phenomenon, and avoid overheating or damage to the fuel rod bundle. Attached Figure Description

[0008] Other objects and advantages of this application will become apparent from the following description of embodiments of this application with reference to the accompanying drawings, and will help to provide a comprehensive understanding of this application.

[0009] Figure 1 This is a schematic diagram showing the turbulence field of bubbles in a reactor rod bundle channel, as determined by the method according to an embodiment of this application. Figure 2 This is a schematic diagram of the rod bundle flow channel, showing a numerical model of the vapor-liquid two-phase flow of the reactor rod bundle flow channel determined by the fluid volume method according to the embodiments of this application. Figure 3 This is a schematic diagram of the bubble dynamics multiphysics field of the near-wall region of the rod bundle channel determined by the method according to an embodiment of this application.

[0010] It should be noted that the accompanying drawings are not necessarily drawn to scale, but are shown only in a schematic manner without affecting the reader's understanding. Detailed Implementation

[0011] Exemplary embodiments of this application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of actual implementations are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the development of any such actual embodiment to achieve the developer's specific goals, such as complying with constraints related to the system and business, and these constraints may vary depending on the implementation. Furthermore, it should be understood that while development work can be very complex and time-consuming, such development work is merely a routine task for those skilled in the art who benefit from the content of this application.

[0012] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the equipment structure and / or processing steps closely related to the solution according to this application are shown in the accompanying drawings, while other details that are not closely related to this application are omitted.

[0013] In existing technologies, the gas-liquid phase interaction force coefficient model in reactor rod bundle channels is usually fitted based on experimentally measured data. The accuracy of the model is highly dependent on the experimental setup. Specifically, existing experimental studies generally use an air pump to inject air into still water in a rectangular channel to form bubbles. The upward trajectory and upward speed of the bubbles are determined by visual observation, and the gas-liquid phase interaction force coefficient model is obtained by fitting the obtained experimental data.

[0014] The inventors of this application have discovered that, under actual reactor operating conditions, the fluid in the rod bundle channel is generally in a flowing state. The bubbles in the flowing fluid experience greater disturbances, and their force conditions are significantly different from those in still water. Furthermore, the structure of the reactor rod bundle channel is complex, making it difficult to directly determine the bubble's upward trajectory and upward velocity through visual observation. Therefore, it is impossible to determine a high-precision model of the gas-liquid interphase interaction force coefficient in the rod bundle channel to accurately simulate the interphase interaction force of the gas-liquid two-phase flow.

[0015] Based on this, embodiments of this application provide a method for determining the gas-liquid interphase interaction force coefficient model in a reactor rod bundle channel, which includes the following steps: S10: Numerical model for determining the turbulence field of bubbles in the reactor rod bundle channel.

[0016] S20: Based on the numerical model, determine the numerical model of the fluid volume method for the vapor-liquid two-phase flow in the reactor rod bundle channel.

[0017] S30: Based on the numerical model determined in step S20, determine the multiphysics field of bubble dynamics in the near-wall region of the rod bundle flow channel.

[0018] S40: Determine the coefficient model of the interaction force between the vapor and liquid phases based on the multiphysics field of bubble dynamics.

[0019] The method for determining the gas-liquid interphase interaction force coefficient model in the reactor rod bundle flow channel provided in the embodiments of this application determines the numerical model of the turbulence field of bubbles in the reactor rod bundle flow channel, and then determines the numerical model of the gas-liquid two-phase flow of the reactor rod bundle flow channel by the fluid volume method based on this numerical model. Then, based on the numerical model, the bubble dynamics multiphysics field of the near-wall region of the reactor rod bundle flow channel is determined to accurately describe the bubble dynamic characteristics of the near-wall region of the rod bundle flow channel, which is convenient for accurately simulating the force and motion state of bubbles in the rod bundle flow channel. Based on the bubble dynamics multiphysics field, the gas-liquid interphase interaction force coefficient model is determined. Compared with the gas-liquid interphase interaction force coefficient model obtained by fitting experimental data, it can avoid parameter measurement errors and improve model accuracy. Thus, it can obtain more accurate microscopic characteristics of the gas-liquid two-phase flow in the reactor rod bundle flow channel, accurately simulate the interphase interaction force of the gas-liquid two-phase flow, and thus facilitate the accurate prediction of the cavitation fraction distribution in the supercooled boiling phenomenon, improve the prediction accuracy of the development stage of the supercooled boiling phenomenon, and avoid overheating or damage to the fuel rod bundle.

[0020] like Figure 1 As shown, Figure 1 The diagram shows a numerical model of the turbulence field of bubbles in a reactor rod bundle channel determined by the method of an embodiment of this application. The arrows indicate the direction of fluid flow in the rod bundle channel, and the side marked as the heating surface is the heated surface of the rod bundle channel.

[0021] In some embodiments, step S10 may further include the following steps: S11: Direct numerical simulation of small-scale bubble behavior in single-phase flow containing spherical particles.

[0022] S12: Determine the rationality of the direct numerical simulation in step S11.

[0023] S13: Divide the rod bundle flow channel into multiple sub-channels.

[0024] S14: Perform direct numerical simulation of small-scale bubble behavior and unsteady Reynolds time-averaged numerical simulation of a geometry including two sub-channels.

[0025] S15: Determine the rationality of the direct numerical simulation and the unsteady Reynolds time-averaged numerical simulation in step S14.

[0026] In this embodiment, small-scale bubble behavior of a single-phase flow containing spherical particles is directly simulated numerically, and its rationality is determined. This facilitates the preliminary determination of the ultra-fine distribution of the downstream flow field and temperature field of the spherical particles, making it easier to simulate the motion state of bubbles in the single-phase flow. Small-scale bubble behavior is directly simulated numerically, and unsteady Reynolds time-averaged numerical simulation is performed on the geometry of two sub-channels of the rod bundle flow channel, and its rationality is determined. This facilitates the determination of the wake evolution law of the single-phase flow containing spherical particles, thereby improving the accuracy of the numerical model of the determined bubble disturbance field. This provides a reliable data reference for the subsequent determination of the numerical model of the gas-liquid two-phase flow of the reactor rod bundle flow channel using the fluid volume method.

[0027] In some embodiments, in step S12, the rationality of the direct numerical simulation in step S11 can be determined based on the ultra-fine distribution of the downstream flow field and temperature field of the spherical particle determined by direct numerical simulation and the theoretical values ​​of the ultra-fine distribution of the downstream flow field and temperature field of the spherical particle.

[0028] In this embodiment, the theoretical values ​​of the ultra-fine distribution of the downstream flow field and temperature field of the spherical particle are used as a reference benchmark. By comparing the ultra-fine distribution of the downstream flow field and temperature field of the spherical particle determined by direct numerical simulation with the reference benchmark values, it is beneficial to ensure the rationality of the direct numerical simulation and improve the accuracy of the simulation of the behavior of bubbles in single-phase flow. Thus, it provides an accurate reference for the subsequent determination of the numerical model of the bubble turbulence field.

[0029] In some embodiments, in step S15, the rationality of the direct numerical simulation in step S15 can be determined based on the reference examples of the flow waveform and power spectral density within the sub-channel spacing determined by direct numerical simulation and unsteady Reynolds time-averaged numerical simulation.

[0030] In this embodiment, the reference example of the flow waveform and power spectral density within the sub-channel spacing is used as a reference benchmark. By comparing the flow waveform and power spectral density within the sub-channel spacing determined by direct numerical simulation and unsteady Reynolds time-averaged numerical simulation with the reference benchmark value, it is beneficial to ensure the rationality of performing direct numerical simulation and unsteady Reynolds time-averaged numerical simulation of small-scale bubble behavior on the geometry including two sub-channels. This makes the accuracy of the determined wake evolution law of single-phase flow containing spherical particles higher, thereby facilitating the determination of a more accurate numerical model of the bubble turbulence field.

[0031] In some embodiments, in step S15, the turbulence model, grid scale, and time step of the vapor-liquid two-phase flow simulation of the sub-channel can be determined according to reasonableness, so as to establish a high-precision numerical model of the bubble turbulence field and provide a model and parameter basis for subsequently determining the numerical model of the vapor-liquid two-phase flow of the reactor rod bundle channel using the fluid volume method.

[0032] In some embodiments, step S20 may further include the following steps: S21: Based on the numerical model, determine the pressure gradient field of the fluid in the flow channel through the periodic boundary conditions of the numerical model.

[0033] S22: Based on the pressure gradient field, the interaction between the wall of the rod bundle and the bubble interface in the flow channel is determined using the submerged boundary method.

[0034] S23: Based on the interaction, determine the migration trajectory of bubbles in the flow channel and the evolution of the turbulent pseudo-sequence structure of the liquid.

[0035] In this embodiment, based on the numerical model of the bubble turbulence field, the pressure gradient field of the fluid in the flow channel is accurately determined through periodic boundary conditions. Then, based on the pressure gradient field, the interaction between the wall of the rod bundle and the bubble interface in the flow channel is determined using the submerged boundary method, so as to accurately simulate the dynamic changes of the fluid interface in the rod bundle flow channel. Based on this, the migration trajectory of the bubbles in the flow channel and the evolution of the turbulent pseudo-sequence structure of the liquid are determined, which is conducive to establishing a more accurate numerical model of the fluid volume method for gas-liquid two-phase flow. Thus, it provides a reliable data foundation for the subsequent determination of the multiphysics field of bubble dynamics in the near-wall region of the rod bundle flow channel, which is conducive to accurately simulating the force and motion state of the bubbles in the rod bundle flow channel.

[0036] like Figure 2 and Figure 3 As shown, Figure 2 The diagram shows a numerical model of the vapor-liquid two-phase flow of a reactor rod bundle channel determined by the fluid volume method of an embodiment of this application, wherein 10 represents the rod bundle channel, 20 represents the migration trajectory of the bubbles in the channel, and 30 represents the turbulent pseudo-sequential structure evolution of the liquid. Figure 3 A schematic diagram illustrating the multiphysics field of bubble dynamics in the near-wall region of a rod bundle channel determined by the method of an embodiment of this application.

[0037] In some embodiments, in step S40, the drag coefficient of the vapor-liquid interphase interaction force coefficient model conforms to the following relationship: .

[0038] in, Let be the drag coefficient between the vapor and liquid phases, Re be the Reynolds number, and a and b be empirical constants. This is the relative Reynolds number.

[0039] The interphase forces in the vapor-liquid two-phase flow in the rod bundle channel are of various types. Different types of forces have different effects on the motion state of bubbles in the fluid, thus affecting the distribution of cavitation fraction in the subcooled boiling phenomenon from different aspects. For example, the drag force and lift force experienced by bubbles in the fluid play a decisive role in the axial and radial distribution of cavitation fraction, respectively. Therefore, it is necessary to determine the vapor-liquid interphase interaction force coefficient model when the interphase interaction force is of different types. In this embodiment, the relationship between the vapor-liquid interphase interaction force coefficient and the Reynolds number is established when the interphase interaction force is drag. This facilitates the establishment of a more accurate vapor-liquid interphase interaction force coefficient model when the interphase interaction force is drag, thereby accurately simulating the drag interaction between the vapor-liquid two-phase flow and improving the prediction accuracy of the axial distribution of cavitation fraction in the subcooled boiling phenomenon.

[0040] In some embodiments, in step S40, the lift coefficient of the vapor-liquid interphase interaction force coefficient model conforms to the following relationship: .

[0041] in, The lift coefficient between the vapor and liquid phases. Let be constants determined by the relative Reynolds number and the vortex Reynolds number, and let a and b be empirical constants.

[0042] In this embodiment, the relationship between the vapor-liquid interphase interaction force coefficient and the relative Reynolds number and vortex Reynolds number is established when the vapor-liquid interphase interaction force is lift. This facilitates the establishment of a more accurate vapor-liquid interphase interaction force coefficient model when the vapor-liquid interphase interaction force is lift, thereby accurately simulating the lift interaction between the vapor-liquid two-phase flow and improving the prediction accuracy of the radial distribution of cavitation fraction in the supercooled boiling phenomenon.

[0043] In some embodiments, It is determined by the following relationship: .

[0044] in, For relative Reynolds number, The vorticity Reynolds number is... is a constant determined by the relative Reynolds number and the vortex Reynolds number.

[0045] In some embodiments, the relative Reynolds number is determined by the following relationship: .

[0046] in, For relative Reynolds number, The density of the liquid phase is... For vapor phase velocity, For liquid phase velocity, The diameter of the bubble is _____. This is the dynamic viscosity of the liquid phase.

[0047] In some embodiments, the vorticity Reynolds number is determined by the following relationship: .

[0048] in, The vorticity Reynolds number is... The density of the liquid phase is... For liquid phase velocity, The diameter of the bubble is _____. This is the dynamic viscosity of the liquid phase.

[0049] Regarding the embodiments of this application, it should also be noted that, without conflict, the embodiments of this application and the features in the embodiments can be combined with each other to obtain new embodiments.

[0050] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. The scope of protection of this application shall be determined by the scope of the claims.

Claims

1. A method for determining the gas-liquid phase interaction force coefficient model in a reactor rod bundle channel, characterized in that, It includes the following steps: S10: Determine the numerical model of the turbulence field of the bubbles in the reactor rod bundle channel; S20: Based on the numerical model, determine the numerical model of the fluid volume method for the vapor-liquid two-phase flow in the reactor rod bundle channel; S30: Based on the numerical model determined in step S20, determine the bubble dynamics multiphysics field in the near-wall region of the rod bundle flow channel; S40: Determine the coefficient model of the gas-liquid interphase interaction force based on the multiphysics field of the bubble dynamics.

2. The method according to claim 1, characterized in that, Step S10 also includes the following steps: S11: Direct numerical simulation of small-scale bubble behavior in single-phase flow containing spherical particles; S12: Determine the validity of the direct numerical simulation described in step S11; S13: Divide the rod bundle flow channel into multiple sub-channels; S14: Perform direct numerical simulation of small-scale bubble behavior and unsteady Reynolds time-averaged numerical simulation of geometry including two sub-channels; S15: Determine the rationality of the direct numerical simulation and the unsteady Reynolds time-averaged numerical simulation described in step S14.

3. The method according to claim 2, characterized in that, In step S12, the rationality of the direct numerical simulation in step S11 is determined based on the ultra-fine distribution of the downstream flow field and temperature field of the spherical particle determined by the direct numerical simulation and the theoretical values ​​of the ultra-fine distribution of the downstream flow field and temperature field of the spherical particle.

4. The method according to claim 2, characterized in that, In step S15, the rationality of the direct numerical simulation in step S15 is determined based on the reference examples of the flow waveform and power spectral density within the sub-channel spacing determined by the direct numerical simulation and the unsteady Reynolds time-averaged numerical simulation.

5. The method according to claim 2, characterized in that, In step S15, based on the stated rationality, the turbulence model, grid scale, and time step for simulating the vapor-liquid two-phase flow in the sub-channel are determined.

6. The method according to claim 1, characterized in that, Step S20 also includes the following steps: S21: Based on the numerical model, determine the pressure gradient field of the fluid in the flow channel through the periodic boundary conditions of the numerical model; S22: Based on the pressure gradient field, the interaction between the wall of the rod bundle and the bubble interface in the flow channel is determined using the submerged boundary method; S23: Based on the interaction, determine the migration trajectory of the bubbles in the flow channel and the evolution of the turbulent pseudo-sequence structure of the liquid.

7. The method according to claim 1, characterized in that, In step S40, the drag coefficient of the vapor-liquid interphase interaction force coefficient model conforms to the following relationship: ， in, Let be the drag coefficient between the vapor and liquid phases, Re be the Reynolds number, and a and b be empirical constants. This is the relative Reynolds number.

8. The method according to claim 1, characterized in that, In step S40, the lift coefficient of the vapor-liquid interphase interaction force coefficient model conforms to the following relationship: ， in, The lift coefficient between the vapor and liquid phases. Let be constants determined by the relative Reynolds number and the vortex Reynolds number, and let a and b be empirical constants.

9. The method according to claim 7, characterized in that, The relative Reynolds number is determined by the following relationship: ， in, The relative Reynolds number, The density of the liquid phase is... For vapor phase velocity, For liquid phase velocity, The diameter of the bubble is _____. This is the dynamic viscosity of the liquid phase.

10. The method according to claim 8, characterized in that, in, It is determined by the following relationship: ， in, Let be a constant determined by the relative Reynolds number and the vortex Reynolds number. For relative Reynolds number, denoted as vorticity Reynolds number.

11. The method according to claim 10, characterized in that, The vorticity Reynolds number is determined by the following relationship: ， in, The vorticity Reynolds number is given. The density of the liquid phase is... For liquid phase velocity, The diameter of the bubble is _____. This is the dynamic viscosity of the liquid phase.

Images