Initial parameter generation method based on NUMAP steady-state calculation

Abstract

The invention belongs to the technical field of thermal-hydraulic analysis in a nuclear reactor, and provides an initial parameter generation method based on NUMAP steady-state calculation, which comprises the following steps: acquiring a to-be-initialized thermal-hydraulic simulation system model in NUMAP, and decomposing the to-be-initialized thermal-hydraulic simulation system model into a plurality of single-flow single-pressure boundary chain-shaped structure sub-models; for each single-flow single-pressure boundary chain-shaped structure sub-model, setting the mass gas content of each on-way assembly and the mass gas content of non-condensable gas in the sub-model as 0, and setting the flow as a constant value at the flow boundary; the temperatures of all the on-way assemblies are set to be the mean value of the inlet and outlet temperatures, or the inlet and outlet temperatures serve as end points, and linear filling is conducted according to the lengths of the assemblies to serve as the temperatures of all the on-way assemblies; and subtracting the on-way total gravity pressure drop from the on-way total pressure drop to obtain on-way total friction pressure drop, performing linear division on the on-way total friction pressure drop according to each group of parameters, and sequentially assigning values to the initial pressure of the on-way assembly from the inlet boundary. According to the invention, the NUMAP can reach a steady state as soon as possible.

Description

Technical Field

[0001] The invention relates to the technical field of thermal hydraulic analysis in nuclear reactors, and in particular to an initial parameter generation method based on NUMAP steady-state calculation. Background Art

[0002] Thermal-hydraulic analysis of nuclear reactors is an important part of nuclear energy engineering. Since nuclear reactors involve complex thermodynamic and kinetic processes, such as heat generation, transfer and distribution, as well as the flow state of coolants, these processes directly affect the safety, operating efficiency and life of the reactor. Therefore, thermal-hydraulic analysis of nuclear reactors is a key step to ensure their safe and efficient operation. Efficient and reliable thermal analysis helps provide a scientific basis for the design, operation and safety of reactors, improve reactor efficiency, ensure reactor safety, and promote the continuous development of nuclear energy technology.

[0003] In the past few decades of the development of nuclear power plants, some thermal hydraulic calculation and analysis programs have been developed in the design, dynamic analysis and simulation of light water reactors, among which the more famous ones are RELAP (USA), CATHARE (France), ATHLET (Germany), etc. Nuclear reactor Unified Modeling and Analysis Platform (NUMAP) is the first large-scale unified modeling and simulation platform based on Modelica in China for the field of nuclear power. The platform adopts Modelica, the core language standard of MBSE and CPS. Under the multi-domain unified modeling framework based on Modelica, it innovatively breaks through key technologies such as model expression and compilation and solution technology of complex thermal-hydraulic systems, and coupled solution of multi-professional heterogeneous equation systems. It solves the international difficult problem of unified compilation and solution of two-phase flow partial differential equations and differential algebraic equations. It can be used as a powerful tool for high-precision simulation of multi-condition operating characteristics of the entire system of nuclear power plants under complex conditions such as strong coupling of multiple disciplines, strong correlation of multiple levels, and strong correlation of multiple systems. It can be applied to multiple application scenarios such as scheme design verification, system integration verification, virtual experimental simulation, monitoring and troubleshooting, operation training, twin operation, etc. of nuclear power plants and related experimental equipment.

[0004] The thermal hydraulic simulation system aims to replicate and predict the behavior and performance of the thermal hydraulic system under different working conditions. For the same model, different boundary conditions are set to correspond to different working conditions. The parameters of the boundary conditions are generally given by the user according to the actual working conditions, and may be missing or inaccurate. However, the completion and self-consistency check of boundary conditions is a very complex and difficult challenge, which is beyond the scope of this project.

[0005] Generally speaking, when performing steady-state calculations on a thermal hydraulic simulation system, it is necessary to perform iterative calculations starting from a given initial parameter until a steady state is reached. The initial parameters describe the state of the system at the beginning of the simulation, such as the initial temperature distribution, fluid static or flowing, etc. In theory, the system can quickly reach stability when the steady-state value is used as the initial parameter to start the simulation, that is, the ideal initial parameter is the steady-state value. However, the real-time simulation system of a complex thermal hydraulic circuit system is a typical hyperbolic equation system, and its equation coefficients are often mixed with a large number of engineering empirical models. Due to its poor robustness, it is often difficult to transform the elliptic equation to solve its corresponding steady-state value under specific boundary conditions.

[0006] In traditional thermal hydraulic simulation systems, the initial parameters of components along the process are given by the user during steady-state calculations, or the default values ​​of the system are used, and then continuously adjusted during operation to finally make the model run normally. However, for complex models, it is very cumbersome for users to adjust the initial parameters of hundreds or thousands of control bodies by themselves, and it is very dependent on the user's own experience. Once a parameter is given incorrectly, the system may not run normally. Therefore, a set of methods is needed to calculate a set of initial parameters based on the boundary parameters filled in by the user, so that the software can run normally and reach stability as soon as possible. Summary of the invention

[0007] The purpose of the present invention is to provide an initial parameter generation method based on NUMAP steady-state calculation, which can calculate a set of initial parameters according to the boundary parameters filled in by the user, so that NUMAP can run normally and reach a steady state as soon as possible, which is convenient for the system to perform subsequent transient simulation based on this steady state.

[0008] The present invention solves the technical problem and adopts the following technical solution: The initial parameter generation method based on NUMAP steady-state calculation includes the following steps: Obtain the thermal hydraulic simulation system model to be initialized in NUMAP, and decompose it into multiple single-flow single-pressure boundary chain structure sub-models; For each single-flow single-pressure boundary chain structure sub-model, the mass gas content of each component along the way and the mass gas content of non-condensable gas are set to 0, and the flow rate is set to a constant value at the flow boundary; Set the temperature of each component along the process to the average of the inlet and outlet temperatures, or use the inlet and outlet temperatures as endpoints and fill them linearly according to the component length as the temperature of each component along the process; The total friction pressure drop along the path is obtained by subtracting the total gravity pressure drop along the path from the total pressure drop along the path. It is linearly divided according to each group of parameters, and the initial pressures of the components along the path are assigned sequentially starting from the inlet boundary.

[0009] As a further optimization, after obtaining the thermal-hydraulic simulation system model to be initialized in NUMAP and decomposing it into multiple single-flow single-pressure boundary chain-shaped structure sub-models, the coolant in the first stage of the single-flow single-pressure boundary chain-shaped structure sub-model is a single-phase fluid in each component along the process and is not heated.

[0010] As a further optimization, in the single-flow single-pressure boundary chain structure sub-model, the components from the inlet to the outlet are connected in sequence, with one side being the flow boundary and the other side being the pressure boundary.

[0011] As a further optimization, the total friction pressure drop along the path is obtained by subtracting the total gravity pressure drop along the path from the total pressure drop along the path, and it is linearly divided according to each group of parameters, and the initial pressure of the components along the path is assigned in sequence starting from the inlet boundary, where: The total pressure drop along the process is expressed as , the total gravity pressure drop along the way is expressed as , the total friction pressure drop along the way is expressed as ; The total friction pressure drop along the path is ; The total pressure drop along the is the outlet pressure value Subtract the inlet pressure ,Right now ; The total gravity pressure drop along the The calculation formula is: ,in , is the outlet height of the single-flow single-pressure boundary chain structure submodel, is the inlet height of the single-flow single-pressure boundary chain structure submodel; The total friction pressure drop along the The calculation formula is: ; in, L is the length of the flow channel; D is the diameter of the flow channel; is the coolant density; is the average flow rate of coolant; f is the friction coefficient; Assuming coolant flow m Keeping the same, assuming that the component flow channels are all circular, the coolant flow rate , at this time the total friction pressure drop along the ,in, K is the friction pressure drop proportionality coefficient.

[0012] As a further optimization, the coolant density is calculated during the calculation of the total gravity pressure drop along the way. Obtained by consulting the thermophysical properties table of water.

[0013] As a further optimization, the total friction pressure drop along the and proportional to the total friction pressure drop along the path according to the parameters of each component Perform linear allocation.

[0014] As a further optimization, assume that there are N components along the way starting from the entry boundary. Respectively represent the number of segments, diameter, length and height of each component, The friction pressure drop proportionality coefficient At this time, the outlet pressure of each component Set to ; For a single component , its inlet pressure is the outlet pressure of the previous component, and the pressure inside a single component is distributed linearly with the length. , the distance from the component entrance The pressure value is .

[0015] As a further optimization, the initial pressure and temperature at each segment of each component represent the average pressure and temperature of the corresponding segment, and the pressure and temperature at the midpoint of each segment are used as substitutes when generating the initial parameters, that is, Pick .

[0016] The beneficial effects of the present invention are as follows: through the above-mentioned initial parameter generation method based on NUMAP steady-state calculation, first, the thermal-hydraulic simulation system model to be initialized in NUMAP is obtained, and it is decomposed into multiple single-flow single-pressure boundary chain-shaped structure sub-models; secondly, for each single-flow single-pressure boundary chain-shaped structure sub-model, the mass gas content and the mass gas content of non-condensable gas of each along-the-way component are set to 0, and the flow rate is set to a constant value at the flow boundary; then, the temperature of each along-the-way component is set to the average of the inlet and outlet temperatures, or the inlet and outlet temperatures are used as endpoints, and linear filling is performed according to the component length as the temperature of each along-the-way component; finally, the total friction pressure drop along the way is obtained by subtracting the total gravity pressure drop along the way from the total pressure drop along the way, and it is linearly divided according to each group of parameters, and the initial pressure of the along-the-way components is assigned in sequence starting from the inlet boundary. The method of the present invention can be used only when the initial steady state can be decomposed and simplified into a model of a single-flow single-pressure boundary chain structure, that is, when step S1 can be implemented. Therefore, the present invention can give reasonable and effective initial parameters, so that NUMAP can operate normally and reach a steady state as soon as possible, which is convenient for the system to perform subsequent transient simulation based on this steady state. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1This is a flow chart of the method for generating initial parameters based on NUMAP steady-state calculation in Example 1 of the present invention; Figure 2 This is a schematic diagram of a steam exhaust system in Example 2 of the present invention; Figure 3 This is a schematic diagram of the inlet flow boundary in Example 2 of the present invention; Figure 4 This is a schematic diagram of the outlet pressure boundary in Example 2 of the present invention; Figure 5 Schematic diagram of default initial parameters of the steam generator heating section in Example 2 of the present invention; Figure 6 This is a schematic diagram of the default parameter operation results in Example 2 of the present invention; Figure 7 This is a schematic diagram of unified filling parameters in Example 2 of the present invention; Figure 8 This is a schematic diagram of the operation results of unified filling parameters in Example 2 of the present invention; Fig. 9 This is a schematic diagram of the operation of unified filling parameter pressure in Example 2 of the present invention; Fig.10 This is a schematic diagram of the unified springtail parameter temperature operation in Example 2 of the present invention; Fig.11 Schematic diagram of optimal initial parameters of the heating section of the steam generator in Example 2 of the present invention; Fig.12 This is a schematic diagram of the operation results of the optimal initial parameters in Example 2 of the present invention; Fig.13 This is a schematic diagram of the optimal initial parameter fluid pressure operation in Example 2 of the present invention; Fig.14 This is a schematic diagram of the optimal initial parameter fluid temperature operation in Example 2 of the present invention; Fig.15 This is a schematic diagram of initial parameters of a steam generation section heater generated by the initial parameter generation method based on NUMAP steady-state calculation in Example 2 of the present invention; Fig.16 This is a schematic diagram of the operating results of the parameters of the initial parameter generation method based on NUMAP steady-state calculation in Example 2 of the present invention; Fig.17 It is a schematic diagram of the operation of parameter fluid pressure of the initial parameter generation method based on NUMAP steady-state calculation in Example 2 of the present invention; Fig.18 Schematic diagram of the fluid temperature operation of the initial parameter generation method based on NUMAP steady-state calculation in Example 2 of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations. Example 1

[0019] This embodiment provides a method for generating initial parameters based on NUMAP steady-state calculation. Figure 1 , wherein the method comprises the following steps: S1. Obtain the thermal hydraulic simulation system model to be initialized in NUMAP, and decompose it into multiple single flow single pressure boundary chain structure sub-models; S2. For each single-flow single-pressure boundary chain structure sub-model, the mass gas content of each component along the way and the mass gas content of non-condensable gas are set to 0, and the flow rate is set to a constant value at the flow boundary; S3, setting the temperature of each component along the process to the average of the inlet and outlet temperatures, or taking the inlet and outlet temperatures as endpoints and performing linear filling according to the component length as the temperature of each component along the process; S4. The total friction pressure drop along the path is obtained by subtracting the total gravity pressure drop along the path from the total pressure drop along the path, and it is linearly divided according to each group of parameters, and the initial pressures of the components along the path are assigned in sequence starting from the inlet boundary.

[0020] In this embodiment, based on the NUMAP built-in example Case07_PRS, the following assumptions can be made about the usage scenario of the initial parameter generation method: 1) In the first stage of the model, the coolant in each component along the process is a single-phase (liquid) fluid, that is, no heating is performed. The complex working condition simulation is carried out from a simple single-phase (liquid) steady state through a transient transition; 2) The first stage of the model can be simplified as a "single flow and single pressure boundary chain structure", that is, the components from the inlet to the outlet are connected in sequence, with one side being the flow boundary and the other side being the pressure boundary; 3) The given parameters at each boundary condition must be self-consistent and accurate. For example, the pressure and temperature parameters at the flow boundary must also be close to the steady-state ideal values.

[0021] Therefore, after obtaining the thermal-hydraulic simulation system model to be initialized in NUMAP and decomposing it into multiple single-flow single-pressure boundary chain-shaped structure sub-models, the coolant in the steady state of the first stage of the single-flow single-pressure boundary chain-shaped structure sub-model is a single-phase fluid in each component along the process, and is not heated; and in the single-flow single-pressure boundary chain-shaped structure sub-model, the components from the inlet to the outlet are connected in sequence, with one side being the flow boundary and the other side being the pressure boundary.

[0022] It should be pointed out that in this embodiment, based on the single-phase assumption, for the initial parameters of the components along the process, their mass gas content and the mass gas content of non-condensable gas are both set to 0. Since there is no heating and it is a single pressure boundary, the temperature and flow rate (Kg / s) in the components do not change drastically. The temperature of the components along the process can be the average of the inlet and outlet temperatures or linearly filled according to the length of the component with the inlet and outlet temperatures as endpoints. The flow parameters use the constant value at the flow boundary.

[0023] Therefore, in this embodiment, it is necessary to focus on the initial pressure setting of the components along the way.

[0024] It should be pointed out that in a stable single-phase flow system, the pressure drop between any two cross sections is composed of three parts: friction pressure drop, lifting pressure drop (gravity pressure drop) and acceleration pressure drop, namely The acceleration pressure drop is negligible compared to the other two pressure drops, so only the friction pressure drop is considered. Gravity pressure drop .

[0025] For single-phase flow, the gravity pressure drop , the calculation is relatively easy. The friction pressure drop is calculated by Darcy's formula: ;in, L is the length of the flow channel (m); D is the diameter of the flow channel (m); is the coolant density (Kg / m 3 ); is the average flow velocity of the coolant (m / s); f is the friction coefficient, which is difficult to determine.

[0026] Here, based on the model assumptions, it can be assumed that the coolant flow m Keeping the same, assuming that the component flow channels are all circular, the coolant flow rate , at this time the friction pressure drop , that is, the friction pressure drop and Directly proportional.

[0027] Therefore, the pressure values ​​at the inlet and outlet are known. , , that is, the total pressure drop along the way is The total gravity pressure drop along the model can be calculated from the height difference between the inlet and outlet , ignoring the acceleration pressure drop, the total friction pressure drop along the path is , then naturally, the total friction pressure drop along the way can be calculated according to the parameters of each component Perform linear allocation.

[0028] Specifically, assuming that there are N components along the way starting from the entry boundary, They represent the number of segments, diameter (m), length (m), and height (m) of each component, where the height is the difference between the outlet elevation and the inlet elevation of the component (may be a negative value), and the pressure values ​​at the inlet and outlet are , , then the friction pressure drop proportionality coefficient is , and then, the outlet pressure of each component Should be set to ; For a single component , its inlet pressure is the outlet pressure of the previous component. It can be considered that the pressure in a single component is distributed linearly with the length. , the distance from the component entrance The pressure value is .

[0029] Here, the initial pressure and temperature at each segment of each component represent the average pressure and temperature of the corresponding segment. When the initial parameters are generated, they are replaced by the pressure and temperature at the midpoint of each segment, that is, Pick In addition, in the calculation of gravity pressure drop, the coolant density (liquid water density) It can be obtained by consulting the thermophysical properties table of water. Example 2

[0030] In Example 1, the test examples in this example are all carried out under the NUMAP1.2 development version. Given ideal boundary conditions, based on the secondary side passive residual heat removal system of NUMAP, the example Case07_PRS compares the steady-state simulation and stabilization time of this example under different initial parameter settings. This example has three steady states during the simulation process: the unheated steady state of the steam exhaust system, the heated steady state of the steam exhaust system, and the steady state of the steam-water natural circulation system.

[0031] This embodiment mainly focuses on the steady-state initialization before all transient operations, that is, the first steady-state: the steam exhaust system unheated steady-state. To this end, we established Figure 2 Simplified model (steam exhaust system). In the subsequent experiments, the inlet flow boundary and outlet pressure boundary of the simplified model are set as follows: Figure 3 and Figure 4 , where the inlet flow boundary is a constant value of 0.0262405 Kg / s, the outlet pressure boundary is 10.0717 MPa, and other boundary parameters are the steady-state values ​​that are stable under this boundary, that is, subsequent experiments are carried out under ideal boundary conditions.

[0032] For the secondary side passive residual heat removal system case Case07_PRS, the algorithm for generating the initial parameters of the components along the way under the given ideal boundary conditions includes the following steps: S1: Simplify the secondary side passive residual heat removal system case Case07_PRS into Figure 2 The simplified structure is a steam exhaust system that satisfies the single-flow single-pressure boundary chain structure model; S2: Set the mass gas content and the mass gas content of non-condensable gas of the components pipeline 1, multi-way 1, steam generator heating section, pipeline 2, multi-way 2, pipeline 3, and pipeline 4 to 0 in sequence, and set the flow rate to a constant value at the flow boundary, i.e., 0.0262405 Kg / s; S3: Linear filling is performed according to the order of pipeline 1, multi-pass 1, steam generator heating section, pipeline 2, multi-pass 2, pipeline 3, and pipeline 4, with the inlet and outlet temperatures as endpoints and the length of each component; In this example, the total length of the component is 6.8m, the inlet boundary temperature is 502.15K, and the outlet boundary temperature is 502.137K, so the temperature difference per unit length is (502.137-502.15) / 6.8=-0.001911764705879K. For example, the length of pipe 1 is 1.2m and is divided into 3 sections. Its inlet temperature is the inlet boundary temperature and the outlet temperature is 502.15-0.001911764705879*1.2=502.1477058823529K, so the three temperature values ​​are initialized as 502.15+(502.1477058823529-502.15)*((1.2 / 3)*1 / 2 / 1.2)=502.1496176470588K 502.15+(502.1477058823529-502.15)*((1.2 / 3)*3 / 2 / 1.2)=502.1488529411764K 502.15+(502.1477058823529-502.15)*((1.2 / 3)*5 / 2 / 1.2)=502.1480882352941K.

[0033] S4: The total friction pressure drop along the path is obtained by subtracting the total gravity pressure drop along the path from the total pressure drop along the path. Then, according to the parameters of each component, It is linearly divided, and then its initial pressure is assigned in sequence from the inlet boundary in the order of pipeline 1, multi-way 1, steam generator heating section, pipeline 2, multi-way 2, pipeline 3, and pipeline 4.

[0034] In this embodiment, there are 7 components to be initialized, the inlet boundary pressure is 10.1194*10^6Pa, and the outlet pressure is 10.0717*10^6Pa. By consulting the thermophysical property table of water, it can be seen that at 502.15k and 10MPa, the density of water is approximately 834.2Kg / m 3 , the acceleration due to gravity is g=9.8m / s 2 , the total height of the device is 5.6m, and the parameters of each component are The sum of is 1.87756*10^9, so the friction pressure drop per unit length is (10.0717*10^6-10.1194*10^6+834.2*9.8*5.6) / (1.87756*10^9)=-1.022126589829353*10^-6Pa.

[0035] For example, pipe 1 is 1.2 m long, 0.02 m in diameter, 0 m high, and divided into 3 sections. Its inlet pressure is the inlet boundary pressure, and its outlet pressure is 10.1194*10^6-834.2*9.8*0-1.022126589829353*10^-6*(1.2 / 0.02^5)=10.11901670252881*10^6Pa, then the three temperature values ​​are initialized as 10.1194*10^6+(10.11901670252881*10^6-10.1194*10^6)*(1.2 / 3*1 / 2 / 1.2)=10.11933611708814*10^6Pa 10.1194*10^6+(10.11901670252881*10^6-10.1194*10^6)*(1.2 / 3*3 / 2 / 1.2)=10.11920835126441*10^6Pa 10.1194*10^6+(10.11901670252881*10^6-10.1194*10^6)*(1.2 / 3*5 / 2 / 1.2)=10.11908058544068*10^6Pa.

[0036] Note that for a single component, its inlet temperature and pressure are the outlet temperature and pressure of the previous component. For example, the inlet temperature and pressure of Multi-channel 1 are the outlet temperature and pressure of Pipeline 1, which are 502.1477058823529K and 10.11901670252881*10^6Pa.

[0037] In this embodiment, the initial parameters of the components along the process are all set to the default values ​​of the software. For example, the initial parameters of the steam generator heating section are as follows: Figure 5 , when all components along the process use default parameters, the software cannot run normally, and the error message is as follows Figure 6 As shown, it can be seen that in order to ensure the normal simulation of NUMAP software, it is very necessary to design a reasonable and effective initial parameter generation algorithm.

[0038] Next, in this embodiment, the initial temperature of all pipes is uniformly set to 500k, the initial pressure is uniformly set to 10MPa, and the initial inlet flow rate is uniformly set to 0Kg / s. Taking the steam generator heating section as an example, its initial parameters refer to Figure 7 When the components along the way use the above initial parameters and the steady-state monitoring module of the software is turned on, the model simulation will be judged to be stable at 135.9 seconds. The running results are as follows: Figure 8 shown.

[0039] Taking the steam generator heating section as an example, the pressure and temperature changes of its four sections are as follows: Fig. 9 and Fig.10 As shown, from Fig. 9 and Fig.10 It can be seen that although the use of uniform initial parameters for all components can make the software run normally, its stabilization time is too long, which may result in failure to stabilize when transients occur, affecting further simulation of the system.

[0040] Generally speaking, the optimal method for selecting initial parameters is to use the parameters when the model reaches stability as the initial parameters. Taking the steam generator heating section as an example, its optimal initial parameters can be found in Fig.11 When the components along the way use the above optimal initial parameters and the steady-state monitoring module of the software is turned on, the model simulation will be judged to be stable at 9.18 seconds. The running results are as follows: Fig.12 As shown, Taking the steam generator heating section as an example, the pressure and temperature changes of its four sections are as follows: Fig.13 and Fig.14 As shown by Fig.13 and Fig.14 It can be seen that under the optimal initial parameters, the time it takes for the model simulation to stabilize is extremely short, which means that good initial parameters can indeed greatly shorten the time it takes for the model simulation to stabilize.

[0041] Therefore, in this embodiment, by consulting the thermophysical property table of water, it can be known that at 502.15k and 10MPa, the density of water is approximately 834.2Kg / m 3 , the acceleration due to gravity is g=9.8m / s 2, the total height of the device is 5.6m, so the total gravity pressure drop is -0.0457809MPa, and the total friction pressure drop is -0.0019191MPa. Taking the steam generator heating section as an example, the initial parameters generated by the method proposed in this embodiment are shown in Fig.15 When the components along the way use the initial parameters generated by the algorithm mentioned above, the model simulation reaches stability at 9.18 seconds. The running results are as follows: Fig.16 As shown, taking the steam generator heating section as an example, the pressure and temperature changes of its four sections are as follows Fig.17 and Fig.18 shown.

[0042] Depend on Fig.17 and Fig.18 It can be seen that although the initial parameters generated by the method proposed in this embodiment are not completely consistent with the ideal steady-state initial parameters in terms of numerical value, the changing trends of the parameter values ​​along the process are basically consistent. In addition, the initial parameters generated by this embodiment are used for model simulation, and the stabilization time is the same as the stabilization time under the ideal steady-state initial parameter setting. The simulation of the pressure and temperature values ​​of each section of the key components is very close to the simulation under the ideal steady-state initial parameter setting, which shows that this embodiment can solve the steady-state initialization problem of the model well.

[0043] It should be added that, for a model whose initial steady state can be simplified to a single-flow single-pressure boundary chain structure, the method of this embodiment can also give reasonable and effective initial parameters.

[0044] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. The initial parameter generation method based on NUMAP steady-state calculation is characterized by: The steps include: Obtain the thermal hydraulic simulation system model to be initialized in NUMAP, and decompose it into multiple single-flow single-pressure boundary chain structure sub-models; For each single-flow single-pressure boundary chain structure sub-model, the mass gas content of each component along the way and the mass gas content of non-condensable gas are set to 0, and the flow rate is set to a constant value at the flow boundary; Set the temperature of each component along the process to the average of the inlet and outlet temperatures, or use the inlet and outlet temperatures as endpoints and fill them linearly according to the component length as the temperature of each component along the process; The total friction pressure drop along the path is obtained by subtracting the total gravity pressure drop along the path from the total pressure drop along the path. It is linearly divided according to each group of parameters, and the initial pressures of the components along the path are assigned sequentially starting from the inlet boundary.

2. The method for generating initial parameters based on NUMAP steady-state calculation according to claim 1, characterized in that: After obtaining the thermal-hydraulic simulation system model to be initialized in NUMAP and decomposing it into multiple single-flow single-pressure boundary chain-shaped structure sub-models, the coolant in the first stage of the single-flow single-pressure boundary chain-shaped structure sub-model is a single-phase fluid in each component along the process and is not heated.

3. The method for generating initial parameters based on NUMAP steady-state calculation according to claim 1, characterized in that: In the single-flow single-pressure boundary chain structure sub-model, the components from the inlet to the outlet are connected in sequence, with one side being the flow boundary and the other side being the pressure boundary.

4. The method for generating initial parameters based on NUMAP steady-state calculation according to claim 1, characterized in that: The total friction pressure drop along the path is obtained by subtracting the total gravity pressure drop along the path from the total pressure drop along the path, and is linearly divided according to each group of parameters, and the initial pressure of the components along the path is assigned in sequence starting from the inlet boundary, where: The total pressure drop along the process is expressed as , the total gravity pressure drop along the way is expressed as , the total friction pressure drop along the way is expressed as ; The total friction pressure drop along the path is ; The total pressure drop along the is the outlet pressure value Subtract the inlet pressure ,Right now ; The total gravity pressure drop along the The calculation formula is: ,in , is the outlet height of the single-flow single-pressure boundary chain structure submodel, is the inlet height of the single-flow single-pressure boundary chain structure submodel; The total friction pressure drop along the The calculation formula is: ; in, L is the length of the flow channel; D is the diameter of the flow channel; is the coolant density; is the average flow rate of coolant; f is the friction coefficient; Assuming coolant flow m Keeping the same, assuming that the component flow channels are all circular, the coolant flow rate , at this time the total friction pressure drop along the ,in, K is the friction pressure drop proportionality coefficient.

5. The method for generating initial parameters based on NUMAP steady-state calculation according to claim 4, characterized in that: In the calculation of the total gravity pressure drop along the way, the coolant density Obtained by consulting the thermophysical properties table of water.

6. The method for generating initial parameters based on NUMAP steady-state calculation according to claim 4, characterized in that: The total friction pressure drop along the and proportional to the total friction pressure drop along the path according to the parameters of each component Perform linear allocation.

7. The method for generating initial parameters based on NUMAP steady-state calculation according to claim 4, characterized in that: Assume that there are N components along the way starting from the entrance boundary. Respectively represent the number of segments, diameter, length and height of each component, The friction pressure drop proportionality coefficient At this time, the outlet pressure of each component Set to ; For a single component , its inlet pressure is the outlet pressure of the previous component, and the pressure inside a single component is distributed linearly with the length. , the distance from the component entrance The pressure value is .

8. The method for generating initial parameters based on NUMAP steady-state calculation according to claim 7, characterized in that: The initial pressure and temperature at each segment of each component represent the average pressure and temperature of the corresponding segment. When generating the initial parameters, they are replaced by the pressure and temperature at the midpoint of each segment, that is, Pick .

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