Method for determining flow resistance of gap structure of graphite pebble bed of high-temperature gas cooled reactor

Abstract

The invention relates to a method for determining the flow resistance of a gap structure of a graphite pebble bed of a high-temperature gas cooled reactor. The method comprises the following steps: constructing a three-dimensional geometric model corresponding to a reactor core cavity of the high-temperature gas cooled reactor, which reflects the characteristics of a graphite pebble bed and a gap combined structure; wherein the three-dimensional geometric model comprises a pebble bed and a gap channel in the lateral direction of the pebble bed; identifying a plurality of accumulation structures corresponding to a near-wall area close to the gap channel in the pebble bed, and determining distribution data of each accumulation structure; for each stacking structure, establishing a CFD geometric model provided with a geometric parameter combination in the near-wall area based on the distribution data of the stacking structure; based on the CFD geometric model of each stacking structure, CFD calculation and fitting are carried out, and target flow resistance characteristic parameters corresponding to each stacking structure are determined. According to the method, a scientific basis and a high-precision calculation model can be more accurately provided for thermal hydraulic design, safety analysis and nuclear power engineering simulation of the high-temperature gas cooled reactor, and the accuracy of flow resistance characteristic parameters is improved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of simulation, in particular to a method for determining flow resistance of a graphite sphere bed gap structure of a high temperature gas cooled reactor. BACKGROUND

[0002] In the engineering design and safety analysis of high temperature gas cooled reactors, the pipe network method is widely used in core flow channel flow distribution, pressure drop calculation and coolant flow characteristic prediction due to its high calculation efficiency and strong parameter coupling. At present, the core of the pipe network method is to simplify the complex flow channel into a network composed of nodes and branches, and the energy loss at the geometric discontinuity is represented by the local resistance coefficient. The traditional method usually calculates the resistance by the ratio of the narrow gap area to the corresponding height of the sphere bed circumferential area, but the random accumulation of graphite spheres in the high temperature gas cooled reactor forms a complex pore structure, which significantly interferes with the flow, resulting in underestimation of the actual resistance coefficient.

[0003] The core of a high temperature gas cooled reactor usually contains hundreds of thousands of graphite fuel spheres with a diameter of about 60mm, which are randomly stacked in the core cavity to form a complex pore structure. In the near-wall region, the fuel spheres tend to be arranged in an orderly layered manner, while in the bulk phase region, they exhibit a disordered topological distribution. This random stacking method can significantly affect the flow path of the helium coolant, resulting in changes in local flow resistance. In addition, the contact mode of the fuel spheres with the narrow gap wall surface can affect the separation and vortex generation of the flow, but the traditional model does not correct this. Therefore, there is an urgent need for a high-precision calculation method that can quantify the influence of graphite sphere accumulation structure on flow resistance to improve the reliability of high temperature gas cooled reactor thermal-hydraulic simulation and provide more accurate data support for safety analysis. SUMMARY

[0004] To solve the above technical problems, the present disclosure provides a method for determining flow resistance of a graphite sphere bed gap structure of a high temperature gas cooled reactor.

[0005] According to an aspect of the present disclosure, a method for determining flow resistance of a graphite sphere bed gap structure of a high temperature gas cooled reactor is provided, the method comprising: constructing a three-dimensional geometric model corresponding to a high temperature gas cooled reactor core cavity with a combined structure of a reaction graphite sphere bed and a gap; wherein the three-dimensional geometric model comprises a sphere bed with distributed graphite fuel spheres and a gap channel laterally to the sphere bed; identifying a plurality of accumulation structures corresponding to a near-wall region of the sphere bed close to the gap channel, and determining distribution data of each of the accumulation structures; for each of the accumulation structures, establishing a computational fluid dynamics (CFD) geometric model with a geometric parameter combination in the near-wall region based on the distribution data of the accumulation structure; the geometric parameter combination comprises a gap width d of the gap channel and a target distance l between the center of a graphite fuel sphere and the gap channel. CFD calculation and fitting are performed based on the CFD geometric model of each of the packing structures, and the target flow resistance characteristic parameters corresponding to each of the packing structures are determined.

[0006] According to another aspect of the present disclosure, a device for determining flow resistance of a graphite sphere bed gap structure of a high-temperature gas cooled reactor is also provided, and the device comprises: A first model construction module is configured to construct a three-dimensional geometric model corresponding to a high-temperature gas cooled reactor core cavity of a combined structure of a reactor graphite sphere bed and a gap; wherein the three-dimensional geometric model comprises a sphere bed in which graphite fuel spheres are distributed and a gap channel laterally to the sphere bed; A packing structure identification module is configured to identify a plurality of packing structures corresponding to a near-wall region of the sphere bed close to the gap channel, and determine distribution data of each of the packing structures; A second model construction module is configured to, for each of the packing structures, respectively establish a fluid mechanics CFD geometric model provided with a geometric parameter combination in the near-wall region based on the distribution data of the packing structure; the geometric parameter combination comprises a gap width d of the gap channel and a target distance l between a sphere center of the graphite fuel sphere and the gap channel; A resistance parameter determination module is configured to perform CFD calculation and fitting based on the CFD geometric model of each of the packing structures, and determine target flow resistance characteristic parameters corresponding to each of the packing structures.

[0007] According to another aspect of the present disclosure, an electronic device is also provided, and the electronic device comprises: A processor; A memory for storing executable instructions of the processor; The processor is configured to read the executable instructions from the memory and execute the instructions to implement the above method.

[0008] According to another aspect of the present disclosure, a computer readable storage medium is also provided, and the storage medium stores a computer program for executing the above method.

[0009] The technical solution provided by the embodiments of the present disclosure has the following advantages compared with the prior art: The technical scheme provided by the embodiment of the present disclosure mainly comprises: constructing a three-dimensional geometric model corresponding to a high-temperature gas cooled reactor core cavity of a reaction graphite sphere bed and a gap combination structure feature; wherein the three-dimensional geometric model comprises: a sphere bed in which graphite fuel spheres are distributed and a gap channel on the side of the sphere bed; identifying a plurality of packing structures corresponding to a near-wall region of the sphere bed close to the gap channel, and determining distribution data of each packing structure; for each packing structure, based on the distribution data of the packing structure, a CFD geometric model provided with a geometric parameter combination is established in the near-wall region; the geometric parameter combination comprises: a gap width d of the gap channel, and a target distance l between the center of the graphite fuel sphere and the gap channel; based on the CFD geometric model of each packing structure, CFD calculation and fitting are performed to determine the target flow resistance characteristic parameters corresponding to each packing structure.

[0010] The present scheme is aimed at the core bypass flow distribution and variation characteristics of the high-temperature gas cooled reactor. By establishing a three-dimensional geometric model of the real packing characteristics of graphite spheres (i.e. the reaction graphite sphere bed and the gap combination structure feature), the correction of the resistance coefficient of the sudden contraction region and the sudden expansion region can significantly improve the calculation accuracy of the flow resistance characteristic parameters of the sphere bed and the gap structure of the high-temperature gas cooled reactor. The corrected CFD geometric model significantly improves the error problem caused by not considering the influence of the graphite sphere packing structure on the local resistance in the existing pipe network method, and can more accurately provide scientific basis and high-precision calculation model for the thermal hydraulic design, safety analysis and nuclear power engineering simulation of the high-temperature gas cooled reactor, and improve the accuracy of the flow resistance characteristic parameters. In short, by constructing a three-dimensional geometric model of a multi-scale coupled sphere bed and gap flow simulation system, a CFD geometric model, and combining parameterized modeling, the present disclosure realizes accurate correction of the resistance characteristic parameters of helium passing through the gap channel from the graphite sphere bed, and improves the accuracy of the target flow resistance characteristic parameters. BRIEF DESCRIPTION OF DRAWINGS

[0011] The accompanying drawings, which are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure and, together with the specification, serve to explain the principles of the present disclosure.

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0013] Figure 1 Flow chart of the method for determining the flow resistance of the graphite sphere bed gap structure of the high-temperature gas cooled reactor according to the embodiment of the present disclosure; Figure 2 Schematic diagram of the three-dimensional geometric model of the reaction graphite sphere bed and the gap combination structure feature according to the embodiment of the present disclosure; Figure 3 A sectional view of the CFD geometric model according to an embodiment of the present disclosure; Figure 4 A partial enlarged view of the CFD geometric model according to an embodiment of the present disclosure; Figure 5 A structural schematic diagram of the high-temperature gas cooled reactor graphite pebble bed gap structure flow resistance determination device according to an embodiment of the present disclosure; Figure 6 A structural schematic diagram of the electronic device according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0014] In order to enable a more clear understanding of the above-mentioned objects, features and advantages of the present disclosure, the schemes of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0015] In the following description, many specific details are set forth in order to provide a thorough understanding of the present disclosure, but the present disclosure can also be implemented in other ways different from those described herein; obviously, the embodiments in the description are only some of the embodiments of the present disclosure, not all the embodiments.

[0016] In order to overcome the problem of low precision in calculating the flow resistance coefficient of the high-temperature gas cooled reactor graphite pebble bed and narrow gap structure in the traditional pipe network method in the prior art, the present disclosure provides a high-temperature gas cooled reactor graphite pebble bed gap structure flow resistance determination method, device, equipment and medium; the scheme establishes a geometric model considering the real accumulation characteristics of the graphite pebble, combines multi-scale flow simulation and parameterization correction, significantly improves the calculation precision of the resistance coefficient of the sudden contraction area and sudden expansion area of the narrow gap structure, and provides a reliable basis for the thermal hydraulic design and safety analysis of the high-temperature gas cooled reactor.

[0017] Figure 1 A flowchart of a high-temperature gas cooled reactor graphite pebble bed gap structure flow resistance determination method provided by an embodiment of the present disclosure, the method can be executed by a high-temperature gas cooled reactor graphite pebble bed gap structure flow resistance determination device, the device can be realized by software and / or hardware, and specific examples include electronic equipment or servers. The electronic equipment can include devices such as tablet computers, desktop computers, notebook computers and smart phones. The server can be a cloud server or a server cluster, etc. a device with storage and computing functions.

[0018] Reference Figure 1 The high-temperature gas cooled reactor graphite pebble bed gap structure flow resistance determination method can include the following steps S102-S108.

[0019] S102, a three-dimensional geometric model corresponding to a high-temperature gas cooled reactor core cavity of a combined structure of a reaction graphite pebble bed and a gap is constructed; wherein the three-dimensional geometric model comprises: a pebble bed in which graphite fuel balls are distributed and a gap channel on the side of the pebble bed.

[0020] The embodiment can include: simulating the high-temperature gas cooled reactor core cavity of the combined structure of the reaction graphite pebble bed and the gap by using the discrete element method; in the simulation, the graphite fuel balls are dropped from the top, and after the accumulation is stable, the pebble bed in which the graphite fuel balls are distributed is formed; the gap channel is constructed on the side of the pebble bed to obtain the initial three-dimensional geometric model of the combined structure of the reaction graphite pebble bed and the gap.

[0021] Specifically, in the modeling stage of the three-dimensional geometric model, the typical core cavity of the high-temperature gas cooled reactor is simulated by using the discrete element method (DEM, Discrete Element Method) to construct a three-dimensional geometric model capable of reacting the combined structure of the graphite pebble bed and the gap as shown in Figure 2 .

[0022] In the simulation, in order to truly reproduce the near-wall accumulation characteristics of the pebble bed, the DEM software is called to simulate the natural falling and accumulation process of the graphite fuel balls, that is, the graphite fuel balls are freely dropped from the top with the actual diameter and naturally accumulated under the action of gravity to form a random but locally regular structure. After the accumulation is stable, the pebble bed in which the graphite fuel balls are distributed is formed. Based on this, a large number of graphite fuel balls with a diameter of R (for example, R=60mm) are distributed in the pebble bed.

[0023] The gap channel with a gap width of d is constructed on the side of the pebble bed, and the gap channel can also be generally referred to as a narrow gap channel or a narrow gap structure in the industry. The gap width d of the gap channel ranges for example: .

[0024] The target distance between the center of the graphite fuel ball near the wall in the pebble bed and the center axis of the gap channel is l , .

[0025] The pebble bed in which the graphite fuel balls are distributed and the gap channel on the side of the pebble bed are coupled to constitute the main body of the three-dimensional geometric model capable of reacting the combined structure of the graphite pebble bed and the gap. The three-dimensional geometric model can simulate the real accumulation structure distribution of the graphite fuel balls.

[0026] S104, identifying a plurality of accumulation structures corresponding to the near-wall area of the pebble bed close to the gap channel and determining the distribution data of each accumulation structure.

[0027] The embodiment includes: dividing a near-wall region close to the gap channel in the pebble bed into a plurality of three-dimensional subdomains; and identifying the packing structure of each three-dimensional subdomain; wherein the packing structure is divided into: a face-centered cubic structure, a body-centered cubic structure, or a simple cubic structure; and the occurrence probability of each packing structure in the near-wall region is counted to obtain distribution data of the packing structure.

[0028] Specifically, as shown in Figure 3 , a local region in the pebble bed within a preset distance range (such as a range of 3-5 ball diameters) from the gap channel is selected as the near-wall region to be subjected to local structure identification.

[0029] The near-wall region is uniformly divided into a plurality of three-dimensional subdomains along the axial and radial directions. The local structure of the spheres in each three-dimensional subdomain is identified and classified by using geometric indexes such as the number of inter-sphere contacts and the local porosity, and in combination with a preset determination rule, to obtain the following packing structures: a face-centered cubic structure (FCC), a body-centered cubic structure (BCC), or a simple cubic structure (SC).

[0030] Then, the embodiment can count the occurrence probability of each packing structure in the near-wall region, denoted as P FCC , P BCC , and P SC , respectively, and satisfy: P FCC + P BCC + P SC =1.

[0031] The distribution data of the above packing structures will be used as the probability weight input for subsequent establishment of a CFD geometric model. When the CFD geometric model is modeled, the modeling is performed according to the probabilities of the occurrence probabilities of the above three packing structures, for example, if FCC accounts for 30%, the coefficient of the resistance model obtained by CFD simulation should be multiplied by 30%, and subsequently, the relevant formulas (5) and (6) of the target resistance coefficient benchmark value can be referred to.

[0032] To improve the representativeness and robustness of the statistics, the embodiment performs multiple independent DEM pile simulation of the three-dimensional geometric model, and the packing structures and the corresponding distribution data obtained under the same initial condition are summarized and normalized to obtain stable and reliable packing structures and distribution data.

[0033] S106, for each packing structure, a CFD (Computational Fluid Dynamic) geometric model with a combination of geometric parameters is established in the near-wall region based on the distribution data of the packing structure; the combination of geometric parameters includes: a gap width d of the gap channel, a target distance between the center of the graphite fuel sphere and the gap channel l .

[0034] The embodiment includes: setting multiple combinations of geometric parameters for each packing structure; and establishing a series of CFD geometric models of each packing structure in the near-wall region according to the distribution data of each packing structure and the multiple combinations of geometric parameters.

[0035] Specifically, based on the three-dimensional geometric model, a CFD geometric model of each packing structure (FCC, BCC and SC) in the near-wall region is established. Due to the central axis symmetry of the high-temperature gas cooled reactor pebble bed, the CFD geometric model corresponding to each packing structure is provided with a gap channel and a near-wall pebble bed structure. In combination with the gap width d of the gap channel Figure 4 , the target distance between the center of the graphite fuel sphere in the near-wall pebble bed structure close to the gap channel and the central axis of the gap channel is . The gap width d and the target distance l constitute a combination of geometric parameters (d, and l ). l ) In combination with the parameterized modeling method, the embodiment can set multiple representative combinations of geometric parameters (d, l ) for each packing structure, construct an orthogonal experiment matrix, and generate a series of CFD geometric models corresponding to the calculation conditions. The CFD geometric model established in the above manner fully considers the packing structure, and each packing structure corresponds to a respective CFD geometric model.

[0036] For the graphite fuel sphere intersecting with the wall surface of the gap channel, an accurate geometric cutting operation is performed to retain the arc surface structure of the sphere of the graphite fuel sphere outside the gap channel, and to ensure the geometric continuity between the pebble bed and the gap channel.

[0037] In actual application, the CFD geometric model of each packing structure can be exported as a Parasolid format file.

[0038] S108, based on the CFD geometric model of each packing structure, CFD calculation and fitting are performed to determine the target flow resistance characteristic parameters corresponding to each packing structure.

[0039] The embodiment comprises: obtaining a plurality of sets of pressure drop data corresponding to the process of fluid entering the gap channel from the gap of the graphite fuel sphere under the same fluid boundary condition and different mass flow rates for the CFD geometric model of the current packing structure. The resistance relationship parameters under the current packing structure are determined according to the pressure drop data.

[0040] The current packing structure is any one of a plurality of packing structures. It can be understood that in the embodiment, the implementation process of determining the target flow resistance characteristic parameter is the same for each packing structure, whether it is a face-centered cubic structure, a body-centered cubic structure or a simple cubic structure. Therefore, the embodiment takes any one of the packing structures as the current packing structure for example, which can be a face-centered cubic structure, a body-centered cubic structure or a simple cubic structure.

[0041] In the specific implementation process, the Parasolid format file of the CFD geometric model of the current packing structure can be imported into the CFD simulation calculation platform. In order to ensure numerical accuracy, the core region grid adopts hybrid polyhedral grid, and boundary layer grid, i.e. prismatic layer grid, is set near the gap channel and the surface of the graphite fuel sphere to finely capture the boundary layer flow characteristics.

[0042] The same fluid boundary condition is set for each packing structure, and a plurality of sets of different mass flow rates are calculated to obtain the corresponding pressure drop data of the fluid entering the gap channel from the gap of the graphite fuel sphere.

[0043] The fluid boundary condition comprises: the inlet boundary condition adopts mass flow rate inlet, and the outlet boundary condition is pressure outlet; the core outlet pressure under the operating condition of the high-temperature gas cooled reactor is set as the reference pressure, and all wall surfaces are set as adiabatic wall surfaces. The CFD geometric model of the current packing structure is selected, and the accurate physical parameters of helium at the corresponding temperature, such as dynamic viscosity and helium density, are input in the calculation.

[0044] The convergence condition is monitored during the solution process, and the gap pinch area and the gap expansion area are dynamically monitored during the iteration process, referring to Figure 4 The monitoring sections S3 and S4 are respectively created at the distances X1 and X2 of the gap channel and the ball bed interface, the pressure distribution of each monitoring section is obtained through the field function extractor, the static pressure difference between the ball bed main flow area (S1) and the gap channel inlet (S3) is determined as the pressure drop data corresponding to the gap pinch area, and the static pressure difference between the gap channel outlet (S4) and the ball bed main flow area (S1) is determined as the pressure drop data corresponding to the gap expansion area.

[0045] After the calculation, the static pressure distribution data of each monitoring section is extracted in the post-processing module of the CFD software, and the resistance relationship parameters corresponding to different mass flow rates are calculated according to the static pressure distribution data and the following formulas (1) and (2), which can include the resistance coefficient f and the Reynolds number : (1) (2) wherein, represents the pressure difference of the sudden contraction region or the sudden expansion region, represents the helium density, v represents the flow velocity of helium at the monitoring sections S3 and S4, and L represents the characteristic length of the gap channel, represents the dynamic viscosity.

[0046] According to the total bypass flow rate m of the high-temperature gas cooled reactor core 总 and the variation law of the mass flow rate and the height of the bypass flow entering the gap channel, the bypass flow rate value range of the core interior is (0, m max ). Compared with the actual spherical bed geometric model, the mass flow rate value range of the CFD geometric model in the embodiment is . Through calculation, the Reynolds number Re of the working condition involved in the embodiment is 0<Re<3×10 4 .

[0047] Next, for the CFD geometric model with fixed geometric parameter combination, the resistance relationship parameters corresponding to multiple mass flow rate points are selected for CFD calculation and fitting to obtain the target flow resistance characteristic parameters corresponding to the current accumulation structure. The step specifically can include the following contents.

[0048] For the CFD geometric model of each geometric parameter combination, the resistance relationship parameters corresponding to multiple mass flow rate points are selected for CFD calculation to obtain CFD data; the CFD data is fitted to obtain initial flow resistance characteristic parameters; wherein the initial flow resistance characteristic parameters include an initial resistance coefficient reference value.

[0049] Specifically, for the CFD geometric model of the above geometric parameter combination (d, l), n mass flow rate points are selected, and the resistance relationship parameters (including the resistance coefficient f and the Reynolds number Re) corresponding to the n mass flow rate points are calculated by CFD to obtain CFD data. Then, for the CFD geometric model with fixed geometric parameter combination (d, l), the CFD data is used to fit the power law formula corresponding to the sudden contraction region and the sudden expansion region of the gap channel, as shown in the following formulas (3) and (4): (3) (4) In the above power law formula, , respectively represent the initial flow resistance characteristic parameters corresponding to the sudden expansion region and the sudden contraction region of the gap channel; , respectively represent the initial resistance coefficient reference values corresponding to the sudden expansion region and the sudden contraction region of the gap channel, which are empirical parameters obtained by pre-fitting, and c is a constant; 扩 , c 缩 respectively represent the variation laws of the resistance coefficient corresponding to the sudden expansion region and the sudden contraction region of the gap channel with the Reynolds number Re, which are empirical parameters obtained by pre-fitting, and A is a constant; s , A L respectively represent the area of the sudden contraction region and the area of the sudden expansion region of the gap channel.

[0050] Then, in this embodiment, the resistance coefficient reference values l under different target distances of the same gap width d are equally weighted and averaged to obtain the target resistance coefficient reference value.

[0051] Specifically, for the same kind of packing structure, the CFD geometric model of each geometric parameter combination (d, l) can obtain the initial flow resistance characteristic parameters: , . Considering that in the high temperature gas cooled reactor core pebble bed, the geometric dimensions of the graphite fuel ball and the gap channel are not single, but multiple geometric relationships coexist, and the probabilities of occurrence are different. At the same time, considering the probability weight of the identified packing structure distribution.

[0052] Therefore, in order to obtain the relationship between the resistance coefficient of helium passing through the gap channel of the graphite fuel ball pebble bed and the geometric size of the gap channel, the initial resistance coefficient reference values l corresponding to different target distances under the same gap channel size (i.e. d is the same) are equally weighted and averaged according to the spatial probability obtained by DEM statistics to obtain the target resistance coefficient reference value, which is referred to as the following formula (5) and (6): (5) (6) Wherein, , respectively represent the target resistance coefficient reference values corresponding to the sudden expansion region and the sudden contraction region of the gap channel; i respectively represent the packing structures: face-centered cubic structure, body-centered cubic structure and simple cubic structure; n represents the total number of types of packing structures; P i represents the occurrence probability of the packing structure i.

[0053] The initial flow resistance characteristic parameters are adjusted based on the aforementioned target resistance coefficient benchmark value to obtain the target flow resistance characteristic parameters.

[0054] Specifically, based on the aforementioned target drag coefficient benchmark value , For initial flow resistance characteristic parameters , Adjustments were made to obtain the drag coefficient. With Reynolds number The area ratio of the sudden contraction region to the sudden expansion region The functional relationship is shown in the following (7): (7) in, Indicates the target flow resistance characteristic parameters; , These represent the target drag coefficient reference values ​​corresponding to the sudden expansion and contraction regions of the slot channel, respectively; Re represents the Reynolds number; c 扩 c 缩 The values ​​represent the variation of the drag coefficient with Reynolds number Re in the sudden expansion and contraction regions of the slot channel, respectively. This represents the area ratio of the suddenly contracted region to the suddenly expanded region.

[0055] Among the target flow resistance characteristic parameters mentioned above, the Reynolds number Re can be in the range of: 0 <Re<3×10 4 The aforementioned target flow resistance characteristic parameters are used to accurately predict the flow resistance characteristics under different core operating conditions.

[0056] In summary, the method for determining the flow resistance of the graphite sphere bed slot structure in a high-temperature gas-cooled reactor provided in this disclosure mainly includes: constructing a three-dimensional geometric model corresponding to the core cavity of the high-temperature gas-cooled reactor that reflects the characteristics of the graphite sphere bed and slot combination structure; wherein, the three-dimensional geometric model includes: a sphere bed with distributed graphite fuel spheres and slot channels on the sides of the sphere bed; identifying various packing structures corresponding to the near-wall region of the sphere bed near the slot channels, and determining the distribution data of each packing structure; for each packing structure, establishing a fluid dynamics CFD geometric model with a combination of geometric parameters in the near-wall region based on the distribution data of the packing structure; the combination of geometric parameters includes: the slot width d of the slot channel, and the target distance l between the center of the graphite fuel sphere and the slot channel; performing CFD calculation and fitting based on the CFD geometric model of each packing structure to determine the target flow resistance characteristic parameters corresponding to each packing structure.

[0057] The scheme is aimed at the flow distribution and variation characteristics of the high temperature gas cooled reactor core. By establishing a three-dimensional geometric model of the real packing characteristics of the graphite spheres (i.e. the combined structure characteristics of the reaction graphite sphere bed and the gap), the correction of the resistance coefficient of the sudden contraction area and the sudden expansion area can significantly improve the calculation accuracy of the flow resistance characteristic parameters of the high temperature gas cooled reactor sphere bed and gap structure. The corrected CFD geometric model significantly improves the error problem caused by not considering the influence of the graphite sphere packing structure on the local resistance in the existing pipe network method, and can more accurately provide scientific basis and high-precision calculation model for the thermal hydraulic design, safety analysis and nuclear power engineering simulation of the high temperature gas cooled reactor. In short, the disclosure realizes the accurate correction of the resistance characteristic parameters of the helium gas passing through the graphite sphere bed and the gap channel by constructing a three-dimensional geometric model of the multi-scale coupled sphere bed and gap flow simulation system, a CFD geometric model, and combining parameterized modeling.

[0058] Reference Figure 5 The embodiment of the disclosure provides a high temperature gas cooled reactor graphite sphere bed gap structure flow resistance determination device, which can include the following modules: The first model construction module 210 is used for constructing a three-dimensional geometric model corresponding to the high temperature gas cooled reactor core cavity of the combined structure characteristics of the reaction graphite sphere bed and the gap; wherein the three-dimensional geometric model includes: a sphere bed distributed with graphite fuel spheres and a gap channel laterally of the sphere bed; The packing structure identification module 220 is used for identifying a plurality of packing structures corresponding to the near-wall area of the sphere bed close to the gap channel, and determining the distribution data of each packing structure; The second model construction module 230 is used for establishing a fluid mechanics CFD geometric model provided with a geometric parameter combination in the near-wall area for each packing structure based on the distribution data of the packing structure; the geometric parameter combination includes: the gap width d of the gap channel, and the target distance l of the sphere center of the graphite fuel sphere and the gap channel; The resistance parameter determination module 240 is used for performing CFD calculation and fitting based on the CFD geometric model of each packing structure, and determining the target flow resistance characteristic parameters corresponding to each packing structure.

[0059] The device provided by the embodiment has the same implementation principle and technical effects as the foregoing method embodiments. For brevity, the part not mentioned in the device embodiment can be referred to the corresponding content in the foregoing method embodiments.

[0060] Figure 6 A structural schematic diagram of an electronic device provided by an embodiment of the disclosure is shown in FIG. 3. Figure 6 As shown in FIG. 3, the electronic device 300 includes one or more processors 301 and a memory 302.

[0061] The processor 301 can be a central processing unit (CPU) or other form of processing unit having data processing and / or instruction executing capabilities, and can control other components in the electronic device 300 to perform desired functions.

[0062] The memory 302 can include one or more computer program products that can include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory, for example, can include random access memory (RAM), cache memory, and / or the like. The non-volatile memory, for example, can include read-only memory (ROM), hard disk, flash memory, and / or the like. One or more computer program instructions can be stored on the computer-readable storage media, which the processor 301 can execute to implement the above-mentioned high temperature gas cooled reactor graphite pebble bed gap structure flow resistance determination method of the embodiments of the present disclosure and / or other desired functions. Various contents such as input signals, signal components, noise components, and the like can also be stored in the computer-readable storage media.

[0063] In one example, the electronic device 300 can further include an input device 303 and an output device 304, which are interconnected through a bus system and / or other forms of connection mechanisms (not shown).

[0064] In addition, the input device 303 can further include, for example, a keyboard, a mouse, and the like.

[0065] The output device 304 can output various information including determined distance information, direction information, and the like to the outside. The output device 304 can include, for example, a display, a speaker, a printer, a communication network and a remote output device connected thereto, and the like.

[0066] Of course, in order to simplify, Figure 6 Only some of the components in the electronic device 300 related to the present disclosure are shown in the figure, and components such as buses, input / output interfaces, and the like are omitted. In addition, the electronic device 300 can further include any other appropriate components according to specific application cases.

[0067] Further, the embodiments also provide a computer-readable storage medium storing a computer program for executing the above-mentioned high temperature gas cooled reactor graphite pebble bed gap structure flow resistance determination method.

[0068] The computer program product of the high-temperature gas-cooled reactor graphite ball bed gap structure flow resistance determination method, device, electronic equipment and medium provided by the embodiment of the present disclosure comprises a computer readable storage medium storing program codes, the instructions included in the program codes can be used to execute the method described in the foregoing method embodiments, and specific implementation can be referred to the method embodiments, which will not be described here.

[0069] It should be noted that, in this document, relational terms such as“first” and“second”, and the like, are used solely to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual relationship or order between such entities or actions. Moreover, the terms“comprises”,“comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without more limitations, an element defined by the statement“comprising a……” does not exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0070] The above description is merely one specific implementation of the present disclosure, which enables a person skilled in the art to understand or implement the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to these embodiments described herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for determining flow resistance of a gap structure of a high-temperature gas-cooled reactor graphite pebble bed, characterized by, The method includes: A three-dimensional geometric model of the core cavity of a high-temperature gas-cooled reactor, which reflects the combined structural features of graphite spheres and slots, is constructed; wherein, the three-dimensional geometric model includes: a sphere bed in which graphite fuel spheres are distributed and slot channels on the sides of the sphere bed; Identify multiple stacking structures corresponding to the near-wall region of the ball bed near the slot channel, and determine the distribution data of each stacking structure; For each of the accumulation structures, a fluid mechanics CFD geometric model provided with a geometric parameter combination is respectively established in the near-wall region based on distribution data of the accumulation structure; the geometric parameter combination includes: a gap width d of a gap channel, a target distance between a ball center of a graphite fuel ball and the gap channel l ; CFD calculations and fittings are performed based on the CFD geometric model of each of the aforementioned stacking structures to determine the target flow resistance characteristic parameters corresponding to each of the aforementioned stacking structures.

2. The method of claim 1, wherein, The three-dimensional geometric model corresponding to the high-temperature gas-cooled reactor core cavity, which constructs the reactive graphite spherical bed and slotted composite structure features, includes: The discrete element method was used to simulate the core cavity of a high-temperature gas-cooled reactor with reactive graphite spherical beds and slotted composite structures. During the simulation, graphite fuel balls were dumped from the top and, after the stacking stabilized, a ball bed was formed in which the graphite fuel balls were distributed. A gap channel is constructed laterally on the ball bed to obtain an initial three-dimensional geometric model of the reactive graphite ball bed and gap combination structure features.

3. The method of claim 1, wherein, The process of identifying multiple stacking structures corresponding to the near-wall region of the ball bed near the slot channel, and determining the distribution data of each stacking structure, includes: The near-wall region of the ball bed adjacent to the slot channel is divided into multiple three-dimensional subdomains; Identify the stacking structure of each of the three-dimensional subdomains; wherein the stacking structure is classified as: face-centered cubic structure, body-centered cubic structure, or simple cubic structure; The probability of occurrence of each of the aforementioned stacking structures in the near-wall region is statistically analyzed to obtain the distribution data of the stacking structures.

4. The method according to claim 1, characterized in that, For each of the aforementioned stacking structures, a fluid dynamics CFD geometric model with a combination of geometric parameters is established in the near-wall region based on the distribution data of the stacking structure, including: Multiple sets of geometric parameter combinations are set for each of the aforementioned stacking structures; Based on the distribution data of each of the stacking structures and the multiple sets of geometric parameter combinations, a series of CFD geometric models of each of the stacking structures in the near-wall region are established.

5. The method according to claim 1, characterized in that, The calculation and fitting of CFD based on the CFD geometric model of each of the aforementioned packing structures to determine the target flow resistance characteristic parameters corresponding to each of the aforementioned packing structures includes: For the CFD geometric model of the current packing structure, under the same fluid boundary conditions and different mass flow rates, multiple sets of pressure drop data are obtained corresponding to the process of fluid entering the gap channel from the gap of the graphite fuel sphere; wherein, the current packing structure is any one of the various packing structures; Determine the resistance relationship parameters under the current stacking structure based on the pressure drop data; For the CFD geometric model with a fixed combination of geometric parameters, the resistance relationship parameters corresponding to multiple mass flow points are selected for CFD calculation and fitting to determine the target flow resistance characteristic parameters corresponding to the current stacking structure.

6. The method according to claim 5, characterized in that, For the CFD geometric model with a fixed combination of geometric parameters, CFD calculations and fittings are performed on the drag relationship parameters corresponding to multiple mass flow points to determine the target flow drag characteristic parameters corresponding to the current packing structure, including: For the CFD geometric model of each combination of geometric parameters, the resistance relationship parameters corresponding to multiple mass flow points are selected for CFD calculation to obtain CFD data; The CFD data is fitted to obtain initial flow resistance characteristic parameters; wherein, the initial flow resistance characteristic parameters include a reference value for the initial resistance coefficient; Using the same gap width d, but different target distances l The target drag coefficient benchmark value is obtained by taking the equal-weighted arithmetic average of the existing drag coefficient benchmark values. The initial flow resistance characteristic parameters are adjusted based on the target resistance coefficient benchmark value to obtain the target flow resistance characteristic parameters.

7. The method according to claim 1, characterized in that, The target flow resistance characteristic parameters include: in, Indicates the target flow resistance characteristic parameters; , These represent the target drag coefficient reference values ​​corresponding to the sudden expansion and contraction regions of the slot channel, respectively; Re represents the Reynolds number; c 扩 c 缩 The values ​​represent the variation of the drag coefficient with Reynolds number Re in the sudden expansion and contraction regions of the slot channel, respectively. This represents the area ratio of the suddenly contracted region to the suddenly expanded region.

8. A device for determining the flow resistance of a graphite spherical bed slot structure in a high-temperature gas-cooled reactor, characterized in that, The device includes: The first model construction module is used to construct a three-dimensional geometric model of the core cavity of a high-temperature gas-cooled reactor that reflects the combined structural features of graphite spheres and slots; wherein, the three-dimensional geometric model includes: a sphere bed in which graphite fuel spheres are distributed and slot channels on the sides of the sphere bed; The stacking structure identification module is used to identify multiple stacking structures corresponding to the near-wall region of the ball bed near the gap channel, and to determine the distribution data of each stacking structure. The second model construction module is used to establish a fluid dynamics CFD geometric model with a combination of geometric parameters in the near-wall region for each of the stacking structures based on the distribution data of the stacking structure; the combination of geometric parameters includes: the gap width d of the gap channel and the target distance l between the center of the graphite fuel ball and the gap channel. The drag parameter determination module is used to perform CFD calculations and fitting based on the CFD geometric model of each of the stacking structures, and to determine the target flow drag characteristic parameters corresponding to each of the stacking structures.

9. An electronic device, characterized in that, The electronic device includes: processor; Memory used to store the processor's executable instructions; The processor is configured to read the executable instructions from the memory and execute the instructions to implement the method described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores instructions that, when executed on a terminal device, cause the terminal device to perform the method as described in any one of claims 1-7.

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