CN-115600072-B - Quick mapping method for nuclear power system heat exchanger grid

CN115600072BCN 115600072 BCN115600072 BCN 115600072BCN-115600072-B

Abstract

The invention discloses a quick mapping method for grids of a nuclear power system heat exchanger, which comprises the following steps of 1, modeling and dividing grids of an inner fluid domain and an outer fluid domain of the heat exchanger by utilizing soildworks software, 2, obtaining coordinates of grids of all primary sides, calculating the maximum value of the body-core distances of adjacent grids in three directions, 3, taking the coordinates of the grids of the primary sides as the center, taking the body-core distances as half side lengths, marking all secondary sides in a range, 4, endowing cyclic numbers to the grids of the secondary sides, counting the number of the corresponding grids of the secondary sides, 5, writing the marking process of the grids of the secondary sides into an initialization macro built in Fluent software, and reading the coordinate parameters of the grids by utilizing a predefined macro, and realizing the retrieval and marking of the grids of the secondary sides after the initialization operation. The method solves the problem of lattice mismatch during calculation of fluid coupling between the inside and outside of the heat transfer pipe, and has reasonable marking result when the inner and outer fluid lattices adopt different division modes and the number and arrangement positions of the heat transfer pipe lattices change greatly.

Inventors

WANG MINGJUN
WANG SHIQI
HE SHAOPENG
TIAN WENXI
SU GUANGHUI
QIU SUIZHENG

Assignees

西安交通大学

Dates

Publication Date: 20260505
Application Date: 20221027

Claims (1)

1. A nuclear power system heat exchanger grid rapid mapping method is characterized by comprising the following steps: Modeling a heat transfer pipe of a heat exchanger of a nuclear power system and a secondary side fluid domain outside the heat transfer pipe by soildworks software, dividing grids by using a grid dividing tool ICEM, and selecting to divide structured grids or unstructured grids according to actual conditions in the grid dividing process; step 2, reading the body center coordinates of all primary side grids by using the grid loop body format and the predefined macros built in the Fluent software, and storing the body center coordinates in three one-dimensional arrays In this, assuming that grids that are continuously searched when the primary side grid is circularly read are adjacent, the adjacent grid body center-to-center distance maximum values in three directions are calculated by the following equation: (1) wherein the subscript 1 represents the primary side variable identifier, The total number of primary side grids is dimensionless; -a primary side coordinate array identification, Taking out , ; -Circulate to the first The primary side coordinate array identity at the time of the grid, Representing circulation to the first The primary side coordinates array is identified when the grid is formed, ; -The maximum value of the spacing between the heart of adjacent grids, ; In order to ensure that the value obtained by the formula (1) is the effective value between adjacent grids, the following constraint conditions are adopted for effectiveness judgment: (2) wherein: The distance between the core of adjacent heat transfer pipes, ; The diameter of the heat transfer tube is equal to the diameter of the heat transfer tube, ; Only when two continuously searched grid coordinates meet the formula (2), the formula (1) calculation is carried out, and the calculation value is ensured to be the maximum value of the space between the adjacent grid body centers through the common constraint solution of the formula (1) and the formula (2); After obtaining a primary side grid body center coordinate array and three dimensional body center distance maximum values, marking a secondary side grid by adopting a cuboid marking method, wherein the primary side grid coordinate is taken as a center, the body center distance maximum value is half-side length, forming a cuboid space region taking each primary side grid coordinate as a body center, circularly reading all grid coordinates of a secondary side fluid region, and carrying out digital marking on all secondary side grids in the space region by utilizing a user-defined memory in Fluent software, wherein the method is described as follows: (3) wherein: -the identification of the secondary side coordinates, ; When traversing the primary side coordinate array, carrying out secondary side grid circulation on each primary side grid through a double circulation method, marking through a formula (3), and after the circulation is finished, marking the grids of the tube bundle area in a secondary side fluid domain; Step 4, in order to describe the corresponding relation of the secondary side grids, realize the accurate marking between the secondary side grids, on the basis of the marking result of step 3, according to the different number of grids of the secondary side tube bundle area, select one side grid with smaller number of grids as the benchmark, count the number of grids of the other side corresponding to each grid of this side, assign the same marking number to these grids with corresponding relation at the same time, in order to facilitate subsequent management and call, define as the circulation number +1 when this grid is searched through the marking number, namely: (4) (5) wherein: -first The marking numbers of the circular grid coordinates are dimensionless; -count the first The number of grids at the other side corresponding to the cyclic reference grids; Since the grids are closely arranged, in the marking process, the condition that the same grid is repeatedly marked exists, and the problem can simultaneously lead to errors of the number of the statistical grids, when the grids are marked, all the grids are marked firstly The value is set to 0 and described as follows: When (when) When (1): (6) When (when) When (1): (7) When (when) When (1): (8) (9) (10) wherein: -first The number of the marks which are given to the circular grids is dimensionless; When the searched grids have marking numbers, the grids are re-marked through formulas (7) - (10), the value of the corresponding statistic quantity array is changed, after all grids are circulated, the secondary side grids are accurately searched through the marking numbers, the quantity of the corresponding grids on the other side is counted, and the parameter average in subsequent calculation is facilitated; And 5, writing a secondary side grid marking process, namely the process from step 2 to step 4, into an initialization macro built in the Fluent software by utilizing a user-defined function in the Fluent software, reading grid coordinate parameters by utilizing a predefined macro in the formulas (1) and (2), and realizing the retrieval and marking of the secondary side grid after the initialization operation is carried out in the Fluent software.

Description

Quick mapping method for nuclear power system heat exchanger grid Technical Field The invention belongs to the technical field of nuclear reactor thermodynamic hydraulic calculation methods, and particularly relates to a quick grid mapping method for a nuclear power system heat exchanger. Background The passive waste heat removal system (PRHRS) is used as an important special safety facility in the third-generation advanced nuclear power stations such as the AP1000, the Hualong first-generation advanced nuclear power station and the like, and is used for carrying out the tasks of leading out the heat of the reactor core under the working conditions of reactor start-stop, transient state and accident, and the main equipment in the system is the passive C-type heat exchanger (PRHR HX) which is designed to be soaked in a material-changing water tank arranged in a containment. After the passive C-type heat exchanger is put into operation, heat exchange of the secondary side fluid is carried out through the C-shaped heat transfer tube bundles which are trapped together. The process is conducted to carry out correct numerical simulation, so that the experimental cost is reduced, and a reference is provided for the optimal arrangement mode of the heat transfer tubes. Because of the large number of heat transfer tubes in the actual structure, the difficulty of finely modeling the whole of the C-shaped heat exchanger and the secondary side fluid domain is high, the number of grids can be greatly increased, the consumed computing resources are currently difficult to bear, and the method is necessary to be properly simplified in the modeling process. In order to solve the problem, some common treatment methods are to reduce the number of heat transfer tubes to a plurality of heat transfer tubes, and to carry out fine modeling analysis and calculation on the heat transfer tubes to research the heat transfer characteristics of the secondary side flow, and the method is far from the actual engineering problem due to the fact that the number of the heat transfer tubes is small, so that the method is only used as a scientific research method. Another common method is that the solid modeling is not carried out on the primary side heat transfer tube, the position of the heat transfer tube is marked in the secondary side water area only according to the geometric and position parameters of the heat pipe, the flow in the heat transfer tube is regarded as one-dimensional flow, the heat exchange quantity of the fluid in the heat transfer tube to the secondary side is manually calculated to serve as a heat source item of the secondary side tube bundle area, and the thermodynamic and hydraulic characteristics of the secondary side fluid are studied. The method greatly simplifies the modeling process and improves the calculation efficiency, but the three-dimensional flow of the fluid in the pipe cannot be simulated because the primary side fluid domain is not modeled. In order to simulate the three-dimensional flow of the secondary side fluid domain at the same time, it is necessary to model the primary side fluid domain entity, and the method of modeling the secondary side fluid domain separately can solve the problem, and simultaneously, since two fluid domains adopt two independent grids, the number of grids can be reduced alternatively when the grids are divided, and the calculation speed is improved. However, this method requires a high precision of the marking process and marking results for the primary side heat transfer tube bundle in the secondary side fluid domain. Therefore, the method for rapidly mapping the nuclear power system heat exchanger grids is developed, and has important significance for developing accurate three-dimensional numerical simulation aiming at the heat exchanger in the nuclear power system and improving the calculation efficiency. Disclosure of Invention The invention aims to provide a quick mapping method for a nuclear power system heat exchanger grid, which carries out automatic marking on a secondary side tube bundle area grid for a plurality of times by reading a secondary side grid coordinate parameter, utilizes a Fluent user-defined memory to store marking information, carries out locally refined one-to-many marking on the basis of integral marking, realizes an automatic accurate marking function between the secondary side grid, avoids the complexity of manual marking, enhances the universality of a program and improves the calculation precision. In order to achieve the above purpose, the invention adopts the following technical scheme: a nuclear power system heat exchanger grid rapid mapping method is characterized by comprising the following steps: Modeling a heat transfer pipe of a heat exchanger of a nuclear power system and a secondary side fluid domain outside the heat transfer pipe by soildworks software, dividing grids by using a grid dividing tool ICEM, and selecting to divide struct