Abstract
In practice, often devices are ordered rod structures consisting of a large number of rods. Heat exchangers, fuel assemblies of nuclear reactors, and their cores in the case of using caseless assemblies are examples of such devices. Simulation of heat and mass transfer processes in such devices in porous-body approximation can significantly reduce the required resources compared to computational fluid dynamics (CFD) approaches. The paper describes an integral turbulence model developed for defining anisotropic model parameters of a porous body. The parameters of the integral turbulence model were determined by numerical simulations for assemblies of smooth rods, assemblies with spacer grids, and wire-wrapped fuel assemblies. The results of modeling the flow of a liquid metal coolant in an experimental fuel assembly with local blocking of its flow section in anisotropic porous-body approximation using an integral turbulence model are described. The possibility of using the model of an anisotropic porous body with the integral model of turbulence to describe thermal-hydraulic processes during fluid flow in rod structures is confirmed.
Highlights
In engineering practice, integral and local approaches are used to simulate thermalhydraulic processes in the cores of nuclear power plants and other heat-exchange equipment
The presence of the spacer grid leads to a change in the form of the resistance tensor and the generation of turbulence in the spacer grid
The value of the integral coefficient αv i must be determined for a spacer grid with the help of
Summary
Integral and local approaches are used to simulate thermalhydraulic processes in the cores of nuclear power plants and other heat-exchange equipment. Sub-channel models operate with averaged characteristics, which are of the main interest in most problems but allow one to determine their value only at the corresponding nodes of the elements into which the computational domain is divided. These methods were developed [1,2] and continue to be used now. The finite element method (FEM) [9] or the finite volume method (FVM) [10] applied for discretizing the computational domain allows for calculating geometries of arbitrary shape and does not require the use of structured grids, in contrast to the subchannel approach This approach allows for a determination of the average parameters at any point in the computational domain. Calculated relationships are obtained for the parameters of the integral turbulence model for the main types of rod structures used in heat exchange equipment
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