Modeling and analysis of mixing processes of nonisothermal flows in power plants

The use of modern computational fluid dynamics (CFD) programs for the analysis and justification of individual elements of equipment and operating modes of reactor plants is extremely promising. With the help of these computer systems, it is possible to analyze the operating conditions of elements of the equipment of reactor plants operating under significant thermocycler fluctuations, and to analyze the readings of elements of the complex control system for technical means in order to optimize algorithms and operating modes. Also, an equally important task is to analyze the temperature field at the entrance to the core under asymmetric operating conditions of the reactor plant. To implement these systems in practical use, it is necessary to create an experimental base for verification of these programs. Due to the fact that conducting experiments close in parameters to real reactor plants operating at enormous pressures is associated with significant economic costs, most of the phenomena occurring in the systems under consideration can be studied with a sufficient degree of representativeness on smallscale models operating on water at pressures close to atmospheric or pressures up to 1 MPa. As part of this work, a computational study of mixing processes of non-isothermal flows in a single loop of the ship's nuclear power plant model (NPP) was carried out using COMSOL Multiphysics and Solid Works Flow simulation software systems, and the results were verified at the research stand "Single-Loop NPP model". As a result of this work, the temperature distribution was obtained in the characteristic regions of the single-loop mixing model (ring gap, lower chamber, hole sheet, core simulator), as well as an empirical dependence describing the mixing processes with a sufficient degree of accuracy. In the future, the empirical model will be further refined in order to create universal high-accuracy dependence for predicting mixing processes.

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