ИЯЭ и ТФ Кафедра «ЯР и ЭУ» CFD IN NUCLEAR APPLICATIONS Работу выполнил: магистрант 1 года обучения НГТУ им. Р. Е. Алексеева, Сатаев Александрович 2017 г.
“The clouds scattered and torn, Sand blown up from the seashore, Trees and plants must bend!!!” Leorando da Vinci (1452 -1519)
The Computational Fluid Dynamics
Processes in nuclear reactor
Turbulence Modeling Ø Direct Numerical Simulation Ø Reynolds-averaged Navier Stokes equations (RANS) Ø Large Eddy Simulation (LES) Ø Detached Eddy Simulations (DES) (Philippe Spalart)
CFD codes Ø Finite difference method Ø Finite volume method Ø Finite element method Ø Spectral Method
CFD IN NUCLEAR APPLICATIONS Ø Ø Ø Ø Ø Boron dilution; Mixing of cold and hot water in the cold legs; Thermal shock Counter-current flow in cold and hot legs; Flows in tee junctions; Containment flow in LOCA Natural circulations; Liquid / gas stratification; Bubble dynamics
Mixing
I have chosen a subject of this research as it correlates with a subject of my master thesis. A subject of my master's thesis is modeling the processes of mixing non-isothermal flows. I conduct experiments on mixing non-isothermal flows now, and I am going to visualize these flows in the CFD programs then. The main objective of this article is to present a need and the importance of Computational Fluid Dynamics (CFD) simulation for the complex natural circulation phenomena in water cooled nuclear plant components. The Computational Fluid Dynamics (CFD) is one of the branches of fluid mechanics that uses numerical methods and algorithms to solve and analyze problems that involve fluid flows. Accurate CFD computer programs that can simulate complex scenarios such as turbulent flows are an ongoing challenging area of research. The principal interest of computational fluid dynamics (CFD) in nuclear applications is mainly in the capability to obtain at a lower cost, valuable information on some physical phenomena. The governing processes occurring in water reactors are without exception related to complex multiphase flows. Because of the large scales, inaccessibility and hostile high thermal conditions in and the reactor components, it is extremely difficult to obtain very detailed on line information of theses processes. The fundamental basis of any CFD problem is the Navier-Stokes equations, which define any single -phase fluid flows. Nature is characterized by three dimensional flows and turbulence plays a predominant part in the development of these flows. Turbulence flows have properties that make it difficult to develop an accurate tractable theory. The article describes the different ways to solve The Navier-Stokes equations (NSE) and ways to describe turbulent flow (LES, RANS, RSM, DES). Examples of CFD simulations of natural circulations are given. However, confidence in the CFD calculations should be assessed. Verification and validation (V&V) are the major processes for assessing and quantifying this confidence. A brief review of V&V terminology and approaches will be discussed.
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