scholarly journals Mathematical model of steady flow in a helium loop

2019 ◽  
Vol 20 (7) ◽  
pp. 704
Author(s):  
František Világi ◽  
Branislav Knížat ◽  
Marek Mlkvik ◽  
František Urban ◽  
Róbert Olšiak ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Numerical Model ◽  
Steady Flow ◽  
Gaseous Medium ◽  
Natural Circulation ◽  
Variable Density ◽  
Experimental Facility ◽  
Flowing Medium ◽  
Current State ◽  
Natural Circulation Loop

The article describes the application of a mathematical model to a natural circulation loop. A set of measurements were conducted at the experimental facility. The pressure and velocity relations were observed during the steady flow of helium. The main goal was to create a numerical model of flow capable of determining the velocity of flowing medium. The model describes the flow of highly compressed gaseous medium with variable density in direct pipelines with local resistances. At the current state, the temperature values along the loop are taken as input to the model. The article also includes the evaluation of local resistances in DHR and GFR, which significantly affects the resulting accuracy. The results from a numerical model are compared with experiments.

scholarly journals One dimensional modelling of flow in a helium loop

2018 ◽  
Vol 168 ◽  
pp. 07007
Author(s):  
František Világi ◽  
Branislav Knížat ◽  
Marek Mlkvik ◽  
František Urban ◽  
Róbert Olšiak ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Numerical Model ◽  
Gaseous Medium ◽  
Nuclear Reactors ◽  
Natural Circulation ◽  
Heat Removal ◽  
Variable Density ◽  
Sufficient Accuracy ◽  
One Dimensional ◽  
Decay Heat

The natural circulation helium loop is a facility designed for decay heat removal from ALLEGRO fast nuclear reactors. The article deals with the observation of pressure and velocity relations during steady flow of helium. A one-dimensional numerical model of flow capable of determining the velocity with sufficient accuracy is presented in the article. The model describes the flow of highly compressed gaseous medium with variable density in direct pipelines with local resistances. It’s a hydraulic model, which means that the temperature distribution along the loop must be known. The article also includes the evaluation of local resistances in DHR and GFR, which significantly affects the resulting accuracy. The results from numerical model are compared with experiments.

The mathematical modelling of corrosion in hot dip galvanized steel reinforced concrete

2011 ◽  
Vol 2 (1) ◽  
pp. 1-12
Author(s):  
A. Hegyi ◽  
H. Vermeşan ◽  
V. Rus
Keyword(s):  
Mathematical Model ◽  
Reinforced Concrete ◽  
Numerical Model ◽  
Equation System ◽  
Galvanized Steel ◽  
Steel Reinforced Concrete ◽  
Numeric Model ◽  
Physical And Mathematical Models ◽  
Physical Phenomena ◽  
The Mathematical Model

Abstract In this paper we wish to present the numerical model elaborated in order to simulate some physical phenomena that influence the general deterioration of steel, whether hot dip galvanized or not, in reinforced concrete. We describe the physical and mathematical models, establishing the corresponding equation system, the initial and boundary conditions. We have also presented the numeric model associated to the mathematical model and the numeric methods of discretization and solution of the differential equations system that describes the mathematical model.

scholarly journals Assessment of Steady and Unsteady Friction Models in the Draining Processes of Hydraulic Installations

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1888
Author(s):  
Óscar E. Coronado-Hernández ◽  
Ivan Derpich ◽  
Vicente S. Fuertes-Miquel ◽  
Jairo R. Coronado-Hernández ◽  
Gustavo Gatica
Keyword(s):  
Mathematical Model ◽  
Turbulent Flow ◽  
Water Velocity ◽  
Experimental Facility ◽  
Governing Equations ◽  
Pressure Oscillations ◽  
Air Pocket ◽  
Friction Models ◽  
The Mathematical Model

The study of draining processes without admitting air has been conducted using only steady friction formulations in the implementation of governing equations. However, this hydraulic event involves transitions from laminar to turbulent flow, and vice versa, because of the changes in water velocity. In this sense, this research improves the current mathematical model considering unsteady friction models. An experimental facility composed by a 4.36 m long methacrylate pipe was configured, and measurements of air pocket pressure oscillations were recorded. The mathematical model was performed using steady and unsteady friction models. Comparisons between measured and computed air pocket pressure patterns indicated that unsteady friction models slightly improve the results compared to steady friction models.

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