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ENCIT 2020
18th Brazilian Congress of Thermal Sciences and Engineering
ANALYSIS OF SINGLE PHASE NATURAL CIRCULATION AT SMALL INCLINATION ANGLES AND UNDER ROLLING MOTION
Submission Author:
Natasha Conceição , RJ
Co-Authors:
Natasha Conceição, Su Jian
Presenter: Natasha Conceição
doi://10.26678/ABCM.ENCIT2020.CIT20-0170
Abstract
A naval reactor operates on a ship with six degrees of freedom: heave, sway, surge, roll, pitch, and yaw. This work investigates the behavior of the reactor coolant in a single-phase natural circulation of a rectangular circuit under small inclination angles and under rolling motion. Firstly, the steady state natural circulation is analyzed, with the loop under small inclination angles. The mass flow rate is determined as a function of heating power and the inclination angle by solving a transcendental equation. The transient behavior of the natural circulation is then analyzed for different amplitudes and periods of rolling motion. In this case, the temperature of the fluid varies with space and time. The energy conservation equation is discretized in the spatial variable along the loop by finite difference method, resulting in a system of ordinary differential equations for fluid temperature at discretization nodes, which is solved together with the integrated momentum conservation equation for the transient mass flow rate. All implementations are performed in Wolfram Mathematica 11.3 software. It is found that the mass flow rate decreases with increasing inclination angle at steady-state and that the mass flow rate oscillates with the same period of rolling motion.
Keywords
natural circulation, Naval Reactor, Single phase, Rolling motion, method of lines
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