Experimental Investigation of Natural Convection in a Core of a Marine Reactor in Rolling Motion

Abstract

A series of single-phase natural circulation experiments in a simulated marine reactor mounted on a rolling bed was performed and the average Nusselt number in the core was evaluated in order to investigate effects of the rolling motion on the heat transfer in the core. Heat transfer with an upright attitude is well correlated with the Rayleigh number and is slightly lower than El-Genk's correlation. Heat transfer in the core is not affected by the inclination angle because the inclination of the present experiment is not large enough to cause any remarkable changes in the flow pattern of the core. Heat transfer in the core is enhanced by the rolling motion which is thought to cause internal flow in the core. Heat transfer during the rolling motion is correlated with the Richardson number for rolling motion, R _iR , and is classified into three regimes: (1) region A (0.05<R _iR ≤0.3) where heat transfer is dominated by the inertial force due to the rolling motion; (2) region B (0.3<R _iR ≤2) where heat transfer is affected by the combined effect of the inertial force and natural convection; and (3) region C (R _iR >2) where heat transfer is affected only by the natural convection.

KEYWORDS:

• natural convection
• combined convection
• marine reactor
• rolling
• ship motion
• inclined attitude
• heat transfer
• reactor core
• passive safety
• decay heat removal