Numerical analysis of flowing characteristics of turbulent flow in rectangular channels in ocean environment

摘要

Because of the periodic effects of ocean waves, there are great discrepancies between the operational characteristics of nuclear power systems in ocean environment and that of land-based nuclear power systems. In some special operational status, like natural circulation, the additional forces due to ocean environment may impose so great disturbance on the coolant flow that theatres the safety operation of the systems. In the present paper, the turbulent flow in rectangular channels in ocean environments is investigated theoretically with CFD code FLUENT. The effects of several parameters on turbulent flow are analyzed. The effects of rolling motion includes two parts, the first part is the additional force parallel to flowing direction, which can affect on the pressure drop of the flow and change the flowing velocity, and the other part is the additional force perpendicular to flowing direction. In ocean environments, the flowing characteristics of turbulent flow are dominated by the additional force parallel to flowing direction. The effect of additional force perpendicular to flowing direction is very limited. In rolling and heaving motions, if the flowing velocity is the same, the flowing characteristics of turbulent flow are nearly the same, too. The bigger the Reynolds number is, the more serious the oscillation of turbulent kinetic energy and frictional resistance coefficient is, and the more the oscillation of turbulent flow is. The relationship between average frictional resistance coefficient and velocity oscillating amplitude is quadratic. And the oscillating amplitude of frictional resistance coefficient is in direct ratio with velocity oscillating amplitude.