Flow fluctuation behaviors of single-phase forced circulation under rolling conditions

Marine reactors are received increasing attention recently in the field of ocean engineering. The effect of platform motion on the coolant flow of an offshore nuclear power plants is very complicated, which is required further analysis. In this paper, effects of rolling motion on single-phase flow fluctuation with different loops were investigated experimentally. And a mathematical model was also developed to study the mechanism of the influence of rolling motion on flow fluctuation with different pressure head, rolling parameters and layouts of flow loops. For the closed loop, the flow rate was adjusted by two ways, i.e. regulating the pump rotation speed and changing the state of regulating valve. While for the opened loop, the pressure head was always supplied by elevated water tank. The Reynolds number ranged from 300 to 8000, and ranges of the rolling period and amplitude were 8-20 s and 10-30°, respectively. The results show that increase of the loop resistance and pressure head results in smaller flow fluctuation amplitudes. Effects of rolling motion on single-phase flow fluctuation weaken as the oscillatory pressure drop decreases or the pressure head increases. If the pressure head is high enough, the effect of rolling motion on flow fluctuation could be neglected. Rolling motions influence the flow fluctuation behaviors in different ways for the opened loop and the closed loop, due to the inequable oscillatory pressure drop. The flow fluctuation model shows a good agreement with the experiments and the analyzing method is expected to other oscillating flow system.