Experimental Research on Natural Circulation Complex Oscillations Under Rolling Motion Conditions

Natural circulation flow instability under rolling motion conditions was experimentally studied. Experimental results show that the complex flow oscillations are formed due to the overlapped effect of the rolling motion (trough instability) and density wave oscillation. The system becomes more instable because of the occurrence of complex flow oscillations. Complex flow oscillations only occur in the case of high subcooling and may be divided into two types， regular and irregular complex flow oscillations. Under the same thermohydraulic conditions, the marginal stability boundary (MSB) of regularcomplex oscillations is similar to that of density wave oscillation without rolling motion. And the influences of rolling amplitude and rolling period on its MSB are slight.