Self-induced oscillation of liquid turbulent jet issued into open channel

In the reactor vessel, intermediate heat exchanger, circulating pump system and others of top entry type FBRs, liquid metal flows for the purpose of heat exchange in the vessels having free surfaces. The flow in the vessels is very complex, and various hydrodynamic instability oscillations have been reported. In this research, the self-induced oscillation of jet in the suddenly expanded channel having free surface was shown, and the conditions under which the oscillation phenomena occur, the relation of the oscillation frequency to the flow velocity at nozzle exit, the form of a channel and others were systematically elucidated according to the experimental results, moreover, the mechanism was shown qualitatively. The experimental setup and the experimental method are explained. As the results, the flow pattern at the time of oscillation, the region where oscillation occurs, the oscillation frequency, the Strouhal number, the distance of adhesion on channel surface, and the entrainment of air are reported. It was shown anew that in the turbulent jet issuing from the nozzle of three-dimentional shape into an open channel, oscillation phenomena occurred. (K.I.)