Self-excited oscillation due to the fluid discharge over a flexible weir. (1st report. Excitation mechanism of a sloshing mode).

Abstract

The excitation mechanism of a self-excited oscillation due to the fluid discharge over a flexible weir was investigated both theoretically and experimentally. A new type of hydroelastic instability was discovered during test operations of the Super-Phenix LMFBR reactor in France. According to the recent report by Aita, this phenomenon includes two types of instability modes : one is sloshing mode which means the oscillation of a weir associated with coupled sloshing modes of both feeding and restitution fluid collectors ; the other is a hydroelastic mode which means the oscillation of a weir associated with fluid-shell modes. In this report, the excitation mechanism of a sloshing mode is discussed by calculating the excitation energy brought by discharge to the fluid-structure system. The theoretical results for the range of sloshing mode instability almost agreed with the experimental data.