Flow-induced vibration of cross-shaped tube bundle (the stabilizing effect of circular tubes)

Cross-shaped tube bundle is proposed for a lower plenum structure in a next generation LWR. It was considered how the circular cylinders in the tube bundle affected the random exciting force and the stability boundary of the self-excited vibration of cross-shaped tube bundle experimentally. The circular cylinders could reduce the self-excited vibration of cross-shaped tube bundle at least when single cross-shaped tube was flexibly supported. The circular cylinders could not affect the random fluid excitation force. The increasing rate of the normalized fluid excitation force was 20% or less, which meant that they could not affect the random vibration amplitude so much. (authors)