Vibration Phenomena of Pipes in Fluidized Bed

The quantitative condition starting vibration of pipes by the flow across pipes in fluidized bed was studied experimentally. The occurence of self-excited vibration was observed over the critical flow velocity for a group of pipes, but on the other hand, no self-excited vibration observed for a single pipe. This vibration was found to be fluid elastic vibration. The resonance vibration of pipes caused by karman vortex was not found in fluidized bed even when Re is over 100. From the result of the experiment, the coefficient which determines a critical condition of fluid elastic vibration was found to be close to the value of liquid (water) instead of gas.