Study on Generation Mechanism of Abnormal Vibration of Flow Dynamic Conveyer

The FDC (Flow Dynamics Conveyer) has often been used in power plants and iron works because of superiority in low noise compared with a roller type conveyer and it is excellent in low noise and low power. The FDC consists of a trough and a belt, and the air is supplied from a series of holes provided on the trough. However, large vibrations occur when the flow rate reaches a certain value. This abnormal vibration is defined to be self-excited vibration caused by leakage flow induced vibration here. In this study, as the first step, the theoretical model of a non tapered clearance flow passage is assumed and the natural frequency is calculated. On that basis, experiments are conducted and the validity of the theory is examined. As the second step, in the case of a tapered clearance flow passage, the concentrated load is added to the belt. The effects of the belt deformation, the flow rate and the added loads on the clearance flow are examined and the generation mechanism of the abnormal vibration is considered. As a result, it was clarified that the generation mechanism of the self-excited vibration was due to the phase shift by the change of the parameters.