Experimental Study of Self-Excited Vibration in a Thin Film Wrapped Around an Air-Turn Bar

This paper describes an experimental study for a self-excited vibration in the thin film wrapped around an air-turn bar. The characteristics of a self-excited vibration are investigated by obtaining time histories of the film deflection and distributions of a steady pressure and a pressure fluctuation at a surface of the airturn bar. The experimental results show that this system has two different types of vibration modes. One is a low-frequency mode which the film vibrates radially with respect to the the air-turn bar. The other is a high-frequency mode which the film flaps in the out-of-plane direction of the film. Moreover, a stability diagram of the self-excited vibration is obtained by changing the flow rate and the tensile force acting on the film. It is shown that the low-frequency vibration mode occurs when the flow rate and the tensile force are large, and the high-frequency vibration mode occurs at any flow rate and tensile force in this experiment.