Aerodynamic dancer in web handling

Abstract

This paper discusses the aerodynamic dancer that is effective in a wide range of frequency and do not cause excessive lateral web deflection, touching, or flutter. An aerodynamic model of air-turn bar has been developed. The model can handle air-turn bars that have varying density of air-emitting holes. The model predicts the average flotation height of the web, cushion pressure profile under the web, and the rate of air consumption for given operating conditions. Experimental verification of the aerodynamic model has been done with a stationary-web test setup. The air gap profile, the cushion pressure profile, and the air consumption were measured, and the results were compared with the prediction. Also examined was the possibility of using an air reverser for determination of web tension. Web tension was varied up to 175 N/m (1.5 lbf/in). The measurement error of web tension based on cushion pressure was less than 5 percent in the entire range of test conditions. An air dancer model has been developed based on the aerodynamic model of air-turn bars and compared with experimental results. It was shown that the air dancer system has a much wider useful frequency range compared to the conventional dancer system.