Measurement of critical velocities for fluidelastic instability using vibration control

Fluidelastic effects may be responsible for instabilities of heat exchanger tubes when the fluid flow reaches the critical velocity. The fluidclastic phenomenon is usually studied on experimental mock-ups, which may display only one critical velocity. In this paper, a method based on active vibration control is proposed in order to derive several critical velocities for fluidelastic instability corresponding to several different values of damping, which is artificially varied on the same mock-up. Experimental tests are performed on a flexible tube equipped with piezoelectric actuators in a rigid array under air-water cross-flow. It is shown that the reduced critical velocities thus obtained fit well in a classical stability map.