Possibility of active cascade flutter control with smart structure in transonic flow condition

To study the possibility of active cascade flatter control by application of smart structure, numerical analyses were performed under transonic flow conditions with passage shock waves by a developed flow-structure coupled method. In the flow condition of the present study, the unsteady aerodynamic force induced by the shock oscillation was dominant for instability of blade vibration. The direction of blade movement during oscillation was first adopted as the control parameter, because it was known to be a quite influential factor for vibration instability of blades in the transonic flows. The method could decrease the passage shock movement near the blade surface and effectively suppress the blade vibration, though it was not effective when the blade stiffness was small. For more effective control, the method in which the trailing edge of blade was actively vibrated was sought to control the passage shock oscillation. The trailing edge oscillation might be realized by, for instance, application of piezo-electric device. The method was revealed to change the unsteady aerodynamic force acted on the blade from exciting to damping force if the phase of trailing edge oscillation was properly selected. The suppressing effect of the control method came from its effect on passage shock movement, which was confirmed by developed lbw-structure coupled method.