Electro-active polymer (EAP) “dimple” actuators for flow control: Design and characterisation.

The long-term goal of this work is the development of a ‘smart’ skin capable of sensing and real-time actuation of oncoming turbulent flow, specifically to reduce skin-friction drag. Active “dimples” are time-dependent depressions that optimally alter local flow conditions [2]. Lightweight electro-active polymers (EAPs) are ideal for these control surfaces since they offer high strain rate, fast response, low power consumption and ease of manufacture [13]. Key features for integration into a control system are robustness and repeatable, predictable motion. For this objective dimples are assessed and values for out-of-plane deflection, frequency response and vibrational modes, failure modes as well as power consumption values are presented. The dimple design comprises a buckling actuator, which can actuate without the need of a directional bias, differentiating itself from previous designs [16], [17], [18], [19], [20] and [21]. It also actuates from flush to the surface providing asymmetrical forcing, a key consideration for flow control purposes. It is shown that the dimple actuates with vibrational modes higher than the fundamental, and that these are non-linear, an important consideration for this type of device. The power consumption of the device, as required for net power savings, and device robustness is promising.