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 now, 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 [16-21]. 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. (C) 2009 Elsevier B.V. All rights reserved.