MEMS based active skin for turbulent drag reduction
Additional Document Info
Drag reduction for aerial and underwater vehicles has a range of positive ramifications: reduced fuel consumption, larger operational range, greater endurance and higher achievable speeds. Recent Direct Numerical Simulation (DNS) studies have shown that the application of a transversely acting, traveling waveform like force, that is confined to the viscous sublayer of the flow, can result in significant reduction in turbulent drag. Since the action of this force wave is confined to a very small region of fluid right next to the surface, it is postulated that the application of a traveling surface wave, which is also confined to these dimensions, would in effect result in the necessary traveling force wave. In this work, a generalized actuation principle for generating a traveling wave on the surface of a skin is proposed and analyzed. The flow control technique pursued is "micro" in the sense that only micro-scale wave amplitudes (order of 30 m) and energy inputs are expected to produce significant benefits. Hence, a MEMS based approach to the design of the active skin is considered, that utilizes actuation by active materials such as Shape Memory Alloys (SMA)s and piezoelectric actuators. Specifically, a MEMS based design that incorporates thin film SMA actuators is developed and the process flow methodology required for its microfabrication is discussed. For preliminary testing and validation of the DNS results, a mechanically actuated prototype skin, the operation of which has been refined through several iterations, has been manufactured using a rapid prototyping machine.
name of conference
Smart Structures and Materials 2003: Smart Structures and Integrated Systems