Hello
I have been investigating on improvement of aerodynamic efficiency (lift-to-drag ratio) of pitching airfoil in low Reynolds number as small as 1000.
Most of my works are based on passive method such as Gurney flap or blunt trailing edge. Acceptable results are obtained (lift-to-drag ratio increases), however in all cases drag increases. so, I am looking active method which lift to drag ratio increases and drag decreases.
Literature show that plasma actuator and synthetic jet are effective. Who does know that synthetic jet can be used for pitching airfoil in low dimensions? Most of researchers wok on UAV and larger scales.
models have larger scale for researchers who work on MAV.
Do you think Synthetic jet is effective and manufacturable for flapping wing's dimension?
Can MEMS be a solution and economic?
Best Regard
Synthetic jet is affordable for manufacturing.. MEMS can be applied vigorously for microscopic manf
As a rule, passive control methods have the ability of increasing the lift-to-drag ratio, at least within a certain range of operating conditions, but this is generally achieved at the expense of a drag penalty. These have the advantage, though, of not requiring power to operate, which is definitely an advantage for MAVs due to the resulting weight penalty from additional batteries. To the passive methods you have mentioned, I would add the scalloped leading edges, with similar advantages and pitfalls.
Active flow control can be much more effective, especially because it can be adjusted to the operating conditions and even switched off if not required. But it requires power to be operated. Plasma actuators are very interesting but I foresee a major weight penalty for the implementation of such a system in a MAV. Synthetic jets, though, can be generated using piezoelectric actuators, which have very low power consumption, and these are definitely compatible with MEMS manufacturing. To me, this seems the natural choice for active control in MAVs.
Effective flow control for a pitching airfoil is definitely more complex than for a stationary airfoil, unless it operates at very low Reynolds numbers and pitching rates. Pitching airfoils generally take advantage of the LEV to achieve higher lift, as well as thrust via Knoller-Betz effect. However, the complexity of the vorticity structures at moderate Reynolds numbers and pitch rates is likely to significantly complicate the accomplishment of effective control. But it's definitely worthy to try!
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