The design and validation of a microfabricated pulsed air-jet actuator for practical application to flow-separation control at full-scale operating conditions on a medium/large air vehicle is presented. The actuator device is designed to generate streamwise vortices within the boundary layer and comprises a pitched and skewed orifice of 200 μm diameter through which a high velocity (200-300 m/s) jet of air can be modulated by operation of a piezoelectric microvalve. This paper describes the overall design and manufacture of the actuator device with particular reference to the impact of fluid dynamic effects on the design and operation. Key results obtained from both static and dynamic tests of a prototype device are also presented and compared with original predictions. It is shown that the device that was developed and tested fulfils all the original design requirements with regard to size, jet velocity and operating frequency. The developed device has dimensions of approximately 5 mm × 2 mm in the plane of the aerodynamic surface in which it is imbedded and a thickness of 1 mm. Peak jet velocities in excess of 300 m/s through a 200 μm diameter orifice at 500 Hz have been demonstrated with peak driving voltages of 90 V and a nominal electrical power consumption of 50 mW.
Boundary-layer separation entails significant energy loss, increases flow unsteadiness and limits the performance of many flow devices. Not surprisingly, a substantial amount of research aimed at controlling boundary-layer separation [1, 2] has been conducted. Traditionally, the following approaches have been applied: a) tangential blowing to energize directly the low-momentum region near the wall [3-5]; b) wall suction [6, 7] to remove the low-momentum region; c) vortex generators (VGs and micro VGs) in the form of vanes and bumps [8, 9] and d) forced excitation devices, for example, acoustic excitation [10, 11]
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