An electrostatically actuated valve for turbulent boundary layer control

A large displacement electrostatic valve has been designed and realized for a realistic turbulent boundary layer control. This actuator consists of a pair of rigid electrodes and a flexible film having a S-shape providing local high electrostatic forces required for controling rather large pressure differences. The aim is the reattachment of the boundary layer near an aircraft flap trailing edge by transferring momentum energy via high speed pulsated micro air jets. The valve controls the frequency and the speed of the micro jets. An array of fifteen actuators has been manufactured and characterized by particles images velocimetry (PIV) and hot wire anemometry (HWA). The devices are able to control pressure differences up to 27 kPa with a supply voltage of 400 V. For this maximum pressure, the corresponding jet velocity downstream a 45 degree skew micro orifice (0.4 mm diameter) is close to 100 ms-1