COMPACT, HIGH-POWER BOUNDARY LAYER SEPARATION CONTROL ACTUATION DEVELOPMENT

The development of a self-contained, synthetic jet actuator for stall control of a pitching airfoil is described. The test simulates the full-scale (chord, Reynolds and Mach numbers) conditions of rotorcraft retreating blade stall. The required slot velocity was 65 m/s amplitude at 250 Hz (Cμ =0 .1% and F + =1). The packaging of a selfcontained actuator inside the confined leading edge of the airfoil represented a significant challenge. The approach taken was a voicecoil linear motor driving a piston/spring assembly at resonance (first mass-spring mode). This paper describes the mechanical design aspects of the spring, actuator loss mechanisms, and the electroacoustic modeling of the device. The high stiffness requirement (dictated by the design frequency and moving mass) combined with the large displacement requirement (due to confined space of the leading edge limiting piston size) made the spring design the most difficult challenge. This challenge was overcome, resulting in a successful bench top actuator test that met performance targets and agreed well with the model. The final embodiment designed for use in the wind tunnel blade section leading edge is described.