Flow separation control via synthetic jet actuation

Abstract

A theoretical and experimental analysis is presented for the optimal design of Synthetic Jet Actuators (SJA) driven by electrical motors. The experiments conducted in the water tunnel show that the motor powered zero mass flux tangential jet can completely eliminate separation on an airfoil even in the post stall region. A digital Particle Image Velocimetry system operating at speeds as high as 1,000 frames per second was employed to quantitatively characterize the momentum enhancement in the boundary layer, both parallel and perpendicular to the flow. A theoretical study on the power requirement of the motor is also presented. The analysis is based on the momentum deficit in the separating boundary layer, which has to be supplied by the motor. Methods to optimize the power and the configuration of the motorSJA assembly are discussed. It is shown that the optimized configuration depends on a parameter based on the average momentum added to the flow over a cycle of operation of the oscillatory jet. A new design for a SJA to be housed inside a wing was built and tested. Finally the use of proper orthogonal decomposition (POD) to generate reduced order models of the flowfield generated by SJA’s is introduced and shown to have promising results. Nomenclature A area, [m2] A, ratio of membrane area A, to slot area A,, A,4 A, a moment arm, [m] *Research Assistant, Aerospace Engineering Department, Student Member AIAA. t Postdoctoral Research Associate, Aerospace Engineering Department, Member AIAA $ Professor, Aerospace Engineering Department, Member AIAA § Associate Professor, Aerospace Engineering Department, Member AIAA Copyright