In this work we present the application of the new synthetic jet actuator (SJA) to flow separation control over a NACA 0015 wing. The actuator is compact enough to fit in the interior of the wing that has a chord of 0.375 m. The wing was tested in the Texas A&M University Aerospace Engineering 3 ft×4 ft wind tunnel. An experimental investigation into the effects of the synthetic jet actuator on the performance of the wing is described. Emphasis is placed on the capabilities of the actuator to control the separation of the flow over the wing at high angles of attack. The results include force balance measurements, on surface and off surface flow visualization, surface pressure measurements, and wake surveys. All of the reported tests were performed at a free-stream velocity of 35 m/s, corresponding to a Reynolds number of 8.96×105. The angle of attack was varied from −2.0 deg to 29.0 deg. For the results presented, at angles of attack lower than 10 deg, the actuator has minimal effects. At higher angles of attack, the SJA delays the onset of stall. The use of the actuator causes an 80% increase in the maximum lift coefficient, while the angle at which stall occurs is increased from 12 to 18 deg. The drag on the wing is decreased as a consequence of SJA actuation. For angles of attack larger than 18 deg, where the wing experiences massive separation, the SJA still provides a moderate amount of lift augmentation compared to the unforced case. At angles of attack larger than 25°, a larger frequency of actuation is required to produce significant effects.

The development of a biomimetic active hydrofoil that utilizes shape memory alloy (SMA) actuator technology is presented. This work is the first stage prototype of a vehicle that will consist of many actuated body segments. The current work describes the design, modeling and testing of a single-segment demonstration SMA actuated hydrofoil. The SMA actuation elements are two sets of thin wires on either side of an elastomeric component that joins together the leading and trailing edges of the hydrofoil. Controlled heating and cooling of the two wire sets generates bi-directional bending of the elastomer, which in turn deflects the trailing edge of the hydrofoil. In this paper the design of the hydrofoil and the experimental tests preformed thereon are explained. A detailed account of SMA actuator preparation (training) and material characterization is given. Finite-element method (FEM) modeling of hydrofoil response to electrical heating of the SMA actuators is carried out using a thermomechanical constitutive model for the SMA with input from the material characterization. The modeling predictions are finally compared with experimental measurements of the trailing edge deflection and the SMA actuator temperature.

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Although strong potential of synthetic jets as flow separation control actuators has been demonstrated in the existing literature, there is a large gap between the synthetic jet actuators (SJA) used in laboratory demonstrations and the SJAs needed in realistic fullscale applications, in terms of compactness, weight, efficiency, control authority and power density. In most cases, the SJAs used in demonstrations are either too large or too weak for realistic applications. In this work, we present the development of compact, high-power synthetic jet actuators for realistic flow separation control applications and demonstrate the developed SJA technology in representative, flow separation control problems, including control of steady separation/stall. The developed actuators are compact enough to fit in the interior of a 14.75" chord, NACA0015 wing, have maximum power of 2.0 HP and can produce (for the tested conditions) exit velocities as high as 80 m/sec. Flow separation control was demonstrated over a 14.75" chord, NACA 0015 wing at angles of attack and free stream velocities as high as 25 degrees and 45 m/s, respectively and pressure data was acquired over the wing for a range of conditions.

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