What is it about?
he ultimate objective of this research is flight testing of a DBD plasma-based AFC system on the V-tail panels of a Hermes 450 UAV. The Hermes 450 is a widely used, Class II tactical UAV falling in the 150–600 kg payload range This phase of the research is divided into four main components: 1) actuator and actuation development designed to determine appropriate actuator materials and test lightweight high-voltage electronics; 2) two-dimensional airfoil wind-tunnel evaluations, conductedfor the purpose of determining effective actuation protocols, including pulsation frequencies and amplitudes; 3) full-scale windtunnel tests on a single panel at typical takeoff and landing speeds; and 4) pulsed-actuation-assisted takeoff performance evaluation.
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Why is it important?
Following risk-reduction airfoil experiments, full-scale experiments were performed on an unswept tapered V-tail panel at typical takeoff speeds (22–33 m∕s). Using less than 10 W of input power, significant poststall lift coefficient improvements (up to 0.6 or 100%) were observed, actuation was effective to ≤30 deg, bistable behavior (hysteresis) was eliminated, and a mild sensitivity to pulsation frequency and duty cycle was observed. Takeoff performance calculations indicated a 30 m reduction in ground roll and a 65% increase in allowable crosswind speeds. The physical system proved to be robust in that the silicone rubber dielectric material did not oxidize or degrade during several hundred hours of continuous operation. In summary, pulsed DBD plasma proved to be a viable and practical solution to the problem of flow separation from the panels during crosswind takeoff.
Perspectives
The major conclusion of this study is that pulsed dielectric barrier discharge (DBD) plasma actuators are a viable and practical solution to the problem of separation control on V-tail panels, resulting from crosswinds during takeoff and landing. In terms of performance, poststall lift coefficient increases of 0.6 (or 100%) were observed, and bistable behavior (hysteresis) was eliminated even under deep stall (α 30 deg) conditions. Performance calculations indicated a 30 m reduction in takeoff distance and a 65% increase in allowable crosswind speeds. Low power requirements less than 10 W can easily be fulfilled offline, using batteries; the high-voltage generators are a small fraction of the payload, typically between 1.0 and 4.1 kg; and the actuators themselves are lightweight, around 100 g. The relative insensitivity to reduced frequency in the range examined here, between 0.5 and 2.7, also renders the system very robust. Throughout all experiments, no burn-through and no failures whatsoever were encountered, and no oxidation or degradation of the silicone rubber dielectric was observed during or after completion of the experiments.
David Keisar
Technion Israel Institute of Technology
Read the Original
This page is a summary of: Plasma Actuator Application on a Full-Scale Aircraft Tail, AIAA Journal, February 2019, American Institute of Aeronautics and Astronautics (AIAA),
DOI: 10.2514/1.j057233.
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