Wind tunnel and flight tests of glider flow separation control by microsecond dielectric barrier discharge

As a new kind of active flow control technology, plasma flow control has a bright future, for its simple structure, fast response, and wide frequency band. The wind tunnel and flight tests were conducted with microsecond dielectric barrier discharge on a glider. For the tests, the microsecond pulse power supply and remote control system were designed and built. In the wind tunnel test, the flow separation on the glider wing surface can be controlled effectively, and static pressure at the leading edge pressure is decreases by 177%. The flow control effects under different pulse frequencies are compared, and the optimal pulse frequency for actuation is found to be 100 Hz. A significant hysteresis effect was observed with microsecond dielectric barrier discharge at small angle of attack (α ≤ 18°), which means the flow control effect can last more than 300 s after turning off the plasma actuation. In the flight test, the maximum roll angle decreases by 7.0°, and the maximum aileron deflection angle decreases by 9.4° with plasma actuation at both sides of the wing, which means the glider becomes more stable with microsecond dielectric barrier discharge. With unilateral actuation, the rolling moment generated by the plasma actuation is larger than that produced by the ailerons with the angle of attack within 12.94° ≤ α ≤ 29.77°, which shows strong rolling control ability of microsecond dielectric barrier discharge. The wind tunnel and flight tests results verified the flow control effect of microsecond dielectric barrier discharge, and paved the way for the plasma flow control technology to practical applications.

Experimental Study on Plasma Flow Control of Symmetric Flying Wing Based on Two Kinds of Scaling Models

The symmetric flying wing has a simple structure and a high lift-to-drag ratio. Due to its complicated surface design, the flow field flowing through its surface is also complex and variable, and the three-dimensional effect is obvious. In order to verify the effect of microsecond pulse plasma flow control on the symmetric flying wing, two different sizes of scaling models were selected. The discharge energy was analyzed, and the force and moment characteristics of the two flying wings and the particle image velocimetry (PIV) results on their surface flow field were compared to obtain the following conclusions. The microsecond pulse surface dielectric barrier discharge energy density is independent of the actuator length but increases with the actuation voltage. After actuation, the stall angle of attack of the small flying wing is delayed by 4°, the maximum lift coefficient is increased by 30.9%, and the drag coefficient can be reduced by 17.3%. After the large flying wing is actuated, the stall angle of attack is delayed by 4°, the maximum lift coefficient is increased by 15.1%, but the drag coefficient is increased. The test results of PIV in the flow field of different sections indicate that the stall separation on the surface of the symmetric flying wing starts first from the outer side, and then the separation area begins to appear on the inner side as the angle of attack increases.

Experimental Investigation on the Plasma Flow Control of Axial Compressor Rotating Stall

Experimental investigation on the plasma flow control of axial compressor rotating stall is implemented in this paper. The control effects of axial plasma actuation (inducing body force of compressor axial direction) with three different locations as well as stagger angle plasma actuation (inducing body force perpendicular to the compressor rotor tip chordwise direction) at different rotation speeds are studied. An unsteady plasma actuation is designed to influence the unsteady rotor tip flow at near stall point, and is found to be the most powerful in improving the compressor stall margin. Both the compressor rotation speed and the plasma actuation voltage are found to be very influential on the control effects of the plasma actuation. The abilities of the plasma actuation in suppressing the compressor rotating stall and influencing the compressor static pressure rise coefficient are not directly related. All the plasma actuations studied can improve the compressor stall margin, but the compressor static pressure rise coefficient can be decreased or increased with different plasma actuation layouts.