Slat aerodynamic noise reduction using dielectric barrier discharge plasma actuators

Abstract

The airplane, during the approach to landing, use high-lift devices to produce more lift at lower airspeeds, enabling the landing on shorter runways. In this flight condition, high-lift devices are amongst the main sources of aeroacoustic noise. The solutions found in the literature are mostly based on passive flow control and are reaching an asymptotic level of noise mitigation. Therefore, active flow control devices may have the potential for further improvements. Active flow control can be realized by dielectric barrier discharge plasma actuators. These devices generate a strong electric field that ionizes and accelerates the surrounding air, producing a wall jet. In this research, plasma actuators were installed at the cove and the cusp of a slat. Three geometries of actuators were tested. Acoustic array measurements in a wind tunnel have demonstrated the potential of plasma actuators for slat aerodynamic noise reduction, allowing a decrease of up to (3.3±0.02) dB in the overall slat noise (reducing 12 dB of the dominant tone). However, many configurations were not able to reduce or even increased the overall noise, evidencing the necessity of properly optimizing the plasma actuator geometry, materials, and operational parameters to enhance the control authority of these devices, which remains an obstacle to real flight applications.