Spanwise Control Authority of Synthetic Jets on a Stalled Airfoil

TL;DR

This paper examines how synthetic jets at different frequencies influence flow stability and control on a stalled NACA 0025 airfoil, highlighting the effectiveness of high-frequency actuation.

Contribution

It provides new insights into the spanwise control authority of synthetic jets and their impact on flow reattachment and vortex formation.

Findings

High-frequency synthetic jets promote flow reattachment and steadier aerodynamics.

Flow structures like vortex rings are crucial in flow control effectiveness.

Spanwise variations affect the aerodynamic stability and control authority.

Abstract

This study investigates the aerodynamic effects of low- and high-frequency synthetic jet control strategies on a National Advisory Committee for Aeronautics (NACA) 0025 airfoil. Visualizations and measurements are employed to assess the stability of the flow, focusing on the shear layer and wake dynamics under two forcing frequencies. High-frequency actuation is found to induce steadier flow reattachment and more favorable aerodynamic characteristics compared to low-frequency control. Flow structures resulting from high-frequency actuation, notably vortex rings, are identified and their significance in flow control is evaluated. Furthermore, the spanwise control authority is analyzed, revealing variations in aerodynamic stability away from the midspan. Insights from modal analysis provide additional understanding of flow structures and their evolution across different spanwise planes.