What is it about?

Wings on lightweight aircraft, and blades of wind turbines experience stall which causes a drastic loss of lift, and undesirable aerodynamic effects. Synthetic jets created by piezoelectric microblowers are tested experimentally in a wind tunnel for their use in recovering airfoils from stall and reducing the drag force. While synthetic jets have been studied extensively for their success in active flow control applications, few three-dimensional studies exist. This study evaluates the spanwise effects of synthetic jet flow control, and characterizes the three-dimensional flow structures involved. Furthermore, the effect of varying the actuation frequency is studied, revealing steadier aerodynamic effects when high-frequency oscillation is used.

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Why is it important?

Our findings show that when using an array of microblowers to control a flow, the aerodynamic effects at the midspan may be optimized, while away from the symmetry plane, heightened turbulence is observed resulting in unsteady forces. Additionally, this research highlights the challenge of achieving control across an entire wing due to the influence of the uncontrolled flow at the edges of the array.

Perspectives

While synthetic jets have shown much promise in the past 30 years for flow control, they still have not been widely adopted commercially. With the rise of lightweight and electric aircraft for short haul flights, there will be an increased need for flow control systems that avert stall at low speeds. Practical engineering research must be done to evaluate the feasibility of these systems to bring them a step closer to being implemented in real world applications. The complex three-dimensional nature of the controlled flows suggests that 2D measurements at midspan do not show the full picture, and can lead to misleading results.

Adnan Machado
University of Toronto

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This page is a summary of: Spanwise control authority of synthetic jets on a stalled airfoil, Physics of Fluids, June 2024, American Institute of Physics,
DOI: 10.1063/5.0212135.
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