Mitigating transonic buffet with porous trailing edges*

In today's globalized world, commercial aviation is crucial for international connectivity, offering fast air transport services for passengers and freight. However, aerodynamic instabilities like transonic buffet and the associated aeroelastic effects are still a limiting factor in the high-speed regime. Using simultaneous and synchronized Particle-Image Velocimetry and Background-Oriented Schlieren measurements, we demonstrate that porous trailing edges efficiently mitigate transonic buffet at flight conditions. These devices modify the velocity distribution in the separated boundary layer downstream of the shock wave mimicking pre-buffet flow conditions. The extended recirculation region damps instabilities associated with the shock-wave/boundary-layer interaction, while the less intense boundary layer breathing reduces pressure fluctuations in the trailing edge region with a direct impact on the shock wave oscillation. Moreover, we reveal how the particular porous material can severely affect the aerodynamic performance and that gyroid-based materials influence the aerodynamic forces favorably. Since porous trailing edges have the additional benefit of reducing acoustic aircraft emissions, they could prospectively provide faster air transport with reduced noise emissions.