Cancellation of crossflow instabilities through multiple discrete roughness elements forcing

Cancellation of crossflow instabilities through multiple discrete roughness elements forcing

Zoppini, G. (TU Delft Aerodynamics)
Michelis, Theodorus (TU Delft Aerodynamics)
Ragni, D. (TU Delft Wind Energy)
Kotsonis, M. (TU Delft Aerodynamics)

2022

The presented work introduces a cancellation technique, based on the linear superposition of stationary crossflow instabilities (CFIs) through the application of a streamwise series of optimally positioned discrete roughness element (DRE) arrays on a swept wing surface. The DRE arrays are designed and arranged with suitable amplitude and phase shift to induce velocity disturbance systems that destructively interact, ultimately damping the developing CFIs. The robustness of this technique is investigated for a smooth wing surface as well as in the presence of enhanced distributed surface roughness. The resulting flow fields are measured with infrared thermography and particle tracking velocimetry, allowing for the extraction of the laminar-to-turbulent transition front location and for the characterization of the local boundary layer development. The acquired data show that the superposition of suitably arranged DRE arrays can successfully suppress monochromatic CFIs, reducing their amplitude and growth and delaying the boundary layer transition to turbulence when applied on a smooth wing surface. However, the presence of elevated background roughness significantly reduces the effectiveness of the proposed method.

http://resolver.tudelft.nl/uuid:6d46f079-fe86-4e32-bbb1-7eb451f06478

https://doi.org/10.1103/PhysRevFluids.7.123902

2469-990X

Physical Review Fluids, 7 (12)

Institutional Repository

journal article

© 2022 G. Zoppini, Theodorus Michelis, D. Ragni, M. Kotsonis