Sensitivity of crossflow surfacetransitionroughnessto free-stream conditions and

Sensitivity of crossflow surfacetransitionroughnessto free-stream conditions and

Rizzo, Paolo (Student TU Delft)
Serpieri, J. (TU Delft Aerodynamics)
Kotsonis, M. (TU Delft Aerodynamics)

2019

The present work is an experimental investigation of stationary crossflow (CF) instability-induced transition of the boundary layer over a 45°swept wing, under varying free-stream turbulence, surface roughness, angle of attack and Reynolds number. Key topological features of the transition front, such as the mean transition location and the jaggedness of the front, are retrieved via IR thermography. Linear Stability Theory (LST) is used to extract the N-factor of the most amplified stationary crossflow mode at the transition location, identified experimentally. Results show clear causality between free-stream turbulence, surface roughness, Reynolds number, angle of attack and transition. Large losses of laminarity and a consistent decrease in the transition N-factor are observed with rising turbulence and roughness. Remarkably, N-factor sensitivity to free-stream turbulence is found to vary significantly and non-linearly with angle of attack for the modest levels of turbulence explored in this campaign, whereas the N-factors scale linearly with the log of the surface roughness level, which is consistent with a receptivity mechanism, which is independent of the angle of attack.

http://resolver.tudelft.nl/uuid:f98cb7b2-bec8-4f75-b34a-befec1fc93ab

https://doi.org/10.2514/6.2019-1133

9781624105784

AIAA Scitech 2019 Forum: 7-11 January 2019, San Diego, California, USA

AIAA Scitech Forum, 2019, 2019-01-07 → 2019-01-11, San Diego, United States

Institutional Repository

conference paper

© 2019 Paolo Rizzo, J. Serpieri, M. Kotsonis