Experimental study on the influence of holes on the transition on an incompressible boundary layer
Résumé
In the present experimental study, the effect of holes on the transition of an incompressible boundary layer was investigated. Two configurations of the symmetric profile ONERA-D at a fixed angle of attack were tested: one with zero-, and the other with 60°-sweep angle. These two configurations enabled to study the interaction of holes with either a highly stable (no sweep) or unstable (with sweep) boundary layer. Overall, although some differences between configurations were observed, the main findings from this study were applicable to both. In particular, no gradual upstream shift in transition position occurred as either hole diameter d or depth h were varied: once critical dimensions (for which transition position was immediately downstream of the hole) were reached, transition abruptly moved from the baseline location to that of the hole. Next, characterising hole geometry using the aspect ratio h/d proved to be useful in determining a threshold across which boundary layer sensitivity to holes was modified. Finally, holes with h/δ 1 ≥ 2, and d/δ 1 ≥ 25 tended to trigger transition immediately downstream of their location.
Origine : Fichiers produits par l'(les) auteur(s)