Linear-stability investigations for flow-control experiments related to flow over compliant walls

Abstract

Results of linear stability calculations and direct numerical simulations for flow-control experiments are presented. Good agreements between measurements and simulations are shown. Furthermore, the linear stability of the flow over the experimental wing section is investigated. Hereby, also the use of isotropic and anisotropic compliant materials is assessed. The prevailing surface-based compliantwall model of Carpenter was extended to yaw angles, pressure gradients and oblique-traveling disturbances. The influence of the yaw angle is demonstrated for an anisotropy angle of 75°. Also transient-growth of instabilities over the compliant wall was investigated, since the eigenvalue spectrum of the compliant-wall problem turned out to be sensitive to truncation errors. For the parameters investigated, the maximum transient growth of the compliant-wall case is in the same order as the growth of the rigid-wall case. © 2012 Springer Berlin Heidelberg.