Stability and Transition in Compressible Attachment-Line Boundary-Layer Flow

Linear stability of the three-dimensional compressible attachment-line boundary-layer flow on a 60° -sweep infinite-span cylinder in a Mach 3.5 free-stream is investigated by the two-dimensional (2D) eigenvalue approach. Results of this study indicate that the supersonic attachment-line boundary layer is subjected to the oblique Tollmien-Schlichting instability, and the nonparallel effect is highly destabilizing. The critical Reynolds number based upon momentum thickness is found to be about 125, in contrast with the value of 235 for incompressible flow. The frequencies of unstable travelling modes are on the order of 100KHz for the free-stream Reynolds numbers considered in the study.