Bifurcations and buffet of transonic flow past flattened surfaces

Bifurcations of transonic flow past simple airfoils with elliptic and wedge-shaped noses

“…This study has confirmed the concept proposed in [3][4][5] that the length of the airfoil midpart with a small or zero curvature is of principal importance for the onset of flow bifurcations. The values of M ∞ at the beginning of the bifurcation interval turn out to be the most unfavorable ones, because there are considerable jumps of the lift coefficient under small perturbations of the angle of attack at those Mach numbers.…”

“…In this interval, perturbations that emanate from the oscillating boundary layers trigger restructuring of the flow field and a transition to an asymmetric flow with three local supersonic regions (and positive or negative lift coefficient). The causes of the instability of the flow structure with local supersonic regions residing closely to each other were discussed in [3][4][5].…”

“…The existence of bifurcations of a transonic flow past symmetric and asymmetric airfoils having lengthy portions with a small or zero curvature was established in a number of studies on the basis of the Navier-Stokes equations [1][2][3]. In [4,5], we obtained and analyzed regimes of transonic buffet and bifurcations of the flow past simple airfoils whose nose and tail are circular arcs.…”