Bifurcations and buffet of transonic flow past flattened surfaces

Abstract Turbulent transonic flow past flattened aerodynamic surfaces is investigated numerically using the RANS equations. The study is focused on: ( ★ ) a buffet onset caused by instability of the shock wave/boundary layer interaction, ( ★ ★ ) instability of the entire flow structure and related flow bifurcations. For a symmetric airfoil at zero angle of attack, computations reveal both bifurcations and buffet in a range of the freestream Mach number M ∞ . At nonzero angles of attack, α = ± 1 ° , there are two ranges of M ∞ in which the buffet onset takes place. For a Whitcomb type airfoil, computations demonstrate instability of the flow structure only at negative α . Axisymmetric flow past axisymmetric bodies is also considered, and instability of the flow structure at certain freestream Mach numbers is shown.