Effect of attack angle on stability and transition in a swept-wing boundary layer

Attack angle is one of the key parameters to the cross-flow instability of swept-wing boundary layers. For swept NACA0012 airfoil with infinite spanwise length, the basic flow field was calculated by solving the three-dimensional compressible Navier-Stokes equations numerically, the neutral curve and the evolution curve of growth rate were obtained by solving the Orr-Sommerfeld equation, the effect of attack angle on the cross-flow stability was analyzed by linear stability theory (LST), and the transition position was predicted by eN method. It is found that, the growth of unstable waves in the leeward is inhibited but enhanced in the windward. Transition firstly occurs in the windward, and the transition position predicted by eN method is about 0.1 to 0.2 of the chord length with the N factor of about 6 when the disturbance velocity is 0.05% of the free-stream velocity. © 2015, Beijing University of Aeronautics and Astronautics (BUAA). All right reserved.