Panel flutter induced by transitional shock wave boundary layer interaction
Flutter induced by an oblique shock impinging on a 3-D boundary layer developing over a panel is simulated in order to understand the coupled response of the resulting fluid structure interaction. The incoming flow is at Mach M = 2. The Reynolds number based on panel length is varied from 10, 000 to 120, 000. The flow turning angle associated with the shock, which impinges at the mid-chord length of the panel is 5.62 o , corresponding to an impinging shock strength of p 2 /p 1 = 1.415 and a reflected shock of strength p 3 /p 2 = 1.385. The structural parameters are mass ratio m r = 0.1 and dynamic pressure λ = 875. The coupling of the shock wave boundary layer interaction with the panel flutter results in an unsteady separation region dynamics and a transition of the inflow laminar boundary layer to turbulence for Reynolds numbers higher than a critical value. The flow transition is instigated at lower Reynolds number due to the presence of flexible panel as opposed to rigid wall. To analyze this coupling, a Proper Orthogonal Decomposition analysis of the flow variables and panel deformation is performed. In addition to the low frequency unsteadiness due to separation bubble dynamics, a higher mode of panel vibration is prompted by the high frequency flow structures generated during the flow transition.