Effect of Micro-Vortex Generator on Panel Flutter in Shock Wave-Boundary Layer Interaction

Effect on panel flutter resulting from modification of the boundary layer separation characteristics due to a micro-vortex generator (MVG) in shock wave-turbulent boundary layer interaction (SBLI) is studied. The SBLI occurs near the center of the panel at Mach 2.0 and pressure ratio 2.3. Non-dimensional dynamic pressures of 2400 and 3000 are considered. For the configuration without MVG, the panel exhibits chaotic flutter with a few recurring dominant frequencies that are superposed with small contributions from other irregular frequencies to produce the chaotic flutter. MVG alters the pressure and skin friction distribution on the flexible panel in such a way that the separation is eliminated in certain regions on the panel at the expense of slight increase in shear stress near the center of the separation region. In the MVG configuration, the irregular frequencies are eliminated, hence, suppressing the chaotic flutter and producing limit cycle oscillations (LCO). The LCOs are composed of two dominant frequencies. Dynamic mode decomposition (DMD) is used to investigate spatio-temporal structures in the panel flutter. It is observed that the dominant modes in the non-MVG configuration have predominantly stream-wise evolution. On the other hand, the most dominant mode in MVG configuration has stream-wise evolution and the second most dominant mode has span-wise evolution. Also, the span-wise mode has half the frequency of the stream-wise mode.