Buzz flow diversity in a supersonic inlet ingesting strong shear layers

To further explore the shear-layer-induced buzz diversity recently discovered in an overspeed supersonic inlet, an external-compression supersonic inlet is specially designed and carefully studied through wind-tunnel test at its design Mach number of 2.0. It is observed that the flow instability begins with the little buzz mode featuring a stable terminal shock and a lightly unsteady shock-induced separation bubble. Then a combination of another two stronger buzz styles replaces the little buzz. Of them the medium buzz is characterized by a locally destabilized terminal shock and the varying cowl-side reverse flow, whereas the big buzz is distinguished by intense separation unsteadiness. Interestingly, the medium buzz cannot stay long and vanishes eventually. Instead of an ordinary buzz case in the design Mach number situation, current buzz flows are found pretty similar to the overspeed inlet case superficially and fundamentally under the influence of two strong shear layers, albeit with a clear difference in the duration of the medium buzz. Accordingly, the possibility of buzz flow diversity and the related shear-layer effect proposed recently get further supported. Besides, it is indicated that the overspeed operation is not the only situation allowing for the diversified inlet buzz. (C) 2019 Elsevier Masson SAS. All rights reserved.