Novel Oscillatory Patterns of Hypersonic Inlet Buzz

Unstart flows of a hypersonic inlet were experimentally studied at freestream Mach number of 4.5–6.0. With the aid of high-speed schlieren and time-accurate pressuremeasurements, the unsteady flow processes of the entire inlet, including the shock systemmotions and the surface pressure fluctuations, were recorded and discussed. The started flowfield analysis was conducted first, and then the unstarted flowfield was analyzed by using the unsteady pressure signals and schlieren pictures. Results indicate that two novel oscillatory patterns were observed in comparison with the past reported inlet buzz patterns. One is a mixed oscillatory pattern that mixes the “big buzz”with “little buzz,” and the other is a nonoscillatory violent pattern. These novel findings on oscillatory patterns of hypersonic inlet can provide more insight on inlet buzz mechanism, prediction, and control.