Large-eddy simulations of the unsteady behavior of a hypersonic intake at mach 5

Three-dimensional high-fidelity numerical simulations of a Mach 5 hypersonic ramjet intake are performed combining a high-order and time-accurate large-eddy-simulation model with a sharp-interface immersed boundary method. The analysis provides a detailed characterization of the unsteady behavior of the intake. A systematic investigation is carried out varying the blockage of the intake channel, and, in particular, three blockage levels are investigated as far as their effect on the flow. The analysis shows that two main unsteady phenomena occur, the former at high frequency (little buzz) and the latter at low frequency (big buzz). When the intake channel is entirely opened, only the little buzz is present, whereas in partially blocked conditions, the big buzz prevails. This paper will show how the big buzz is correlated to the convection of high-density, high-pressure spots from the entrance of the intake channel, which creates the oscillatory unsteady behavior.