Evolution Characteristics Analysis of Supersonic Inlet Buzz with High-Order Dynamic Mode Decomposition Method

Abstract

The buzz evolution process of an axisymmetric supersonic inlet was investigated numerically and analyzed using the high-order dynamic mode decomposition (HODMD) method. Driven by an increasing back-pressure, the flow field evolves from a steady state to little buzz and then to big buzz. The computational dominant frequencies in the stages of little buzz and big buzz were basically consistent with those in the experiment. To analyze the buzz evolution of the global flow field quantitatively, the HODMD method was adopted to provide some dynamics information of modal amplitude and growth rate. During the buzz onset period, the disturbance from the oscillating shock gradually induces pressure fluctuation of the entire inlet. During the buzz transition, the shockwave dynamics at the entrance section of the inlet change first. When the amplitude of the big buzz mode exceeds that of the little buzz mode, the inlet is in the big buzz state, in which the pressure oscillation intensity in the downstream channel is significantly greater than that in the region swept by the shock at the entrance. During the buzz triggering and transition, the growth and attenuation rates of the little buzz mode are higher than those of the big buzz mode, suggesting that the little buzz is less stable than the big buzz. The appearance of high growth rates could be regarded as the precursor of the buzz triggering and the buzz transition.