Mathematical modeling and characteristic analysis of scramjet buzz

Abstract

Buzz is an important issue for a scramjet engine. A mathematical model of buzz oscillations is necessary for control system design. Control-oriented models of hypersonic vehicle propulsion systems require a reduced-order model that is accurate to some extent but requires less than a few seconds of computational time. To achieve this goal, a reducedorder model of buzz oscillations for a scramjet engine is built by introducing the modeling idea of Moore-Greitzed model for compressors. The introduction of characteristic lines avoids the complex interactions in hypersonic inlet, such as shock-shock interactions and shock-boundary layer interaction. And the inlet characteristics are obtained from the pressure signal of combustor. Based on the established buzz model, we can predict the inlet performance, characterize the stability margin of inlet, reflect the oscillatory characteristics of inlet buzz including the dominant amplitude and frequency and describe the transition process of inlet buzz.

Response of an oblique shock train to downstream periodic pressure perturbations

“…The frequency response of a normal shock in a diverging channel is also discussed. Similar researches were investigated by Chang et al 31 , Hu et al 32 and Chang et al 33 on the mathematical modeling and prediction of buzz oscillations and shock train leading edge position with backpressure and freestream Mach number variations, including the dominant amplitude and frequency and the transition process of inlet buzz. However, those studies are focused on the normal shock self-excited or forced oscillation with low-flow Mach numbers.…”

“…32 and Chang et al. 33 on the mathematical modeling and prediction of buzz oscillations and shock train leading edge position with backpressure and freestream Mach number variations, including the dominant amplitude and frequency and the transition process of inlet buzz.…”

Acoustic Modeling and Vibration Characteristics of Supersonic Inlet Buzz

“…Chang et al [21] introduced the deterministic learning theory and rapid recognition methods to model the oscillatory behavior and detect the buzz pattern, respectively. In their other paper [22], the idea of Moore-Greitzed model was employed to build the reduced-order model for buzz oscillations. Recently, Yamamoto et al [23] proposed a model for the prediction of the buzz onset, which indicates that the buzz system could be represented by a delay differential equation containing a delayed negative feedback.…”