Prediction of the onset of supersonic inlet buzz

Numerical investigation of impact of fixed-exit boundary-layer bleed on supersonic intake performance

“…As shown in Refs. [16][17][18][19][20][21][22][23][24], the chosen location a) helps in better pumping characteristics due to higher static pressure realized after the compression shocks, b) augments in eliminating the flow separation due to incident cowl shock and hence improves the starting characteristics [19][20][21], c) avoids the formation of shock train at the throat as well as d) stabilizes the terminal shock within the intake entrance such that the captured mass flow is not altered and the buzz oscillation is delayed [6][7][8]. The exit of the bleed system has been designed in the shape of a convergent-divergent nozzle to dump the flow supersonically and approximately in line with the external flow to reduce the bleed drag.…”

“…However, in the subcritical modes of operation, it is usually observed that till a certain low mass flow ratio the flowfield remains stable or shows low amplitude oscillations (little buzz), known as the stability margin. Below the stable subcritical operation, the shock patterns begin to oscillate resulting in large fluctuations in pressure recovery and the mass flow capture, known as buzz [6][7][8]. This unstable condition leads to generate an additional and strong structural load, and can damage the model.…”

“…Typically, a ramjet powered missile that operates over a range of Mach numbers and maneuverability conditions uses a fixed geometry intake to ensure cost-efficiency. Such an intake system at off-design conditions would experience adverse flow conditions related to shock-shock interactions, shock wave/boundary-layer interactions (SWBLIs) [3,4] and many other flow phenomena (secondary cross flows or vortices [5]); affecting the performance parameters such as pressure recovery, mass flow capture, drag, flow distortion at its exit as well as the stability margin or the flow unsteadiness (buzz) in the subcritical modes of operation [6][7][8] (discussed in Sec. 2.3).…”

“…A number of studies have been carried out in the literature to provide an understanding of the effects of various internal geometric concepts (for supersonic diffuser, throat and subsonic diffuser) [1,2,[11][12][13], upstream flow conditions [13,14], unstart [12,14], buzz oscillations [6][7][8] as well as the various active and passive boundary-layer control methods [14][15][16][17][18][19] on intake performance. According to these studies, out of the various boundarylayer control methods, the active control using a bleed system is the most preferred method for practical usage because of its strong impact on performance improvement.…”

Acoustic Modeling and Vibration Characteristics of Supersonic Inlet Buzz

“…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.…”