Spatiotemporal Characterization and Suppression Mechanism of Supersonic Inlet Buzz with Proper Orthogonal Decomposition Method

Abstract

The buzz phenomenon of a typical supersonic inlet is analyzed using the unsteady Reynolds Average Navier-Stokes (RANS) simulation and proper orthogonal decomposition (POD) method. The dominant flow patterns and characteristics of the buzzed flow are obtained by decoupling the computed pressure field into spatial and temporal sub-parts based on the POD method. The supersonic inlet buzz phenomenon could be approximated as a product of decoupled temporal and spatial terms, and the one-dimensional (1D) mathematical model is therefore proposed. The standard deviations of the unsteady pressure fields from both the numerical simulation and the model prediction are compared. The limited discrepancy can be observed, and the good agreement validates the credibility of the proposed 1D model. The numerical simulation and the 1D model prediction are presented to explore the unsteady-jet control with a small perturbation. The results of the 1D model and the numerical simulation achieve good agreements with each other in terms of the overall trend. Finally, POD modal energy is employed to analyze the buzz suppression mechanism. When the jet frequency is identical to the dominant frequency of the buzz and the jet phase is opposite to the oscillation phase of the captured mass flow, the buzz suppression could be more efficient. The buzz suppression mechanism could be explained in two aspects. For one thing, the complex flow structure is suppressed and the first average modal energy in the inlet is increased. For another, the energy redistribution among each POD mode is achieved and the flow stability is gradually enhanced.

Acoustic Modeling and Vibration Characteristics of Supersonic Inlet Buzz

“…To solve the flow field accurately and efficiently, the grid refinement and the time-step sensitivity tests were carried out in advance. For more detail of verification of the adopted numerical method please refer to [28].…”

Control of a Supersonic Inlet in Off-Design Conditions with Plasma Actuators and Bleed

“…The performance indexes which are used to evaluate the different control techniques and is defined in Section 6 are based on time-averaged quantities: for this reason steady RANS simulations are performed in this work. It is possible to use unsteady RANS approaches to study some unsteady phenomena in supersonic inlets [35]: an example is represented by the inlet buzz which is observed when the inlet operates in a subcritical regime [36]. However, the present work is focused on the performances of a started inlet in off-design conditions and so the buzz phenomenon is not investigated here but only the average fields in the started inlet are required.…”