Computational Study on Hysteretic Inlet Buzz Characteristics Under Varying Mass Flow Conditions

Abstract

This paper presents a computational investigation of the hysteretic buzz characteristics of a supersonic inlet under a complete historic path of a mass flow change. It is observed that the amplitude and frequency of inlet buzz suddenly change in spite of the gradual variation in the mass flow rate. Furthermore, inlet buzz is found to exhibit quite different behavior depending on the historic path of the mass flow rate change, which leads to the hysteretic inlet buzz phenomenon. To investigate the hysteretic characteristics of inlet buzz and to provide a physical explanation of such a phenomenon, a series of numerical simulations are performed with the following three stages. First, an inlet without a center body is calculated to validate the flow solver and basic resonance mode results. Second, an inlet under a decreasing mass flow rate condition is simulated. Last, the effect of an increasing mass flow rate on inlet buzz is examined. Through computations, multiple inlet buzz transitions from fundamental to higher buzz modes are obtained, in accordance with previous experimental observations. The three sets of the computed results are compared and discussed from the viewpoint of acoustics to explain the physical mechanism of the hysteretic buzz characteristics and the buzz transition phenomenon.