INTERACTION OF A JET-SLOT OSCILLATOR WITH A DEEP CAVITY RESONATOR AND ITS CONTROL

Abstract The coupling mechanism between a jet-slot oscillator and a deep cavity resonator as well as the effect of feedback control on this coupling mechanism are investigated experimentally. Strong nonresonant and resonant oscillations have been observed. The nonresonant oscillations are generated by the natural instability of the jet-slot oscillator, in which the jet oscillates symmetrically. However, when resonant oscillations of the cavity are initiated, the jet switches to an antisymmetric mode of oscillation. This mode switching may be accompanied by an abrupt jump in the oscillation frequency. The paper focuses on the nature of these different types of flow oscillations and on the response of this complex flow oscillator as the resonant oscillations are gradually suppressed by means of a simple feedback controller. It is shown that the resonant oscillations can be attenuated by a maximum amount ranging from 11 to 13dB. Further attenuation results in destabilization of the natural instability mode of the jet-slot oscillator. A method for improving the performance of the control system is suggested.