Reduced-order modeling of vortex-driven excitation of acoustic modes

Abstract

Vortex shedding that occurs in ducts with baffles in the presence of mean flow often leads to excitation of acoustic modes. Resulting flow oscillations may feed back to the process of vortex formation. A simple model is proposed for describing this complex interaction using the hypotheses for a quasi-steadiness of vortex shedding and for a short-period acoustic perturbation at the moment of vortex collision with a downstream baffle. The model is capable of predicting typical real-system phenomena, such as the lock-in of a dominant frequency of the vortex-acoustic instability in some ranges of the mean flow velocity.