A Numerical Study of the Aeroacoustic Interaction of a Cavity With a Confined Flow: Effect of Edge Geometry in Corrugated Pipes

Abstract

In the present work a numerical study is carried out to investigate the aeroacoustic interaction of a 2D cavity with a confined flow. Incompressible flow simulations are performed with imposed incoming velocity perturbations. Equivalent time averaged acoustic source power is calculated through enthalpy differences using the theory of Vortex Sound. Information required for the estimation of acoustic source strength in high Reynolds number flows are acquired from relatively low Reynolds number, Re = O (103) simulations. This is done by an extrapolation method in which the effect of friction is estimated by considering a reference flow in a straight channel. The proposed methodology is employed to explain the whistling phenomenon observed in corrugated pipes, which can be considered as rows of acoustically coupled cavities. The method successfully predicts the Strouhal number ranges where acoustic energy production and absorption occur. The method can also explain the effect of edge geometry on sound production, which is known to be important in corrugated pipes. In accordance with the earlier experimental study, round upstream - sharp downstream edge case leads to higher sound production levels than sharp upstream - round downstream case.