U-rans model for the prediction of the acoustic sound power generated in a whistling corrugated pipe

Corrugated pipes, as used in flexible risers for gas production or in domestic appliances, can whistle when a flow is imposed through the pipe. Nakiboglu et al [1, 2] have developed a method to compute the acoustic source term for axi-symmetric cavities. The method is based on the resolution of incompressible Navier-Stoke equations without turbulence modeling. This is a quasi-laminar flow model. A single cavity in a short pipe is considered with, as inlet boundary condition, a pipe flow with an imposed harmonic velocity perturbation. At low Reynolds numbers most of the effect of the turbulence is accounted by the steady velocity profile imposed at the inlet. However, this model fails when applied to high Reynolds number flows as encountered in gas-transport systems (Re = 106 or higher). In this paper, a modified model, using a 2-D unsteady Reynolds Averaged Navier Stokes turbulent solver, is presented. Turbulence determines the development of the approaching boundary layer and of the shear layer above the cavity. The shear-layer velocity profile controls the acoustic power generated by the cavity in response to the imposed acoustic oscillations. Comparison with experimental results obtained for a single cavity shows that the modification of the method considerably increases its accuracy for a deep cavity. Copyright © 2013 by ASME