Prediction of rod-airfoil interaction noise using the Ffowcs-Williams-Hawkings analogy

Sound generated at low Mach number by an airfoil in the wake of a rod is investigated numerically. The Gaussian spanwise loss of coherence of the vortex shedding is shown to have a significant influence on the broadband noise. Spanwise effects are successfully introduced into a time-domain formulation of the Ffowcs-Williams-Hawkings analogy, which is applied to aerodynamic data computed on various contours around the source region. It is shown that a careful choice of these contours is required. The flowfield is obtained from a two-dimensional Reynolds averaged Navier-Stokes calculation. Computed far-field spectra compare very well to measurements obtained in an accompanying experiment.