Numerical study of flow and noise predictions for tandem cylinders using incompressible improved delayed detached eddy simulation combined with acoustic perturbation equations

Abstract

The method of combining incompressible hybrid Reynolds average Navier–Stokes/large eddy simulation (RANS/LES) with an acoustic perturbation equation was studied to accurately predict the flow and noise performances in NASA tandem cylinder experiments. In this approach, acoustic waves simultaneously propagate in the time domain with an unsteady turbulent flow. The experiment was performed under the condition of a Reynolds number of 1.66 × 105, based on the cylinder diameter, which provided detailed surface pressure and flow field measurements. The improved delayed detached eddy simulation (IDDES) model established in this study was consistent with the experimental results, except for the flow field behind the rear cylinder, which was caused by an early separation relative to the experiment. The acoustic results showed that the rear cylinder dominated the noise radiation, which indicated that the pressure fluctuation caused by wake interference was greater than that caused by vortex shedding. Acoustic predictions were also obtained using an acoustic analogy approach based on the FH-W method. Three kinds of integral surfaces (PS-open, PS-close, and IPS) were made for the acoustic predictions using the Ffowcs Williams–Hawkings method. This study also showed that wavenumber decomposition could be utilised to quantify the mechanisms related to turbulent convection and sound propagation. An IDDES hybrid model for predicting near-field and far-field noise was established, which could be applied to practical engineering applications.