Simulation of the sound radiation of turbulent flows with DES

Abstract

Detached eddy simulation (DES) is a suitable method for the simulation of the sound radiation of turbulent flows, providing access to resolved turbulent scales at minimal computational cost. The near-wall region is solved efficiently by RANS while LES is applied to detached regions of large scale turbulence. The various DES implementations of the Institute of Fluid Mechanics and Engineering Acoustics (ISTA) at the TU-Berlin are described. Simplified academic flow cases are used for the validation of the method and the suitability of the method for complex industrial flow applications is also demonstrated. The method proves robust and reliable for a wide range of applications, ranging from external to internal flows, from bluff bodies with massive separation to the partial resolution of attached boundary layers. Examples of applications to noise emission problems are presented for (i) slat noise, (ii) interaction noise, (iii) jet mixing noise, and (iv) trailing-edge noise. The jet noise predictions include a study on the influence of serrations on the noise emission. The overall sound pressure levels as well as the noise reducing effect of the serrations are well predicted. With respect to the prediction of flow noise, further work is required to improve the predictive capabilities for higher frequencies.