Application of a Synthetic Turbulence Generator in Aircraft and Turbomachinery Aerodynamics

Abstract

Methods for generating synthetic turbulent fluctuations in numerical flow simulations have gained increasing attention over the past years. Applications of synthetic turbulence generators (STG) range from initializing whole turbulent flow fields to posing turbulent boundary conditions in LES simulations to generating acoustic sources for the computation of sound propagation. In the DLR project ADaMant one specific method, the NTS-STG, has been applied in two rather different fields with different underlying mechanisms in mind: on the one hand, in order to allow for local wall-modelled LES (WM-LES) on the surface of e.g. an aircraft wing or engine nacelle, the STG is applied inside the fully turbulent boundary layer to ensure quick transition from RANS to WMLES. On the other hand, the STG is used to provide realistic ambient turbulence levels in the freestream of turbomachine components, in order to simulate transitional (laminar/turbulent) flow. Both types of applications of the NTS-STG are put in a common context, highlighting their specific requirements on the STG as well as current deficiencies and potential improvements.