SENSITIVITY OF LARGE EDDY SIMULATIONS TO INFLOW CONDITION AND MODELING IF APPLIED TO A TRANSONIC HIGH-PRESSURE CASCADE VANE

摘要

Large Eddy Simulation (LES) prediction of the flow around transonic high-pressure turbine cascade vanes is an active subject of research. For such problems, the flow topology is dictated by the geometry, inflow conditions and irreversibilities. When studied experimentally, input specifications necessarily suffer from uncertainties inherent to experimental measurement facilities. Such limits are also present in numerical applications. The following paper proposes to evaluate the relative importance of uncertainty sources in determining the adequate LES flow behaviour for the T120 transonic blade experimentally tested at UniBw (Munich) during the European project AITEB II. To do so, the nominal operating point is targeted and different simulations are obtained by changing inflow specifications with and without turbulence injection. As expected, changes in the static pressure ratio between the inlet and the outlet by more or less 4%, alter significantly the flow topology and the aerodynamic losses. Impact of turbulence injection at inlet is also addressed. Investigation of dissipation fields, including the laminar and sub-grid model contributions, allows the identification of the underlying mechanisms. Although irreversibilities have a smaller impact on the flow prediction relative to the static pressure ratio (and associated uncertainties), its relevance on the flow prediction and topology is found to be of primary importance.