Embedded WMLES of Transonic Buffet on a Nacelle-Aircraft Configuration

Research on a long-range transport aircraft with Ultra High Bypass Ratio (UHBR) nacelles under transonic flow conditions is presented. Therefore different numerical as well as experimental methodologies are employed. A major research issue is the aerodynamic interaction of the flow field with UHBR nacelle, pylon, fuselage and wing lower side. The interactions of transonic shocks with the boundary layer are analyzed by RANS simulations with regard to flow separation and flow recirculation. Further investigations are performed for an isolated shock boundary layer interaction at the nacelle lower side with a scale resolving simulation approach. Therefore the embedded wall modeled LES (EWMLES) method in combination with a synthetic turbulence generator is employed. This allows to analyze the dynamics of the transonic shock front with regard to shock buffet. The results are compared to experimental data of pressure sensors and unsteady pressure sensitive paint (PSP) measurements obtained in wind tunnel testing at the the European Transonic Windtunnel (ETW). The impact of the angle of attack on the shock boundary layer interaction is assessed by numerical and experimental data showing consistent results with regard to the shock positions and shock dynamics.