Aerodynamic Studies of Jets using High-fidelity CFD Modelling

The propelling nozzles of a high-bypass jet engine convert the internal energy of a hot and highly pressurised gas into kinetic energy to produce thrust. A well designed exhaust nozzle will maximise the thrust, by accelerating the gas to a sonic velocity at the nozzle exit, while minimising drag and weight. The subsequent jet represents a complex flow pattern that can feature shock and expansion waves that interact with and are reflected by the free shear layers. Numerical modelling of these jets can range from simple axisymmetric nozzle shapes to fully integrated geometries taking account of the external geometry including the nacelle, pylon and wing. Furthermore, modern engines are incorporating a serrated or chevron shaped nacelle trailing-edge, to enhance mixing of the free shear layers that can reduce aero-acoustic noise. This research will investigate appropriate computational modelling techniques for these jet flows with consideration given to the type of mesh and physics models and to the complexity of turbulence model required.