Modeling jet--plate interactions using large-eddy simulation

Aircraft propulsion systems such as the ultra high bypass ratio turbofan engine, by virtue of their design, impose a constraint on engine installation below the wing, causing jet-wing interactions. Similar interactions are encountered when a jet-powered aircraft takes off on airport runway or aircraft carrier deck. High-speed jet flow near a solid surface shows markedly different turbulence characteristics compared with free jet, attachment of jet flow and development of non-equilibrium turbulent boundary layer downstream. Pressure fluctuations on the surface tend to be more unsteady and stronger, leading to increased vibration affecting aircraft cabin noise and modified jet noise radiation. Large-eddy simulation (LES) is useful to characterize turbulent jet flows over a solid surface as well as wall pressure distribution to promote physical understanding and modeling studies. We perform LES in a simplified configuration of jet-plate interaction, with the jet-plate distance fixed at 2D, where D is the nozzle-exit diameter. For jet Mach number of 0.7, LES is performed using the dynamic Smagorinsky model on an unstructured grid. Comparisons with the corresponding experiments are encouraging including turbulence statistics and spectra.