Aerodynamic Optimisation of Acoustic Liners

We present pore-resolved direct numerical simulations (DNS) of turbulent flows grazing over acoustic liners with aerodynamically and/or acoustically optimised orifice configurations. Our DNS explore a large parameter space, studying different families of orifice geometries including the influence of orifice shape, orientation, and number. All flow cases show an increase in drag compared to the smooth wall. However, the added drag can be reduced by as much as ∼60%, as compared to conventional acoustic liners by simply changing the shape of the orifice or the orientation in the case of a non-circular orifice. Complementary acoustic simulations show that this drag reduction can be achieved while retaining the same noise reduction properties.