Numerical investigations on acoustic propagation effects for highly integrated intake ducts

Aeroacoustic assessment of highly integrated propulsion systems is a challenging task at an early design stage and requires detailed physical understanding with validated numerical prediction capabilities. This work presents numerical studies of an UCAV configuration with a complex intake duct as a complementary analysis to measurements. The setup is based on the agile (unmanned) NATO air vehicle MULDICON UCAV (MULti-DIsciplinary CONfiguration) with an S-shaped intake duct to primarily shield the engine from radar. A laser-based sound source is modeled as monopole in the intake duct. The computation of the acoustic field is performed in the time domain with the Discontinuous Galerkin (DG) code DISCO++ developed by DLR. RANS mean flow fields are calculated with DLR’s TAU solver as background flow input for the aeroacoustic noise propagation. A parametric study is conducted for the monopole sound source. Dependencies of the noise propagation on the intake mass flow rate and the ambient flow velocity are investigated by directivities and spectral characteristics.