Blended wing body configurations are emerging as a promising design for future aircraft, offering improved aerodynamic efficiency and a compact airframe that enhances the overall thrust-to-weight ratio. By integrating the engines within the fuselage, these designs also reduce radar cross-section and fuel consumption. However, such compact layouts require complex inlet systems, like serpentine ducts, which can ingest the large boundary layer that develops over the aircraft body. A major challenge with serpentine ducts is flow separation, induced by the high-curvature walls at duct bends. This can lead to severe consequences, including flow distortion, increased stress on turbine blades, reduced stall margin, and in extreme cases, engine failure. To this end, the present simulation campaign will perform direct numerical simulations (DNS) of a serpentine inlet (SD-2, from Burrows et al., PhD. Thesis, Georgia Tech, 2020). 

This campaign consists of two parts. First, we will simulate the SD-2 diffuser at three set points (Mach number/mass flow rate) to predict quantitative and qualitative trends in flow separation and distortion with incoming flow. As the time-varying flow distortion is of interest in designing these new engines, our simulations will also develop probability distribution maps of flow recovery and distortions as a function of Mach number for serpentine inlets. These maps will be compared with the experimental data. Second, a simulation campaign performing active flow control, with realistic zero net mass flux actuators (developed at Georgia Tech) will be pursued. The inclusion of zero net mass flux actuators was able to control the onset of flow separation in the experiments of Burrows et al., PhD. Thesis, Georgia Tech, 2020. These will help determine whether simulations can accurately predict the augmentation of the flow structures in the presence of active control strategies.