Unsteady Separated Flows in an S-Duct and a Bifurcating Duct

Aircraft-mounted gas turbine engines may need to employ a variety of inlet ducts to perform various missions. An inertial particle separator (IPS) is a type of inlet duct that can remove harmful dust and debris from an engine's flow path. The IPS is a bifurcating duct that is designed to remove particles, but it may also cause undesired flow separation. A novel study on such a bifurcating duct at high Reynolds number is undertaken. This is the first study to perform unsteady, three-dimensional simulations of the flow inside an IPS. The improved delayed detached eddy simulation numerical method is applied to a time-resolved experimental S-duct case to ensure the approach is valid. Results showed highly unsteady, separated flow, consistent with experiments. The time-resolved, three-dimensional structure of flow inside an IPS is visualized for the first time.