Flow Control for a Nacelle Inlet in Crosswind

Control strategies targeting azimuthal flow separation over the inner windward surface of an engine nacelle inlet in the presence of a crossflow are explored in a wind tunnel investigation at inlet Mach numbers up to [Formula: see text] and crossflow [Formula: see text]. Three fluidic control approaches using arrays of surface jet actuators are considered, which include steady jets and fluidically oscillating jets with and without internal feedback flow. The effects of each of the jet types are evaluated using the same array configuration over a range of [Formula: see text], [Formula: see text], and the control mass flow rate parameter [Formula: see text]. Although each actuation approach engenders significant improvements in distortion [Formula: see text] compared to the base flow, unsteady actuation using fluidically oscillating jets generally outperforms steady jet actuation at the same actuation mass flow rate. Furthermore, it is found that fluidically oscillating jet actuation is more effective at low [Formula: see text] in the presence of internal feedback and at high [Formula: see text] in the absence of internal feedback. Specifically, fluidic actuation in the absence of internal feedback reduces the distortion measure [Formula: see text] by 50–55% across the present range of [Formula: see text], at [Formula: see text] lower than 0.3%. The present investigations also showed that changes in the topology of flow separation with varying [Formula: see text] and [Formula: see text] underscored the need for reconfiguration of the active jet actuators within the jet array to conform to the flow separation pattern to achieve optimal effectiveness.