Fan nacelle flow control and method of controlling a boundary layer at the inlet of a fan nacelle

摘要

A gas turbine engine (10) includes a core engine that drives a fan (20). A fan nacelle (134) surrounds the fan (20) and provides an inner surface (44) facing the fan (20). The fan nacelle (134) includes an inlet lip (42) adjoining the inner surface (44). A ring (46) is arranged at the inner surface (44) and is axially upstream from the fan (20). The ring (46) includes a deployed position in which the ring (46) is spaced radially inwardly from the inner surface (44) to provide a gap (48) therebetween through which air flows. The ring (46) also includes a stowed position in which the ring (46) is arranged radially inwardly from the deployed position and proximate to the inner surface (44). The ring (46) is commanded to the deployed position in response to detecting a first condition, which corresponds to a flow separation condition at the fan nacelle inlet (42). The ring (46) may be stowed during cruise conditions, for example.
A method of controlling a boundary layer at the inlet of a fan nacelle is also disclosed.