A gas turbine engine comprising a fan section, a compressor, a combustor and a turbine, includes a nacelle having an inner nacelle surface defining an inlet duct designed to reduce an inlet duct area of the inlet duct to increase acoustic attenuation. The gas turbine engine also includes a spinner, disposed forward of the fan section, that includes features to increase acoustic attenuation. In one embodiment of the present invention, the nacelle includes a nacelle contoured surface protruding radially inward from the inner nacelle surface to reduce the inlet duct area. In a further embodiment of the present invention, the spinner includes a spinner contoured surface for reducing the inlet duct area. In other embodiments, the nacelle and/or the spinner include an inflatable bladder, a SMA actuator, a fluidic actuator, or a combination thereof, selectively activated to increase acoustic attenuation during certain conditions of an aircraft.

Gas turbine engine inlet with noise reduction features

A blown boundary layer control system for an aircraft having a jet engine with an engine compressor, an inlet including a compression surface with an external part and internal part, a cowl lip including an internal lip surface and an external lip surface and an external afterbody. The system includes several ducts from the engine compressor. A series of nozzles and valves control and direct air flow to various surfaces. A computer is electrically connected to the valves to control the operation of the valves thereby controlling the blowing of air from a commanded number of nozzles. The computer controls the valves in position as functions of RPM of the engine, free stream flight conditions and aircraft attitude.

Blown boundary layer control system for a jet aircraft

Boundary layer separation at the boundary surface of an intake duct (18) of a turbofan aeroengine nacelle (12) at conditions of high incidence and high engine mass flow arises from shockwave induced pressure gradients in the boundary layer. To control separation, gaseous fluid is withdrawn from a high pressure region of the boundary layer at a downstream region of the boundary surface, conveyed within the intake duct structure (19) and discharged at an upstream region of the boundary surface into a low pressure region of the boundary layer. The intake duct (18) embodies a noise attenuation panel (19), and fluid is withdrawn from the high pressure region of the boundary layer into a modified panel section (191) by passage through apertures (30) in the front face of the panel section (191) at a downstream region of the panel section, conveyed along a fluid communication path within the panel section (191) and discharged into the low pressure region of the boundary layer by passage through apertures (30) in the front face of the panel section (191) at an upstream region of the panel section (191). Gaseous fluid is conveyed solely as a consequence of the difference in pressures in the boundary layer at the downstream and upstream regions.

Aerodynamic low drag structure

A hybrid laminar flow nacelle for housing an engine of an aircraft includes an outer annular cowl having a leading lip and radially spaced and axially extending annular outer and inner forward surface portions which merge at the leading lip. The nacelle incorporates a suction bleed system between the surfaces and a tailored outer surface geometry shape for producing reduced friction drag laminar flow over the outer cowl at cruise operation of the aircraft and producing separation-free flow over the inner surface of the cowl at off-cruise operation of the aircraft.

Hybrid laminar flow nacelle

A gas turbine engine system includes nacelle, a first boundary layer control device, a second boundary layer control device, at least one sensor, and a controller. The nacelle is defined about an axis and includes an inlet lip section, an inlet internal diffuser section, and a variable area fan nozzle moveable to influence a discharge airflow area of the nacelle. The first boundary layer control device is positioned near the inlet lip section and is actuable to introduce a first airflow at the inlet lip section. The second boundary layer control device is positioned near the inlet internal diffuser section and is actuable to introduce a second airflow at the inlet internal diffuser section. The sensor produces a signal that represents an operability condition. The controller receives the signal and simultaneously moves the variable area fan nozzle and actuates the first boundary layer control device and the second boundary layer control device in response to receiving the signal to achieve a slim-line nacelle.

Gas turbine engine having slim-line nacelle

There is disclosed an air inlet for a turbine engine suitable for use on a short takeoff and landing (STOL), a vertical takeoff and landing (VTOL) or a conventional takeoff and landing (CTOL) type of aircraft. A critical region in which critical flow occurs under certain conditions communicates with a less critical region of lower static pressure. Air is drawn away from the critical region and reinjected into the air flow at the less critical region. In one embodiment a circumferentially extended slot is provided in the inner surface of the air inlet at the windward side and downstream of the throat region. The slot communicates with a circumferential plenum chamber formed in the front of the air inlet just behind the lip. Circumferentially extending rows of apertures are provided on the lip establishing two sets of apertures spaced circumferentially away from the slot in opposite directions. The slot removes the boundary layer from the critical portion of the diffuser to minimize or eliminate flow pressure loss or separations resulting from diffusion or turning. The apertures are in a region of low static pressure on the lip of the inlet and serve as a source of suction to cause air flow into the slot.

Brent A. Miller

Papers

Self stabilizing sonic inlet