Individual bypass injector valves for a double bypass variable cycle

Abstract

A double bypass, variable cycle gas turbofan engine is provided with a variable area bypass injector which varies the area through which the inner bypass stream is injected into the outer bypass stream. The bypass injector comprises an upstream variable area, double bypass selector valve, the position of which determines whether the engine will operate in the single or double bypass mode, and a downstream static pressure valve which defines an optimum flow path for injecting the inner bypass stream into the outer bypass stream. The ability to vary the area through which the inner bypass stream is injected into the outer bypass stream permits the static pressure valve to operate as an ejector and permits control of the two bypass air streams through creation of a static pressure balance at the exit of the variable area bypass injector. The ability to control the bypass operating mode and the static pressure balance at the confluence of the two bypass streams eliminates the necessity for one exhaust duct and one exhaust nozzle, thereby reducing complexity and weight, and improves the engine-aircraft integration by reducing engine and nozzle diameters.