A variable cycle turbofan engine featuring an additional bypass stream has been conceptualized. In conjunction with the conventional, thrust producing duct and core streams, the concept features and independent, coannular bypass stream to provide pressurized air for special application aircraft. This 'turbocompressor' stream can be sized to provide much more flow than possible from core engine bleed and without the attendant debit on core performance. Powered-lift aircraft, such as Augmentor Wing and X-Wing, require engine air bleed magnitudes of one to two times core flow. This could be provided by auxiliary compression systems. However, a three-stream engine can provide the required flow from the main engine without additional compressors, inlets, shafting, and gearboxes. Variable inlet guide vanes in the conventional bypass stream are used to modulate total net thrust independently from the turbocompressor stream. Thrust output can be continuously modulated from minimum to maximum at essentially constant bleed air delivery. Maximum lift power can be developed at hover or low-speed approach with rapid thrust response for control, go-around, or maneuver. In the low thrust mode, the engine functions mainly as a turbocompressor. The system can quickly transition to high thrust output while simultaneously supplying bleed power for lift.
Three stream turbofan - variable cycle engine with integral turbocompressor
Dreistrom-Turbopropantrieb mit variablem Zyklus und integriertem Turbokompressor
AIAA-Papers ; Jul ; 1-5
1987
5 Seiten, 12 Bilder
Aufsatz (Konferenz)
Englisch
A CONTRA-ROTATING VARIABLE CYCLE TURBOFAN ENGINE
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