GAS TURBINE ENGINE WITH VARIABLE PRESSURE RATIO FAN SYSTEM

摘要

A multiple bypass turbofan engine (10) includes axially spaced-apart first a nd second stage fans (31 and 33) of the engine fan (35) connected in driving engagemen t to a low pressure shaft (30). A fan bypass duct (40) circumscribes the second sta ge fan (33). A first bypass inlet (42) to the fan bypass duct (40) is disposed axially between the first and second stage fans (31 and 33) and a second bypass inlet (46) i s axially disposed between the second stage fan (33) and an annular core engine inlet (47). A fan shroud (108) divides the second stage fan blades (36) into radially inne r and outer fan hub and tip sections (37 and 39), respectively. The tip sections (39) ar e radially disposed in a fan tip duct (146). An axially translatable deflector (44) is positioned to close the fan tip duct (146) when it opens the first bypass inlet (42) and open the fan tip duct (146) when it closes the first bypass inlet (42).