1,197,711. Gas turbine ducted fan engines. GENERAL ELECTRIC CO. Nov. 12, 1965 [Dec. 2, 1964 (2)], No.48228/65. Heading F1J. A front fan jet engine has an air inlet, an axial-flow compressor, a combustion chamber or chambers, a turbine driven by gases from the combustion chamber(s) for driving the compressor and an exhaust nozzle, the air inlet being divided into inner and outer concentric annular passages by a flow splitter and the compressor comprising a first wheel secured to a shaft and having a plurality of compressor blades rotatable in the inner passage and a second wheel secured to the shaft downstream of the first and having a plurality of compressor blades rotatable in the inner and outer passages. The compressor 10 shown in Fig. 2 comprises a first wheel 64 from the hub 65 of which project a plurality of radially extending rotor blades 66. A hub fairing 67 provides a smooth entry into the wheel 64 and the peripheral surface 68 of the hub 65 between the blades 66 forms a smooth continuation of the fairing 67. The wheel 64 is connected by a cylindrical spacer 69 to a second wheel 70 having a hub 72 from which project a plurality of rotor blades 74, the peripheral surface 73 of the hub 72 between the blades 74 continuing the smooth inner flow path boundary wall of the compressor. A casing surrounds the wheels 64, 70 to define an annular flow passage 14 and includes a first plurality of stator vanes 78 intermediate the wheels 64, 70 and a second plurality of stator vanes 80 downstream of the wheel 70. Shrouds 84, 85 are provided at the inner ends of the stator vanes 78, 80, respectively, and are shaped to form a continuation of the peripheral surfaces 68, 73, respectively. Each blade 74 comprises an inner portion 74a and an outer portion 74b separated by a shroud member 88 which forms part of a contoured flowsplitter 90 dividing the annular flow passage 14 into an inner annulus 14a and an outer annulus 14b. In addition to the shroud member 88, the flow-splitter 90 comprises a forwardly-extending portion 92, having a first section 92a affixed to the stator vanes 78 and second section 92b affixed to the rotor blades 66 extending forwardly of the first, and a rearwardlyextending member 94 affixed to the stator vanes 80. The outer annulus 14b is designed to pass approximately the same mass flow in a single rotor stage comprising rotor blade means 74b as the inner annulus 14a , wherein the inner portion of a second rotor stage comprising rotor blade means 74a is supercharged by a first rotor stage comprising rotor blade means 66. The outer wall 94a of the member 94 and the rear portion of the outer surface 88a of the member 88 are sloped to provide, in combination with a sloping portion 18b of the inner surface 18 of the casing, a convergent flow passage such that the slope of the blade tips 74c of the outer portions 74b of the rotor blades 74 is minimized.
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