| 摘要 |
<p>1535681 Gas turbine ducted fan engines BOEING CO 12 April 1977 [26 April 1976] 15083/77 Heading F1J In a gas turbine ducted fan engine, means are provided to bleed off some of the air discharged by the fan rotor at a point upstream of the stator blade now downstream thereof, the object being to reduce fan noise. In Fig. 1 the engine comprises a ducted fan rotor 10 having blades 22 and downstream thereof a row of stator blades 12, an annular opening being formed in the inner wall of the fan casing between elements 34, 16, an axially movable annular valve-member 36 being provided such that in the rearward position of the valve member shown an annular opening is provided whereby air discharging from the fan rotor may be bled off and passed through the passage between walls 16, 46 to atmosphere. In Fig. 3 the inner wall of the fan casing comprises a part 54 formed with a plurality of inclined bores 52, an angularly-rotatable valve-member 56 formed with similar bores 58 being disposed outwardly of the member 54 whereby the bleed passages may be either open or closed. Other arrangements are described.</p> |
