IMPROVEMENTS IN OR RELATING TO FAN DUCTS FOR GAS TURBINE DUCTED FAN ENGINES

摘要

1,247,691. Thrust reversers. BOLLS-ROYCE Ltd. 8 Aug., 1968, No. 37881/68. Heading B7G. A ducted fan gas turbine engine has thrust reversing o spoiling means comprising two sets of flaps whose members are spaced alternately around the circumference of the outer wall of the fan duct, the members of the first set of flaps being pivotable about their downstream ends to meet the inner wall of the duct and thus to obturate the duct, the second set being translatable parallel to the axis of the duct so that this motion of the two sets of flaps exposes an annular gap in the outer duct wall. In Fig. 1, the duct for air from fan blades 14 of a gas turbine engine 10 is defined by inner wall 12 and an outer wall 16, spaced apart by members 18. The outer wall 16 comprises three parts, fore and aft fixed parts 22 and 26 and a movable part 24. Pivotally attached at 46 to brackets 34 on the movable part 24 are the fore ends of the members of the first set of flaps, 38, so that when the movable part 24 is translated by rams 30 to the position shown dotted the flaps 38 are also moved. These flaps are pivotally attached at 42 to fixed wall part 26, and also have pivot points adjacent their mid-lengths, so that ram 30 pivots them to the duct obturating position shown dotted. The second set of flaps, 40, whose members are pivotally connected at their forward ends to the members of the first set of flaps are also moved by ram 30 to the position shown dotted. Guide vanes 36 supported on members 28, Fig. 1, may be provided to direct the flow of gases forwardly from the annular gap in the obturated duct. For clarity, the vanes and supports are omitted from Fig. 3. Since the circumference of wall 12 is less than that of wall 16, the members of the first set of flaps, 38, are tapered to allow close fitting when the duct is obturated. The shape of flaps 38, their connection to wall parts 24 and 26, and to the second set of flaps, 40, are seen in Fig. 3. Not shown in Fig. 3 are supporting pins which pass through slots 56 in the raised spines of the members of the second set of flaps 40, the pins being mounted on brackets attached to fixed part 26. These pins support the downstream ends of the flaps when in the Fig. 3 position, and the slots 56 allow translation of the supported flaps as in Fig. 6 (not shown).