GB826963A - Turbine engine power plant - Google Patents

Abstract

826,963. Gas turbine power plant. ARMSTRONG SIDDELEY MOTORS Ltd. March 14, 1957 [March 28, 1956], No. 9642/56. Class 110(3). A power plant including one or more gas turbine engines, the exhaust from which may be diverted from one or more effluent pipes terminating in a propulsive jet nozzle to supply a free power turbine has the effective outlet area of the jet nozzle or nozzles and the effective area of admission to the free power turbine arranged to be varied simultaneously and inversely so that the sum of the two divided mass flows of gas is kept substantially constant. This allows a change-over from maximum free turbine power with zero jet nozzle opening to zero free turbine power with maximum jet nozzle opening to be effected without varying the turbine engine operating conditions. Air compressed in a compressor 12 is fed to one or more combustion chambers 13 supplying gas to a turbine 14 driving the compressor 12. The exhaust from the turbine 14 may pass through a pipe 15 either to a free power turbine 16 which drives a lift fan (not shown) of the aircraft or to a propulsive jet 17 or to perform both of these functions simultaneously. The free power turbine 16 has variable area admission which may be of the kind described in Specification 825,547, in which pivoted nozzle vanes may be moved from the fully open to the fully closed position by a cam-ring 26, Fig. 2, rotatable by a reversible electric motor 27. A bullet 28 is mounted in the exhaust-pipe 15 by struts 29. The exhaust pipe 15 terminates in a circular arrangement of pivoted flaps 30 which may be moved by jacks 39 operated by reversible electric motors 42 from a position in which they define the outer periphery of the maximum area nozzle to a position in which their downstream edges effect a seal with the bullet to close the nozzle. The jacks 39 are connected to the flaps 30 through a ring member 38. Power is supplied to the motors 27, 42 through a control switch 45 and a change-over switch 44. Closing of the switch 45 causes the motors 42 to open the flaps 30 and to close the nozzle vanes 19. Operation of the switch 44 causes this operation to be reversed. The switch 45 can be used to inch the motors 27, 42 to replace the flaps 30 and nozzle vanes 19 in any intermediate position between the fully open and fully closed positions. The flaps 30 and vanes 19 are arranged to move so that the instantaneous sum of the nozzle area and the turbine admission area is kept substantially constant so that the sum of the mass flows is also substantially constant. In a modification, Fig. 4 (not shown), two gas turbine engines supply working fluid to a single free power turbine.