GB750147A - Jet-propulsion prime movers - Google Patents

Abstract

750,147. Axial flow compressors; gas turbine jet propulsion plant. LUCAS (INDUSTRIES), Ltd., J. April 7,1954 [Jan. 13, 1953], No. 980/53. Classes 110(1) and 110(3) [Also in Group XXIX] A gas turbine jet propulsion plant comprising two independent rotors consisting of low pressure and high pressure compressors driven by low pressure and high pressure turbines respectively has a passage through which a portion of the discharge of the low pressure compressor may be led controlled by a throttle actuated by means responsive directly or indirectly to the temperature of the air entering the low pressure compressor so that the flow of air is increased with fall of temperature. The gas turbine shown has a low pressure compressor a driven by a low pressure turbine d through a shaft e which feeds through an air chamber g a high pressdre compressor b driven by a high pressure turbine c through a shaft f. A portion of the air discharged from the compressor a may be passed through a passage k controlled by a valve m. This air may be passed to the jet pipe n or to the atmosphere through a propelling nozzle. The valve m is operated by a servomotor 5 which is controlled by a leak-off valve z. The valve z is mounted on a lever q which is acted on by a spring 3 and by elastic bellows v, t, mounted in a chamber o. The chamber o is 'connected to the chamber g by a pipe p. The inside of the bellows t is connected to the intake of the compressor a through a pipe u. The bellows v is evacuated and is carried by an angularly adjustable arm w actuated by a servomotor 16 in response to changes of engine speed. The arrangement is such that changes of air temperature entering the compressor cause changes of the compression ratio across the compressor a so that when the temperature is below a given amount, the valve z will be opened and the valve m moved to the open position. When the temperature exceeds the given amount, the valves z and m are closed. In a modification, Fig. 2, the valve z is controlled by a lever q which is acted upon by a spring 3, a diaphragm 23 responsive to the pressure drop across an orifice 25 and an adjustable spring 29. The spring 29 is supported by an abutment 30 adjusted by a cam 31 connected by a link 32 to the arm 11 of the throttle m. Fluid supplied by a pump is passed through a conduit 24 and orifice 25. A throttle valve .26 actuated by a thermometric device 28 is also provided in the conduit 24. When the temperature at the inlet of the compressor is below a given amount the valve 26 is fully open which causes the valve z and consequently the throttle m to be fully open. A further modification in which the lever q is acted upon by two adjustable springs and by elastic bellows responsive to changes in. compressor air inlet temperature is also described.