GB734018A - Improvements in or relating to gas turbine engines - Google Patents

Abstract

734,018. Gas turbine jet propulsion plant. ROLLS-ROYCE, Ltd. June 5,1953 [June 17, 1952], No. 15278/52. Class 110 (3). A by-pass gas turbine engine has pressuresensitive means sensitive to the rate of change of pressure in the by-pass duct which reduces the fuel supply when the pressure in the by-pass duct falls at or above a selected rate of fall of pressure. A by-pass gas turbine engine is defined as one having a compressor system including low and high pressure stages, combustion equipment connected to the outlet of the high pressure compressor stage, turbine means to drive the compressor system, a turbine exhaust duct and a by-pass duct fed with a proportion of the compressed air delivered by the low pressure compressor stage, which discharges into the turbine exhaust duct or directly to atmosphere via a propelling nozzle. Air compressed in the low pressure compressor 11 is divided. Part flows to the high pressure compressor 13 feeding the combustion equipment 15 and part flows through a by-pass duct 23 which opens into the turbine exhaust pipe 20 or, as shown, into the atmosphere through an auxiliary propelling nozzle 23a. The combustion gases from the equipment 15 pass to a turbine 18 having two independent rotors 18a, 18b. The rotor 18a drives the high pressure compressor 13 and the rotor 18b the low pressure compressor 11. Fuel is supplied to the combustion equipment 15 from a tank 24 through a shut-off cock 25, fuel pump 26, throttle valve 27 and shut-off cock 40. The cock 40 is actuated by a spring-loaded piston 30 contained in a cylinder 31. The two ends of the cylinder are connected by a passage 34' containing a fixed area orifice 36. The righthand end of the cylinder is connected to the by-pass duct 23 by a connection 37. The effective areas of the two sides of the piston 30 and the orifice 36 and the strength of the spring 32 are so chosen that if the pressure in the duct 23 falls rapidly, the pressure in the space 33 falls rapidly relative to that in the space 35 and the piston moves against the action of the spring 32 to close the cock 40. The piston 30 may be connected to the cock 40 through a toggle mechanism or an electrical switch controlling a relay or any other convenient servo-mechanism. In a modification, the spring 32 is omitted and the connection 37 made to the space 35. In another arrangement the area of the orifice is made variable by a needle valve connected to a capsule responsive to the ambient atmospheric pressure so that the effective area is reduced as the ambient pressure decreases.