Improvements relating to the ignition of jet propulsion engines

1,064,424. Gas turbine engines. SOC. NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIATION. March 23, 1964 [March 28, 1963], No. 12144/64. Heading F1G. Ignition in the combustion chamber of a gas turbine jet propulsion engine is effected by modulating the pressure of the starting fuel injected into the combustion chamber whilst an ignition device is continuously operated, the pressure modulation causing the pressure to fluctuate between two limits at a predetermined frequency, the two limits defining a range which includes all the values of the starting fuel injection pressure which permit ignition in the engine under the various working conditions of the latter. As shown, starting fuel is supplied to a pressure modulator 1 through inlet 3 at a pressure higher than all the values of pressure permitting ignition. An electromagnetically operated valve 4 is opened by a modulation device 9 and closed under the action of spring 5 at the predetermined frequency and starting fuel at modulated pressure is supplied to an injector (not shown) through outlet 2. The open and closed periods of the valve may be 0À6 and 0À4 seconds respectively. The valve 4 may be pneumatically or hydraulically operated.