GB680136A - Improvements relating to combustion systems for jet engines - Google Patents

Abstract

680,136. Jet propulsion plant. LUCAS, Ltd., J. Oct. 23, 1950 [Nov. 17, 1949], No. 29411/49. Class 110 (iii) [Also in Group XXIX] In a jet propulsion engine in which additional fuel is admitted to the jet pipe, the rate of supply of the additional fuel is varied by means responsive to the joint control of the pressure of the air at the compressor inlet and the pressure of the gas in the jet pipe between the turbine and the point of admission of the additional fuel. A control means 14 comprises a lever s pivotally mounted in a partition or, as shown, carried by a flexible diaphragm t which separates two compartments u, v. Compartment u is in communication with the inlet of the fuel pump g or with a sump. Compartment v communicates by way of a passage 4 with the inlet of the compressor c. A diaphragm 3 which is connected by a link z to the lever s is subject on one side to the pressure in the compartment v and on the other side, by way of a passage 5, to the pressure of the gases on the exit side of the turbine d. A lever 6 is loaded by a spring 7 and an evacuated capsule 8, and acts on the lever s through a slidable abutment 9. The position of the abutment 9 can be manually adjusted through a lever 10 so as to vary the relative effects of the two pressures on the lever s. When a valve r carried by the lever s is closed, the liquid pressures acting on opposite sides of the piston j<SP>1</SP> of a servomotor 12 through a passage o<SP>1</SP> and a restricted passage p<SP>1</SP> are balanced, and a spring k<SP>1</SP> moves a throttle 11 in a direction for increasing the supply of fuel to a re-heat burner f. When the valve r is opened, there is a preponderating liquid pressure on one side of the piston in opposition to the spring, and the throttle is moved so as to reduce the supply of fuel. To control the supply of fuel to the main burners b, a control means 13 of any conventional type acts through a servomotor 15 similar to the servomotor 12, to vary the obliquity of the swashplate h of the fuel pump. In a modification, the throttle 11 and the control means 13 are eliminated, and the fuel pump g supplies fuel to the burner f only, the control means 14 operating the swashplate servomotor 15. Alternatively, the servomotor 15 may actuate a throttle in the supply pipe leading to the burner f, or may open a by-pass whereby fuel is diverted from the burner. According to the Provisional Specification, the control means 14 comprises a single lever, one arm of which is connected to a diaphragm or piston, one side of which is in communication with the turbine discharge pressure. The other arm is loaded by a spring and an evacuated capsule exposed to the compressor inlet pressure. The lever is supported by a fulcrum. the position of which is controlled manually.