Patent GB-787855-A (GB)
Title: Improvements in or relating to gas turbine jet propulsion engines
Inventor: HODGE JAMES
IPC: F02K3/11
Filed: 1955-02-24
Abstract: 787,855. Generating combustion products under pressure. POWER JETS (RESEARCH & DEVELOPMENT), Ltd. Feb. 27, 1956 [Feb. 24, 1955], No. 5553/55. Class 51 (1). [Also in Group XXVI] In a gas turbine jet propulsion engine of either the by-pass or the ducted fan type, i.e. an engine in which air flows through a first path from an intake through compression and combustion stages, through a gas turbine to a propulsion nozzle, while a second stream of air flows from an intake through compression means to a propulsion nozzle, combustion equipment is provided in the second flow path and comprises means to form a flame stabilizing zone downstream of the compression means, and a duct connecting the flame stabilizing zone with a point in the first flow path downstream of the compression stage therein. The invention is shown applied to an engine of the by-pass type, the by-pass air flowing in an annular duct 13, 18 surrounding the main compressor, combustion equipment and turbine 17. The by-pass combustion equipment comprises a number of interconnected tubular flame tubes 22 each having air inlet openings, a fuel injector 27 and a connection 23 from the flow path downstream of the turbine 17. The duct 23 is controlled by a valve 29 and terminates in a perforated conical member 28. An electric igniter 30 is disposed in two of the flame tubes. The opening of the valve 29, supply of fuel through injector 27, energization of the igniter 30 and opening of the eyelids 24 of the variable area propulsion nozzle are controlled by one lever 39 which actuates a rack against pressure of a spring 41. Movement of the rack 40 first operates the pinion 42 which causes the valve 29 to open, whereby hot gases enter the flame tube 22. Further movement of the rack operates the pinion 43 which causes the valve 38 to rotate so that oil under pressure flows from the pump 48 to the right-hand side of the piston 32 within the cylinder 34, movement of the piston causing the eyelid 24 to move to the open position. Continued movement of the rack 40 causes the contacts 45, 46 to close, whereby the igniter 30 is energized. Further movement of the rack operates the pinion 44 which causes the throttle valve 37 to open, whereby fuel flows to the injector 27, and combustion within the flame tube is initiated. The fuel injector may alternatively discharge in a downstream direction, or the fuel may be vaporized in a J-shaped tube. The tapping 23 may be from the space between the main combustion equipment and the turbine inlet, or from the space between two turbine stages. The by-pass combustion equipment may comprise an annular flame tube instead of the tubular flame tubes as shown in Fig. 2. The duct 23 may have a Pitot head disposed within the main gas stream or a scoop pivoted so that it may be lowered into the main stream. The nozzle eyelids 24 are held in the closed position by oil pressure acting on the left-hand side of the piston 32 against the action of the spring 50, the valve 38 then being in the position shown in Fig. 2. Specification 471,368, [Group XXXIII], is referred to.