Patent GB-647344-A (GB)
Title: Improvements in or relating to combustion apparatus
Inventor: FLETCHER WALTER GEORGE
IPC: F23D11/28
Filed: 1947-05-23
Abstract: 647,344. Gas turbine plant. POWER JETS (RESEARCH & DEVELOPMENT), Ltd. May 23, 1947, No. 13871. [Class 110(iii)] [Also in Groups XI and XII] In a combustion apparatus in which liquid fuel and air are burnt in a combustion chamber arranged in a duct to receive air therefrom and having an outlet at one end for the products of combustion, the fuel suppply means is arranged to introduce into one region of the combustion chamber remote from the outlet a pilot supply of fuel and into another region nearer the outlet a main supply of fuel, said combustion chamber having air entry defining means which limit the air entry to the region of the pilot supply to a minor part of the total air flow for combustion and allow the major part of the air for combustion to enter downstream of that region so that the conditions of the air supply for combustion in the first supply region remain relatively constant during wide variations of the conditions of air supply to said main supply region. The main and pilot fuel discharge devices may be combined as a single unit supplied with fuel through an inlet 23, Fig. 1, and having a spill return pipe 24, and the pilot discharge is directed upstream of the main air flow, the discharge port 26 being screened by a perforated conical baffle 31 ensuring- burning of the pilot fuel at a substantially constant rate independent of variations in the air flow which are allowed to influence the combustion of the main fuel discharge. The conical baffle is combined with a flame tube 34 provided with comparatively large perforations 35 admitting air to the main combustion zone. In an aircraft propulsion unit, as shown in Fig. 3, a main fuel pump 36 driven by a gas turbine compressor 37 may draw fuel from a tank 39 through a pipe 38 and deliver it through filter 41, manual cock 42, dump valves 43, 44 to manifolds 45, 46 supplying starting spill burners 10s and main spill burners 10. The fuel is returned through spill manifolds 47, 48, non return valves 50, 51, pipe 52 and throttle valve 53 to the fuel tank 39. The throttle valve 53 is manually controlled and has a relief valve controlled in accordance with barometric pressure to obviate adjustment by the pilot to maintain constant turbine speed at changing altitude or changing barometric pressure at constant altitude, as described in Specification 600,654, [Group XXIX]. An excess fuel return pipe 60 having a non-return valve 61 connects the main supply pipe 40 with the tank 39 and a pipe 63 connects the pipes 52, 60 and includes a valve 62 controlled in. accordance with the speed of the compressor 37. At starting a motor 59 is energized to drive an auxiliary fuel pump 58 which supplies fuel to the burners 10s only until the fuel pressure rises sufficiently to operate dump valves 43, 44 to supply fuel to the main burners 10. The increasing speed of the compressor 37 driving the fuel pump 36 builds up the pressure in the pipe 40 to close a non-return valve 57 and cut off the starter motor 59. To shut down the gas turbine the manual cock 42 is closed and fuel in the manifolds 45, 46, 47, 48 is returned to the tank 39 by the air pressure existing in the flame tubes. Specifications 599,257 and 620,343, [both in Group XII], also are referred to.