GB761167A - Flame spreading device for combustion systems - Google Patents

Abstract

761,167. Generating combustion products under pressure. SOC. NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIATION. May 6, 1954 [June 27, 1953], No. 13256/54. Class 51 (1). In combustion equipment, for example exhaust reheat equipment of a gas turbine jet. propulsion engine, there is provided downstream of a flame stabilizing or flame-holding device, means for producing auxiliary gaseous jets which create local turbulence in the main gas flow so as to facilitate the transverse spread. ing of the flame. The means comprises a plurality of orifices or nozzles spaced from each other transversely with respect to the direction of the main gas flow by a distance equal to or greater than their size measured transversely. In Fig. 1, fuel is injected in an upstream direction by means of an injector 1 and a flame stabilizing device 5 is disposed downstream of the injector, the flame front being indicated at F<SP>1</SP>. A manifold 4 disposed around the combustion chamber downstream of the flame stabilizer 5 is supplied with air under pressure and the air issues through small orifices 8 to form vortices t which cause the flame front F<SP>2</SP> to spread transversely more rapidly than it would do so otherwise. Fuel may also be injected into the air supply pipe 6 through the injector 1a. In Fig. 2 the device for causing the flame to spread transversely comprises a hollow ring 4a of aerofoil section formed with orifices 8 in its inner and outer surfaces through which jets of air under pressure issue. The resulting turbulence causes the flame front to spread as indicated at F<SP>2</SP>. In Fig. 3 the flame stabilizer is formed by means of a fluid instead of a solid screen. Air under pressure issues through orifices 11 in a hollow ring member 10 of aerofoil section, the resulting flame front being indicated at F<SP>1</SP>, F<SP>8</SP>. Downstream of the flame stabilizer is a similar but larger ring 4a, jets of air under pressure issuing through the orifices 8 to cause turbulence and transverse spreading of the flame. Additional fuel may be supplied through injectors 1<SP>1</SP>a, 1a into the air inlets to the rings 10, 4a. In Fig. 4 flame stabilization is by means of a fluid screen, air under pressure issuing through the slot 14; fuel is injected from the injector 1 into the air supply to the slot 14. The flame is caused to spread transversely by means of a device similar to that shown in Fig. 1. In Fig. 5 flame stabilization is again by means of a fluid screen, air under pressure issuing through slots 17 in the hollow radial arms 18. Fuel is injected through injectors 1 on the upstream side of the spaces between the arms. Downstream of the flame stabilizer is a second set of radial arms 22 formed with orifices 8, the arms 22 being disposed in line with the fuel injectors 1. Air under pressure is also supplied to the arms 22 and issues through the orifices 8 to cause turbulence and transverse spreading of the flame. Fuel supplied through injectors 1<SP>1</SP>a, 1a is mixed with the air issuing through the slots 17 and orifices 8. The invention is shown applied in the case of exhaust reheat equipment of a gas turbine jet-propulsion engine in Fig. 7. Flame stabilization is obtained by means of a jet of air under pressure issuing through the slot 14 and jets of air under pressure issuing through the orifices 11 in the hollow ring member 10. Transverse spreading of the flame fronts is achieved by jets of air under pressure issuing through the orifices 8 in the hollow ring 4a. Additional fuel is mixed with the air supplied through the slot 14 and orifices 11 and 8. In an embodiment similar to Fig. 7, the annular slot 14 is replaced by a series of orifices through which a series of jets of air under pressure issue to constitute a flame stabilizing screen. The invention is also applicable to reheat equipment between turbine stages and to main combustion equipment of gas turbine jet-propulsion engines and to ram jet engines. Specification 751,013 is referred to.