GB824306A - Improvements in or relating to combustion equipment of gas-turbine engines - Google Patents

Abstract

824,306. Generating combustion products under pressure. ROLLS-ROYCE Ltd. April 18, 1957 [April 25, 1956], No. 12752/56. Class 51 (1). In gas turbine engine combustion equipment of the kind comprising a flame tube or flame tubes disposed in an air casing or air casings, there is provided first means to introduce fuel and air into a first region of the flame tube adjacent its upstream end so as to produce a swirling motion in one direction, the fuel and air being substantially in the stoichiometric ratio, and second means to introduce fuel and air into a second region of the flame tube just downstream of the first region so as to produce swirling motion in the opposite direction. The combustion equipment shown in Fig. 1 comprises a tubular flame tube 10 disposed within a tubular air casing 11, a tubular member 16 being supported by means of a flange 17 thereon within the upstream end of the flame tube so as to provide an air passage 18 leading to holes 20 in the member 16. A tube 21 is mounted within the tubular member 16 and has at its downstream end a cap 22 which has in its frusto-conical wall a ring of holes 23. A hollow spider member 24 having radial arms 25 is mounted in the tube 21, the arms projecting through the wall of the tube and opening behind a frusto-conical baffle 29 secured within the tubular member 16. A fuel injector 26 projects into the spider member so that a mixture of fuel and air discharges through the radial arms 25 on to the flange 29, this mixture together with air discharging through the holes 23 in the cap 22 forming a toroidal eddy which swirls in the direction of the arrows 33. A second fuel injector 28 is provided, fuel discharging therefrom through orifices 30, 31 in both the upstream and downstream directions. Fuel discharged in an upstream direction through the orifice 30 mixes with air entering through the holes 20 and creates a toroidal eddy which swirls in the direction of the arrows 35, that is in a direction opposite to that of the toroidal eddy 33. Further air enters the flame tube through openings 15. The combustion equipment shown in Fig. 2 comprises an annular flame tube 42, 43 mounted within an annular air-casing 40, 41 and annular members 46, 47 are supported within the upstream end of the flame tube by means of flanges 48, rings of air inlet openings 50 being formed at the downstream ends of the members. The upstream ends of the annular members 46, 47 are bent to form an annular air inlet passage 49, at the downstream end of which is supported an annular member providing an annular ridge 51 having air discharge openings 51a in its side walls, and annular troughs 52 facing downstream. Fuel supplied through injector 53 into the air stream flowing in passage 49 discharges through openings 51a and forms two toroidal eddies within the annular troughs 52, the eddies swirling in the directions of the arrows 59. Fuel injected through a second injector 55 in an upstream direction mixes with air entering through the openings 50 and forms two toroidal eddies which swirl in the directions of the arrows 60. Further fuel is injected in a downstream direction from the injector 55 and further air is admitted through openings 44. In a further embodiment similar to Fig. 1 the spider member 24, 25 is omitted and only one fuel injector is provided, the injector having outlet orifices in its side wall from which fuel is discharged through the openings 23 in the tube 21, this fuel and air mixture forming a toroidal eddy similar to that shown at 33 in Fig. 1. Further fuel is discharged in an axial direction from the injector through an opening in the end wall of the cap 22, which fuel mixes with air entering through the openings 20 in the tubular member 16 to form a toroidal eddy similar to that shown at 35 in Fig. 1. In the tubular flame tube shown in Fig. 4 a hollow spider member 81 having radial arms 81a is disposed within the tube 78, fuel from the injecter 86 and air discharging from the radial arms 81a together with some air discharging from the openings 80 in the end cap 79 forming a toroidal eddy as indicated by the arrows 91. Fuel supplied by the injector 88 and air discharging through the openings 80 in the end cap 79, together with air entering through openings 89 in the tubular member 75 forms a second toroidal eddy which swirls in the direction of the arrows 93.