GB812317A - Improvements in combustion chambers for gas turbines and ram-jets - Google Patents

Abstract

812,317. Jet-propulsion plant. LEDUC, R. May 17, 1957 [May 18, 1956], No. 15721/57. Class 110 (3). [Also in Group XII] A combustion chamber assembly for a ramjet unit or a gas-turbine engine comprises a staggered series of annular flame tubes 1, 2 ... 6 of progressively increasing diameter in the downstream direction, the flame tubes being defined by partially-overlapping sleeve-like annular walls 7, 8 . . . 12. Each of these walls has a bell-shaped upstream portion such as 9b which defines the outer boundary of one flame tube 3, and a substantially cylindrical downstream portion 9a which defines the inner boundary of the adjacent flame tube 4. The trailing edge of each wall is substantially in line axially of the assembly with the upstream limit of the cylindrical portion of the adjacent wall lying radially outside it, and the leading edge of each wall is in line with, axially of the assembly, or slightly in advance of the upstream limit of the cylindrical portion of the adjacent wall lying radially inside it. The leading portion of the bell-shaped portion 9b of each annular wall is shaped so as to be approximately cylindrical. The assembly of flame tubes is disposed within an outer casing 26, the propulsion nozzle 25 of a gas turbine jet engine being disposed centrally within the flame tube assembly, the surface of the nozzle 25 forming the inner boundary of the upstream annular flame tube 1. The annular walls 7, 8. . . 12 are supported at their leading edges on longitudinally-extending struts 24. The downstream annular wall 12 is not formed with a cylindrical portion such as 9a. Each annular flame tube 1, 2 . . . 6 is formed at its entry with an annular diffuser 14, and is provided with a flame holder comprising a series of radiallydisposed bars 13 of V-section pointing upstream and possibly also with a ring member 13a of V-section, also with a series of fuel injectors 15. The inner wall of each annular flame tube may be double-walled as shown at 9a, 9d so as to afford an annular passage 16 open at the upstream and downstream ends for the flow of cooling air therethrough and the walls 9a, 9d are perforated as at 17 so that streams of cooling air may pass therethrough. The walls 8a, 8b, 8d, 9a, 9b, 9d may be longitudinally corrugated as shown in Fig. 4, spacer members being disposed at axially-spaced intervals between the walls, each spacer comprising a pair of cylindrical members 21, 22 with a corrugated ring 23 therebetween the parts being bonded together. The wall portions 9a, 9b may be arranged to overlap as indicated at 18, 19 in Fig. 2, so that the boundary layer on the outer surface of the wall portion 9b is sucked off into the outlet of the annular flame tube 3. Alternatively, the wall 9b may be louvred to permit boundary layer removal.