Patent GB-803698-A (GB)
Title: Improvements in or relating to internal combustion gas turbine or jet propulsion engines
IPC: F02C5/10
Filed: 1954-02-25
Abstract: 803,698. Gas turbine plant; jet-propulsion plant. PARAVICINI, T. P. DE. Feb. 25, 1955 [Feb. 25, 1954], No. 5615/54. Class 110 (3). [Also in Groups XII and XXIX] Combustion equipment for an internal combustion gas turbine or jet-propulsion engine comprises an oscillating column combustion chamber having an air inlet controlled by a non- return valve, a fuel inlet, an exhaust port and a front end portion of reduced crosssectional area forming a compression and combustion zone. The gas turbine engine shown in Fig. 1, comprises an annular inlet passage 1, a centrifugal compressor 2 mounted on a shaft 3 which is driven by a turbine 36. Air from the compressor enters a diffuser 4 which has a plurality of outlets 6 each outlet leading to a frustoconical cooling jacket 7 and pressure equalization reservoir 8 which has an outlet port 9 leading to a rotary non-return valve 10 which is common to all the jackets 7. The valve 10 is connected to inlet ports 16 into resonance or oscillating column combustion chambers 17. Each chamber 17 has closed ends 18, 19, a fuel injector 21 and each chamber is connected to adjacent chambers by means of interconnector pipes 28. One chamber has an ignition plug 27 and constitutes a starting chamber. Each chamber has two outlets 30, 31 leading to ducts 32, 33 which lead to the inlet nozzle guide vane ring 35 of the turbine 36. Groups of nested frusto-conical rings are disposed in the ducts 32, 33 also in the interconnectors 28 to act as one-way baffles. The non- return valve 10 comprises a set of stationary inlet guide vanes 11, rotor vanes 12 mounted on a rotor 13 which is mounted on the shaft 3, and a set of stationary outlet vanes 14. A gearbox 38 at the forward end of the shaft 3 provides drive for fuel pump 24, speed governor 40, generator 42 and starter motor 41. Fuel is supplied through a throttle valve 26 and pipe 23 to a fuel manifold ring 22. An air-screw shaft 39 is also driven from the gear-box 38. Pressure waves created by explosions in each combustion chamber 17, cause compression ignition of fresh charges of fuel-air mixture so that the igniter 27 may be switched off after starting. The supply of fuel to each chamber 17 is continuous but the supply of air is intermittent and admission takes place only when the pressure wave is away from the front end 18 of the chamber 17. The engine shown in Fig. 6 is of the ram-jet type, air flowing through the annular divergent-convergent inlet chamber 50 to the rotary non-return valve 10 and thence through the inlet port 16 into the annular resonance type combustion chamber 51. The central portion of the rearward end 53 of the chamber 51 is open to provide an exhaust port 54 leading to a discharge nozzle 37. The rotor 13 of the non-return valve 10 is mounted on a shaft 57 which is connected to engine auxiliary apparatus as before. The engine is started by rotating the rotor 13 by the starter motor, the rotor blades 12 acting as a fan. The rotor 13 is rotated by the inflowing air once the engine is started. Each rearwardly travelling pressure wave is partly exhausted while the remainder is reflected at the end 53 of the chamber 51. The engine shown in Fig. 7 is similar to that of Fig. 6, but has in addition, means for bypassing the valve 10 comprising ports 60 in the wall 56 controlled by cylindrical member 61; also means for varying the area of the exhaust port 54 comprising an axially-movable plug 65. When the ports 60 are closed and the plug 65 is in its forward position the engine operates similarly to that shown in Fig. 6. When the plug 65 is in its rearward position however, rearwardly-travelling pressure waves are reflected at the open end of the chamber as rarefaction waves which travel forwardly and are reflected at the forward end, and travel rearwardly. The rearwardly-travelling rarefaction wave is reflected at the open end of the chamber as a pressure wave which travels forwardly and causes the next explosion. If irrespective of the position of the plug 65, the ports 60 are opened, pressure oscillations in the chamber 51 disappear, combustion becomes continuous and the engine operates as a constant pressure ram-jet cycle.