Patent GB-632568-A (GB)
Abstract: 632,568. Jet propulsion plant. POWER JETS (RESEARCH & DEVELOPMENT), Ltd., HOWELL, A. R., and FEILDEN, G. B. R. Jan. 23, 1945, No. 1853 [Class 110(iii)] In a gas turbine jet propulsion power plant, a multi-stage axial flow compressor 1, a contrarotating axial flow turbine 3 having two contrarotating elements which exhausts through a duct 4 to a propulsion jet, an annular combustion system 2 and a thrust augmenting fan 5 which is driven by one element of the turbine 3, are coaxially and symmetrically arranged with respect to the shaft 7 by means of which the other element of the turbine 3 drives the compressor 1. The path of the working fluid through the compressor, combustion system and turbine is preferably a straight line. The rotor 21 driving the thrust-augmenting fan rotates on bearings 20b mounted on a sleeve 17a surrounding the shaft 7 and forming an extension of an inner annular wall 17 of the combustion system 2. The turbine blades of the rotor 21 form the nozzles for the rotor 20 which drives the axial flow compressor 1 and supports the drum 23 carrying the augmentor fan blades 5a. The shroud ring 22 of these turbine blades is extended to form a tip shroud for the turbine blades of the rotor 20 and also to carry the interstage blades 21a. A number of cylindrical flame tubes 30 circumferentially disposed with an annulus formed by inner and outer air casing members 17, 27 form the combustion system. The members 17, 27 are made strong enough to resist the whole of the internal air pressure and the flame tubes 30 are so arranged that they do not have to sustain a major differential pressure. The members 17, 27 are provided with sheet metal liners 28, 29 forming an air jacket shielding the members from the heat of the flame tubes. The flame tubes discharge into chutes 32 which are connected to the turbine inlet nozzle ring 19 and are supported by hollow struts 33 on the casing members 18, 25. The flame tubes 30 are supported on the burner 31 and by flexible tie members as described in Specification 610,021 to the liners 28, 29. The inner casing member 17 is made hollow to form passages 36 for the cooling air supply to the bearings 17b and 20b, to the hollow shaft 7 for the cooling of the rear and inner faces of the rotor discs 20 and to the front of rotor discs 20 and 21, the latter disc being provided with a liner 37 to force the air along its surface. The cooling air is taken from the compressor and its pressure is greater than that at the turbine inlet so as to mitigate leakage of the working gases. The cooling air from the chamber enclosed by the shaft 20a and the member 18 passes through the hollow struts 33 to the augmentor inlet. The engine may be started by means of a drive to the shaft 7 through the gearbox at its forward end 'or by a removable shaft engaging the main shaft along its length. If a remqvable shaft is used, it may be provided with a device to prevent rotation of the rotor 21 until after it has been withdrawn. Fuel may be burnt in the duct 6 after the augmentor to increase the energy of the gases. Specifications 578,005, 591,113, 594,550, [Group XXV], and 624,768 also are referred to.