Patent GB-617977-A (GB)
Title: Improvements in gas turbine power plants
IPC: F23R3/54
Filed: 1946-03-29
Abstract: 617,977. Gas turbine plant. LYSHOLM, A. March 29, 1946, No. 9839. Convention date, April 4, 1945. [Class 110 (iii)] [Also in Group XII] A gas turbine plant comprises a combustion chamber provided with openings for the supply of excess air, which openings are so arranged and located that the air sweeps over the inside of the turbine gas inlet walls and the temperature of the motive fluid in the section immediately ahead of the first row of moving blades is lowest at the inner ends of the blades and increases radially outwardly and the maximum temperature is radially outwardly of the mean diameter of the moving blades. The gas turbine plant shown comprises a shell 10 surrounding a compressor 11 supplying air to a combustion chamber 12 in which fuel injected through nozzles 13 is burnt. Primary air is supplied through openings 14a, 14b and 14c. The openings 14a are substantially tangential to the wall of the combustion chamber to impart a rotational movement to the gases. Around the fuel nozzles 13 are arranged conical sleeves 19 to which air is admitted through openings 14b and further openings 14c surround the edges of the sleeves. Excess air is supplied to the combustion chamber through the openings 15, 16, 17 and 18 and the openings 16 are narrow slots arranged so that the air supplied will sweep over the radial wall of the combustion chamber. Additional cooling air is supplied through a slot 18a. The effect of the openings 16 and 18a is to keep the temperature of the combustion gases lowest at the roots of the blades and allow it to increase radially outwardly so that the maximum temperature is reached at a point outwardly of the mean diameter of the blades. To cool the bearings, sealing air is admitted to an annular chamber 34 from which it flows through the bearing to the inner end of the first moving blade row as indicated by arrows. Further cooling air from the openings 17 and 18 flows parallel to the walls of the combustion chamber and the turbine gas inlet 30 and serves to cool the turbine casing 25 and the supporting rings 26 of the guide vanes 21. This cooling air will cause the maximum gas temperature to be at some distance from the outer ends of the blades. The four-stage axial flow turbine has the moving blades 20 welded to the discs 22 which are welded to each other to form an integral structure which constitutes the shaft of the turbine. The discs 22 have bores to form a hollow space 23. In the space 23 there is a tube 32 so that comparatively cold partially expanded gases are conducted along the inner surface of the first disc 22 and back through the tube 32 from which they are discharged through the openings 33 communicating with the space behind the last disc. The pressure drop across the last stage thus causes a flow of comparatively cool gases to pass through the first stages. When starting and the rotor system is cold, these gases serve as a heating agent. The turbine is surrounded by an undivided conical casing 25 on the inside of which are mounted rings 26 by means of bolts 27. The rings 26 which support the guide vanes 21 are divided into two halves and to the tips of the vanes attached partition walls 28. When assembling the turbine, the rings 26, associated guide vanes and partition walls are inserted between adjacent discs 22. The rotor is then introduced into the conical casing 25 until the conical edges of the rings 26 abut against the conical seats on the casing where they are held in place by the bolts 27. The Specification as open to inspection under Sect. 91 also includes the subject-matter of Specification 612,838. This subject-matter does not appear in the Specification as accepted.