GB716811A - Improvements in gas turbines for the propulsion of vehicles, particularly locomotives - Google Patents

Abstract

716,811.. Gas turbines. AKTIEBOLAGET GOTAVERKEN. Jan. 17, 1952. [Jan. 23, 1951], No. 1386/52. Class 110(3) [Also in Group XXVII] A gas turbine for the propulsion of vehicles comprises three sections, namely, an impulse stage with a full admission one or more subsequent reaction stages having guide vanes and moving blades with rounded inlet edges and inlet angles so that at starting and slow speeds they essentially correspond to the direction of the absolute inlet velocity of the motive fluid from the preceding vanes and one or more subsequent reaction stages having guide vanes and moving blades with inlet edges which are rounded to a greater radius of curvature than the inlet edges of the preceding reaction blades. The invention is described with reference to a gas turbine plant, Fig. 1, comprising two stroke internal combustion engine 1 feeding a gas turbine 14 through a conduit 10 with combustion gases mixed with scavenging air supplied by a compressor 3. A governor 19 acts on a fuel pump 71 to limit the speed of the engine. The supply of fuel can also be controlled manually by means of a lever 74. An auxiliary control device 75 actuated by the pressure at the discharge of the compressor 3 connects the conduit 10 to an outlet 24 when this pressure falls below a given value. The admission valve 13 to the turbine 14 is controlled by a lever 67. The turbine 14 comprises three sections, Fig. 2, namely, an impulse stage having guide vanes Ao and moving blades Bo, two subsequent reaction-stages A 1 B 1 , A 2 B 2 and four reaction stages A 3 B 3 -A 6 B,. The impulse stage is designed for full admission and the second section or reaction stages A 1 B 1 , A 2 B, are provided with slightly rounded inlet edges and have such inlet angles that at starting or slow speeds they essentially correspond to the absolute inlet velocity of the working fluid leaving the preceding stage. The blade rim B, should have substantially the same diameter as the blade rim B o . The guide vanes and moving blades of the third section A 3 B 3 -A 6 B 6 have considerably rounded inlet edges and are shaped that the smallest inlet losses will occur when the motive fluid has a substantially axial direction of flow. The turbine is so designed that the heat drop across the guide vanes Ao is greater than half the total heat drop in the turbine at starting and at normal speed is less than one half the same heat drop preferably a third. The pressure ratio across these guide vanes at normal speed should be between 0.50 and 0.75. To reduce the losses in the guide vanes and moving blades of the second section which are stated to act, at starting, as velocity stages for the impulse stage and during normal running as reaction stages, the rear portion of the usual profile is cut away, Fig. 3, and the blades have substantially plane rear faces d.