GB746596A - Improvements in or relating to gas turbine engines having multi-stage compressors - Google Patents

Abstract

746,596. Axial flow compressors; gas turbine plant. ROLLS-ROYCE, Ltd. April 23, 1954 [Jan. 26, 1953], No. 2275/53. Classes 110(1) and 110(3) [Also in Group XXIX] In a gas turbine plant with a multi-stage compressor provided with means for introducing hot gas into the compressor inlet duct or in the region of the low pressure blading stages or both and at least one ring of adjustable pitch stator blades in the inlet duct or in the low pressure stages, the pitch of the stator blades is adjusted to increase the swirl velocity of air passing through them when hot gas is introduced for anti-icing purposes. The invention is described with reference to a gas turbine plant having a multi-stage axial-flow compressor as described and claimed in Specification 704,849 in which provision is made for adjusting the pitch of the stator blades so that for each rotational speed of the compressor, the stator blades have a corresponding pitch. The arrangement shown in Figs. 1 and 2 of Specification 704,849 is provided with the following additions. An annular manifold 100 encircling the compressor inlet is fed with hot air from the compressor delivery through a conduit 101 under control of a valve 102. The air flows from the manifold into hollow struts 108 having outlets 109 in their leading edges. The valve 102 is operated by a solenoid 103 the coil of which is connected in parallel with the coil of a solenoid 1.04 operating a valve 105. The valve 105 is located in a pipe 106 containing a restriction 107 connecting the suction and discharge pipes 18, 47 of the pump 14. The arrangement is such that when the valves 102, 105 are opened hot air is supplied to the manifold 100 and ram device 30 causes the guide vanes 24a to take up a position giving an increase swirl to the incoming air. Modifications in which the control arrangements shown in Figs. 3, 4 and 5 of Specification 704,849 are employed are also described. In a further modification in which a two-position control for the adjustable stator blades is used; a solenoid-operated valve controlling the air supply to a pneumatic ram effecting the pitch adjustment of the blades is wired in parallel with a solenoid-operated valve controlling the supply of hot gas to the compressor.