GB801771A - Improvements in axial-flow air compressors - Google Patents

Abstract

801,771. Axial-flow compressors. GENERAL MOTORS CORPORATION. Feb. 27, 1957, No. 6567/57. Class 110 (1). [Also in Group XXIX] An axial-flow compressor comprises a row of bleed passages in the compressor casing, a valve casing secured over the bleed passages and containing a flexible diaphragm on which is a row of valve plugs for closing the bleed passages, a pipe connecting the valve casing with a higher-pressure part of the compressor so that the higher pressure can press the diaphragm inwards to close the bleed passages, and a valve by which the pipe can be disconnected from the higher pressure part and connected instead to atmosphere, thereby allowing the valve plugs to be forced from their seats to open the bleed passages. During starting and low-speed operation of a gasturbine engine, air is bled to atmosphere from an intermediate stage of the engine compressor through a row of bleed ports 38 arranged circumferentially around each half 22 of the split cylindrical casing and adjacent the rotor blading 30 of the intermediate stage. A valve assembly disposed around each row of ports 38 comprises arcuate walls 46, 48 bolted to pillars 44. An arcuate flexible diaphragm 50 between the walls 46, 48 carries valve plugs 56 which protude through holes in the wall 48. A pipe leading to the space between the wall 46 and the diaphragm 50 can be connected by a change-over valve either to the diffuser at the discharge end of the compressor or to atmosphere. In the former case, the diaphragm 50 is pressed inwards to seat the plugs 56 over the ports 38, and in the latter case the plugs 56 are unseated, as shown, to allow the intermediate stage to bleed to atmosphere.