GB611726A - Improvements relating to diffusers, especially of centrifugal compressors, and control thereof - Google Patents

Abstract

611,726. Fluid-pressure servomotor-control systems. POWER JETS (RESEARCH & DEVELOPMENT), Ltd., and OGSTON; W. M. Sept. 14, 1945, No. 23830. [Class 135] [Also in Group XXVI] In a gas turbine plant with a centrifugal compressor having a plurality of tangential diffuser ducts, the entry area of each duct is adjustable in accordance with the mass flow. The variation may be effected by means of a flexible steel strip 2, Fig. 2, forming part of the diffuser wall which is distorted by a synthetic rubber pressure cell 3. Or, the tip 1A may be pivoted to the main wall and all the tips controlled by a rotary multiple cam. The control may include a diaphragm 5, Fig. 4, subjected on opposite sides to the pressures at the entry to the diffuser channel and at a selected point up-stream from that entry. A piston 8 follows the movement of the diaphragm and controls the supply of pressure fluid to all the cells 3. The movement is controlled by a lever 14, loaded by springs 13 and having a pivot 15, the position of which is determined by a barometric capsule 16. In a simpler form the parts 13-16 are omitted. To secure exact equality in the movement of the flexible wall strips 2, the piston 8 controls the supply of pressure fluid acting upon a piston 20, Fig. 5, by which individual capsules 22, each connected by a pipe 23 to one cell, are varyingly compressed between a cross-head 21 and a base-plate and the cells 3 are correspondingly dilated. The rotary cam operating the pivoted wall tips may be operated solely by a barometric capsule acting through a servomotor..