MODULATED CLEARANCE CONTROL FOR AN AXIAL FLOW ROTARY MACHINE

摘要

A structure and method for providing cooling fluids from a compression section to a turbine section of an axially flow rotary machine is disclosed. Various construction details and steps of the method enable the machine to minimize the effect that unscheduled variations in the temperature of the cooling fluids have on operating clearances in the turbine section. These unscheduled variations may result from changes in ambient temperature and component deterioration. An internal cooling fluid from the discharge region of the rearmost compressor is used to modulate the flow of a second fluid impinged on the exterior of the outer case for controlling the clearance between an array of rotor blades and a coolable stator shroud spaced radially outwardly of the rotor blades. In one embodiment, a valve for modulating the flow of the second fluid has at least one thermostatic bimetallic spring for transducing a change in temperature into a displacement. The displacement changes the flow area Af between a valve head and a conical seat in the conduit for the second fluid through the valve.