Patent ID: 8206089

Claim:
A flow control device for controlling fluid flow into a turbine, said turbine comprising: a stator comprising a plurality of vanes extending radially inwards from a casing and arranged to define a plurality of nozzles extending radially inwards from said casing, each nozzle being defined by adjacent pairs of vanes; a rotor located in a fluid flow direction downstream of said stator and comprising a plurality of blades extending radially from a turbine shaft, wherein a fluid is arranged to be admitted to said turbine upstream of said stator and to flow around said plurality of vanes through said plurality of nozzles for impingement upon said plurality of blades of said rotor; and flow control means arranged to control a nozzle area open for fluid flow by altering a radial length of at least one of said plurality of nozzles, said flow control means comprising: an actuating means comprising a plurality of arcuate plates located within a peripheral cavity in a housing of said turbine such that a longer curved edge of each of said arcuate plates is outermost within said housing of said turbine and a shorter curved edge is innermost; and a baffle arrangement comprising a plurality of baffle plates connected at first ends thereof to a periphery of said turbine and at second ends thereof to said arcuate plates, each baffle plate extending through a corresponding nozzle from an upstream side of said stator to a downstream side of said stator, wherein said actuating means is arranged to selectively move said baffle arrangement between a retracted position and an extended position where at least one of said baffle plates extends into a flow channel of a corresponding nozzle, and to maintain said baffle arrangement at either said retracted or extended positions, or at any selected position therebetween, thereby effectively controlling the radial length of at least one of said plurality of nozzles.