US Patent 8240986 Turbine inter-stage seal control

A turbine inter-stage seal with active clearance control. The inner diameter of the stator vane includes a seal support structure with a plurality of segmented seal supports each movable by an actuator located on the vane outer diameter with a plunger or push rod extending through the hollow portion of the vanes. A segmented seal arrangement, such as segmented brush seals, are secured to the underside of the seal support segments and form a complete annular seal for the inter-stage between adjacent rotor disks. A proximity probe or microwave sensor detects the brush seal clearance, and a controller regulates the brush seal clearance.