Test rig for evaluating active turbine blade tip clearance control concepts

Improved blade tip sealing in the high-pressure compressor and high-pressure turbine can provide dramatic improvements in specific fuel consumption, time on wing, compressor stall margin, and engine efficiency, as well as increased payload and mission range capabilities of both military and commercial gas-turbine engines. The design of a first-generation mechanically actuated active clearance control system for turbine blade tip clearance management is presented, along with the design of a bench top test rig in which the system is to be evaluated. The active clearance control system utilizes mechanically actuated seal carrier segments and clearance measurement feedback to provide fast and precise active clearance control throughout engine operation. The purpose of this active clearance control system is to improve on current case cooling methods. These systems have relatively slow response and do not use clearance measurement, thereby forcing cold-build clearances to set the minimum clearances at extreme operating conditions and not allowing cruise clearances to be minimized due to the possibility of throttle transients. The test rig will simulate proper seal carrier pressure and temperature loading, as well as the magnitudes and rates of blade tip clearance changes of an actual gas-turbine engine. The results of these evaluations will be presented in future works.