Patent ID: 8230726

Claim:
In a combustion turbine engine that includes an inner turbine shell and an outer turbine shell, and a row of rotor blades having blade tips and surrounding stationary structure that surrounds the row of rotor blades at a position just outboard of the blade tips thereby defining a tip clearance between the blade tips and the surrounding stationary structure, a method of calculating the tip clearance during operation of the combustion turbine engine, the method comprising the steps of: measuring a cold tip clearance and a cold shell-to-shell distance while the combustion turbine engine is not operating; while the combustion turbine engine is operating, measuring an operating parameter; while the combustion turbine engine is operating, measuring a shell-to-shell distance with a proximity sensor; calculating the tip clearance based on the cold tip clearance measurement and the operating parameter measurement; calculating the shell-to-shell distance based on the cold shell-to-shell distance measurement and the operating parameter measurement; comparing the shell-to-shell distance measurement of the proximity sensor with the shell-to-shell distance calculation; and calibrating the calculated tip clearance calculation based on the comparison between shell-to-shell distance measurement of the proximity sensor and the shell-to-shell distance calculation.