Method and apparatus for measuring turbine blade tip clearance

摘要

A method of determining blade tip clearance in a gas turbine includes (a) measuring the distance A between an ultrasonic sensor (16) and a stator shroud surface (14), (b) measuring the distance between B a radio frequency sensor (20) and rotating blade tips (13) of the gas turbine; and (c) subtracting the distance measured by the ultrasonic sensor (16) from the distance measured by the radio frequency sensor (20). The apparatus includes an ultrasonic sensor for measuring the distance between a stator shroud surface (14) and the ultrasonic sensor (16), a radio frequency sensor (20) for measuring the distance between rotating blade tips (13) of the gas turbine and the radio frequency sensor; and a computer system (24) for receiving and subtracting the ultrasonic sensor measurements from the radio frequency sensor measurements.