This paper describes how blade tip clearances can be measured with capacitive sensors and the right electronic devices. The design of a capacitive sensor is tightly connected to the engine environment, but also the electronic system which is used to calculate the blade tip clearance. We present two kinds of capacitive sensors : the composite and the integral sensors we developed for use in a compressor. Based on that experience we are developing and testing turbine versions of these designs. In an aero gas turbine the design aim is sensors that shall survive temperatures and vibrations as high as 1,300°C and 150 G’s.

This content is only available via PDF.