Measurement of clearances using capacitive proximity sensors in turbine rotor stator cavities

Experimental displacement measurements are to be made using in-house designed and manufactured capacitive proximity sensors inside the Sussex Rim Seal, RiSe, Rig. Currently prototype sensors have been tested to understand the significance of measuring clearances when a sensor is responsive to both radial and axial movement of a component. The results presented here show how the signal from a sensor designed to measure displacement of a parallel target, changes as the orthogonal distance to the target is also altered. A two-sensor (orthogonal axis) approach has been adopted, calibrated and tested in a mock-up geometry. The measurement accuracy has been shown to have increased to within 0.05mm.