An Investigation into the Use of a Cone-Jet Sensor for Clearance and Eccentricity Measurement in Turbomachinery

Abstract

SYNOPSIS The paper describes experiments which demonstrate the feasibility of using a fluidic cone-jet sensor supplied with air and producing a pressure output to measure mean clearance, eccentricity and rotor speed inside a steam turbine. Mean clearance can be indicated on a bourdon tube pressure gauge whilst eccentricity can be measured using a piezo-electric pressure transducer and phase sensitive detection. Variation in mean clearance from 2mm to 4mm and eccentricity up to 0.37 mm have been shown to provide linear outputs within ± 5% of full scale. There is no significant fall-off in eccentricity signal up to a turbine rotor speed of 6000 rev/min.