Online monitoring of dynamic tip clearance of turbine blades in high temperature environments

Abstract

Minimized tip clearance reduces the gas leakage over turbine blade tips and improves the thrust and efficiency of turbomachinery. An accurate tip clearance sensor, measuring the dynamic clearances between blade tips and the turbine case, is a critical component for tip clearance control. This paper presents a robust inductive tip clearance sensor capable of monitoring dynamic tip clearances of turbine machines in high-temperature environments and at high rotational speeds. The sensor can also self-sense the temperature at a blade tip in situ such that temperature effect on tip clearance measurement can be estimated and compensated. To evaluate the sensor’s performance, the sensor was tested for measuring the tip clearances of turbine blades under various working temperatures ranging from 700 K to 1300 K and at turbine rotational speeds ranging from 3000 to 10 000 rpm. The blade tip clearance was varied from 50 to 2000 µm. The experiment results proved that the sensor can accurately measure the blade tip clearances with a temporal resolution of 10 µm. The capability of accurately measuring the tip clearances at high temperatures (~1300 K) and high turbine rotation speeds (~30 000 rpm), along with its compact size, makes it promising for online monitoring and active control of blade tip clearances of high-temperature turbomachinery.

Experimental Investigation of High Temperature-Resistant Inductive Sensor for Blade Tip Clearance Measurement

“…Du L. and Zhu X.L. et al [20,21] verified the eddy current method in laboratory with 3000 rpm revolution and 1300 K temperature.…”

A review of blade tip clearance–measuring technologies for gas turbine engines

“…29,35 The eddy current method is verified in a laboratory with 3000 r/min revolution and 1300 K temperature. 21 They all belong to the ''with hole'' scheme.…”

Error Analysis of a Spherical Capacitive Sensor for the Micro-Clearance Detection in Spherical Joints

“…Many methods have been proposed to detect displacement or clearance over the last few decades (e.g., capacitive sensors [ 12 ], magnetic sensors [ 13 , 14 , 15 ], microwave sensors [ 16 ], optical sensors [ 17 ], and inductive sensors [ 18 , 19 , 20 ]). Compared with other methods, capacitive sensors have the advantages of high resolution and good dynamic performance [ 21 , 22 , 23 , 24 , 25 ].…”