Numerical study on influence law of turbine wide temperature range on inductive tip clearance characteristics

To reveal the generation mechanism of temperature drift of inductive tip clearance sensor under turbine wide temperature range， and guide the sensor design to meet the limit of compact installation space and tip clearance detect requirements， the induction coil structure， excitation frequency and high temperature effects on sensor parameters and clearance induction characteristics were simulated based on COMSOL Multiphysics. The effects of coil structure parameters and excitation frequency on sensor performance parameters and sensing characteristics were calculated based on the simplified sensing model， and the main structural parameters and their influence rules are determined. Based on the electromagnetic-temperature coupling model， the influence of wide temperature range on the sensor performance parameters and induction characteristics was further investigated. Results shows the main structure parameter that affects the sensor performance is the number of turns， while wire diameter and inner diameter have effects on the equivalent resistance and the equivalent inductance respectively. In the temperature range of 500~1 200 ℃， when the clearance changes from 0.5 mm to 4.0 mm， the equivalent resistance variation is less than 20%， the equivalent inductance variation is about 34%， and the temperature change has no effect on the clearance inductive characteristic curve of the inductance.