Tip clearance optical measurement for rotating blades

The radial tip clearance of engine blades is the distance of blade tip to casing, and the usual clearance is about 1–2mm. Generally there are many electromagnetic interferences in clearance environment, so the paper adopts an optical-fiber sensor to measure the tip clearance while the blades are rotating from lowest speed to the highest speed. With no touchable mode and less size, the sensor doesn't affect the work of status of engine. The sensor can efficiently eliminate the effect of tip surface reflectivity variation and light source fluctuation to measurement results; The sensor can also reduce the effect of inter-angle between the measured tip surface and sensor end surface to the results greatly.