Tip-Clearance Measurement in the First Stage of the Compressor of an Aircraft Engine

Abstract

In this article, we report the design of a reflective intensity-modulated optical fiber sensor for blade tip-clearance measurement, and the experimental results for the first stage of a compressor of an aircraft engine operating in real conditions. The tests were performed in a ground test cell, where the engine completed four cycles from idling state to takeoff and back to idling state. During these tests, the rotational speed of the compressor ranged between 7000 and 15,600 rpm. The main component of the sensor is a tetrafurcated bundle of optical fibers, with which the resulting precision of the experimental measurements was 12 µm for a measurement range from 2 to 4 mm. To get this precision the effect of temperature on the optoelectronic components of the sensor was compensated by calibrating the sensor in a climate chamber. A custom-designed MATLAB program was employed to simulate the behavior of the sensor prior to its manufacture.

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

“…As early as 1982, NASA and GE published their cooperative research results of an optical sensor for measuring tip clearance, including test results on the compressor disk [7]. Since 2013, García I. and Zubia J. et al from University of the Basque Country had been continuously published the results of optical method application in tip clearance measurement [8,9,10,11,12]. While, the study of Andreas K. et.al.…”

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

“…[63][64][65] Based on past results, they applied the reflected intensity-modulated optical fiber sensor for the health monitoring of engine by measuring real-time tip-timing and tip-clearance measurements, and the tipclearance measurement for the first stage of an aircraft engine's compressor was carried out using the optical fiber sensor; its main component was a tetra-furcated bundle of optical fibers, with which the resulting precision of the experimental measurements could reach 12 mm. [66][67][68] Recently, they carried out experimental researches on the vibrational behavior of a rotating disk by three optical fiber sensors, which demonstrated the suitability of this innovative optical system to characterize rotating disks in simulated working environments of the engine. Using this sensor, not only the amplitude and frequency of the vibration but also the number of nodal diameters of the disk and its variations during the tests can be identified.…”

Design, Fabrication and Testing of a High-Sensitive Fibre Sensor for Tip Clearance Measurements

“…Those regions are at both sides of the peak signal and are designated as “front slope” and “back slope”, respectively. Figure 1 b only shows the front slope, which exhibits clear advantages in terms of sensitivity, protection against noise and temperature fluctuations, in comparison to the back slope [ 31 ]. In practice, however, for distance security reasons typical TC values found in turbine rigs makes it necessary to operate in the back slope of the sensor, resulting in a lower signal sensitivity and higher dependency on the type of surface and on the temperature.…”