Design and Verification of Turbofan Engine Clearance Measurement Based on High Energy X-ray

The clearance has an imperative influence on the efficiency and safety of the aero-engine, and the clearance should be obtained by measuring in a working engine for the design and control of the clearance. Foreign aero-engine companies have applied high-energy X-ray technology to engine measurement to analyze the motion of working components. At present, there is no precedent for the application of this field in China, its specific measurement and verification methods were not mastered, and there was no ability to use high-energy X-rays to measure the clearance of the engine. In this paper, the measuring principle of high energy X-ray is analyzed, and the test method of turbofan engine clearance measurement based on high energy X-ray is investigated according to the structural characteristics of a turbofan engine. Besides, the test scheme of the clearance measurement and the calibration method of test data are proposed, and the turbofan engine clearance measurement based on high energy X-ray is achieved for the first time in China. This breaks through the bottleneck of engine rotor and stator axial absolute deformation and the thermal clearance measurement after working, contributing to the improvement of engine clearance design ability in China. Depending on the comprehensive analysis of engine measurement requirements, equipment acquisition ability, data reading boundary, test procedure, absolute coordinates, and engine temperature, an effective test scheme is developed for the first time. The valid data of the deformation and clearance in the axial and radial directions between rotors and stators (labyrinth seals and blade tip) are achieved. Three kinds of comprehensive calibration methods are innovatively established, namely, the clearance measurement of the capacitive sensor, the differential measurement of the wear deformation of labyrinth seals, and the measurement of axial deformation of rotor axial force. Additionally, the correction and verification of high-energy X-ray measurement data are completed by those data. Finally, the motion law of key components in the working and the change law of key clearance after working of a certain engine are obtained. This result can provide a useful reference for the popularization and application of high-energy X-ray technology in the field of engine clearance measurement technology in China.