Diagnostics of Fracture of the Blower Impeller of Gas Turbine Engine Core by Using the Holographic Interferometry
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RAFT AND ROCKET ENGINE DESIGN AND DEVELOPMENT
Diagnostics of Fracture of the Blower Impeller of Gas Turbine Engine Core by Using the Holographic Interferometry A. M. Tsarevaa, R. Kh. Makaevaa, *, D. M. Safinaa, and R. K. Galimovaa a
Tupolev Kazan National Research Technical University, ul. Karla Marksa 10, Kazan, 420111 Tatarstan, Russia *e-mail: [email protected] Received November 26, 2019; revised December 17, 2019; accepted December 18, 2019
Abstract—The results of studies are presented of fatigue-determined failure causes of the blower impeller of aircraft gas turbine engine core based on vibration mode patterns obtained by the holographic interferometry. Recommendations for detuning from the resonance are given that allows the part destruction to be eliminated. DOI: 10.3103/S1068799820020257 Keywords: blower impeller of the gas turbine engine core, holographic interferometry, vibration mode, resonance frequency.
In the process of production, operation, and repair of aircraft gas turbine engines (GTE), various methods of diagnostics and non-destructive testing are used to ensure high reliability and increase the service life of modern products. While in design and creation of new engines, the numerical methods of calculation using software systems are currently applied [1], in diagnostics and non-destructive testing practical methods are used that are based on various physical phenomena, namely, acoustic, magnetic, electromagnetic, optical, radiation, etc. [2, 3]. As a rule, each of these methods is used to detect defects of a certain type. During mechanical testing of objects, the holographic interferometry is successfully used [4–6]—a non-contact, highly sensitive method that provides the clear information about changes in the surface of a part of complex geometric shape. To visualize oscillatory processes, a holographic recording by averaging over time is used. When the image is restored, an interference pattern (holographic interferogram) is created, namely, alternating dark and light stripes connecting the places of equal displacements of the object surface. Bright light stripes correspond to nodal lines. According to experimental data, at low energy losses, the resonance frequency and shape coincide with the natural frequency and shape of the object vibrations. Investigations were made of the causes of fatigue failure of the blower impeller of gas turbine engine core using the patterns of the vibration modes obtained by holographic interferometry. This part is one of the most stressed structural members in the course of the product operation. When the frequency of the operational vibration loads coincides with the natural frequency of the impeller, resonant vibrations occur leading to formation of fatigue cracks, their further development and destruction. The operational defect of the impeller under study was the reason for the unscheduled removal of the turbine generator out of service. Running time of the impeller is 1492 starts. The impeller has clippings of three adjacent blades and body sector of t
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