VIBRATION FEATURES OF TITANIUM ALLOY BLADES WITH EROSIVE DAMAGES

Authors

Yurii S. Vorobiov, A. Podgorny Institute of Mechanical Engineering Problems of NASU (2/10, Pozharskyi Str., Kharkiv, 61046, Ukraine), e-mail: vorobiev@ipmach.kharkov.ua, ORCID: 0000-0001-6595-476X

Nataliia Yu. Ovcharova, A. Podgorny Institute of Mechanical Engineering Problems of NASU (2/10, Pozharskyi Str., Kharkiv, 61046, Ukraine), ORCID: 0000-0003-1180-033X

Anton S. Olkhovskyi, A. Podgorny Institute of Mechanical Engineering Problems of NASU (2/10, Pozharskyi Str., Kharkiv, 61046, Ukraine)

Oleg V. Makhnenko, E. O. Paton Electric Welding Institute of NASU (11, Kazymyr Malevych Str., Kyiv, 03680, Ukraine), e-mail: makhnenko@paton.kiev.ua, ORCID: 0000-0002-8583-0163

Vasyl M. Torop, E. O. Paton Electric Welding Institute of NASU (11, Kazymyr Malevych Str., Kyiv, 03680, Ukraine)

Olena Ye. Hopkalo, G. S. Pisarenko Institute for Problems of Strength of NASU (2, Timiryazevska Str., Kyiv, 01014, Ukraine), ORCID: 0000-0003-0586-4951

Abstract

This paper deals with erosive damage influence on the vibration features of the working blades of the fifth-stage of the low pressure cylinder (LPC) of a K-1000-60/3000 steam turbine for a nuclear power plant (NPP). The blades are made of the TS5 titanium alloy and have a length of 1,200 mm. Notable erosive damages were observed in the fifth-stage LPC blades after more than 180,000 hours of operation at the Khmelnytska NPP, the greatest danger arising due to the formation of craters and slit-type damages. Such damage causes stress concentration, which leads to a decrease in fatigue and residual life. The radius of the erosive damage front mouth is noticeably larger than that of a fatigue crack. With such damages to the edge-to-edge contact, no damages can be observed. In the course of research, there was developed a finite-element model of a blade having a more condensed grid in the damage area, but a less condensed one in the main volume of the blade. There have been performed multivariate numerical oscillation studies of blades with different numbers of damages, which are located in different places along the blade length in the stress localization zone arising due to the features of vibration forms. There have been revealed the features of stress distribution in damage zones. It has been shown that an increase in the number of damages leads to an increase in the area of increased stresses but does not increase their concentration. There have been considered vibrations of the blades under the load of a conditional value, which made it possible to determine the real vibration stress concentration factors in the damage zones. This allows one to use the experience of analyzing the vibrations of damaged titanium alloy compressor blades. The degree of reduction of the endurance limit of damaged titanium alloy blades has been revealed. Recommendations on preventing damaged K-1000-60/3000 turbine blades from being used have been developed.

Keywords: erosive damage, vibration, blade, resource, titanium alloy.

Full text: Download in PDF

References

1. Shubenko, A. L., Kovalskiy, A. E., Vorobyev, Yu. S., Kartmazov, G. N., & Romanenko, V. N. (2010). Vliyaniye erozii na osnovnyye ekspluatatsionnyye kharakteristiki rabochey lopatki posledney stupeni tsilindra nizkogo davleniya moshchnoy parovoy turbiny [Effect of erosion on the main operational characteristics of the working blade of the last stage of a low-pressure cylinder of a powerful steam turbine]. Problemy Mashinostroyeniya – Journal of Mechanical Engineering, vol. 13, no. 1, pp. 3–10 (in Russian).
2. Shubenko, A. L., Kovalskiy, A. E., Vorobyev, Yu. S., Kanilo, S. P., & Romanenko, V. N. (2003). Vliyaniye erozii na vibratsionnyye kharakteristiki rabochikh lopatok vlazhno-parovykh turbin [Effect of erosion on the vibration characteristics of wet-steam turbine blades]. Problemy Mashinostroyeniya – Journal of Mechanical Engineering, vol. 6, no. 1, pp. 10–26 (in Russian).
3. Zinkovskiy, A. P., Tokar, I. G., Kruts, V. A., & Krugliy, Ya. D. (2012). Vliyaniye rasseyaniya energii v materiale na kolebaniya lopatok s neodnorodnostyami [Effect of energy dissipation in a material on oscillations of blades with inhomogeneities]. Aviats.-kosm. tekhnika i tekhnologiya − Aerospace Technic and Technology, no. 9 (96), pp. 132–137 (in Russian).
4. Tokar’, I. G. & Zinkovskiy, A. P. (2010). Influence of the parameters of a local defect in a regular system on the range of eigenfrequencies of vibrations and the level of vibration stresses in elements of the same type. Strength of Materials, vol. 42, iss. 2, pp. 167–174. https://doi.org/10.1007/s11223-010-9203-7
5. Borovkov, V. M., Getsov, L. B., Vorobyev, Yu. S., Kopsov, A. Ya., Petinov, S. V., Pigrova, G. D., & Rybnikov, A. I. (2008). Materialy i prochnost oborudovaniya TEC [Materials and strength of TPP equipment]. St. Petersburg: Izd-vo Politekhn. un-ta, 612 p. (in Russian).
6. Vorobyev, Yu. S., Makhnenko, O. V., Ovcharova, N. Yu., Berlizova, T. Yu., & Kulakov, P. N. (2016). Problemy ispolzovaniya novykh materialov dlya lopatochnogo apparata turbomashin [Problems of the use of new materials for turbine bkade systems]. Visnyk NTU «KhPI». Ser.: Enerhetychni ta teplotekhnichni protsesy i ustatkuvannia – Bulletin of the NTU “KhPI”. Series: Power and Heat Engineering Processes and Equipment, no. 9 (1181), pp. 44–49 (in Russian).
7. Kanel, G. I., Razorenov, S. V., Utkin, A. V., & Fortov, V. Ye. (1996). Udarno-volnovyye yavleniya v kondensirovannykh sredakh [Shock-wave phenomena in condensed media]. Moscow: Yanus-K, 408 p. (in Russian).
8. Krylov, N. A., Skotnikova, M. A., Tsvetkova, G. V., & Ivanova, G. V. (2016). Vliyaniye struktury i fazovogo sostava materiala lopatok parovykh turbin iz titanovogo splava na ikh ustoychivost k erozionnomu razrusheniyu [Influence of the structure and phase composition of the material of steam turbine blades made of titanium alloy on their resistance to erosion destruction]. Nauch.-tekhn. vedomosti SPbPU. Estestvennyye i inzhenernyye nauki – Scientific-tech. statements SPbPU. Natural and engineering sciences, iss. 3 (249), pp. 86–92 (in Russian). https://doi.org/10.5862/JEST.249.10
9. Petukhov, A. N. (1993). Soprotivleniye ustalosti detaley GTD [Fatigue resistance to GTE components]. Moscow: Mashinostroyeniye, 232 p. (in Russian).
10. (1978). TU 1-5-130-78. Prutki katanyye i kovanyye iz titanovogo splava. Marka TS5. Vved. 10.05.78 [TS 1-5-130-78. Rods rolled and forged from titanium alloy. TS5 alloy. Enacted October 5, 1978], 17 p. (in Russian).

Received 13 July 2018

Published 30 December 2018